US20020037682A1

US20020037682A1 - Polishing or grinding method, processing method of optical element, processing method of fluorite, polishing or grinding apparatus, polishing and/or grinding apparatus for optical element, apparatus for processing surface of optical element, and lens

Info

Publication number: US20020037682A1
Application number: US09/949,768
Authority: US
Inventors: Junji Takashita
Original assignee: Individual
Current assignee: Canon Inc
Priority date: 2000-09-25
Filing date: 2001-09-12
Publication date: 2002-03-28
Also published as: JP2002103227A

Abstract

During grinding and polishing of an optical element made of a crystalline material such as fluorite, tarnish and a reaction with diamond polishing abrasive grains included in processing liquid are prevented. To this end, processing liquid supplied to a processing region of a surface to be processed and processing liquid supplied to a non-processing region are divided.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a technique of grinding or polishing a surface to be processed.

The present invention also relates to a supplying technique of processing liquid when grinding or polishing a surface to be processed of an object.

The present invention also relates to a grinding or polishing apparatus.

The present invention also relates to a supplying method and apparatus in which plural processing liquids are supplied when grinding or polishing by bringing a processing tool in touch with a surface to be processed.

The present invention also relates to a supplying method and apparatus of processing liquid when grinding or polishing an optically functional surface of an optical element.

The present invention further relates to a supplying method and apparatus in which processing liquid is separately supplied according to a processing region when grinding or polishing an optically functional surface of an optical element.

2. Description of the Related Art

An optically functional surface of a lens for use in a camera or the like is sequentially processed by taking the steps of rough machining of a glass raw material, rough grinding, polishing, and fine polishing with a predetermined surface processing accuracy established for each step.

In these steps, a processing position in which a processing tool comes into contact on a lens surface to be processed and a surrounding area of the processing position are thoroughly supplied with polishing liquid including polishing abrasive grains.

In order to polish a lens having a large diameter, the lens surface is scanned with a processing tool having a diameter smaller than that of the lens so as to partially remove the processing surface.

During processing of the large-diameter lens, the processing liquid may be supplied enough only in the processing region; however, when doing so, a part of the liquid is splashed on the region which is already processed or will be processed, whereby diamond abrasive grains in the processing liquid adhere to the lens surface so as to form a reaction product thereon by the reaction therebetween, resulting in deterioration in accuracies of the lens surface.

In particular, a fluoride lens made of a crystalline glass material of calcium fluoride is soft and liable to be damaged and may be reacted with diamond abrasive grains in the processing liquid in comparison with a conventional non-crystalline optical lens.

Therefore, it is difficult to obtain a desired processing accuracy by a method in which the processing liquid is supplied over the entire surface of the lens just like in the conventional method due to the reaction with abrasive grains.

SUMMARY OF THE INVENTION

In order to solve the problem described above, a polishing method according to an aspect of the present invention comprises supplying liquids functionally different from each other to a processing region which is processed with a tool and a non-processing region, respectively.

In accordance with another aspect of the present invention, a polishing method of a surface to be processed of an object, the method comprises dividing the surface to be processed into a region to be processed by a processing tool and a region other than the region to be processed, and supplying different processing liquids according to the divided region.

In accordance with another aspect of the present invention, a polishing method comprises separately supplying a processing liquid which includes polishing abrasive grains to a region to be processed by a processing tool of an object and a processing liquid without the polishing abrasive grains to a region other than the region to be processed.

In accordance with another aspect of the present invention, a processing method of an optical element comprises supplying liquids functionally different from each other to a region to be processed by a tool of the optical element and a region other than the region to be processed, respectively.

In the processing method of an optical element, the optical element may be fluorite.

In order to solve the problem described above, a processing method of an optical element according to another aspect of the present invention comprises using a processing tool having a processing area which is small relative to a processed area of a surface of the optical element, and supplying liquids functionally different from each other to a region to be processed by the processing tool and a region other than the region to be processed, respectively.

In accordance with another aspect of the present invention, a processing method of an optical element comprises supplying a liquid having a polishing function to a processed surface of the optical element and a liquid having a dry-protecting function to a region other than the processed surface of the optical element.

In accordance with another aspect of the present invention, a processing method of an optical element comprises supplying liquid having a dry-protecting function to a region other than a processed surface of the optical element.

In accordance with another aspect of the present invention, a processing method of an optical element by polishing, the method comprises keeping a region other than a processed surface of the optical element in a non-dry state during processing.

In accordance with another aspect of the present invention, a processing method of an optical element by polishing, the method comprises keeping a region other than a region processed by a tool of the optical element wet during processing.

In accordance with another aspect of the present invention, a processing method of an optically functional surface of fluorite comprises keeping a region other than a region processed by a tool for processing the optically functional surface of the fluorite in a non-dry state during processing.

In accordance with another aspect of the present invention, a processing method of an optically functional surface of fluorite comprises supplying a liquid for dry-protecting to a region other than a processed region on the optically functional surface during the processing the optically functional surface.

In accordance with another aspect of the present invention, a processing apparatus for polishing an optical element comprises a plurality of supplying means for supplying processing liquid to a surface to be processed of the optical element.

In the processing apparatus for polishing an optical element, the kind of the processing liquid supplied by the supplying means for supplying processing liquid may differ according to the region on the processed surface to which the processing liquid is applied.

The processing apparatus for polishing an optical element may further comprise dividing means for dividing the processing liquid.

In accordance with another aspect of the present invention, a processing apparatus for polishing an optical element comprises first processing-liquid-supplying means for supplying processing liquid to a region to be processed of the optical element, dividing means for dividing a region other than a region processed by the tool on the surface of the optical element, and second processing-liquid-supplying means for supplying processing liquid to a region other than the processed region.

In the processing apparatus for polishing an optical element, the optical element may be fluorite.

In accordance with another aspect of the present invention, an apparatus for processing a surface of an optical element comprises supplying means for supplying a plurality of processing liquids functionally different from each other to the surface to be processed of the optical element and mixture preventing means for preventing the plurality of processing liquids from mixing.

In the processing apparatus processing a surface of an optical element, the mixture preventing means may be compressed air.

In accordance with another aspect of the present invention, an apparatus for processing a surface of an optical element comprises means for supplying processing liquids functionally different from each other to the surface to be processed of the optical element and for independently recovering the processing liquids.

In the processing apparatus processing a surface of an optical element, the optical element may be fluorite.

In accordance with another aspect of the present invention, a fluoride lens prepared by a process comprises supplying a first processing liquid to a portion to be processed by a processing tool and supplying a second processing liquid to a region other than the portion to be processed by the processing tool during processing of an optical surface of the lens.

As described above, according to the present invention, processing liquid supplied to a processing region of an object to be processed and processing liquid supplied to a non-processing region are functionally divided so that a bad influence on the non-processing region is eliminated to thereby obtain a processing method and a processing apparatus with a high degree of efficiency.

Further objects, features and advantages of the present invention will become apparent from the following description of the preferred embodiments with reference to the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic representation of a structure of the present invention. [0039]
FIG. 2 is a schematic representation of a second embodiment according to the present invention. [0040]
FIG. 3 is a schematic representation of a third embodiment according to the present invention. [0041]
FIG. 4 is a schematic representation of a fourth embodiment according to the present invention.[0042]

DESCRIPTION OF THE PREFERRED EMBODIMENTS

First Embodiment [0043]
Description of the Structure of a Processing Apparatus [0044]
FIG. 1 shows an essential structure of a processing apparatus according to the present invention. [0045]
In the drawing, an X-Y table [0046] 2 places a lens 4 thereon, which is an object to be processed, for moving the lens 4 in the X- and Y-axial directions along the horizontal surface of a base 1 of the processing apparatus.
A processing-liquid-[0047] receiving tank 6 accommodates the table 2 and processing liquid.
A supporting [0048] member 8 attached to the base 1 supports a processing tool 10.
The [0049] processing tool 10 comes into contact on a surface to be processed 4A of the lens 4 for removing-work of the surface to be processed 4A by grinding or polishing. The processing tool 10 is made of pitch manufactured from asphalt as a raw material.
The [0050] processing tool 10 held by a tool holding member 12A is tilted and rotated by pressurizing means and rotating means (both not shown), respectively.
A cylindrical [0051] tubular member 14 locates the processing tool 10 in the center thereof and has a function of separating means for separating a first processing liquid and a second processing liquid.
The [0052] tubular member 14 is made of an anti-corrosion material such as a resin and metal having an elastic member such as sponge and felt bonded at the end thereof and is attached to the holding member 12A via a spring member 18.
The [0053] tubular member 14 is configured so as to lightly urge in contact with a surface to be processed due to a spring force of the spring member 18.
The [0054] tubular member 14 locates the processing tool 10 in the center of the tube and separates a processing region and a non-processing region so that the processing region is inside the tube and the non-processing region is outside the tube and spaced from the center of the processing tool 10 by the radius of the tubular member 14.
A [0055] contact portion 14A to the surface of the lens 4 at the end of the tubular member 14 has a resin such as Teflon, a nonwoven cloth, and an elastic member such as polyurethane attached thereto so as to eliminate the effect on the lens due to the contact pressure.
The first processing liquid is supplied on a surface to be processed of the [0056] lens 4 within the tubular member 14 from a first processing-liquid tank 22 via a pump 24, supplying member 26, and a first processing-liquid-supply pipe 20.
The first grinding/polishing liquid including diamond abrasive grains is supplied into the first processing-liquid tank [0057] 22.
A supply nozzle [0058] 28A of a second processing-liquid-supply pipe 28 is located in the outer periphery of the tubular member 14, and the liquid from the second processing-liquid-supply pipe 28 is supplied to the non-processing region of the lens 4.
The second processing liquid is supplied to the second processing-liquid-supply pipe [0059] 28 from a second processing-liquid tank (not shown).
A processing-liquid-recovery-[0060] pipe member 30 is connected to a discharge outlet of the processing-liquid-receiving tank 6 so as to send the processing liquid to a recovery tank 32.
Description of a Processing Method [0061]
A polishing liquid including diamond powder controlled to have a predetermined particle size is prepared in the first processing-liquid tank [0062] 22 as the first processing liquid to have a constant consistency by agitating means built in the tank 22.
The [0063] lens 4 to be processed is placed on the X-Y table 2 so as to prepare the processing.
Dry-preventing liquid for preventing the non-processing region of the lens surface from being dried is prepared in a second processing-liquid tank (not shown). [0064]
The dry-preventing liquid uses the same kind of the liquid (water) as the first processing liquid without the diamond abrasive grains. [0065]
When the lens to be processed is fluoride and the liquid including the diamond abrasive grains just like the first processing liquid is used, the diamond abrasive grains react with the surface ingredient of the fluoride so as to form a reaction product on the surface of the non-processing region of the fluoride. [0066]
When the surface of the fluoride is dried, a reaction called as “tarnish” is produced on the surface. [0067]
In the embodiment, the consistency of the diamond abrasive grains in the first processing liquid is adjusted to be approximately 0.5% by weight. [0068]
Polishing Conditions in the Embodiment [0069]
Lens Diameter Size: 200 mm [0070]
Lens Shape: non-spherical lens (lens for exposing a substrate for a semi-conductor) [0071]
Inner Diameter of the Tubular Member 14: 80 mm [0072]
Supplying Rate of the First Processing Liquid: 10 cc/min [0073]
Supplying Rate of the Second Processing Liquid: 400 cc/min [0074]
Processing Tool Size: 20 mm [0075]
Rotation Speed of the Processing Tool: 100 rpm [0076]
The [0077] processing tool 10 is brought into contact on the surface to be processed 4A of the lens 4; the first processing liquid is supplied within the tubular member 14 at the supplying rate mentioned above; furthermore, the second processing liquid is supplied to the non-processing region of the lens 4 via the second processing-liquid-supply pipe 28, whereby the processing is performed while rotating the processing tool 10 and feeding the table 2.
In the processing region within the [0078] tubular member 14, the removing process of the lens surface by the diamond abrasive grains included in the first processing liquid is performed while the second processing liquid for keeping wet is supplied in the non-processing region outside the tubular member 14 so that the reaction described above in the non-processing region is suppressed.
By the feed operation of the X-Y table [0079] 2, the processing region and the non-processing region on the lens surface are changed; however, because the tubular member 14 is also moved by following the table 2, the processing region and the non-processing region always keep up with the table 2.
Water is adopted as an example of the processing liquid; however, when the lens material to be processed is a crystalline glass material such as fluorite, any liquid other than water may be used as far as it has a low viscosity, high-dispersibility of the diamond abrasive grains, non-reactivity, and non-volatility. [0080]
For example, it may be silicone oil, mineral oil, or ethylene glycol. [0081]
Second Embodiment [0082]
FIG. 2 shows an essential structure according to a second embodiment of the present invention. [0083]
FIG. 2 shows separating means for separating the processing liquid into the first processing liquid and the second processing liquid on a surface of a lens to be processed as the second embodiment. [0084]
A lens to be processed [0085] 40 is placed on the X-Y table 2 shown in FIG. 1 and a holding member 44 is attached on the base 1.
In the separating means for the processing liquid according to the embodiment, an air curtain utilizing air pressure is formed around a [0086] processing tool 42, whereby the mixing between the first processing liquid and the second processing liquid is protected.
A hollow [0087] cylindrical member 46 attached to the holding member 44 is provided with numerous holes 46A and 46B for supplying compressed air formed at the center.
A first processing-liquid-supplying [0088] pipe 48 is for supplying processing liquid including abrasive grains.
A second processing-liquid-supplying [0089] pipe 50 is for supplying dry-protecting liquid such as water.
In the structure according to the embodiment configured as above, the lens to be processed [0090] 40 is attached on the table 2; the processing tool 42 is urged in contact on a surface to be processed; compressed air at a predetermined pressure is supplied by compressed-air-supplying means 52 toward the lens surface via the supplying holes 46A and 46B while the first processing liquid and second processing liquid are supplied, respectively; and the polishing process is performed.
The supplying [0091] holes 46A are equally spaced in the circumferential direction around the processing tool 42, and the compressed air from the supplying holes 46A strikes on the lens surface so as to form an air curtain 54 for preventing the first processing liquid from dispersing from the vicinity of the tool 42 and for preventing the second processing liquid from moving toward the tool 42.
In the embodiment, when the conditions such as a lens shape, a supplying rate of processing liquid, and a processing tool are the same as those of the first embodiment, the compressed air pressure is 0.2 Kg/cm[0092] ².
Third Embodiment [0093]
FIG. 3 shows a third embodiment, and in the embodiment, sucking means for sucking liquid is provided at the position in which the first processing liquid and second processing liquid are to be mixed with each other so as to prevent the first processing liquid and second processing liquid from being mixed, so that diamond abrasive grains included in the first processing liquid is prevented from entering into the non-processing region. [0094]
As shown in FIG. 3, a [0095] cylindrical member 62 is arranged around a processing tool 60, and the cylindrical member 62 is provided with sucking holes 62A and 62B equally spaced for sucking processing liquid on the surface of a lens to be processed 64.
The sucking [0096] holes 62A and 62B are connected to sucking means 68.
To the processing region inside the [0097] cylindrical member 62, processing liquid is supplied via a first processing-liquid-supplying pipe 66, and to the non-processing region outside the cylindrical member 62, dry-protecting liquid is supplied via a second processing-liquid-supplying pipe 70.
Fourth Embodiment [0098]
FIG. 4 shows a fourth embodiment, and in the embodiment, a [0099] processing tool 80 is provided with a central hole 80A which is connected to a through-hole of a tool-supporting shaft 82, so that abrasive grains are supplied to the processing tool 80 from the upper end of the through-hole.
A [0100] cylindrical member 84 arranged around the processing tool 80 is provided with plural processing-liquid-supplying holes 84A formed therein.
The liquid supplied to the processing-liquid-supplying [0101] holes 84A is water.
A second processing-liquid-supplying [0102] pipe 86 is arranged outside the cylindrical member 84 for dry-protection.
In the embodiment, the liquid supplied from the [0103] holes 84A and the liquid supplied from the processing-liquid-supplying pipe 86 are the same kind of water.
The water supplied from the [0104] holes 84A is mixed with the diamond abrasive grains supplied from the hole 80A at the center of the processing tool 80 so as to form the processing liquid for polishing while the water supplied from the supplying pipe 86 to the outside of the cylindrical member 84 covers the non-processing region of the lens to perform the dry-protection.
While the present invention has been described with reference to what are presently considered to be the preferred embodiments, it is to be understood that the invention is not limited to the disclosed embodiments. On the contrary, the invention is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions. [0105]

Claims

What is claimed is:

1. A polishing method comprising:

supplying liquids functionally different from each other to a processing region which is processed with a tool and a non-processing region, respectively.

2. A polishing method of a surface to be processed of an object, the method comprising:

dividing the surface to be processed into a region to be processed by a processing tool and a region other than the region to be processed; and

supplying different processing liquids according to the divided region.

3. A polishing method comprising:

separately supplying a processing liquid which includes polishing abrasive grains to a region to be processed by a processing tool of an object and a processing liquid without the polishing abrasive grains to a region other than the region to be processed.

4. A processing method of an optical element comprising:

supplying liquids functionally different from each other to a region to be processed by a tool of the optical element and a region other than the region to be processed, respectively.

5. A method according to claim 4, wherein the optical element is fluorite.

6. A processing method of an optical element comprising:

using a processing tool having a processing area which is small relative to a processed area of a surface of the optical element; and

supplying liquids functionally different from each other to a region to be processed by the processing tool and a region other than the region to be processed, respectively.

7. A processing method of an optical element comprising:

supplying a liquid having a polishing function to a processed surface of the optical element and a liquid having a dry-protecting function to a region other than the processed surface of the optical element.

8. A processing method of an optical element comprising:

supplying a liquid having a dry-protecting function to a region other than a processed surface of the optical element.

9. A processing method of an optical element by polishing, the method comprising:

keeping a region other than a processed surface of the optical element in a non-dry state during processing.

10. A processing method of an optical element by polishing, the method comprising:

keeping a region other than a region processed by a tool of the optical element wet during processing.

11. A processing method of an optically functional surface of fluorite comprising:

keeping a region other than a region processed by a tool for processing the optically functional surface of the fluorite in a non-dry state during processing.

12. A processing method of an optically functional surface of fluorite comprising:

supplying a liquid for dry-protecting to a region other than a processed region on the optically functional surface during processing the optically functional surface.

13. A processing apparatus for polishing an optical element comprising:

a plurality of supplying means for supplying processing liquid to a surface to be processed of the optical element.

14. An apparatus according to claim 13, wherein the kind of the processing liquid supplied by the supplying means for supplying processing liquid differs according to the region on the processed surface to which the processing liquid is applied.

15. An apparatus according to claim 14, further comprising dividing means for dividing the processing liquid.

16. A processing apparatus for polishing an optical element comprising:

first processing-liquid-supplying means for supplying processing liquid to a region to be processed of the optical element;

dividing means for dividing a region other than a region processed by the tool on the surface of the optical element; and

second processing-liquid-supplying means for supplying processing liquid to a region other than the processed region.

17. An apparatus according to any one of claims 13 to 16, wherein the optical element is fluorite.

18. An apparatus for processing a surface of an optical element comprising:

supplying means for supplying a plurality of processing liquids functionally different from each other to the surface to be processed of the optical element; and

mixture preventing means for preventing the plurality of processing liquids from mixing.

19. An apparatus according to claim 18, wherein the mixture preventing means is compressed air.

20. An apparatus for processing a surface of an optical element comprising:

means for supplying processing liquids functionally different from each other to the surface to be processed of the optical element and for independently recovering the processing liquids.

21. An apparatus according to any one of claims 18 to 20, wherein the optical element is fluorite.

22. A fluoride lens prepared by a process comprising:

supplying a first processing liquid to a portion to be processed by a processing tool and supplying a second processing liquid to a region other than the portion to be processed by the processing tool during processing of an optical surface of the lens.