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Publication numberUS20040218282 A1
Publication typeApplication
Application numberUS 10/424,264
Publication dateNov 4, 2004
Filing dateApr 28, 2003
Priority dateMar 19, 2002
Also published asUS6819498
Publication number10424264, 424264, US 2004/0218282 A1, US 2004/218282 A1, US 20040218282 A1, US 20040218282A1, US 2004218282 A1, US 2004218282A1, US-A1-20040218282, US-A1-2004218282, US2004/0218282A1, US2004/218282A1, US20040218282 A1, US20040218282A1, US2004218282 A1, US2004218282A1
InventorsTadashi Watanabe, Hideto Yamashita, Masato Kohsaka, Takao Yamauchi, Kiyonobu Kurata
Original AssigneeOlympus Optical Co. , Ltd.
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Two-wavelength antireflection film and objective lens coated with two-wavelength antireflection film
US 20040218282 A1
Abstract
A two-wavelength antireflection film to prevent light in two-wavelength regions of a deep-ultraviolet region and a region from a visible region to the near-infrared region on a surface of a substrate by coating the two-wavelength antireflection film on the surface of the substrate which penetrates light from the deep-ultraviolet region to the near-infrared region, comprising a first thin film which is formed on the substrate, and has a refractive index of 1.6 to 2.0 and optical film thickness of 0.4λ to 0.7λ for design main wavelength (λ), a second thin film which is formed on the first thin film, and has a refractive index of 1.35 to 1.55 and an optical film thickness of 0.05λ to 0.6λ for the design main wavelength λ, a third thin film which is formed on the second thin film, and has a refractive index of 1.6 to 2.0 and an optical film thickness of 0.1λ to 0.5λ for the design main wavelength λ, and a fourth thin film which is formed on the third thin film, and has a refractive index of 1.35 to 1.55 and an optical film thickness of 0.2λ to 0.35λ for the design main wavelength λ.
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Claims(11)
1. A two-wavelength antireflection film for antireflection in two-wavelength regions of light between 200 nanometers and 850 nanometers wherein one of the two-wavelength regions ranges from about 200 nanometers to 350 nanometers and includes a design main wavelength and the other two-wavelength region extends from about 650 nanometers to 850 nanaometers comprising:
a substrate which is transparent in wavelength regions in which the substrate is to be used;
a first thin film which is formed on the substrate, and has a refractive index of 1.6 to 2.0 and optical film thickness of 0.4λ to 0.7λ for the design main wavelength (λ);
a second thin film which is formed on the first thin film, and has a refractive index of 1.35 to 1.55 and an optical film thickness of 0.05λto 0.6λ for the design main wavelength λ;
a third thin film which is formed on the second thin film, and has a refractive index of 1.6 to 2.0 and an optical film thickness of 0.1λ to 0.5λ for the design main wavelength λ; and
a fourth thin film which is formed on the third thin film, and has a refractive index of 1.35 to 1.55 and optical film thickness of 0.2λ to 0.35λ for design main wavelength λ.
2. The two-wavelength antireflection film according to claim 1, wherein, the substrate is quartz glass or fluorite glass.
3. The two-wavelength antireflection film according to claim 1, wherein,
the first thin film and the third thin film contain material which has a plurality of components chosen by a group of Al2O3, LaF3, NdF3, YF3, La2O3, and mixture or compound thereof, and the second thin film and the fourth thin film contain material which has a plurality of components chosen by a group of MgF2, SiO2, NaF, LiF, and mixture or compound thereof.
4. The two-wavelength antireflection film according to claim 1, wherein an incident angle of the light of the design main wavelength is set within a range of 0 to 70.
5. The two-wavelength antireflection film according to claim 1, wherein the design main wavelength is 248 nm.
6. The two-wavelength antireflection film according to claim 5, wherein
a wavelength which performs antireflection includes two wavelength regions of a wavelength in vicinity of main design wavelength and a wavelength from 650 to 800 nm,
an optical film thickness of the first thin film is 0.4λ to 0.6λ,
an optical film thickness of the second thin film is 0.4λ to 0.6λ,
an optical film thickness of the third thin film is 0.1λ to 0.3λ, and
an optical film thickness of the fourth thin film is from 0.35λ to 0.2λ.
7. The two-wavelength antireflection film according to claim 5, wherein,
a wavelength which performs antireflection includes two wavelength regions of a wavelength in vicinity of main design wave length and a wavelength in the vicinity of 750 nm,
the first thin film and the third thin film include mixture of Al2O3 and La2O3, and the second thin film and fourth thin film include MgF2,
an optical film thickness of the first thin film is 0.4λ to 0.6λ,
an optical film thickness of the second thin film is 0.4λ to 0.6λ,
an optical film thickness of the third thin film is 0.2λ to 0.3λ, and
an optical film thickness of the fourth thin film is 0.2λ to 0.3.
8. The two-wavelength antireflection film according to claim 5, wherein, a wavelength which performs antireflection includes two wavelength regions of a wavelength in vicinity of main design wavelength and a wavelength from 550 to 650 nm,
an optical film thickness of the first thin film is 0.5λ to 0.7λ,
an optical film thickness of the second thin film is 0.05λ to 0.2λ,
an optical film thickness of the third thin film is 0.25λ to 0.5λ, and
an optical film thickness of the fourth thin film is 0.2λ to 0.35λ.
9. The two-wavelength antireflection film according to claim 5, wherein a wavelength which performs antireflection includes two wavelength regions of a wavelength in vicinity of main design wave length and a wavelength in vicinity of 600 nm,
the first thin film and the third thin film include mixture of Al2O3, and La2O3, and the second thin film and fourth thin film include MgF2,
an optical film thickness of the first thin film is 0.6λ to 0.7λ,
an optical film thickness of the second thin film is 0.05λ to 0.1λ,
an optical film thickness of the third thin film is 0.25λ to 0.35λ, and
an optical film thickness of the second thin film is 0.25λ to 0.35λ.
10. An objective lens used for an optical equipment, which performs an observation by the light of the deep-ultraviolet region wavelength of 300 nm or less and has a focusing mechanism (auto focus) in the wavelength region from a visible region to a near-infrared region, comprising a plurality of single lenses, wherein
each of the plurality of single lenses has a two-wavelength antireflection film according to claim 1 on the surface thereof.
11. The objective lens according to claim 10, further comprising
a first lens group which contains a plurality of single lenses having positive lens and negative lens whose medium are different from each other and has negative power as a whole; and
a second lens group which is arranged from the first lens group to the object side, and contains a plurality of single lenses having positive lens and negative lens whose medium are different form each other, wherein
the first and second lens groups have air intervals between the positive lens and negative lens, respectively, and
a numerical aperture is 0.7 or more.
Description
BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a two-wavelength antireflection film which prevents reflection for two-wavelength regions of a deep-ultraviolet region and a region from a visible region to a near-infrared region, and relates to an objective lens for optical device with a high numerical aperture and a high magnification, on which the two-wavelength antireflection film is coated.

[0003] 2. Description of the Related Art

[0004] Recently, the magnetic head used for the semiconductor such as CPU and the hard disk drive etc. is remarkably downsized, and extremely high resolving power is required, to accurately detect the defect of the product etc. in the inspection apparatus used for these inspections.

[0005] An optical microscope using a visible ray is used for the above-mentioned inspection apparatus in general. In this case, a resolution of the optical microscope is determined by 0.61λ (wavelength/NA) Therefore, it is necessary to enlarge an NA of the objective lens or to shorten the wavelength of the ray in order to obtain an enough resolution.

[0006] However, recently, enlarging NA of object lens is near limitation. Therefore, to obtain further resolving power, a microscope which shortens wavelength, i.e., a DUV microscope which makes resolving power twice or more by using a deep-ultraviolet region (Deep UV), has been put to practical use.

[0007] By the way, the DUV microscope uses the laser and/or a general-purpose arc lamp such as the mercury lamps, as a light source. The laser outputs light with high intensity ray at a specific wavelength, but apparatus thereof becomes large and expensive. On the other hand, the general-purpose arc lamp outputs light with low intensity at a specific wavelength, but apparatus thereof can be downsized and becomes cheap.

[0008] Then, it is noted that the general-purpose arc lamp emits light in wideband. The general-purpose arc lamp, that an optical amount is secured by widening the wavelength region, is considered to be used as a light source. However, when such a general-purpose arc lamp is used as the light source, it is necessary to compensate the chromatic aberration. Therefore, the single lens having the medium with different refractive index, for example, a lens which can compensate the chromatic aberration by bonding, for instance, fluorite glass and quartz glass with the bonding agent has been put to practical use as the DUV objective lens used for the DUV microscope.

[0009] However, irradiation of light in the DUV region degrades the bonding agent to reduce the transmittance of the objective lens in the lens in which fluorite glass and quartz glass are bonded.

[0010] Therefore, recently, as disclosed in, for example, Japanese Patent Application KOKAI Publication No. 11-167067 and Japanese Patent Application KOKAI Publication No. 2001-318317, the objective lens with no bonding to correct the chromatic aberration using a single lens of the medium with a different refractive index (fluorite glass and quartz glass), and to prevent the reduce in transmittance caused by the degradation of the adhesive by not bonding between these single lenses is developed.

[0011] By the way, the objective lens of no bonding as mentioned above is used to observe the sample image by the light of the deep-ultraviolet region wavelength (for instance, 248 nm). In addition, the objective lens of no bonding might be used to correspond also to the automatic focusing by using the light of wavelength from the visible region to the near-infrared region (for instance, 650 to 1000 nm), so-called auto focus function (hereafter, AF).

[0012] In this case, the objective lens should have high transmittance simultaneously with the light of the deep-ultraviolet region wavelength and for the light of wavelength from the visible region to the near-infrared region.

BRIEF SUMMARY OF THE INVENTION

[0013] The two-wavelength antireflection film to prevent light in two-wavelength regions of a deep-ultraviolet region and a region from a visible region to the near-infrared region on a surface of a substrate by coating the two-wavelength antireflection film on the surface of the substrate which penetrates light from the deep-ultraviolet region to the near-infrared region according to one aspect of the present invention is characterized by comprising: a first thin film which is formed on the substrate, and has a refractive index of 1.6 to 2.0 and optical film thickness of 0.4λ to 0.7λ for design main wavelength (λ); a second thin film which is formed on the first thin film, and has a refractive index of 1.35 to 1.55 and an optical film thickness of 0.05λ to 0.6λ for the design main wavelength λ; a third thin film which is formed on the second thin film, and has a refractive index of 1.6 to 2.0 and an optical film thickness of 0.1λ to 0.5λ for the design main wavelength λ; and a fourth thin film which is formed on the third thin film, and has a refractive index of 1.35 to 1.55 and an optical film thickness of 0.2λ to 0.35λ for the design main wavelength λ.

[0014] The objective lens used for an optical equipment, which performs an observation by the light of the deep-ultraviolet region wavelength of 300 nm or less and has a focusing mechanism (auto focus) in the wavelength region from a visible region to a near-infrared region according to one aspect of the present invention is characterized by comprising a plurality of single lenses, wherein each of the plurality of single lenses has a two-wavelength antireflection film according to claim 1 on the surface thereof.

[0015] Advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

[0016] The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the invention, and together with the general description given above and the detailed description of the embodiments given below, serve to explain the principles of the invention.

[0017]FIG. 1 is a figure showing a schematic configuration of the two-wavelength antireflection film according to the first embodiment of the present invention;

[0018]FIG. 2 is a figure showing spectral reflectance characteristic of two-wavelength antireflection film according to the first embodiment of the present invention;

[0019]FIG. 3 is a figure showing spectral reflectance characteristic of two-wavelength antireflection film according to the second embodiment of the present invention;

[0020]FIG. 4 is a figure showing spectral reflectance characteristic of two-wavelength antireflection film according to the third embodiment of the present invention;

[0021]FIG. 5 is a figure showing change of 246 nm reflectance according to the incident angle in the first to third embodiments of the present invention;

[0022]FIG. 6 is a figure showing spectral reflectance characteristic of two-wavelength antireflection film according to the fourth embodiment of the present invention;

[0023]FIG. 7 is a figure showing spectral reflectance characteristic of two-wavelength antireflection film according to the fifth embodiment of the present invention;

[0024]FIG. 8 is a figure showing spectral reflectance characteristic of two-wavelength antireflection film according to the sixth embodiment of the present invention;

[0025]FIG. 9 is a figure showing change of 248 nm reflectance according to the incident angle in the fourth to seventh embodiments of the present invention;

[0026]FIG. 10 is a figure showing spectral reflectance characteristic of two-wavelength antireflection film according to the seventh embodiment of the present invention;

[0027]FIG. 11 is a figure showing spectral reflectance characteristic of two-wavelength antireflection film according to the eighth embodiment of the present invention;

[0028]FIG. 12 is a figure showing spectral reflectance characteristic of two-wavelength antireflection film according to the ninth embodiment of the present invention;

[0029]FIG. 13 is a figure showing spectral reflectance characteristic of two-wavelength antireflection film according to the tenth embodiment of the present invention;

[0030]FIG. 14 is a figure showing change of 248 nm reflectance according to the incident angle in the eighth to twelfth embodiments of the present invention;

[0031]FIG. 15 is a figure showing spectral reflectance characteristic of two-wavelength antireflection film according to the eleventh embodiment of the present invention;

[0032]FIG. 16 is a figure showing spectral reflectance characteristic of two-wavelength antireflection film according to the twelfth embodiment of the present invention;

[0033]FIG. 17 is a figure showing spectral reflectance characteristic of two-wavelength antireflection film in the first comparison example to explain the present invention;

[0034]FIG. 18 is a figure showing spectral reflectance characteristic of two-wavelength antireflection film in the second comparison example to explain the present invention;

[0035]FIG. 19 is a figure showing a schematic configuration of the objective lens used for the thirteenth embodiment of the present invention;

[0036]FIG. 20 is a figure to explain the angle of the incident (or output) light into (or from) the normal of the lens of the thirteenth embodiment of the present invention;

[0037]FIG. 21 is a figure to explain an example of comparing transmittance of the thirteenth embodiment of the present invention;

[0038]FIG. 22 is a figure showing a schematic configuration of the objective lens used for the fourteenth embodiment of the present invention; and

[0039]FIG. 23 is a figure to explain an example of comparing transmittance of the fourteenth embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

[0040] Hereinafter, embodiments of the present invention will be explained referring to the drawings.

[0041] (First Embodiment)

[0042]FIG. 1 shows a schematic configuration of the two-wavelength antireflection film to which the first embodiment of the present invention is applied. In FIG. 1, quartz glass, which is transparent from the deep-ultraviolet region to the near-infrared region, is used as a substrate material for the substrate 1. Thin films 2, 3, 4, and 5 are formed on the substrate 1 as two-wavelength antireflection film to form a four-layer structure.

[0043] The film material and the film thickness of each of thin films 2, 3, 4, and 5 is shown in (A) of Table 1. Table 1 collectively shows the film material and the film thickness corresponding to the first to third embodiments ((A) to (C)) as described later

TABLE 1
A B C
Substrate 1
Quartz glass Quartz glass Quartz glass
Design wavelength λ
248 nm 248 nm 248 nm
Film Film Film
Film thickness thickness thickness
material (λ) Film material (λ) Film material (λ)
Thin film 2 Al2O3 0.51 Al2O3 + La2O3 0.46 Al2O3 + La2O3 0.46
(Substance M2) (Substance M3)
Thin film 3 MgF2 0.46 MgF2 0.47 MgF2 0.50
Thin film 4 Al2O3 0.16 Al2O3 + La2O3 0.26 Al2O3 + La2O3 0.16
(Substance M2) (Substance M3)
Thin film 5 MgF2 0.30 MgF2 0.25 MgF2 0.30

[0044] In (A) of Table 1, the film materials of thin films 2, 3, 4, and 5, each of which forms each layer, are as follows. Al2O3 whose refractive index in design main wavelength (248 nm in the deep-ultraviolet region) is the middle refractive index of about 1.7 is used to thin film 2 of the first layer and thin film 4 of the third layer from the substrate 1. MgF2 whose refractive index in design main wavelength (248 nm in the deep-ultraviolet region) is the low refractive index of about 1.4 is used to thin film 3 in the second layer and thin film 5 in the fourth layer from the substrate 1. Each film thickness of these thin films 2, 3, 4, and 5 is shown in (A) of Table 1.

[0045]FIG. 2 shows each spectral reflectance characteristic for the two wavelength antireflection film made for trial purposes with the configuration shown in (A) of Table 1, when changing the incident angle of the light to 0, 30, 50, and 65, respectively. By changing the incident angle of the light, the curve (a) of FIG. 5 is obtained as a result of simulating the numerical value how the reflectance of the light of design main wavelength (248 nm) is changed.

[0046] As is clear from FIG. 2, it becomes possible to perform antireflection because reflectance becomes small in two-wavelength region in the vicinity of 248 nm and within the range of 650 nm to 800 nm. It is also clear that the reflection of design main wavelength (248 nm) is small in the range of 0 to 70 in incident angle of light as shown in curve (a) of FIG. 5. Therefore, by forming the two-wavelength antireflection film configured with thin films 2, 3, 4, and 5 according to the first embodiment on the substrate 1 of quartz glass which is transparent from the deep-ultraviolet region to the near-infrared region, high transmittance can be achieved for light in the deep-ultraviolet region in the vicinity of design main wavelength (248 nm) and light from the visible region to the near-infrared region in the vicinity of the range of 650 nm to 800 nm, which are used for auto focus.

[0047] (Second Embodiment)

[0048] The schematic configuration of the two-wavelength antireflection film according to the second embodiment is similar to that in FIG. 1, and the explanation will be described by using FIG. 1.

[0049] The film material and the film thickness of each of thin films 2, 3, 4, and 5 of two-wavelength antireflection films configured as FIG. 1 is shown in (B) of Table 1.

[0050] In this case, the film materials of thin films 2, 3, 4, and 5, each of which forms each layer, are as follows The mixture of Al2O3 and La2O3 with the middle refractive index material is used to thin film 2 of the first layer and thin film 4 of the third layer from the substrate 1. Specifically, Substance M2 made by the Merck, which is the mixture of Al2O3 and La2O3 whose refractive index is about 1.8 in design main wavelength (248 nm in the deep-ultraviolet region) is used. MgF2 whose refractive index in design main wavelength (248 nm in the deep-ultraviolet region) is the low refractive index of about 1.4 is used to thin film 3 in the second layer and thin film 5 in the fourth layer from the substrate 1 similar to the first embodiment. Each film thickness of these thin films 2, 3, 4, and 5 is shown in (B) of Table 1.

[0051]FIG. 3 shows each spectral reflectance characteristic for the two wavelength antireflection film made for trial purposes with the configuration shown in (B) of Table 1, when changing the incident angle of the light to 0, 30, 50, and 65, respectively. By changing the incident angle of the light, the curve (b) of FIG. 5 is obtained as a result of simulating the numerical value how the reflectance of the light of design main wavelength (248 nm) is changed.

[0052] As is clear from FIG. 3, it becomes possible to perform antireflection because reflectance becomes small in two- two-wavelength region in the vicinity of 248 nm and within the range of 650 nm to 800 nm. It is also clear that the reflection of design main wavelength (248 nm) is small in the range of 0 to 70 in incident angle of light as shown in curve (b) of FIG. 5.

[0053] Therefore, high transmittance can be achieved for light in the deep-ultraviolet region in the vicinity of design main wavelength (248 nm) and light from the visible region to the near-infrared region in the vicinity of the range of 650 nm to 800 nm, which are used for auto focus similar to that described in the first embodiment.

[0054] (Third Embodiment)

[0055] The schematic configuration of the two-wavelength antireflection film according to the third embodiment is similar to that in FIG. 1, and the explanation will be described by using FIG. 1.

[0056] The film material and the film thickness of each of thin films 2, 3, 4, and 5 of two-wavelength antireflection films configured as FIG. 1 is shown in (C) of Table 1.

[0057] In this case, the film materials of thin films 2, 3, 4, and 5, each of which forms each layer, are as follows. The mixture of Al2O3 and La2O3 with the middle refractive index material, whose mixture ratio of Al2O3 and La2O3 and refractive index are different from those in the second embodiment, is used to thin film 2 of the first layer and thin film 4 of the third layer from the substrate 1. Specifically, Substance M3 made by the Merck, which as the mixture of Al2O3 and La2O3 whose refractive index in design main wavelength (248 nm in the deep-ultraviolet region) is about 1.95, is used. MgF2 whose refractive index in design main wavelength (248 nm in the deep-ultraviolet region) is the low refractive index of about 1.4 is used to thin film 3 in the second layer and thin film 5 in the fourth layer from the substrate 1 similar to the firsts embodiment. Each film thickness of these thin films 2, 3, 4, and 5 is shown in (C) of Table 1.

[0058]FIG. 4 shows each spectral reflectance characteristic for the two wavelength antireflection film made for trial purposes with the configuration shown in (C) of Table 1, when changing the incident angle of the light to 0, 30, 50, and 65, respectively. By changing the incident angle of the light, the curve (c) of FIG. 5 is obtained as a result of simulating the numerical value how the reflectance of the light of design main wavelength (248 nm) is changed.

[0059] As is clear from FIG. 4, it becomes possible to perform antireflection because reflectance becomes small in two- two-wavelength region in the vicinity of 248 nm and within the range of 650 nm to 800 nm. It is also clear that the reflection of design main wavelength (248 nm) is small in the range of 0 to 70 in incident angle of light as shown in curve (c) of FIG. 5.

[0060] Therefore, high transmittance can be achieved for light in the deep-ultraviolet region in the vicinity of design main wavelength (248 nm) and light from the visible region to the near-infrared region in the vicinity of the range of 650 nm to 800 nm, which are used for auto focus similar to that described in the first embodiment.

[0061] (Fourth Embodiment)

[0062] The schematic configuration of the two-wavelength antireflection film according to the fourth embodiment is similar to that in FIG. 1, and the explanation will be described by using FIG. 1. In this case, fluorite glass, which is transparent from the deep-ultraviolet region to the near-infrared region, is used as a substrate material for the substrate 1.

[0063] The film material and the film thickness of each of thin films 2, 3, 4, and 5 of two-wavelength antireflection films configured as FIG. 1 is shown in (A) of Table 2. Table 2 collectively shows the film material and the film thickness corresponding to the fourth to fifth embodiments ((A) to (C)) as described later.

TABLE 2
A B C
Substrate 1
Fluorite glass Fluorite glass Fluorite glass
Design wavelength λ
248 nm 248 nm 248 nm
Film Film Film
Film thickness thickness thickness
material (λ) Film material (λ) Film material (λ)
Thin film 2 Al2O3 0.47 Al2O3 + La2O3 0.48 Al2O3 + La2O3 0.49
(Substance M2) (Substance M3)
Thin film 3 MgF2 0.41 MgF2 0.44 MgF2 0.49
Thin film 4 Al2O3 0.20 Al2O3 + La2O3 0.27 Al2O3 + La2O3 0.11
(Substance M2) (Substance M3)
Thin film 5 MgF2 0.27 MgF2 0.25 MgF2 0.31

[0064] In (A) of Table 2, the film materials of thin films 2, 3, 4, and 5, each of which forms each layer, are similar to the first embodiment. Al2O3 whose refractive index in design main wavelength (248 nm in the deep-ultraviolet region) is the middle refractive index of about 1.7 is used to thin film 2 of the first layer and thin film 4 of the third layer from the substrate 1. MgF2 whose refractive index in design main wavelength (248 nm in the deep-ultraviolet region) is the low refractive index of about 1.4 is used to thin film 3 in the second layer and thin film 5 in the fourth layer from the substrate 1. Each film thickness of these thin films 2, 3, 4, and 5 is shown in (A) of Table 2.

[0065]FIG. 6 shows spectral reflectance characteristic for the two wavelength antireflection film made for trial purposes with the configuration shown in (A) of Table 2, when the incident angle of light is assumed to be 0 (vertical). By changing the incident angle of the light, the curve (a) of FIG. 9 is obtained as a result of simulating the numerical value how the reflectance of the light of design main wavelength (248 nm) is changed.

[0066] As is clear from FIG. 6, it becomes possible to perform antireflection because reflectance becomes small in two-wavelength region in the vicinity of 248 nm and within the range of 650 nm to 800 nm. It is also clear that the reflection of design main wavelength (248 nm) is small in the range of 0 to 70 in incident angle of light as shown in curve (a) of FIG. 9. As a result, a similar advantage to the first embodiment can be expected.

[0067] (Fifth Embodiment)

[0068] The schematic configuration of the two-wavelength antireflection film according to the fifth embodiment is similar to that in FIG. 1, and the explanation will be described by using FIG. 1. In this case, fluorite glass, which is transparent from the deep-ultraviolet region to the near-infrared region, is used as a substrate material for the substrate 1.

[0069] The film material and the film thickness of each of thin film 2, 3, 4, and 5 of two-wavelength antireflection films configured as FIG. 1 is shown in (B) of Table 2.

[0070] In this case, the film materials of thin films 2, 3, 4, and 5, each of which forms each layer, are similar to the second embodiment. Substance M2 made by the Merck, which is the mixture of Al2O3 and La2O3 whose refractive index is about 1.8 in design main wavelength (248 nm in the deep-ultraviolet region) is used to thin film 2 of the first layer and thin film 4 of the third layer from the substrate 1. MgF2 whose refractive index in design main wavelength (248 nm in the deep-ultraviolet region) is the low refractive index of about 1.4 is used to thin film 3 in the second layer and thin film 5 in the fourth layer from the substrate 1. Each film thickness of these thin films 2, 3, 4, and 5 is shown in (B) of Table 2.

[0071]FIG. 7 shows spectral reflectance characteristic for the two wavelength antireflection film made for trial purposes with the configuration shown in (B) of Table 2, when the incident angle of light is assumed to be 0 (vertical). By changing the incident angle of the light, the curve (b) of FIG. 9 is obtained as a result of simulating the numerical value how the reflectance of the light of design main wavelength (248 nm) is changed.

[0072] As is clear from FIG. 7, it becomes possible to perform antireflection because reflectance becomes small in two-wavelength region in the vicinity of 248 nm and within the range of 650 nm to 800 nm. It is also clear that the reflection of design main wavelength (248 nm) is small in the range of 0 to 70 in incident angle of light as shown in curve (b) of FIG. 9. As a result, a similar advantage to the second embodiment can be expected.

[0073] (Sixth Embodiment)

[0074] The schematic configuration of the two-wavelength antireflection film according to the sixth embodiment is similar to that in FIG. 1, and the explanation will be described by using FIG. 1. In this case, fluorite glass, which is transparent from the deep-ultraviolet region to the near-infrared region, is used as a substrate material for the substrate 1.

[0075] The film material and the film thickness of each of thin films 2, 3, 4, and 5 of two-wavelength antireflection films configured as FIG. 1 is shown in (C) of Table 2.

[0076] In this case, the film materials of thin films 2, 3, 4, and 5, each of which forms each layer, are similar to the second embodiment. Substance M3 made by the Merck, which is the mixture of Al2O3 and La2O3 whose refractive index in design main wavelength (248 nm in the deep-ultraviolet region) is about 1.95, is used is used to thin film 2 of the first layer and thin film 4 of the third layer from the substrate 1. MgF2 whose refractive index in design main wavelength (248 nm in the deep-ultraviolet region) is the low refractive index of about 1.4 is used to thin film 3 in the second layer and thin film 5 in the fourth layer from the substrate 1. Each film thickness of these thin films 2, 3, 4, and 5 is shown in (C) of Table 2.

[0077]FIG. 8 shows spectral reflectance characteristic for the two wavelength antireflection film made for trial purposes with the configuration shown in (C) of Table 2, when the incident angle of light is assumed to be 0 (vertical). By changing the incident angle of the light, the curve (c) of FIG. 9 is obtained as a result of simulating the numerical value how the reflectance of the light of design main wavelength (248 nm) is changed.

[0078] As is clear from FIG. 8, it becomes possible to perform antireflection because reflectance becomes small in two-wavelength region in the vicinity of 248 nm and within the range of 650 nm to 800 nm. It is also clear that the reflection of design main wavelength (248 nm) is small in the range of 0 to 70 in incident angle of light as shown in curve (c) of FIG. 9. As a result, a similar advantage the third embodiment can be expected.

[0079] (Seventh Embodiment)

[0080] The schematic configuration of the two-wavelength antireflection film according to the seventh embodiment is similar to that in FIG. 1, and the explanation will be described by using FIG. 1.

[0081] The film material and the film thickness of each of thin films 2, 3, 4, and 5 of two-wavelength antireflection films configured as FIG. 1 is shown in Table 4.

TABLE 3
Substrate 1 Quartz glass
Design
wavelength λ 248 nm
Layer number Film
(from substrate) Film material thickness (λ)
Thin film 2 Al2O3 + La2O3 0.52
(Substance M2)
Thin film 3 MgF2 0.53
Thin film 4 Al2O3 + La2O3 0.29
(Substance M2)
Thin film 5 MgF2 0.28

[0082] In this case, the film materials of thin films 2, 3, 4, and 5, each of which forms each layer, are similar to the second embodiment Substance M2 made by the Merck, which is the mixture of Al2O3 and La2O3 whose refractive index is about 1.8 in design main wavelength (248 nm in the deep-ultraviolet region) is used to thin film 2 of the first layer and thin film 4 of the third layer from the substrate 1. MgF2 whose refractive index in design main wavelength (248 nm in the deep-ultraviolet region) is the low refractive index of about 1.4 is used to thin film 3 in the second layer and thin film 5 in the fourth layer from the substrate 1. Each film thickness of these thin films 2, 3, 4, and 5 is shown in Table 3.

[0083]FIG. 10 shows spectral reflectance characteristic for the two wavelength antireflection film made for trial purposes with the configuration shown in Table 3, when the incident angle of light is assumed to be 0 (vertical). By changing the incident angle of the light, the curve (d) of FIG. 9 is obtained as a result of simulating the numerical value how the reflectance of the light of design main wavelength (248 nm) is changed.

[0084] As is clear from FIG. 10, it becomes possible to perform antireflection because reflectance becomes small in two-wavelength region in the vicinity of 248 nm and within the range of 650 nm to 800 nm. Especially, it becomes possible to reduce reflectance further within the range from 30 to 50 in incident angle of design main wavelength (248 nm) as shown in curve (d) of FIG. 9. Therefore, transmittance can be further improved by using such two-wavelength antireflection film.

[0085] (Eighth Embodiment)

[0086] The schematic configuration of the two-wavelength antireflection film according to the eighth embodiment is similar to that in FIG. 1, and the explanation will be described by using FIG. 1. In this case, quartz glass, which is transparent from the deep-ultraviolet region to the near-infrared region, is used as a substrate material for the substrate 1.

[0087] The film material and the film thickness of each of thin films 2, 3, 4, and 5 of two-wavelength antireflection films configured as FIG. 1 is shown in (A) of Table 4. Table 4 collectively shows the film material and the film thickness corresponding to the eighth to tenth embodiments ((A) to (C)) as described later.

TABLE 4
A B C
Substrate 1
Fluorite glass Fluorite glass Fluorite glass
Design wavelength λ
248 nm 248 nm 248 nm
Film Film Film
Film thickness thickness thickness
material (λ) Film material (λ) Film material (λ)
Thin film 2 Al2O3 0.60 Al2O3 + La2O3 0.67 Al2O3 + La2O3 0.59
(Substance M2) (Substance M3)
Thin film 3 MgF2 0.12 MgF2 0.87 MgF2 0.98
Thin film 4 Al2O3 0.34 Al2O3 + La2O3 0.31 Al2O3 + La2O3 0.48
(Substance M2) (Substance M3)
Thin film 5 MgF2 0.26 MgF2 0.30 MgF2 0.22

[0088] In this case, the film materials of thin films 2, 3, 4, and 5, each of which forms each layer, are similar to the first embodiment. Al2O3 whose refractive index in design main wavelength (248 nm in the deep-ultraviolet region) is the middle refractive index of about 1.7 is used to thin film 2 of the first layer and thin film 4 of the third layer from the substrate 1. MgF2 whose refractive index in design main wavelength (248 nm in the deep-ultraviolet region) is the low refractive index of about 1.4 is used to thin film 3 in the second layer and thin film 5 in the fourth layer from the substrate 1. Each film thickness of these thin films 2, 3, 4, and 5 is shown in (A) of Table 4.

[0089]FIG. 11 shows spectral reflectance characteristic for the two wavelength antireflection film made for trial purposes with the configuration shown in (A) of Table 4, when the incident angle of light is assumed to be 0 (vertical). By changing the incident angle of the light, the curve (a) of FIG. 14 is obtained as a result of simulating the numerical value how the reflectance of the light of design main wavelength (248 nm) is changed.

[0090] As is clear from FIG. 11, it becomes possible to perform antireflection because reflectance becomes small in two-wavelength region in the vicinity of 248 nm and within the range of 650 nm to 800 nm. It is also clear that the reflection of design main wavelength (248 nm) is small in the range of 0 to 70 in incident angle of light as shown in curve (a) of FIG. 14. Therefore, if two wavelength antireflection film configured with thin films 2, 3, 4, and 5 of the eighth embodiment is formed on the substrate 1 of quartz glass which is transparent from the deep-ultraviolet region to the near-infrared region, high transmittance can be achieved for light in the deep-ultraviolet region in the vicinity of design main wavelength (248 nm) and light in the visible region used for auto focus within the range of 550 nm to 650 nm different from light from the visible region to the near-infrared region used for auto focus within the range of 650 nm to 800 nm described in the first to seventh embodiments.

[0091] (Ninth Embodiment)

[0092] The schematic configuration of the two-wavelength antireflection film according to the ninth embodiment is similar to that in FIG. 1, and the explanation will be described by using FIG. 1.

[0093] The film material and the film thickness of each of thin films 2, 3, 4, and 5 of two-wavelength antireflection films configured as FIG. 1 is shown in (B) of Table 4.

[0094] In this case, the film materials of thin films 2, 3, 4, and 5, each of which forms each layer, are as follows. The mixture of Al2O3 and La2O3 with the middle refractive index material is used to thin film 2 of the first layer and thin film 4 of the third layer from the substrate 1. Specifically, Substance M2 made by the Merck, which is the mixture of Al2O3 and La2C3 whose refractive index is about 1.8 in design main wavelength (248 nm in the deep-ultraviolet region) is used. MgF2 whose refractive index in design main wavelength (248 nm in the deep-ultraviolet region) is the low refractive index of about 1.4 is used to thin film 3 in the second layer and thin film 5 in the fourth layer from the substrate 1 similar to the first embodiment. Each film thickness of these thin films 2, 3, 4, and 5 is shown in (2) of Table 4.

[0095]FIG. 12 shows spectral reflectance characteristic for the two wavelength antireflection film made for trial purposes with the configuration shown in (B) of Table 4, when the incident angle of light is assumed to be 0 (vertical). By changing the incident angle of the light, the curve (b) of FIG. 14 is obtained as a result of simulating the numerical value how the reflectance of the light of design main wavelength (248 nm) is changed.

[0096] As is clear from FIG. 12, it becomes possible to perform antireflection because reflectance becomes small in two-wavelength region within the range of the vicinity of 248 nm and 550 nm to 800 nm. It is also clear that the reflection of design main wavelength (248 nm) is small in the range of 0 to 70 in incident angle of light as shown in curve (b) of FIG. 14. Therefore, high transmittance can be achieved for light in the visible region similarly used for auto focus within the range of light in the deep-ultraviolet region in the vicinity of design main wavelength (248 nm) and 550 nm to 650 nm when having described in the eighth embodiment.

[0097] (Tenth Embodiment)

[0098] The schematic configuration of the two-wavelength antireflection film according to the tenth embodiment is similar to that in FIG. 1, and the explanation will be described by using FIG. 1.

[0099] The film material and the film thickness of each of thin films 2, 3, 4, and 5 of two-wavelength antireflection films configured as FIG. 1 is shown in (C) of Table 4.

[0100] The film materials of thin films 2, 3, 4, and 5, each of which forms each layer, are as follows. Substance M3 made by the Merck, which is the mixture of Al2O3 and La2O3 whose refractive index in design main wavelength (248 nm in the deep-ultraviolet region) is about 1.95, is used is used to thin film 2 of the first layer and thin film 4 of the third layer from the substrate 1. MgF2 whose refractive index in design main wavelength (248 nm in the deep-ultraviolet region) is the low refractive index of about 1.4 is used to thin film 3 in the second layer and thin film 5 in the fourth layer from the substrate 1. Each film thickness of these thin fills 2, 3, 4, and 5 is shown in (C) of Table 4.

[0101]FIG. 13 shows spectral reflectance characteristic for the two wavelength antireflection film made for trial purposes with the configuration shown in (C) of Table 4, when the incident angle of light is assumed to be 0 (vertical). By changing the incident angle of the light, the curve (c) of FIG. 14 is obtained as a result of simulating the numerical value how the reflectance of the light of design main wavelength (248 nm) is changed.

[0102] As is clear from FIG. 13, it becomes possible to perform antireflection because reflectance becomes small in two-wavelength region in the vicinity of 248 nm and within the range of 650 nm to 800 nm. It is also clear that the reflection of design main wavelength (248 nm) is small in the range of 0 to 70 in incident angle of light as shown in curve (c) of FIG. 14. Therefore, high transmittance can be achieved for light from the visible region used for auto focus in the vicinity of the range of light in the deep-ultraviolet region in the vicinity of design main wavelength (248 nm) and 550 nm to 650 nm to the near-infrared region similar to that described in the eighth embodiment.

[0103] In the above-mentioned first to tenth embodiment, MgF2 as the low refraction material and Al2O3 or the mixture of Al2O3 and La2O3 as the middle refractive index material is used. It is not limited to this, even when material having similar refractive index to these materials such as a plurality of components selected from group of MgF2, SiO2, NaF, LiF, and mixture thereof or compound thereof as the low refractive index material and material one or more components selected from group of Al2O3, LaF3, NdF3, YF3, La2O3, and mixture thereof or compound thereof as the middle refractive index material is used, and advantages of above mentioned embodiments can be expected.

[0104] (Eleventh Embodiment)

[0105] The schematic configuration of the two-wavelength antireflection film according to the eleventh embodiment is similar to that in FIG. 1, and the explanation will be described by using FIG. 1.

[0106] The film material and the film thickness of each of thin films 2, 3, 4, and 5 of two-wavelength antireflection films configured as FIG. 1 is shown in (A) of Table 5. Table 5 collectively shows the film material and the film thickness corresponding to the fourth and fifth embodiments ((A) and (B)) as described later.

TABLE 5
B C
Substrate 1
Quartz glass Quartz glass
Design wavelength λ
248 nm 248 nm
Film Film
thickness thickness
Film material (λ) Film material (λ)
Thin film 2 Al2O3 + La2O3 0.64 Al2O3 + La2O3 0.50
(Substance M2) (Substance M2)
Thin film 3 SiO2 0.11 SiO2 0.19
Thin film 4 Al2O3 + La2O3 0.37 Al2O3 + La2O3 0.32
(Substance M2) (Substance M2)
Thin film 5 MgF2 0.28 SiO2 0.28

[0107] The film materials of thin films 2, 3, 4, and 5, each of which forms each layer, are as follows. Substance M2 made by the Merck, which is the mixture of Al2O3 and La2O3 whose refractive index is about 1.8 in design main wavelength (248 nm in the deep-ultraviolet region) is used to thin film 2 of the first layer and thin film 4 of the third layer from the substrate 1. SiO2 whose refractive index in design main wavelength (248 nm in the deep-ultraviolet region) is the low refractive index of about 1.5, is used to thin film 3 in the second layer from the substrate 1. MgF2 whose refractive index in design main wavelength (248 nm in the deep-ultraviolet region) is the low refractive index of about 1.4 is used to thin film 5 in the fourth layer front the substrate 1. Each film thickness of these thin films 2, 3, 4, and 5 is shown in (A) of Table 5.

[0108]FIG. 15 shows spectral reflectance characteristic for the two wavelength antireflection film made for trial purposes with the configuration shown in (A) of Table 5, when the incident angle of light is assumed to be 0 (vertical). By changing the incident angle of the light, the curve (d) of FIG. 14 is obtained as a result of simulating the numerical value how the reflectance of the light of design main wavelength (248 nm) is changed.

[0109] As is clear from FIG. 15, it becomes possible to perform antireflection because reflectance becomes small in two-wavelength region in the vicinity of 248 nm and within the range of 650 nm to 800 nm. It is also clear that the reflection of design main wavelength (248 nm) is small in the range of 0 to 70 in incident angle of light as shown in curve (d) of FIG. 14. As a result, a similar advantage to the first embodiment can be expected.

[0110] (Twelfth Embodiment)

[0111] The schematic configuration of the two-wavelength antireflection film according to the twelfth embodiment is similar to that in FIG. 1, and the explanation will be described by using FIG. 1.

[0112] The film material and the film thickness of each of thin films 2, 3, 4, and 5 of two-wavelength antireflection films configured as FIG. 1 is shown in (B) of Table 5.

[0113] The film materials of thin films 2, 3, 4, and 5, each of which forms each layer, are as follows. Substance M2 made by the Merck, which is the mixture of Al2O3 and La2O3 whose refractive index is about 1.8 in design main wavelength (248 nm in the deep-ultraviolet region) is used to thin film 2 of the first layer and thin film 4 of the third layer from the substrate 1. SiO2 whose refractive index in design main wavelength (248 nm in the deep-ultraviolet region) is the low refractive index of about 1.5, is used to thin film 3 in the second layer and thin film 5 in the fourth layer from the substrate 1. Each film thickness of these thin films 2, 3, 4, and 5 is shown in (B) of Table 5.

[0114]FIG. 16 shows spectral reflectance characteristic for the two wavelength antireflection film made for trial purposes with the configuration shown in (B) of Table 5, when the incident angle of light is assumed to be 0 (vertical). By changing the incident angle of the light, the curve (e) of FIG. 14 is obtained as a result of simulating the numerical value how the reflectance of the light of design main wavelength (248 nm) is changed.

[0115] As is clear from FIG. 16, it becomes possible to perform antireflection because reflectance becomes small in two-wavelength region in the vicinity of 248 nm and within the range of 650 nm to 800 nm. It is also clear that the reflection of design main wavelength (248 nm) is small in the range of 0 to 70 in incident angle of light as shown in curve (e) of FIG. 14. As a result, a similar advantage to the first embodiment can be expected.

FIRST COMPARISON EXAMPLE

[0116] Next, two-wavelength antireflection film of the film configuration and the design value indicated in Table 6 as a comparison example with two-wavelength antireflection film by each embodiment mentioned above has been examined. The schematic configuration of the two-wavelength antireflection film of this case is similar to that in FIG. 1, and the explanation will be described by using FIG. 1.

TABLE 6
Substrate 1 Quartz glass
Design
wavelength λ 248 nm
Layer number Film
(from substrate) Film material thickness (λ)
Thin film 2 Al2O3 + La2O3 0.96
(Substance M2)
Thin film 3 MgF2 0.35
Thin film 4 Al2O3 + La2O3 0.12
(Substance M2)
Thin film 5 MgF2 0.29

[0117] In the above-mentioned configuration, substance M2 made by the Merck, which is the mixture of Al2O3 and La2O3 whose refractive index in design main wavelength (248 nm in the deep-ultraviolet region) is about 1.8, is used to thin film 2 of the first layer and thin film 4 of the third layer from the substrate 1. MgF2 whose refractive index in design main wavelength (248 nm in the deep-ultraviolet region) is the low refractive index of about 1.4 is used to thin film 3 in the second layer and thin film 5 in the fourth layer from the substrate 1 similar to the second embodiment. Each film thickness of these thin films 2, 3, 4, and 5 is shown in Table 6.

[0118]FIG. 17 shows each spectral reflectance characteristic for the two wavelength antireflection film made for trial purposes with the configuration shown in Table 6, when changing the incident angle of the light to 0, 30, 50, and 65, respectively. By changing the incident angle of the light, the curve (d) of FIG. 5 is obtained as a result of simulating the numerical value how the reflectance of the light of design main wavelength (248 nm) is changed.

[0119] As is clear from FIG. 17, it becomes possible to perform antireflection because reflectance becomes small in two-wavelength region in the vicinity of 248 nm and within the range of 650 nm to 800 nm when the incident angle of light is 00 and 30. However, reflectance in the vicinity of 248 nm becomes large as the incident angle of light becomes large. Especially, as shown in curve (d) of FIG. 5, when the incident angle becomes 55 or more, the function as the antireflection film is nor obtained at all because the reflectance of 248 nm becomes larger than the substrate on which the film is not coated as shown in curve (e) of FIG. 5.

SECOND COMPARISON EXAMPLE

[0120] Next, two-wavelength antireflection film of the film configuration and the design value indicated in Table 7 as other comparison example with two-wavelength antireflection film by each embodiment mentioned above has been examined. The schematic configuration of the two-wavelength antireflection film of this case is similar to that in FIG. 1, and the explanation will be described by using FIG. 1.

TABLE 7
Substrate 1 Quartz glass
Design
wavelength λ 248 nm
Layer number Film
(from substrate) Film material thickness (λ)
Thin film 2 Al2O3 + La2O3 0.47
(Substance M2)
Thin film 3 MgF2 0.35
Thin film 4 Al2O3 + La2O3 0.13
(Substance M2)
Thin film 5 MgF2 0.29

[0121] Substance M2 made by the Merck, which is the mixture of Al2O3 and La2o3 whose refractive index in design main wavelength (248 nm in the deep-ultraviolet region) is about 1.8, is used to thin film 2 of the first layer and thin film 4 of the third layer from the substrate 1. MgF2 whose refractive index in design main wavelength (248 nm in the deep-ultraviolet region) is the low refractive index of about 1.4 is used to thin film 3 in the second layer and thin film 5 in the fourth layer from the substrate 1. Each film thickness of these thin films 2, 3, 4, and 5 is shown in Table 7.

[0122]FIG. 18 shows spectral reflectance characteristic for the two wavelength antireflection film made for trial purposes with the configuration shown in Table 7, when the incident angle of light is assumed to be 0 (vertical). By changing the incident angle of the light, the curve (f) of FIG. 14 is obtained as a result of simulating the numerical value how the reflectance of the light of design main wavelength (248 nm) is changed.

[0123] As is clear from FIG. 18, it becomes possible to perform antireflection because reflectance becomes small in two-wavelength region in the vicinity of 248 nm and within the range of 650 nm to 800 nm when the incident angle of light is 0. However, when the incident angle becomes large, the reflectance of 248 nm abruptly becomes large as shown in curve (f) of FIG. 14. Especially, when the incident angle becomes 65 or more, the reflectance of 248 nm becomes large, and becomes larger than the reflectance of the substrate on which the film is not coated as shown in curve (g) of FIG. 14. The function as the antireflection film is not obtained at all.

[0124] Next, the objective lens on which two-wavelength antireflection film mentioned above is actually coated on the surface of the lens will be explained.

[0125] (Thirteenth Embodiment)

[0126]FIG. 19 is a figure showing a schematic configuration of the objective lens applied to the thirteenth embodiment of the present invention.

[0127] The objective lens is used for an optical equipment which observes by the light of wavelength of the ultra-violet region of 300 mm or less and has the mechanism to focus (auto focus) by the light in the wavelength region from a visible region to the near-infrared region. Specifically, light of 2485 nm in the deep-ultraviolet region as wavelength used for the observation and light of 785 nm in the near-infrared region as wavelength used for auto focus are applied.

[0128] The objective lens has the first lens group 1G and the second lens group G2 arranged between the first lens group 1G and the object as shown in FIG. 19. The first lens group 1G has five single lenses L1 to L5 which include positive lens and negative lens with the different medium and has negative power as a whole. The second lens group 2G has thirteen single lenses L6 to L18 which include positive lens and negative lens with the different medium In the first and second lens group 1G and 2G, the air interval is provided between a positive lens and negative lens.

[0129] Tables 8 to 11 show the angle of the light which is incident (emitted) to (from) the normal of the lens, reflectance and the transmittance, etc. corresponding thereto, which are obtained when two wavelength antireflection film explained in detail in the seventh embodiment is coated to each lens surface of each single lens L1 to L18 for each of NA=09, 0.8, 0.7, and 0.5 of such an objective lens, and the lens data of each single lens L1 to L18 (curvature, thickness, interval, and material name).

[0130] The angle of the light which is incident (emitted) to (from) the normal of the lens is an angle r of the light which is incident (emitted) to (from) normal h of the objective lens L as shown in FIG. 20.

[0131] Reflectance and transmittance are obtained from the value of the incident angle obtained as mentioned above.

TABLE 8
Surface Thickness and Incident
number Curvature Interval Material Angle Reflectance Transmittance
L1 1 2.562 2.562 Quartz glass 40 0.476 0.995
2 2.11 0.7 23 0.421 0.996
L2 3 −2.503 0.7 Fluorite glass 31 0.329 0.997
4 3.929 5.212314 29 0.057 0.999
L3 5 INF 2.786 Fluorite glass 13 1.091 0.989
6 −4.1 0.585821 47 0.68 0.993
L4 7 −3.179 1 Quartz glass 61 10.316 0.897
8 13.25 0.205879 53 10823 0.982
L5 9 14.51 2.792 Fluorite glass 53 1.787 0.982
10 −8.069 0.135719 16 0.278 0.997
L6 11 9.175 4.016 Fluorite glass 43 0.959 0.990
12 −8.107 0.473387 59 2.554 0.974
L7 13 −6.806 1 Quartz glass 65 7.46 0.925
14 9.394 0.205775 54 1.668 0.983
L8 15 9.73 4.65 Fluorite glass 54 1.709 0.983
16 −7.998 0.105412 53 1.314 0.987
L9 17 −8.397 1 Quartz glass 50 0.958 0.990
18 13.99 0.1 40 0.611 0.994
L10 19 12.513 4.035695 Fluorite glass 43 0.968 0.990
20 −10.732 0.1 39 0.852 0.991
L11 21 35.892 1 Quartz glass 2 0.079 0.999
22 6.835 0.201239 52 1.419 0.986
L12 23 6.916 4.203 Fluorite glass 52 1.359 0.986
24 −10.627 0.2075 51 1.626 0.984
L13 25 −10.072 0.96 Quartz glass 52 1.71 0.983
26 101.798 0.1 7 1.232 0.988
L14 27 10.53 0.9 Quartz glass 12 0.037 1.000
28 4.509 0.527319 62 9.5 0.905
L15 29 5.379 2.576 Fluorite glass 52 1.308 0.987
30 −51.505 0.1 16 0.888 0.991
L16 31 6.736 1.742 Fluorite glass 15 0.157 0.998
32 17.567 0.1 12 0.814 0.992
L17 33 4.099 1.818 Fluorite glass 15 0.656 0.993
34 9.003 0.10016 21 0.357 0.996
L18 35 1.883 1.872 Quartz glass 17 0.27 0.997
36 5.293 0.262779 58 2.765 0.972

[0132]

TABLE 9
Surface Thickness and Incident
number Curvature Interval Material Angle Reflectance Transmittance
L1 1 2.562 2.562 Quartz glass 35 0.774 0.993
2 2.11 0.7 21 0.195 0.998
L2 3 −2.503 0.7 Fluorite glass 26 0.091 0.999
4 3.929 5.212314 26 0.122 0.999
L3 5 INF 2.786 Fluorite glass 12 1.12 0.989
6 −4.1 0.585821 41 0.702 0.993
L4 7 −3.179 1 Quartz glass 53 2.825 0.972
8 13.25 0.205879 44 0.541 0.995
L5 9 14.51 2.792 Fluorite glass 43 0.435 0.996
10 −8.069 0.135719 15 0.019 1.000
L6 11 9.175 4.016 Fluorite glass 36 0.616 0.994
12 −8.107 0.473387 46 1.128 0.989
L7 13 −6.806 1 Quartz glass 51 1.157 0.988
14 9.394 0.205775 41 0.845 0.992
L8 15 9.73 4.65 Fluorite glass 41 0.82 0.992
16 −7.998 0.105412 42 0.931 0.991
L9 17 −8.397 1 Quartz glass 40 0.881 0.991
18 13.99 0.1 31 0.079 0.999
L10 19 12.513 4.035695 Fluorite glass 33 0.196 0.998
20 −10.732 0.1 31 0.329 0.997
L11 21 35.892 1 Quartz glass 2 1.029 0.990
22 6.835 0.201239 42 0.77 0.992
L12 23 6.916 4.203 Fluorite glass 42 0.77 0.992
24 −10.627 0.2075 41 0.648 0.994
L13 25 −10.072 0.96 Quartz glass 41 0.686 0.993
26 101.798 0.1 6 1.25 0.988
L14 27 10.53 0.9 Quartz glass 10 0.178 0.998
28 4.509 0.527319 49 0.881 0.991
L15 29 5.379 2.576 Fluorite glass 42 0.77 0.992
30 −51.505 0.1 15 1.032 0.990
L16 31 6.736 1.742 Fluorite glass 12 0.021 1.000
32 17.567 0.1 12 0.912 0.991
L17 33 4.099 1.818 Fluorite glass 12 0.333 0.997
34 9.003 0.10016 20 0.465 0.995
L18 35 1.883 1.872 Quartz glass 13 0.68 0.993
36 5.293 0.262779 50 0.893 0.991

[0133]

TABLE 10
Surface Thickness and Incident
number Curvature Interval Material Angle Reflectance Transmittance
L1 1 2.562 2.562 Quartz glass 30 00.604 0.994
2 2.11 0.7 19 0.04 1.000
L2 3 −2.503 0.7 Fluorite glass 23 0.04 1.000
4 3.929 5.212314 23 0.235 0.998
L3 5 INF 2.786 Fluorite glass 11 1.15 0.989
6 −4.1 0.585821 36 0.788 0.992
L4 7 −3.179 1 Quartz glass 46 0.59 0.994
8 13.25 0.205879 37 0.155 0.998
L5 9 14.51 2.792 Fluorite glass 36 0.134 0.999
10 −8.069 0.135719 13 0.023 1.000
L6 11 9.175 4.016 Fluorite glass 30 0.151 0.998
12 −8.107 0.473387 38 0.65 0.990
L7 13 −6.806 1 Quartz glass 42 0.959 0.994
14 9.394 0.205775 33 0.227 0.990
L8 15 9.73 4.65 Fluorite glass 33 0.196 0.998
16 −7.998 0.105412 34 0.527 0.995
L9 17 −8.397 1 Quartz glass 33 0.411 0.996
18 13.99 0.1 25 0.135 0.999
L10 19 12.513 4.035695 Fluorite glass 27 0.064 0.999
20 −10.732 0.1 26 0.046 1.000
L11 21 35.892 1 Quartz glass 1 1.189 0.988
22 6.835 0.201239 35 0.728 0.993
L12 23 6.916 4.203 Fluorite glass 35 0.709 0.993
24 −10.627 0.2075 33 0.122 0.999
L13 25 −10.072 0.96 Quartz glass 34 0.143 0.999
26 101.798 0.1 5 1.268 0.987
L14 27 10.53 0.9 Quartz glass 9 0.443 0.996
28 4.509 0.527319 40 0.725 0.993
L15 29 5.379 2.576 Fluorite glass 34 0.698 0.993
30 −51.505 0.1 13 1.091 0.989
L16 31 6.736 1.742 Fluorite glass 9 0.105 0.999
32 17.567 0.1 11 1.146 0.989
L17 33 4.099 1.818 Fluorite glass 9 0.056 0.999
34 9.003 0.10016 17 0.75 0.993
L18 35 1.883 1.872 Quartz glass 10 0.573 0.994
36 5.293 0.262779 42 0.288 0.997

[0134]

TABLE 11
Surface Thickness and Incident
number Curvature Interval Material Angle Reflectance Transmittance
L1 1 2.562 2.562 Quartz glass 21 0.027 1.000
2 2.11 0.7 14 0.277 0.997
L2 3 −2.503 0.7 Fluorite glass 16 0.436 0.996
4 3.929 5.212314 17 0.657 0.993
L3 5 INF 2.786 Fluorite glass 8 1.215 0.988
6 −4.1 0.585821 25 0.091 0.999
L4 7 −3.179 1 Quartz glass 32 0.637 0.994
8 13.25 0.205879 25 0.433 0.996
L5 9 14.51 2.792 Fluorite glass 24 0.474 0.995
10 −8.069 0.135719 10 1.282 0.987
L6 11 9.175 4.016 Fluorite glass 20 0.255 0.997
12 −8.107 0.473387 25 0.071 0.999
L7 13 −6.806 1 Quartz glass 27 0.051 0.999
14 9.394 0.205775 21 0.231 0.998
L8 15 9.73 4.65 Fluorite glass 21 0.29 0.997
16 −7.998 0.105412 23 0.074 0.999
L9 17 −8.397 1 Quartz glass 22 0.119 0.999
18 13.99 0.1 16 0.693 0.993
L10 19 12.513 4.035695 Fluorite glass 17 0.568 0.994
20 −10.732 0.1 17 0.28 0.997
L11 21 35.892 1 Quartz glass 1 0.189 0.998
22 6.835 0.201239 23 0.034 1.000
L12 23 6.916 4.203 Fluorite glass 23 0.034 1.000
24 −10.627 0.2075 22 0.395 0.996
L13 25 −10.072 0.96 Quartz glass 22 0.326 0.997
26 101.798 0.1 3 1.28 0.987
L14 27 10.53 0.9 Quartz glass 6 0.844 0.992
28 4.509 0.527319 26 0.144 0.999
L15 29 5.379 2.576 Fluorite glass 22 0.035 1.000
30 −51.505 0.1 9 1.197 0.988
L16 31 6.736 1.742 Fluorite glass 6 0.6 0.994
32 17.567 0.1 8 1.11 0.989
L17 33 4.099 1.818 Fluorite glass 6 0.274 0.997
34 9.003 0.10016 12 1.015 0.990
L18 35 1.883 1.872 Quartz glass 6 0.018 1.000
36 5.293 0.262779 28 0.476 0.995

[0135] Thus, the transmittance at wavelength 248 nm and NA=0.9 shown in Table 8 becomes 53.8%. Similarly, the transmittance at wavelength 248 nm and NA=0.8 shown in Table 9 becomes 77.7%. The transmittance at wavelength 248 nm and NA=0.7 shown in Table 10 becomes 84.2%. The transmittance at wavelength 248 nm and NA=0.5 shown in Table 11 becomes 85%.

[0136] On the other hand, Tables 12 to 15 show the angle of the light which is incident (emitted) to (from) the normal of the lens, reflectance and the transmittance, etc. corresponding thereto, which are obtained when two wavelength antireflection film explained in detail in the first comparison example is provided to each lens surface of each single lens L1 to L18 for each of NA=0.9, 10.8, 0.7, and 0.5 of such an objective lens, and the lens data of each single lens L1 to L18 (curvature, thickness, interval, and material name).

TABLE 12
Surface Thickness and Incident
number Curvature Interval Material Angle Reflectance Transmittance
L1 1 2.562 2.562 Quartz glass 40 12.006 0.880
2 2.11 0.7 23 4.17 0.958
L2 3 −2.503 0.7 Fluorite glass 31 3.548 0.965
4 3.929 5.212314 29 0.916 0.991
L3 5 INF 2.786 Fluorite glass 13 0.02 1.000
6 −4.1 0.585821 47 13.356 0.866
L4 7 −3.179 1 Quartz glass 61 12.418 0.876
8 13.25 0.205879 53 9.536 0.905
L5 9 14.51 2.792 Fluorite glass 53 9.126 0.909
10 −8.069 0.135719 16 2.994 0.970
L6 11 9.175 4.016 Fluorite glass 43 10.694 0.893
12 −8.107 0.473387 59 17.194 0.828
L7 13 −6.806 1 Quartz glass 65 17.58 0.824
14 9.394 0.205775 54 15.092 0.849
L8 15 9.73 4.65 Fluorite glass 54 14.998 0.850
16 −7.998 0.105412 53 14.768 0.852
L9 17 −8.397 1 Quartz glass 50 14.076 0.859
18 13.99 0.1 40 5.229 0.948
L10 19 12.513 4.035695 Fluorite glass 43 8.244 0.918
20 −10.732 0.1 39 8.632 0.914
L11 21 35.892 1 Quartz glass 2 0.026 1.000
22 6.835 0.201239 52 13.928 0.861
L12 23 6.916 4.203 Fluorite glass 52 14.038 0.860
24 −10.627 0.2075 51 11.992 0.880
L13 25 −10.072 0.96 Quartz glass 52 13.038 0.870
26 101.798 0.1 7 0.032 1.000
L14 27 10.53 0.9 Quartz glass 12 0.51 0.995
28 4.509 0.527319 62 13.7 0.863
L15 29 5.379 2.576 Fluorite glass 52 14.144 0.859
30 −51.505 0.1 16 0.0085 1.000
L16 31 6.736 1.742 Fluorite glass 15 2.163 0.978
32 17.567 0.1 12 0.006 1.000
L17 33 4.099 1.818 Fluorite glass 15 6.229 0.938
34 9.003 0.10016 21 0.079 0.999
L18 35 1.883 1.872 Quartz glass 17 10.502 0.895
36 5.293 0.262779 58 10.261 0.897

[0137]

TABLE 13
Surface Thickness and Incident
number Curvature Interval Material Angle Reflectance Transmittance
L1 1 2.562 2.562 Quartz glass 35 9.479 0.905
2 2.11 0.7 21 2.506 0.975
L2 3 −2.503 0.7 Fluorite glass 26 1.75 0.983
4 3.929 5.212314 26 0.402 0.996
L3 5 INF 2.786 Fluorite glass 12 0.022 1.000
6 −4.1 0.585821 41 11.585 0.884
L4 7 −3.179 1 Quartz glass 53 12.649 0.874
8 13.25 0.205879 44 3.864 0.961
L5 9 14.51 2.792 Fluorite glass 43 3.204 0.968
10 −8.069 0.135719 15 0.886 0.991
L6 11 9.175 4.016 Fluorite glass 36 5.7 0.943
12 −8.107 0.473387 46 11.252 0.887
L7 13 −6.806 1 Quartz glass 51 14.298 0.857
14 9.394 0.205775 41 7.34 0.927
L8 15 9.73 4.65 Fluorite glass 41 7.022 0.930
16 −7.998 0.105412 42 10.306 0.897
L9 17 −8.397 1 Quartz glass 40 8.73 0.913
18 13.99 0.1 31 1.38 0.986
L10 19 12.513 4.035695 Fluorite glass 33 2.464 0.975
20 −10.732 0.1 31 3.548 0.965
L11 21 35.892 1 Quartz glass 2 0.026 1.000
22 6.835 0.201239 42 11.607 0.884
L12 23 6.916 4.203 Fluorite glass 42 11.607 0.884
24 −10.627 0.2075 41 5.334 0.947
L13 25 −10.072 0.96 Quartz glass 41 5.678 0.943
26 101.798 0.1 6 0.034 1.000
L14 27 10.53 0.9 Quartz glass 10 0.145 0.999
28 4.509 0.527319 49 13.44 0.866
L15 29 5.379 2.576 Fluorite glass 42 11.607 0.884
30 −51.505 0.1 15 0.0148 1.000
L16 31 6.736 1.742 Fluorite glass 12 0.868 0.991
32 17.567 0.1 12 0.01 1.000
L17 33 4.099 1.818 Fluorite glass 12 3.288 0.967
34 9.003 0.10016 20 0.0315 1.000
L18 35 1.883 1.872 Quartz glass 13 8.304 0.917
36 5.293 0.262779 50 4.377 0.956

[0138]

TABLE 14
Surface Thickness and Incident
number Curvature Interval Material Angle Reflectance Transmittance
L1 1 2.562 2.562 Quartz glass 30 5.862 0.941
2 2.11 0.7 19 1.2252 0.988
L2 3 −2.503 0.7 Fluorite glass 23 0.717 0.993
4 3.929 5.212314 23 0.181 0.998
L3 5 INF 2.786 Fluorite glass 11 0.25 0.998
6 −4.1 0.585821 36 8.619 0.914
L4 7 −3.179 1 Quartz glass 46 13.062 0.869
8 13.25 0.205879 37 1.346 0.987
L5 9 14.51 2.792 Fluorite glass 36 1.148 0.989
10 −8.069 0.135719 13 0.662 0.993
L6 11 9.175 4.016 Fluorite glass 30 2.228 0.978
12 −8.107 0.473387 38 5.819 0.942
L7 13 −6.806 1 Quartz glass 42 9.288 0.907
14 9.394 0.205775 33 2.72 0.973
L8 15 9.73 4.65 Fluorite glass 33 2.447 0.976
16 −7.998 0.105412 34 5.018 0.950
L9 17 −8.397 1 Quartz glass 33 4.12 0.959
18 13.99 0.1 25 0.32 0.997
L10 19 12.513 4.035695 Fluorite glass 27 0.708 0.993
20 −10.732 0.1 26 1.18 0.988
L11 21 35.892 1 Quartz glass 1 0.033 1.000
22 6.835 0.201239 35 7.157 0.928
L12 23 6.916 4.203 Fluorite glass 35 6.861 0.931
24 −10.627 0.2075 33 1.76 0.982
L13 25 −10.072 0.96 Quartz glass 34 1.95 0.981
26 101.798 0.1 5 0.0359 1.000
L14 27 10.53 0.9 Quartz glass 9 0.019 1.000
28 4.509 0.527319 40 11.156 0.888
L15 29 5.379 2.576 Fluorite glass 34 6.839 0.932
30 −51.505 0.1 13 0.02 1.000
L16 31 6.736 1.742 Fluorite glass 9 0.25 0.998
32 17.567 0.1 11 0.019 1.000
L17 33 4.099 1.818 Fluorite glass 9 1.33 0.987
34 9.003 0.10016 17 0.006 1.000
L18 35 1.883 1.872 Quartz glass 10 5.136 0.949
36 5.293 0.262779 42 1.632 0.984

[0139]

TABLE 15
Surface Thickness and Incident
number Curvature Interval Material Angle Reflectance Transmittance
L1 1 2.562 2.562 Quartz glass 21 0.938 0.991
2 2.11 0.7 14 0.084 0.999
L2 3 −2.503 0.7 Fluorite glass 16 0.032 1.000
4 3.929 5.212314 17 0.008 1.000
L3 5 INF 2.786 Fluorite glass 8 0.031 1.000
6 −4.1 0.585821 25 1.769 0.982
L4 7 −3.179 1 Quartz glass 32 6.208 0.938
8 13.25 0.205879 25 0.0686 0.999
L5 9 14.51 2.792 Fluorite glass 24 0.057 0.999
10 −8.069 0.135719 10 0.04 1.000
L6 11 9.175 4.016 Fluorite glass 20 0.12 0.999
12 −8.107 0.473387 25 0.503 0.995
L7 13 −6.806 1 Quartz glass 27 1.154 0.988
14 9.394 0.205775 21 0.16 0.998
L8 15 9.73 4.65 Fluorite glass 21 0.115 0.999
16 −7.998 0.105412 23 0.483 0.995
L9 17 −8.397 1 Quartz glass 22 0.337 0.997
18 13.99 0.1 16 0.005 1.000
L10 19 12.513 4.035695 Fluorite glass 17 0.014 1.000
20 −10.732 0.1 17 0.044 1.000
L11 21 35.892 1 Quartz glass 1 0.033 1.000
22 6.835 0.201239 23 0.85 0.992
L12 23 6.916 4.203 Fluorite glass 23 0.85 0.992
24 −10.627 0.2075 22 0.074 0.999
L13 25 −10.072 0.96 Quartz glass 22 0.106 0.999
26 101.798 0.1 3 0.0371 1.000
L14 27 10.53 0.9 Quartz glass 6 0.009 1.000
28 4.509 0.527319 26 2.185 0.978
L15 29 5.379 2.576 Fluorite glass 22 0.076 0.992
30 −51.505 0.1 9 0.029 1.000
L16 31 6.736 1.742 Fluorite glass 6 0.005 1.000
32 17.567 0.1 8 0.025 1.000
L17 33 4.099 1.818 Fluorite glass 6 0.07 0.999
34 9.003 0.10016 12 0.016 1.000
L18 35 1.883 1.872 Quartz glass 6 0.772 0.992
36 5.293 0.262779 28 0.105 0.999

[0140] Thus, the transmittance at wavelength 248 nm and NA=0.9 shown in Table 12 becomes 3.8%. Similarly, the transmittance at wavelength 248 nm and NA=0.8 shown in Table 13 becomes 12.9%. The transmittance at wavelength 248 nm and NA=0.7 shown in Table 14 becomes 31.6%. The transmittance at wavelength 248 nm and NA=0.5 shown in Table 15 becomes 83.5%.

[0141] As a result, when comparing the transmittance of the objective lens of the seventh embodiment in which two wavelength antireflection film is coated and the objective lens of the first comparison example in which two wavelength antireflection film is coated with each lens surface of each single lens L1 to L18, when two wavelength antireflection film of the seventh embodiment as shown in FIG. 21 is coated, high transmittance can be obtained even when NA is 0.9, 0.8, 0.7, and 0.5 as shown in curve A. In contrast, when two-wavelength antireflection film of the first comparison example is applied, it is apparent that transmittance reduces rapidly as shown in curve B as NA becomes large such as 0.7, 0.8, 0.9 as shown in curve B. As a result, high transmittance in 248 nm used for the observation and a high NA, that is, high resolutions can be achieved by coating two-wavelength antireflection film according to the seventh embodiment to each lens surface of each single lens L1 to L18 which configures the objective lens.

[0142] (Fourteenth Embodiment)

[0143]FIG. 22 is a figure showing a schematic configuration of the objective lens applied to the fourteenth embodiment of the present invention.

[0144] In this case, the objective lens is used for an optical equipment which observes by the light of wavelength of the ultra-violet region of 300 nm or less and has the mechanism to focus (auto focus) by the light in the wavelength region from a visible region to the near-infrared region. Specifically, 248 nm in the deep-ultraviolet region as wavelength used for the observation and 633 nm in the visible region as wavelength used for auto focus are applied.

[0145] The objective lens has the first lens group 1G and the second lens group G2 arranged between the first lens group 1G and the object side as shown in FIG. 22. The first lens group 1G has four single lenses L21 to L24 which include positive lens and negative lens with the different medium and has negative power as a whole. The second lens group 2G has eight single lenses L25 to L32 which include positive lens and negative lens with the different medium. In the first and second lens groups 1G and 2G, the air interval is provided between a positive lens and negative lens.

[0146] Tables 16 to 19 show the angle of the light which is incident (emitted) to (from) the normal of the lens, reflectance and the transmittance, etc. corresponding thereto, which are obtained when two wavelength antireflection film explained in detail in the seventh embodiment is coated to each lens surface of each single lens L21 to L32 for each of NA=0.9, 0.8, 0.7, and 0.5 of such an objective lens, and the lens data of each single lens L21 to L32 (curvature, thickness, interval, and material name).

TABLE 16
Surface Thickness and Incident
number Curvature Interval Material Angle Reflectance Transmittance
L21 1 −3.543 2.15 Quartz glass 31 0.4 0.996
2 6.765 0.10358 52 1.5 0.958
L22 3 6.181 3.06 Fluorite glass 55 2.06 0.979
4 −4.042 0.153241 53 4.6 0.954
L23 5 −4.08 0.92 Quartz glass 52 4 0.960
6 8.682 0.16626 54 2 0.980
L24 7 8.883 3.11 Fluorite glass 54 2 0.980
8 −6.824 0.106344 31 0.32 0.997
L25 9 24.853 0.9 Quartz glass 9 0.03 1.000
10 6.181 0.101063 55 3.54 0.965
L26 11 5.251 3.77 Fluorite glass 66 13 0.870
12 −9.936 0.61551 45 0.96 0.990
L27 13 −6.165 0.9 Quartz glass 58 5 0.950
14 6.165 0.502246 59 5.5 0.945
L28 15 8.596 2.78 Fluorite glass 49 1.2 0.988
16 −12.005 0.197219 17 0.47 0.995
L29 17 5.353 3.51 Fluorite glass 46 2.9 0.971
18 −11.031 0.488166 54 2 0.980
L30 19 −6.791 1.35 Quartz glass 65 7.52 0.925
20 −155.13 0.196741 14 0.01 1.000
L31 21 4.438 2.12 Quartz glass 23 0.22 0.998
22 13.067 0.095 19 0.15 0.999
L32 23 7.961 2.33 Quartz glass 30 2.58 0.974
24 10.691 0.2647.8 61 4.1 0.959

[0147]

TABLE 17
Surface Thickness and Incident
number Curvature Interval Material Angle Reflectance Transmittance
L21 1 −3.543 2.15 Quartz glass 27 0.52 0.995
2 6.765 0.10358 44 1 0.990
L22 3 6.181 3.06 fluorite glass 46 1 0.990
4 −4.042 0.153241 44 1.3 0.987
L23 5 −4.08 0.92 Quartz glass 43 1.2 0.988
6 8.682 0.16626 46 1.2 0.988
L24 7 8.883 3.11 fluorite glass 46 1.2 0.988
8 −6.824 0.106344 27 0.48 0.995
L25 9 24.853 0.9 Quartz glass 9 0.01 1.000
10 6.181 0.101063 48 1.3 0.987
L26 11 5.251 3.77 fluorite glass 56 5 0.950
12 −9.936 0.61551 36 0.8 0.992
L27 13 −6.165 0.9 Quartz glass 47 1 0.990
14 6.165 0.502246 51 1.5 0.985
L28 15 8.596 2.78 Fluorite glass 43 0.85 0.992
16 −12.005 0.197219 16 0.4 0.996
L29 17 5.353 3.51 Fluorite glass 40 1.07 0.989
18 −11.031 0.488166 45 1.16 0.988
L30 19 −6.791 1.35 Quartz glass 54 5 0.950
20 −155.13 0.196741 14 0.01 1.000
L31 21 4.438 2.12 Quartz glass 18 0.43 0.996
22 13.067 0.095 18 0.1 0.999
L32 23 7.961 2.33 Quartz glass 22 0.6 0.994
24 10.691 0.2647.8 51 1.9 0.981

[0148]

TABLE 18
Surface Thickness and Incident
number Curvature Interval Material Angle Reflectance Transmittance
L21 1 −3.543 2.562 Quartz glass 23 0.61 0.994
2 6.765 0.10358 37 0.83 0.992
L22 3 6.181 3.06 Fluorite glass 39 0.88 0.991
4 −4.042 0.153241 37 0.4 0.996
L23 5 −4.08 0.92 Quartz glass 36 0.4 0.996
6 8.682 0.16626 39 0.9 0.991
L24 7 8.883 3.11 Fluorite glass 39 0.9 0.991
8 −6.824 0.106344 23 0.61 0.994
L25 9 24.853 0.9 Quartz glass 8 0.01 1.000
10 6.181 0.101063 41 0.6 0.994
L26 11 5.251 3.77 Fluorite glass 47 1.2 0.988
12 −9.936 0.61551 29 0.62 0.994
L27 13 −6.165 0.9 Quartz glass 38 0.59 0.994
14 6.165 0.502246 43 0.7 0.992
L28 15 8.596 2.78 Fluorite glass 37 0.8 0.992
16 −12.005 0.197219 14 0.22 0.998
L29 17 5.353 3.51 Fluorite glass 34 0.33 0.997
18 −11.031 0.488166 38 0.85 0.992
L30 19 −6.791 1.35 Quartz glass 45 0.96 0.990
20 −155.13 0.196741 13 0.01 1.000
L31 21 4.438 2.12 Quartz glass 15 0.58 0.994
22 13.067 0.095 16 0.07 0.999
L32 23 7.961 2.33 Quartz glass 18 0.19 0.998
24 10.691 0.2647.8 43 1.15 0.989

[0149]

TABLE 19
Surface Thickness and Incident
number Curvature Interval Material Angle Reflectance Transmittance
L21 1 −3.543 2.15 Quartz glass 16 0.4 0.996
2 6.765 0.10358 25 0.15 0.999
L22 3 6.181 3.06 Fluorite glass 26 0.4 0.996
4 −4.042 0.153241 25 0.64 0.994
L23 5 −4.08 0.92 Quartz glass 24 0.64 0.994
6 8.682 0.16626 26 0.4 0.996
L24 7 8.883 3.11 Fluorite glass 26 0.4 0.996
8 −6.824 0.106344 16 0.42 0.996
L25 9 24.853 0.9 Quartz glass 6 0.004 1.000
10 6.181 0.101063 28 0.65 0.994
L26 11 5.251 3.77 Fluorite glass 32 0.66 0.993
12 −9.936 0.61551 19 0.23 0.998
L27 13 −6.165 0.9 Quartz glass 26 0.6 0.994
14 6.165 0.502246 29 0.67 0.993
L28 15 8.596 2.78 Fluorite glass 25 0.46 0.995
16 −12.005 0.197219 10 0.07 0.999
L29 17 5.353 3.51 Fluorite glass 23 0.61 0.994
18 −11.031 0.488166 25 0.29 0.997
L30 19 −6.791 1.35 Quartz glass 30 0.61 0.994
20 −155.13 0.196741 9 0.01 1.000
L31 21 4.438 2.12 Quartz glass 10 0.39 0.996
22 13.067 0.095 11 0.01 1.000
L32 23 7.961 2.33 Quartz glass 12 0.57 0.994
24 10.691 0.2647.8 29 0.3 0.997

[0150] Thus, the transmittance at wavelength 248 nm and NA=0.9 shown in Table 16 becomes 50.6%. Similarly, the transmittance at wavelength 248 nm and NA=0.8 shown in Table 17 becomes 74.5%. The transmittance at wavelength 248 nm and NA=0.7 shown in Table 18 becomes 86.5%. The transmittance at wavelength 248 nm and NA=0.5 shown in Table 19 becomes 90.8%.

[0151] On the other hand, Tables 20 to 23 show the angle of the light which is incident (emitted) to (from) the normal of the lens, reflectance and the transmittance, etc. corresponding thereto, which are obtained when two wavelength antireflection film explained in detail in the first comparison example is provided to each lens surface of each single lens L21 to L32 for each of NA 0.9, 0.8, 0.7, and 0.5 of such an objective lens, and the lens data of each single lens L21 to L32 (curvature, thickness, interval, and material name).

TABLE 20
Surface Thickness and Incident
number Curvature Interval Material Angle Reflectance Transmittance
L21 1 −3.543 2.15 Quartz glass 31 3.3 0.967
2 6.765 0.10358 52 7 0.930
L22 3 6.181 3.06 Fluorite glass 55 10 0.900
4 −4.042 0.153241 53 14 0.860
L23 5 −4.08 0.92 Quartz glass 52 14 0.860
6 8.682 0.16626 54 9 0.910
L24 7 8.883 3.11 Fluorite glass 54 9.3 0.907
8 −6.824 0.106344 31 3.9 0.961
L25 9 24.853 0.9 Quartz glass 9 0.01 1.000
10 6.181 0.101063 55 11.5 0.885
L26 11 5.251 3.77 Fluorite glass 66 22 0.780
12 −9.936 0.61551 45 4.2 0.958
L27 13 −6.165 0.9 Quartz glass 58 15 0.850
14 6.165 0.502246 59 16 0.840
L28 15 8.596 2.78 Fluorite glass 49 7.5 0.925
16 −12.005 0.197219 17 0.2 0.998
L29 17 5.353 3.51 Fluorite glass 46 12.5 0.975
18 −11.031 0.488166 54 7.5 0.925
L30 19 −6.791 1.35 Quartz glass 65 19.5 0.805
20 −155.13 0.196741 14 0.02 1.000
L31 21 4.438 2.12 Quartz glass 23 4 0.960
22 13.067 0.095 19 0.04 1.000
L32 23 7.961 2.33 Quartz glass 30 11 0.890
24 10.691 0.2647.8 61 9 0.910

[0152]

TABLE 21
Surface Thickness and Incident
number Curvature Interval Material Angle Reflectance Transmittance
L21 1 −3.543 2.15 Quartz glass 27 2 0.980
2 6.765 0.10358 44 3.3 0.967
L22 3 6.181 3.06 Fluorite glass 46 4.3 0.957
4 −4.042 0.153241 44 10 0.900
L23 5 −4.08 0.92 Quartz glass 43 9 0.910
6 8.682 0.16626 46 4 0.960
L24 7 8.883 3.11 Fluorite glass 46 4 0.960
8 −6.824 0.106344 27 2 0.980
L25 9 24.853 0.9 Quartz glass 9 0.01 1.000
10 6.181 0.101063 48 9 0.910
L26 11 5.251 3.77 Fluorite glass 56 15 0.850
12 −9.936 0.61551 36 1.6 0.984
L27 13 −6.165 0.9 Quartz glass 47 8 0.920
14 6.165 0.502246 51 10 0.900
L28 15 8.596 2.78 Fluorite glass 43 4 0.960
16 −12.005 0.197219 16 0.1 0.999
L29 17 5.353 3.51 Fluorite glass 40 9 0.910
18 −11.031 0.488166 45 3 0.970
L30 19 −6.791 1.35 Quartz glass 54 10 0.900
20 −155.13 0.196741 14 0.02 1.000
L31 21 4.438 2.12 Quartz glass 18 1.9 0.981
22 13.067 0.095 18 0.03 1.000
L32 23 7.961 2.33 Quartz glass 22 7 0.930
24 10.691 0.2647.8 51 3 0.970

[0153]

TABLE 22
Surface Thickness and Incident
number Curvature Interval Material Angle Reflectance Transmittance
L21 1 −3.543 2.15 Quartz glass 23 0.9 0.991
2 6.765 0.10358 37 1.2 0.988
L22 3 6.181 3.06 Fluorite glass 39 2 0.980
4 −4.042 0.153241 37 5.5 0.945
L23 5 −4.08 0.92 Quartz glass 36 5 0.950
6 8.682 0.16626 39 1.5 0.985
L24 7 8.883 3.11 Fluorite glass 39 1.5 0.985
8 −6.824 0.106344 23 1.95 0.981
L25 9 24.853 0.9 Quartz glass 8 0.01 1.000
10 6.181 0.101063 41 5 0.950
L26 11 5.251 3.77 Fluorite glass 47 9.5 0.905
12 −9.936 0.61551 29 0.55 0.995
L27 13 −6.165 0.9 Quartz glass 38 3.6 0.964
14 6.165 0.502246 43 5.5 0.945
L28 15 8.596 2.78 Fluorite glass 37 2 0.980
16 −12.005 0.197219 14 0.05 1.000
L29 17 5.353 3.51 Fluorite glass 34 5.3 0.947
18 −11.031 0.488166 38 1.2 0.988
L30 19 −6.791 1.35 Quartz glass 45 4.2 0.958
20 −155.13 0.196741 13 0.01 1.000
L31 21 4.438 2.12 Quartz glass 15 0.85 0.992
22 13.067 0.095 16 0.02 1.000
L32 23 7.961 2.33 Quartz glass 18 4.5 0.955
24 10.691 0.2647.8 43 1.6 0.984

[0154]

TABLE 23
Surface Thickness and Incident
number Curvature Interval Material Angle Reflectance Transmittance
L21 1 −3.543 2.15 Quartz glass 16 0.1 0.999
2 6.765 0.10358 25 0.15 0.999
L22 3 6.181 3.06 Fluorite glass 26 0.2 0.998
4 −4.042 0.153241 25 0.85 0.992
L23 5 −4.08 0.92 Quartz glass 24 0.85 0.992
6 8.682 0.16626 26 0.2 0.998
L24 7 8.883 3.11 Fluorite glass 26 0.2 0.998
8 −6.824 0.106344 16 0.15 0.999
L25 9 24.853 0.9 Quartz glass 6 0.01 1.000
10 6.181 0.101063 28 0.75 0.993
L26 11 5.251 3.77 Fluorite glass 32 1.8 0.982
12 −9.936 0.61551 19 0.07 0.999
L27 13 −6.165 0.9 Quartz glass 26 0.45 0.996
14 6.165 0.502246 29 0.7 0.993
L28 15 8.596 2.78 Fluorite glass 25 0.24 0.998
16 −12.005 0.197219 10 0.02 1.000
L29 17 5.353 3.51 Fluorite glass 23 0.85 0.992
18 −11.031 0.488166 25 0.13 0.999
L30 19 −6.791 1.35 Quartz glass 30 0.47 0.995
20 −155.13 0.196741 9 0.01 1.000
L31 21 4.438 2.12 Quartz glass 10 0.1 0.999
22 13.067 0.095 11 0.01 1.000
L32 23 7.961 2.33 Quartz glass 12 0.8 0.992
24 10.691 0.2647.8 29 0.19 0.998

[0155] Thus, the transmittance at wavelength 248 nm and NA=0.9 shown in Table 20 becomes 105%. Similarly, the transmittance at wavelength 248 nm and NA=0.8 shown in Table 21 becomes 28.5%. The transmittance at wavelength 248 nm and NA=0.7 shown in Table 22 becomes 52.2%. The transmittance at wavelength 248 nm and NA=0.5 shown in Table 23 becomes 91.1%.

[0156] As a result, when comparing the transmittance of the objective lens of the seventh embodiment in which two wavelength antireflection film is coated and the objective lens of the first comparison example in which two wavelength antireflection film is coated with each lens surface of each single lens L21 to L32, when two wavelength antireflection film of the ninth embodiment as shown in FIG. 23 is coated, high transmittance can be obtained even in a case that NA is 0.8, and 0.9 as shown in curve A. In contrast, when two-wavelength antireflection film of the second comparison example is coated, it is apparent that transmittance reduces rapidly as shown in curve B as NA becomes large such as 0.7, 0.8, 0.9 as shown in curve B. As a result, high transmittance in 248 nm used for the observation and a high NA, that is, high resolutions can be achieved by coating two-wavelength antireflection film according to the ninth embodiment to each lens surface of each single lens L21 to L32 which configures the objective lens.

[0157] As mentioned above, according to the embodiment of the present invention, the antireflection effect can be achieved in the vicinity of 248 nm and the wavelength region of 600 to 800 nm for substrate (lens) material whose refractive index in the deep-ultraviolet region is 1.4 to 1.52. Even when the incident angle of light becomes large, the antireflection effect is never lost in the vicinity of especially 248 nm. Therefore, high transmittance can be achieved even when the incident angle of the light to the surface of the lens is from vertical to about 65.

[0158] A high antireflection effect can be achieved according to the embodiment of the present invention when applying to quartz glass and fluorite glass which are transparent material in the deep-ultraviolet region used well, especially 248 nm wavelength.

[0159] It is preferable the material of refractive index of 1.35 to 1.5 in the deep-ultraviolet region is used as a low refractive index material according to the embodiment of the present invention. Especially, a higher effect can be achieved by using one or more component chosen by the group of MgF2, SiO2, NaF, LiF, and mixture or compound thereof as a material with excellent productivity and a little absorption film in the low refractive index. Among these, MgF2 and SiO2, which have withstand extreme environmental conditions and can be easily obtained, is easy to use for production the effect is high. A high antireflection characteristic can be obtained by using MgF2 to the low refraction layer of the fourth layer (surface layer) from the substrate caused by the low refractive index thereof. Similarly, It is preferable the material is used as the middle refractive index material whose the refractive index in the deep-ultraviolet region is 1.6 to 1.9. Especially, a higher effect can be achieved by using one or more component chosen by the group of Al2O3, CaF3, NdF3, YF3, La2O3, and mixture or compound thereof as a material with excellent productivity and a little absorption film in the low refractive index.

[0160] According to the embodiment of the present invention, when the visible or the near-infrared wavelength (auto focus wavelength), which performs antireflection, is within the rage of 650 to 800 nm, the above-mentioned effect can be achieved by setting the range of the film thickness of the first layer from the substrate to 0.4λ≦nd1≦0.6λ, that of the second layer to 0.4λ≦nd2≦0.6λ, that of the third layer to 0.1λ<nd3≦0.3λ, and that of the fourth layer to 0.2λnd4≦0.35λ, for wavelength λ (λ=248 nm). In addition, when the range of the film thickness of the first to fourth layer from the substrate are set to 0.4λ≦nd1≦0.6λ, 0.4λ≦nd2≦0.6λ, 0.2λ≦nd3≦0.3λ, and 0.2λ≦nd4≦0.3λ, respectively, two wavelength antireflection film with high antireflection performance can be obtained in the combination of film material with high refractive index stability and excellent productivity (MgF2, La2O3, and Al2O3 mixture material). When the auto focus wavelength is selected in the vicinity of 750 nm, a higher effect can be obtained according to such a range of the film thickness.

[0161] Similarly, when auto focus wavelength is in 650 to 800 nm, the above-mentioned effect can be achieved by setting the range of the film thickness of the first layer from the substrate to 0.5λ≦nd1≦0.7λ, that of the second layer to 0.05λ≦nd2≦0.2λ, that of the third layer to 0.25λ≦nd3≦0.5λ, and that of the fourth layer to 0.2λ≦nd4≦0.35λ, for wavelength λ (λ=248 nm). In addition, when the range of the film thickness of the first to fourth layer from the substrate are set to 0.6λ≦nd1≦0.7λ, 0.05λ≦nd2≦0.1λ, 0.25λ≦nd3≦0.35λ, and 0.25λ<nd4≦0.35λ, respectively, two wavelength antireflection film with high antireflection performance can be obtained in the combination of film material with high refractive index stability and excellent productivity (MgF2, La2O3, and Al2O3 mixture material). When the auto focus wavelength is selected in the vicinity of 750 nm, a higher effect can be obtained according to such a range of the film thickness.

[0162] In the objective lens used for the microscope, which observes by the light of wavelength of the ultraviolet region of 300 nm or less and has the focusing mechanism (auto focus) in the wavelength from the visible region to the near-infrared region, high transmittance and a high NA, that is, high resolving power can be achieved.

[0163] The present invention is not limited to the above-described embodiments. Various modifications can occur at its embodying stage without departing from the scope of the invention.

[0164] In addition, for example, even if some of all the constituent elements shown in the embodiments are deleted, in the case where the problems described in the Brief Summary of the Invention section can be solved, and advantageous effect described in the Advantageous Effect of the Invention section can be achieved, the configuration can be excerpted after these constituent elements have been deleted.

[0165] As mentioned above, according to the present invention, two-wavelength antireflection film in which high transmittance can be achieved in a deep-ultraviolet region and from the visible region to the near-infrared region, and the objective lens on which two-wavelength antireflection film is coated can be achieved.

[0166] Additional advantages and modifications will readily occur to those skilled in the art. Therefore, the present invention in its broader aspects is nor limited to the specific details, representative devices, and illustrated examples shown and described herein. Accordingly, various modifications may be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and their equivalents.

Classifications
U.S. Classification359/656
International ClassificationG02B1/11, G02B21/02, G02B5/28
Cooperative ClassificationG02B5/283, G02B1/115, G02B5/281
European ClassificationG02B5/28A, G02B5/28B, G02B1/11D2
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