WO1994004948A1

WO1994004948A1 - Apparatus for providing autostereoscopic and dynamic images and method of manufacturing same

Info

Publication number: WO1994004948A1
Application number: PCT/US1993/007784
Authority: WO
Inventors: Richard A. Steenblik; Mark J. Hurt
Original assignee: Applied Physics Research, L.P.
Priority date: 1992-08-18
Filing date: 1993-08-17
Publication date: 1994-03-03
Also published as: US5461495A; US5568313A; AU5080293A; US5359454A

Abstract

A light control material having a two-layer optical system (Fig. 4a, its 31 and 32) producing autostereoscopic and dynamic images in thin-film materials. The first layer (31) comprises focusing optics which have a plurality of focusing elements. These elements may consist of refractive optics, binary optics, or mixed optics. The second layer (32) comprises light control optics having dark zones (34) and bright zones (33) for providing directional control of light through the focusing optics (31). The bright zones (33) may be comprised of a light transmissive material, or the light control optics may include a reflective layer for reflecting light at the bright zones. The dark zones (34) may be formed by creating light traps in the light control optics which absorb light. The light traps (Fig. 4b, it. 34) are comprised of structures having high aspect ratios. The light entering the light trap is reflected internally until all of the incident light has been absorbed. By controlling the number of bright zones (33) and dark zones (34) per focusing element (35), the field of view (Fig. 4c, it. 47) of an autostereoscopic or dynamic image can be controlled. A method for creating the light control material includes the steps of applying liquid photopolymer to opposite sides of a transparent substrate (Fig. 12) and embossing each side of the then created substrate to form the focusing and light control optics.

Description

APPARATUS FOR PROVIDING

AUTOSTEREOSCOPIC AND DYNAMIC IMAGES

AND METHOD OF MANUFACTURING SAME

This application is a continuation-in-part of a currently pending U.S. application having application Serial Number 07/931,871 filed August 18, 1992, entitled "Apparatus for Providing Autostereoscopic and Dynamic Images".

TECHNICAL FIELD The present invention relates to the production and display of autostereoscopic and dynamic images, and more particularly to a technique for producing autostereoscopic and dynamic images in thin-film material. The present invention further relates to controlling the field of view of autostereoscopic and dynamic images. BACKGROUND OF THE INVENTION

Currently, image display methods which enable the presentation of multiple images from different viewing angles fall into three broad categories: projection-type (non- holographic) displays, lens-sheet displays and holographic displays. Any of these methods can be used to display autostereoscopic depth images, motion images and color changing images.

The most common technique of producing projection-type displays is the barrier strip method. A barrier strip display device consists of an interleaved image which typically consists of strips taken from each of the images that are to be displayed. The strips comprising each of the images are interleaved parallel to each other so that every Nth strip is from the same image, where N is the number of images. This number may be as small as two or as large as nineteen or more.

The interleaved image is disposed in close proximity to and parallel to a viewing mask. The viewing mask contains parallel opaque lines of equal width which are separated by transparent zones having a uniform width which is equal to or less than that of the opaque lines. Barrier strip images are usually viewed from the mask side by means of light transmitted through the interleaved image and the mask. The intensity of the back illumination required depends on the brightness of the viewing environment and on the number of images which are interleaved. The color that is perceived at a particular point and at a particular viewing angle with a barrier strip display device is determined by the color of the image strip which is visible through the mask at that point.

Though barrier strips are capable of displaying autostereoscopic images, a barrier strip display device will produce this effect only when certain conditions are satisfied. First, the mask lines must lie in a plane orthogonal to that of the observer's eyes. Also, the width and spacing of the transparent mask lines and the distance from the interleaved image to the mask must be such that each of the viewer's eyes sees different, non-overlapping regions of the interleaved image through the transparent mask lines. The interleaved image must have been constructed such that each of the image lines visible to the right eye is part of a right eye stereo pair image, and the image lines visible to the left eye are each part of a matching left eye stereo pair image. The distances and positions at which stereoscopic depth is perceived is restricted by the geometry of the mask, the number of interleaved images and the mask-to-image distance.

In addition to the difficulty in achieving an autostereoscopic effect, a significant limitation on barrier strip image devices is that the thickness of such a device is governed by the number of images it presents, the width of the image strips and the intended viewing distance. The distance between the barrier strips mask and the interleaved image is generally a large multiple of the width of a single image strip. A typical barrier strip device has a thickness of about six (6) millimeters, making it an unacceptable technology for mass production. The barrier strip method is further limited in that it is only useful as a back- illuminated image display method.

Among the most common lens-sheet display techniques are integral photography, integrams and lenticular sheets. Integral photography (referred to in the trade as the "fly- eye" approach) involves photographing an image through a plastic sheet into which small fly's-eye lenses (typically 50,000 lenses per sheet) have been impressed. The lenses cause a complete reproduction of the photographed image to be reproduced behind each tiny lens. This approach can recreate a visually complete three-dimensional image, but can only be reproduced at great expense. A further limitation of this lens sheet is that the images are at such a fine resolution that they cannot be reproduced on printing presses, but have to be reproduced photographically. Images produced by this method also have a very restricted viewing angle within which the image reconstructs correctly.

The integram approach to lens-sheet displays is a complex extension of the fly-eye approach. It involves positioning the captured image along a precisely curved surface

(dimensionally matching the focal surface of the fly-eye lens) to overcome the viewing angle restrictions. The expense and difficulty in producing high quality three-dimensional images with this method, however, have prevented any large scale commercial success.

A third method of the lens-sheet display technique currently known is the lenticular screen display device. A lenticular screen display device employs an array of cylindrical lenses to control the viewing angle of interleaved image strip. The lenses are disposed parallel to the image strips between the observer and the image strips such that the image strips directly underneath a lens lies at or near the lens' focal plane. The range of angles through which the image will be visible is determined by the position of each image strip underneath the lens array. As with the barrier strip method, the color of the image strip determines the color that will be perceived at the point of the lenticular screen processed image.

As with the barrier strip method, a significant limitation on the lenticular screen display device is that its thickness is dependent on the width of the image strips. The thickness also is limited by the number of images presented, the designed viewing distance, and the focal properties of the lens. The thickness of these devices is in general greater than the width of the image strip multiplied by the number of images. As a result, a typical lenticular screen display device has a thickness of about one (1) millimeter, making it relatively expensive for mass production, and generally too thick for automated printing press equipment. The third broad category of currently known methods of producing and displaying autostereoscopic ^— images is holographic displays. Holographic displays use holograms to reconstruct the appearance of an object over an angular range __ of view without the use of a lens. A hologram is a record of a diffraction pattern representing an object as viewed from a certain range of positions. There are many types of holograms, each of which possesses its own range of viewing conditions. Some holograms require laser illumination for the reconstruction of an image, while others can be viewed by means of incoherent white light. Holograms displaying full color over a range of viewing angles normally require illumination by three lasers - red, blue and green simultaneously. White light viewable holograms are generally either monochromatic or display a rainbow coloration which varies according to the viewing angle. Holograms are capable of displaying autostereoscopic, motion, combined autostereoscopic and motion, and color-change images. However, creating and reproducing a high quality hologram is a time-consuming and difficult process. Holograms cannot be created by printing and are not easily combined with the mass production of printed articles. Holograms are expensive and difficult to originate. They also require special equipment to impress onto a printing substrate. Because of their restrictive viewing conditions and limited control of color, the practical applications of holographic displays is very limited.

Until the present invention, no one has developed a device for providing printed autostereoscopic and dynamic images on thin-films (e.g., those with the approximate thickness of conventional paper) . Due to their thickness limitations, neither the barrier strip devices nor the lenticular screen devices are amenable to the production of thin-film images. This has prevented the widespread application of these devices because conventional printing presses are designed to handle paper and paper-like materials. The thickness of barrier strips and lenticular screen display devices also makes them inherently stiff, further limiting their mass production potential. These devices are further limited in application because of the inherent inflexibility in the location of the printing within their structure. The print must be at the focus of the lenticular screen or be on the opposite side of the substrate from the barrier strips. It is not possible to print on top of the lenticular screen nor on top of the barrier strip surface and still retain the ability to display the desired set of multiple images.

SUMMARY OF THE INVENTION

The present invention comprises an apparatus for producing thin-film autostereoscopic and dynamic images. The present invention differs from a conventional lenticular screen display structure in that the thickness of the present structure is independent of the width of the image strips. The invention is therefore capable of producing autostereoscopic and dynamic images with a structure that is approximately as thin as conventional typing paper, on the order of two to three (2-3) mils, or 50 to 75 microns, thick. This is accomplished through the use of a light control material comprised of a multi-layer optical system. In one embodiment of the present invention, the first layer of the optical system (generally referred to as the "outer optic", i.e., the layer closest to the observer) consists of focusing elements. These elements may consist of refractive cylindrical lenses, diffractive optic lenses or mixed optic lenses. The second layer consists of light control optics (often referred to as the "inner optic"). This layer is designed to provide directional control of the light passing out through the outer optic to the observer. The inner optic consists of a pattern of bright zones disposed parallel to the axial direction of the outer optic lenses. Light absorbing or light dispersing zones (dark zones) separate the bright zones on the inner optic from each other.

In the present invention, the inner and outer optics cooperate to perform the light directional control function. This differs from the conventional approach in which the light directional control function is performed solely by the position of each image element under the lenticular screen. The image to be displayed is divided into a number of image elements. To produce an autostereoscopic or dynamic image, it generally is desirable to direct the light passing through a single image element in a particular direction. In the present invention, the inner optic pattern is designed to direct the light emitted from all the lenses . associated with that image element in the same direction. If it is desirable to direct the light passing through the adjacent image element elsewhere, the inner optic pattern may be adjusted in that area to send all of the emitted light in the desired direction. The end result is that the present invention enables an observer to perceive one image element with one eye and a different image element with the other eye, thus creating the perception of autostereoscopic depth, motion or color change. The present invention provides for controlling the field of view of the autostereoscopic or dynamic image, or the angles through which an observer will perceive an autostereoscopic or dynamic image. The field of view is controlled by providing a plurality of bright zones for each lens. The bright zones are separated by dark zones. When the field of view is narrowed, the distance from which an observer will see an autostereoscopic image is increased. The field of view is narrowed by decreasing the width of each of the bright zones. By having a plurality of bright zones separated by dark zones for each lens, the brightness of the image is maintained. Furthermore, the pattern of the bright zones and dark zones is such that the interlacing of the images is maintained. The present invention may be used as a transmission material, in which case the bright zones of the inner optic are substantially transparent and the image is back- illuminated. It may also be used as a reflection material, in which case the bright zones of the inner optic may be specularly reflective, diffusively reflective, or may bear a reflective diffraction pattern which concentrates light from one direction and redirects it towards the observer.

In a second embodiment, a low refractive index layer, preferably a polymer, is applied to the layer of high refractive index focusing optics. The polymer creates a smooth surface which is more suitable for printing than conventional devices.

In a third embodiment, the position of the focusing optics and the light control optics is reversed. In this third embodiment, the light control optics, including the bright and dark zones, is the outer layer of the light control material and the focusing optics are positioned underneath the light control optics.

The light control material of the present invention is intended for use with a series of image elements which have the effect of serving as a color filter. Unlike prior approaches, the image elements may be positioned between the focusing optics and the light control optics or to one side or the other of the bi-layer optics as described in more detail below. The positioning of the image elements is unrelated to the focal length of the focusing optics.

Accordingly, it is an object of the present invention to provide a method for producing novel materials which display multiple images from different viewing directions. It is also an object of the present invention to provide a method for producing multiple-image display materials in which the thickness of the material is independent of the image strip width.

It is another object of the present invention to provide means for controlling the field of view of the autostereoscopic image.

It is another object of the present invention to provide an embossing system for embossing the light control optics and the focusing optics onto opposite sides of a film. It is also an object of the present invention to provide a method for producing autostereoscopic images in thin film materials.

It is a further object of the present invention to provide a method for printing thin film autostereoscopic images.

It is yet another object of the present invention to provide a method for producing engineered light control films. It is still another object of the present invention to provide a method for increasing the brightness of printed images.

A further object of the present invention is to provide a method for producing thin film images which display motion.

It is a final object of the present invention to provide a method for producing thin film images which display color changes when viewed from different angles. BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is a cross-sectional view of a prior-art conventional lenticular screen structure.

Figs. 2a-2c are cross-sectional views of a conventional lenticular screen structure illustrating the direction of view from each of the right, center, and left image strips.

Figs. 3a-3b are comparison scale drawings illustrating the thickness of a conventional lenticular screen structure and that of the present invention. Fig. 4a is a cross-sectional view of a first embodiment according to the present invention including three image elements.

Fig. 4b ilustrates an alternative embodiment of the light control optics of the present invention. Fig. 4c illustrates how the field of view is controlled.

Fig. 5 is a cross-sectional view of the first embodiment of the present invention.

Fig. 6 shows a first alternative embodiment of the light control optics of the present invention. Fig. 7 shows a second alternative embodiment of the light control optics of the present invention.

Fig. 8 shows a third alternative embodiment of the light control optics of the present invention.

Fig. 9 is a cross-sectional view of another alternative embodiment of the present invention.

Fig. 10 is a cross-sectional view . of a further alternative embodiment of the present invention.

Fig. 11 is a cross-sectional view of yet another alternative embodiment of the present invention. Fig. 12 shows a functional block diagram of the embossing system of the present invention.

Fig. 13a illustrates the interference pattern utilized by the laser scale detection unit.

Fig. 13b illustrates a functional block diagram of one of the detectors of the laser scale detection unit. Figs. 14a-14g illustrate a method for creating the light control optics and focusing optics masters.

Figs. 15a-15d illustrate a preferred embodiment for forming the dark zones in the light control optics master. Figs. 16a-16b illustrate an alternative embodiment for forming the dark zones in the light control optics master.

Figs. 17a and 17b illustrate an alternative embodiment for creating the light control optics master.

DETAILED DESCRIPTION Referring now in detail to the drawing figures, in which like reference numerals represent like parts throughout the several figures, Figs. 1 and 2a-c show a conventional lenticular screen display device 20, which consists of a layer of optical material 21 bearing an array of cylindrical lenses 22 on its upper surface and an image 23 in contact with its lower surface. The image 23 is generally supported upon a substrate 24. The image 23 is typically created _%by interleaving image strips from a multiplicity of images. If, for example, three images are used, then image 23 would consist of right, center, and left image strips 26, 27 and 28.

Fig. 2a depicts how the array of lenses 22 in the conventional lenticular screen display device 20 controls the direction of view of each of the right image strips 26. Light reflecting from each image strip 26 is directed by the lenses 22 toward the observer's right eye. Fig. 2b depicts that the center image strips 27 are located adjacent to the right image strips. By virtue of their different positions underneath the lens array 22, the light reflected from the center image strips 27 is directed by the lenses 22 in a slightly different direction than that of the right image strips. Light form these strips may be intercepted by the observer's left eye. In the case of an autostereoscopic image, the observer would be viewing a stereo pair, different images with each eye, and would thus perceive a stereoscopic image. Fig. 2c depicts how light reflecting from the left image strip is similarly directed in a third direction. If the observer's position changes such that the center image is intercepted by the right eye and the left image is intercepted by the left eye, a slightly different view of the autostereoscopic scene will be perceived, since right and center images comprise a stereo pair, and center and left comprise a stereo pair.

The width of the individual lenses in the conventional lenticular screen method must be some multiple, n, of the image strip width, where n is an integer. Because of the limitations of the focusing optics 22, the thickness of the lens in a lenticular screen display device will also be some multiple of the print strip width 29, as shown in Fig. 3a.

The minimum strip width of printed images is set by the smallest shape which can be reliable printed, which will generally be the size of a single print dot. Printing presses vary in their printing resolution, but a commercial printing press rarely exceeds a printing resolution of 175 lines/inch, or a print dot spacing of about six thousandths of an inch

(152 microns) . As a result, the width and thickness of a conventional lenticular screen device 20 can never be less and is typically much larger than the dimensions of the print dot spacing.

The present invention circumvents this size limitation. The thickness of the present invention is independent of the print dot spacing and the size of the print. Fig. 3B illustrates the relative thickness of the present invention 30 for the same print width 29. Figs. 3A and 3B are drawn to the same scale to show the magnitude of the difference between the thickness of a conventional lenticular screen device and that of the present invention for the same print width. The optical thickness of the present invention for images printed at 175 lines/inch would typically fall in the range of from 1- 3 mils, compared with 17 to 50 mils for a conventional lenticular screen device. Referring now to Fig. 4a, the basic operation of the present invention will be described. The light control material 30 comprises a two-layer optical system separated by a refractive material 36. It is the two-layer optical system that allows the thickness of the device to be independent of the print size. In one embodiment of the present invention, the first layer comprises focusing optics 31 and is sometimes referred to as the "outer optic" (i.e., closest to the observer) . The focusing optics 31 generally consist of an array of lens elements 35. The second layer contains light control optics 32 and is sometime referred to as the "inner optic" . The layer of light control optics 32 consists of a pattern of bright zones 33 disposed generally parallel- to the axial direction of the focusing elements 35. The bright zones 33 are separated from each other by dark zones 34, which may be either light absorbing or light dispersing. The composition of the focusing optics 31 and the light control optics 32 will be discussed in detail below.

Fig. 4a also illustrates the cooperation of the focusing optics 31 and the light control optics 32 for light directional control. In Fig. 4a the light source (not shown) is located underneath the light control optics 32, and the light control material 30 is operating in a light transmissive mode. Three image elements (left image element 41, center image element 42, and right image element 43) are placed above the focusing optics 31. While Fig. 4a shows three image elements, the present invention is not limited to that number of image sets. The device will operate with as few as two sets of image elements (e.g., up/down or left/right) or with many more than that. Some applications which are not brightness sensitive could tolerate (and benefit from) a large number of image sets, such as four, five, or more. The relative positions of the image elements 41-43 and the focusing optics also is not important. The light directional control function may be performed with the image elements 41- 43 placed either above the focusing optics 31 as shown in Fig. 4a, in between the focusing optics 31 and the light control optics 32, or below the light control optics 32.

Assuming the device is operating with three sets of image elements, the light control material is divided into three image zones - a left image zone 51, a center image zone 52 and a right image zone 53. The center image zone 52 is formed by positioning the associated bright zones 33 directly below the center of the lens elements 35. Light passing through the center image zone 52 will be directed through the focusing optics 31 above it and transmitted through the center image element 42 as center directed light (this light may be intercepted by the observer's right eye). The left image zone 51 is formed by laterally shifting the position of the associated bright zones 33 to the right so that the center of the bright zones are no longer aligned with the center of the lens elements 35. Light passing through the left image zone 51 will then be directed through the left image element 41 and transmitted as left directed light (this light may be intercepted by the observer's left eye, forming a stereo pair with the center image zone light directed to the right eye) . The right image zone 53 is similarly formed by laterally shifting the associated bright zones 33 to the left. Light passing through the right image zone 53 will be directed through the right element 43 and transmitted as right directed light (if the observer's position shifts so that the center image light is intercepted by the observer's left eye, then the right directed light may be intercepted by the observer's right eye, forming a stereo pair) . The image elements 41-43 can be composed of transparent, colored print dots that serve to color the light but will not control the directions of visibility of the lenses depicted. The resulting system therefore enables an observer to perceive one set of image elements from one eye and a different set of image elements from the other eye, thereby creating the perception of autostereoscopic depth, motion or color change.

Fig. 4a shows three sets of lenses 35 for each image element for simplicity. However, the present invention need not be limited to this number. The number of lenses that are spanned by each image element will be a design variable, depending on the printing resolution, the width of the image elements, and the size of the lenses. The actual number of lenses devoted to a single image element can range from one lens to more than twenty. A typical number will be six to nine lenses per image element. The image elements do not necessarily have to cover the entire surface of the light control material. In general, each image element need only lie over its respective image zone, but the image elements do not have to be in perfect registration with the image zones. Also, the spacing between the image elements is not critical. Each image element does not have to be equally spaced from he edge of its respective image zone.

Fig. 4b illustrates how the present invention enables the field of view (F.O.V.) to be adjusted without altering the distance between the light control optics 32 and the focusing optics 31. The field of view 46 corresponds to the area over which an observer will see a particular image element. With the light control material 30, Fig. 4a, the field of view can be adjusted by selectively altering the distance between the inner and outer optics and by correspondingly adjusting the focal length of the outer optic. As indicated in Fig. 4b the field of view 46 is related to the distance 44 between the inner and outer optics and the width of the bright zones 45. The relationship is described by the equation F.O.V. = arc tan (w/h) . If the widths of the bright zones 45 in Fig. 4b are decreased, the fields of view 46 become narrower. However, merely decreasing the widths of the bright zones will distort the interlacing of the images with respect to the observer. Furthermore, merely decreasing the width of the bright zones will decrease the amount of brightness coming from the light control optics 110, thereby decreasing the brightness of the image. Increasing the width of the bright zones will expand the fields of view but it will also distort the interlacing of the images with respect to the observer.

Fig. 4c illustrates how the fields of view can be controlled without decreasing the amount of light coming from the light control optics and without distorting the interlacing of the image. In the embodiments of Figs. 4b and 4c, two sets of image elements (not shown) are utilized to obtain the autostereoscopic image. By decreasing the widths of the bright zones 33, the fields of view 47 are narrowed. However, the amount of light coming from the inner optic 32 has not decreased since there are two bright zones 33 under each lens 35, the sum of the areas of which equals the area of one of the bright zones 33 shown in Fig. 4b. Also, the alternating pattern of the bright and dark zones in the inner optic shown in Fig. 4c maintains the interlacing of the images with respect to the observer. Therefore, by having multiple bright zones with respect to each lens, the field of view can be controlled while maintaining the brightness and interlacing of the images. Furthermore, the field of view can be controlled in this manner regardless of the number of sets of image elements utilized to create the autostereoscopic image. However, the pattern of the bright and dark zones in the inner optic will vary depending on the number of sets of image elements used to create the autostereoscopic image. The period of the light control optics, as indicated by the pattern of bright zones and dark zones, changes from one image strip to the next (i.e., in accordance with the interleaving of the image strips) . Although Fig. 4c illustrates two bright zones for each lens, the present invention is not limited to a particular number of bright zones and dark zones for each lens. Furthermore, the bright zones can be transmissive or reflective, although the preferred embodiment of the invention utilizes bright zones which are reflective.

The light control optics shown in Figs. 4b and 4c represent a preferred embodiment of the present invention for the bright zones and dark zones. Cylindrical reflectors can be used to create the bright zones. By using cylindrical reflectors, light is reflected from the light control optics through a wide range of viewing angles. The light reflected from the light control optic avoids any specular reflection off of the surface of the image, thereby avoiding glare and enhancing the brightness of the image. Other arcuate reflectors, such as domes or ellipses, can also be used in the light control optics. When ellipses are used, an even wider range of viewing angles is realized. However, the intensity of the light reflected from the inner optics will be somewhat less when ellipses rather than cylinders are used as the bright zones.

The shape of the reflector used in the light control optic is selected in accordance with the range of viewing angles over which the brightness of the image is intended to be enhanced. Also, inverted dome-shaped (i.e., dish-shaped) reflectors can be used in the light control optic instead of dome-shaped reflectors. The effect of using dome-shaped or inverted dome-shaped reflectors is essentially the same, i.e., both enhance the brightness of an image over a particular range of viewing angles. The bright zones will be arcuate in shape regardless of whether the light control optic is operating in a transmissive or reflective mode. The light control optic will be coated with a reflective layer of metal when it is operating in the reflective mode. When operating in the transmissive mode, the bright zones will not be coated with a reflective layer of metal. The light control optic will be discussed in greater detail below.

The dark zones 34 are preferably comprised of a field of tapered elements. The tapered elements are formed by using reactive ion etching with oxygen as the reactive gas to create a non-uniform etch in a photopolymer. The result is a light trap comprised of stalagtite shaped structures which have large height-to-width ratios. The light traps will be described in detail below with respect to Figs. 14a-17b.

While Fig. 5 shows the bright zones in the center image zone 52 aligned directly beneath the center of the associated lens elements 35, this alignment is not critical to the performance of the invention. The actual position of the lens elements over the light control optics is not important. What is important is the pattern of the light control optics 32. The spacing of the bright zones is periodic in each image zone so that the period of the bright zones matches the period of the lens elements. As long as the lateral spacing of the light control optics is fixed and the lateral positioning of the focusing optics is fixed, the relative positions of the two layers is not important. This allows "slip" in he operation of the device and thus makes it easier to manufacture. Viewed from above without any image elements, an observer looking at the light control material would see a set of very fine bright strips separated by very fine black strips. The relative width of the bright strips would depend on the pattern of the light control optics. With one eye, an observer would see one set of strips that are bright. The other eye would see a different set of strips that are bright. The set of strips that appear bright with the left eye will appear dark with the right eye, and vice versa. When the image elements are imposed onto the light control material, the observer is able to see one image element set with one eye and another image element set with the other eye, thus creating the perception of autostereoscopic depth, motion or color change.

Referring now to Fig. 5, the details of the focusing and light control optics will be explained. The focusing optics 31 consists of an array of refractive cylindrical lenses 35. Alternatively, the focusing optics may consist of diffractive lenses, hybrid refractive/diffractive cylindrical lenses, or reflective focusing troughs of conventional geometry, diffractive form or hybrid form. These lenses 35 will generally be made from a photopolymer 66 or other photo- initiated acrylated epoxies. A preferred method for producing the focusing optics is by "soft" embossing the photopolymer 66 onto an optical substrate 65, i.e., casting the liquid plastic against a roller that has the desired geometry and allowing it to cure. While "soft embossing" is preferred, other methods may be used to produce the focusing optics. For example, "hard" embossing, i.e., impressing a soft, but not liquid, plastic against a roller that has the desired pattern, can also be used to obtain the same desired effect. Additional methods suitable for producing the focusing optics include injection molding, compression molding, extrusion, and casting. The soft embossing technique is preferred because it generally enables higher precision replication than hard embossing and it also reduces the amount of tool wear. The width of the individual lenses 35 in the focusing optics 31 is very small, generally falling in the range from 8 to 25 microns.

Fig. 5 is a small enlarged section of the light control material of the present invention, showing a single image element 64 positioned between the focusing optics 31 and the light control optics 32. As noted above, however, the invention also will produce the desired effects if the positions of the image element 64 and focusing optics 31 are reversed.

The photopolymer 66 is embossed onto a transparent optical substrate 65. This substrate will preferably be a polyester material, but other commercial plastic film materials such as polypropylene can also be used. The second layer of the light control material 30 contains light control optics 32. The light control optics 32 are designed to provide directional control of the light passing out through the focusing optics 31 to the observer. The layer of light control optics 32 consists of a pattern of bright zones 33 separated from each other by dark zones 34. In one embodiment, the distance from one edge of one bright zone 33 to the corresponding edge of the next bright zone is the same as the width of one lens above it. In another embodiment, the dark zones 34 are formed by applying an opaque material 67 onto those areas of a reflective surface 68 that are to absorb incident light. The opaque material 67 preferably comprises pigmented ink, but any light absorbing optical structure or light dispersing optical structure can also be used. Those zones of the reflective surface 68 not covered by the opaque material 67 form the bright zones 33 of the light control optics. Optionally, those areas that are,to be bright zones 33 can also be formed by applying a diffractive, holographic, or diffusing pattern 69 on the bright zones of the light control optics. The reflective surface 68 conforms to diffractive, holographic, or diffusing pattern 69. The addition of a diffractive pattern 69 to the surface 68 serves to enhance the brightness of the bright zones 33 at chosen viewing angles. The light control optics 32 may be embossed with the same photopolymer 66 that is used to emboss the focusing optics 31. Layer 68 consists of a layer of highly reflective metal, preferably aluminum.

In the embodiment of Fig. 5, the light source (not shown) is above the focusing optics 31, and the invention will operate in a light reflective mode as compared to the light transmissive mode of the embodiment shown in Fig. 4a.

While Fig. 5 shows one embodiment of the invention, there are numerous alternative ways of designing the light control optics, as shown in Figs. 6-8. Fig. 6 shows an alternative design in which the geometric pattern of the light control optics 132 is the reverse of that shown in Fig. 5. In other words, the bright zones in this embodiment are located in those areas where the dark zones were located in the first embodiment. In this embodiment, the dark zones 134 are formed in the recessed notches created in the reflective substrate 168 with an opaque material 167 and the bright zones 133 are formed between. The relative positions of the dark zones and the bright zones along the light control optics are reversed from that of the embodiment shown in Fig. 5. In the embodiment of Fig. 6, the present invention will function in a light reflective mode due to the presence of the reflective layer 168.

Fig. 7 shows a second alternative design for the light control optics 232. In this design, the opaque material 267 is in effect the substrate. The bright zones 233 are shown with . a reflective layer 268, preferably of aluminum, and a diffractive pattern 269. The bright zones 233 here are formed by covering selected portions of the opaque substrate with reflective layers 268. Fig. 8 shows a third alternative design for the light control optics. In this embodiment, the light control optics 332 consist of a photographic emulsion layer 376. The bright zones are formed as transparent emulsion zones 378, and the dark zones are formed as opaque emulsions zones 379. A transparent material 366 (preferably a photopolymer) is layered below the photographic emulsion layer 376. Below the transparent material 366, a reflective layer 368 is applied to the diffractive pattern 369 so that the device will function as a reflective material. Fig. 9 shows another embodiment of the invention in which focusing optics 431 with a high refractive index are embedded in a low refractive index layer 471. Image elements 443 are located on top of layer 471. An inner optic 432 comprised of bright zones 433 and dark zones 434 is also provided. The focusing optics 431 will preferably be made from a photopolymer 466 with a refractive index of up to about 1.55, but other photopolymers with refractive indexes of about 1.6 can also be used. The low refractive index layer 471 will preferably consist of a polymer. The polymer does not necessarily have to be a photopolymer, but one could be used if it had a low enough refractive index. It is desirable that the polymer have as low a refractive index as possible in order to counterbalance the high refractive index of the focusing optics 431. Examples of polymers that can be used for the low refractive index layer 471 (and their respective refractive index) are polytetrafluoroethylene (PTFE, "Teflon") (1.35) , fluorinated ethylene propylene (FEP) (1.34), polyvinylidene fluoride (PVDF) (1.42) , and polytrifluorochloroethylene (PTFCE) (1.43) . The function of the low refractive index layer 471 is to make the surface of the light control material smooth, thereby making the device more amenable for printing. The low refractive index layer may be formed by, for example, a melt process allowing the polymer to be applied as a liquid and to be self-leveling. The low refractive index layer 471 may also be used as an adhesive between the high refractive index lenses 431 and a polymer film having better printing characteristics. The focusing optics 431 are designed with a particular radius of curvature depending on the refractive index of the polymer. The lower the refractive index of the polymer 471, the lower the curvature of the lenses. The closer the refractive index of the polymer 471 approaches the refractive index of the photopolymer 466, the more curved the lenses have to be. The higher the refractive index of the photopolymer 466, the thinner the light control material. The greater the difference between the refractive indices, the shorter the focal length of the lenses. The smaller the difference, the longer the focal length of the lenses. Preferably, the difference between the refractive indices is on the order of 0.1 or greater. The photopolymer 466 is embossed onto an optical substrate 465, consisting of a commercial plastic film such as polyester. In this embodiment, the refractive index of the optical substrate 465 is not critical. A change in the refractive index of the optical substrate 465 is easily compensated for by changing the thickness of the plastic film material. In general, the higher the refractive index of the optical substrate, the thicker the film material required. Photopolymer 466 is also used to fill the dark zones of the inner optic 432. For this purpose photopolymer 466 carries an opaque pigment.

Fig. 10 shows a further alternative embodiment for the light control optics 632 of the present invention. In this embodiment, the substrate is formed of a reflective layer 668 which comprises both bright zones 633 and dark zones 634. The bright zones have a diffractive pattern 669. The dark zones are formed of fields of tapered elements. In their preferred form the tapered elements in the dark zones have an aspect ratio of their height being 4 times their width or greater. In this manner, light entering the dark zones does not reflect back out of the dark zones. A photopolymer 666 as previously described covers the substrate.

Fig. 11 shows another embodiment of the invention in which the relative positions of the focusing optics and light control optics are reversed. This embodiment also is formed using a transparent substrate 565. The light control optics 532, here used as the "outer optic", consists of zones 534 which appear dark from the outside of the structure but reflective from the inside of the structure, which zones are made by applying an opaque material 567 to a reflective substrate 568, such as aluminum. A diffractive pattern 569 may also be applied to the reflective substrate 568 to enhance the brightness of the image element 564. The dark zones of the light control outer optic consist of the transparent spaces between the reflective zones. The opaque material 567 prevents the reflective substrate regions 568 from reflecting light back to the observer without having first been reflected from the focusing optics 531. The focusing optics 531 are likewise used as the "inner optic" in this embodiment. The focusing elements are formed by embossing a photopolymer 566 to a transparent substrate 565 and coating the photopolymer surface with a reflective substrate 570. In this embodiment, the focusing optics 531 will function as focusing reflectors. The same photopolymer or other transparent embossing material 566 may be used to emboss the focusing optics 531 and the light control optics 532.

Fig. 12 illustrates a block diagram of the embossing system used to emboss the focusing optics and the light control optics onto a film. Film Roll 701 is a roll of treated polyester or treated polypropaline which functions as the substrate upon which the inner and outer optics will be embossed. As the film 700 passes over the roller 702, the top surface of the film 700 is coated with a layer of liquid photopolymer. Roller 702 is preferably a Gravure roller which is a metal roller having a large number of very small pits etched into the surface. At the top of the roller there is a reservoir of liquid photopolymer (not shown) . As the liquid photopolymer is applied to the surface of roller 702 from the reservoir, roller 704 scrapes the surface of roller 702 thereby allowing only the liquid photopolymer in the pits to remain on the roller. The excess liquid photopolymer is scraped away. This allows a metered amount of liquid photopolymer to be applied to the top surface of the film 700.

The film is then moved over embossing roller 705 which carries the master for the focusing optics. Rollers 705 and 706 are preferably thermosiphon chill rolls. A thermosiphon is an evacuated roller which is filled with a working fluid. The roller contains a large number of water cooling lines 703 which are located in close proximity to the surface of the roller. The working fluid is kept in contact with the surface of the roller through centrifugal force.

As heat is applied to the surface of the roller, the working fluid in contact therewith immediately evaporates. As the vapor comes into contact with the water cooling lines, it condenses and drips back down into the working fluid. This isothermal process allows large amounts of heat to be absorbed very uniformly while maintaining the entire surface of the roller at a constant temperature. ' As the film moves over the embossing roller 705, the pattern of the focusing optics is formed in the liquid photopolymer. Once the pattern has been formed in the liquid photopolymer, ultraviolet light is applied to the film. This causes the photopolymer to harden and bond to the film. In general, during the hardening process the pattern formed in the -photopolymer shrinks. By using the thermosiphon as the embossing roller, the photopolymer is maintained at a constant temperature. This reduces the possibility of local hot or cold spots in the photopolymer which result in nonuniformity in the scale of the pattern formed in the photopolymer. Once the focusing optic pattern has been formed, a laser scale detection unit 707a, b (described in detail below) is used to determine whether the scale of the outer optic embossment is correct. The film with the focusing optics embossed thereon is then moved over a second Gravure roller 712. Gravure roller 712 in conjunction with roller 714 applies a metered amount of liquid photopolymer to the bottom surface of the film 700. The film is then moved over embossing roller 706 which carries the master for the inner optic. Once the inner optic pattern has been formed in the liquid photopolymer, ultraviolet light is applied to the film, thereby causing the photopolymer to harden and bond to the film.

The film having the inner and outer optic embossments formed thereon is then examined by a second laser scale detection unit 711a, b to determine whether the patterns are sufficiently close in scale. This information is then sent to the control unit 710. The control unit 710 receives information from the laser scale detection units and controls the temperatures of the thermosiphons 705 and 706 in accordance with this information. Therefore, the temperature of the thermosiphons 705 and 706 can be adjusted such that the scale of the inner optic embossment matches the scale of the outer optic embossment by means of thermal expansion and contraction of the embossing rollers 705 and 706.

Fig. 13a illustrates how the laser scale detection unit determines the scale of the embossments. The width of laser beam 716 is typically on the order of 1 millimeter. The focusing elements of the focusing optic 715 are typically on the order of 24 microns. Therefore, the focusing optic is comprised of approximately 40 focusing elements per millimeter. Due to the extremely small size of the focusing elements with respect to the laser beam, the focusing optic behaves like a diffraction grating which causes an interference pattern 717 to be created. The interference pattern 717 forms an array of spots 718, 719 and 720. Spots 718, 719 and 720 represent the zero order out, the first order out, and the minus one order out, respectively. By monitoring the exact locations of the first order out and the minus one order out, any change in the scale or period of the focusing optic can be determined.

Fig. 13b illustrates a block diagram of one of the laser detectors used to monitor the exact locations of the first order out and the minus order out of the interference pattern. Laser beam 716 has a gaussian distribution 723. Detector 707b (located at the projection of the spot pattern 717) tracks the location of the centroid of the spots in two dimensions. The detector 707b has a high enough resolution to track the location of the centroid to within one tenth of a micron. The distance D between the focusing optic 715 and the detectors 707b, 711b is known and therefore, the angle 720 can be calculated by control unit 710 in accordance with the distance D and the coordinates of the centroids. Angle 720 is used to determine the scale of the focusing optics pattern. This information is then utilized by the control unit 710 to control the temperatures of thermosiphons 705 and 706 to create embossments of the desired scale.

Once the focusing optics and the light control optics have been embossed on the film, laser scale detection 707a, b and 711a, b is used to determine whether the structure is satisfactory, i.e., whether the scale of the focusing optics matches the scale of the light control optics. If the periods do not match, detector 707b and/or 711b will detect two centroids instead of one. The control unit 710 will then notify an operator that the light control embossment is defective. The control unit 710 will then adjust the temperatures of either or both of the thermosiphons 705 and 706 in accordance with the scale information. Also, if the embossments do not match in scale, a human observer viewing the structure will see moire banding and thereby detect a defect. The observer can then adjust the temperatures of the thermosiphons 705 and 706 accordingly.

Preferably, the photopolymer used to create the inner and outer optic embossments is a blend consisting of Ebercryl 3700 40%, trimethylolpropane triacrylate 40%, isobornyl acrylate 17% and CIBA-GEIGY Irgacure 184 3%. This blend cures by means of ultraviolet light. Other types of radiation cured material can also be used for this purpose.

Although the above-described embossing system represents a preferred embodiment for creating the light control material of the present invention, it will be apparent to those skilled in the art that variations of the system and the elements comprised therein can be used to create the necessary embossments. Figs. 14a-14g illustrate a preferred embodiment of the present invention for fabricating the outer and inner optic masters. As shown in Fig. 14a, a substrate 750 is covered with a layer of chrome 751. On top of the layer of chrome 751 is a layer of photoreist 752. A mask 755 is placed over the structure as shown in Fig. 14b. The structure is then exposed to ultraviolet light. Clear areas in mask 755 correspond to areas in the photoresist which will be exposed to the ultraviolet light and subsequently developed away. After the exposed areas are developed away, pads of photoresist 753 are left on top of the chrome layer 751. An acid bath (not shown) is then used to etch away the chrome in positions which are not covered by the photoresist pads 753. The result is the structure shown in Fig. 14c. The chrome pads 754 act as an adhesion promotor between the photoresist pads 753 and the substrate 750. Photoresist heat flowing is then used to cause the photoresist pads 753 to flow, thereby creating dome shapes on top of the chrome pads as shown in Fig. 14d. A glass substrate 756 is placed in contact with liquid photopolymer 757 which is in contact with the structure of Fig. 14d, as shown in Fig. 14e. The structure is then exposed to ultraviolet light which causes inverted dome shapes to be created in the photopolymer 757. The master is comprised of layers 756 and 757 shown in Fig. 14f. Fig. 14f also shows how an embossment can be made from the master. A substrate 760, preferably a plastic film such as polyester, is placed in contact with liquid photopolymer 761. This structure is then exposed to ultraviolet light thereby causing photopolymer 761 to harden. The master and the embossment are then separated and the result is the embossment 763 shown in Fig. 14g.

The method discussed with respect to Figs. 14a-14g may be used to create the outer optic master which is then used in the system discussed above with respect to Figs. 12-13b to create the outer optic embossments. The method of Figs. 14a- 14g is also used to create the inner optic master. However, additional steps are required to form the dark zones in the master. Also, the size and geometry of the domed shapes in the master may vary depending on whether the inner optic master or the outer optic master is being created. The preferred embodiment for creating the inner optic master will now be described with reference to Figs. 14a-15d. The method discussed above with respect to Figs. 14a-14f is first used to produce the structure shown in Fig. 14g in which substrate 760 is preferably glass. Fig. 15a shows a front view of the structure of Fig. 14g. The structure 763 is coated with a thin layer of metal 782 which is preferably chrome. The layer of metal 782 is spin coated with a layer of photoresist 784. Photoresist layer 784 is then exposed to ultraviolet light through a mask 785, as shown in Fig. 15b. The exposed photoresist is then developed away leaving the metal layer 782 exposed at the locations where the photoresist has been removed. The chrome is then etched away by an acid bath thereby exposing the cured layer of photopolymer 761 as shown in Fig. 15b. The photopolymer layer 761 is then etched by reactive ion etching. Preferably, oxygen is used as the reactive gas. Due to impurities in the composition of the cured photopolymer 761, the dry etching process creates stalagtite-shaped light trap structures 787 in the photopolymer 761. These structures 787 have large aspect ratios which cause light entering the light traps to be reflected at very shallow angles, thereby resulting in a great number of reflections within the light traps. Depending on the reflective characteristics of the light trap surface, approximately 40% of the light may be absorbed on initial impact and at each additional reflection. Therefore, very few reflections are required for the light to be absorbed. Virtually all of the light which enters the light trap will eventually be absorbed.

As shown in Fig. 15c, once the light traps 787 have been formed in the cured photopolymer layer 761, a layer of liquid photopolymer 790 is placed in contact with cured photopolymer layer 761. A transparent substrate 791 is placed in contact with the liquid photopolymer. The structure is then exposed to ultraviolet light (not shown) which hardens the liquid photopolymer 790. The hardened photopolymer 790 bonds with substrate 791. The substrate 791 and the hardened photopolymer 790 are then separated from the photopolymer layer 761 having the light traps 787 formed therein. The resulting master is shown in Fig. 15d. Alternatively, a metal embossing master may be formed from photopolymer layer 761 by conventional electroforming processes. For example, photopolymer layer 761 may be coated with a thin layer of metal, such as silver, by vapor deposition in order to render it electrically conductive. Electrical contact can then be made to the metal surface and a thick layer of nickel can be plated onto the surface by conventional electroforming processes. After deposition of a sufficient thickness ,of nickel, the nickel plated photopolymer layer 761 may be removed from the electroplating bath and the nickel master separated from photopolymer layer 761.

Figs. 16a and 16b illustrate an alternative embodiment for creating the inner optic master. A structure comprising substrate 756 and a cured photopolymer layer 757, such as the one shown in Fig. 14f, is covered with a thin layer of metal 793 such as chrome. Metal layer 793 is covered with a layer of photoresist 795. The photoresist is exposed to ultraviolet light through mask 796 and the exposed photoresist is developed away leaving certain areas of metal layer 793 exposed. The exposed areas of the metal are then etched away by using an acid bath. The resulting structure is shown in Fig. 16a. Reactive ion etching is then used to etch the light traps into the photopolymer in the same manner as described above with respect to Fig. 15b. Fig. 16b represents the resulting inner optic master. Figs. 17a and 17b represent another alternative embodiment for generating the inner optic master. A master comprised of glass substrate 800 and a layer of cured photopolymer 801 having a light trap 802 formed throughout its entire surface is placed in contact with a layer of liquid photopolymer 805. The liquid photopolymer is also in contact with a cured layer of photopolymer 806 having inverted domed shapes formed therein. The structure is exposed to ultraviolet light through mask 808 which selectively cures photopolymer 810 in the regions exposed to ultraviolet light. The cured photopolymer 810 adheres to photopolymer 806 and remains with it when photopolymer 806 is separated from photopolymer 801. The residual uncured liquid photopolymer

805 remaining on photopolymer layer 806 may be removed by a solvent wash. The resulting inner optic master shown in Fig.

17b is comprised of substrate 807 and cured photopolymer layer

806 having the light traps 810 selectively formed therein. ,

It should be apparent to those skilled in the art that other techniques may be used to create the light control optics master of the present invention. For example, conventional techniques, such as diamond turning, may be used to form domed shapes in a layer of photopolymer. Reactive ion etching may then be used to generate the fields of tapered elements which constitute the light traps. Once the light control optic master has been produced, embossments can be easily generated therefrom by the procedures discussed above with respect to Figs. 14f and 14g and with respect to Figs. 15c and 15d. If it is desirable to use dome-shaped bright zones in the light control optic, one of the structures shown in Figs. 15d, 16b or 17b may be used as the light control optic master. If it is desirable to use inverted, or dish- shaped, bright zones in the light control optic, one of the structures shown in Figs. 15d, 16b or 17b will constitute the light control optic embossments. While the invention has been disclosed in preferred forms, it will be apparent to those skilled in the art that many modifications can be made to the invention without departing from the spirit and scope of the invention as set forth in the appended claims.

Claims

What is claimed is:

1. A light control material comprising focusing optics having a plurality of focusing elements and light control optics having dark zones and bright zones for providing directional control of light through the focusing optics.

2. A light control material as described in Claim 1 wherein the bright zones are comprised of a light transmissive material.

3. A light control material as described in Claim 1 wherein the light control optics further include a reflective layer for reflecting light at the bright zones. . A light control material as described in Claim 1 wherein the light control optics comprise a substrate and an opaque material on the substrate for forming the dark zones. 5. A light control material as described in Claim 4 wherein the substrate is comprised of a reflective layer and the opaque material covers selected portions of the < reflective layer thereby forming the bright zones at those portions of the reflective material not covered by the opaque material.

6. A light control material as described in Claim 4 wherein the substrate is comprised of an opaque material.

7. A light control material as described in Claim 4 wherein the a diffractive, holographic or diffusing pattern is applied to the bright zones.

8. A light control material as described in Claim 4 wherein the opaque material is selected from the group consisting of pigmented ink, light absorbing optical structure or light dispersing optical structure. 9. A light control material as described in Claim 1 wherein the focusing optics are selected from the group consisting of refractive optics, diffractive optics and mixed refractive and diffractive optics.

10. A light control material as described in Claim 1 further comprising a color filtering means. 11. A light control material as described in Claim 10 wherein the color filtering means is an image comprising a series of image elements.

12. A light control material as described in Claim 11 wherein the image elements are provided in registration with at least one set of focusing elements.

13. A light control material as described in Claim 10 wherein the image elements are provided in sets of at least two image elements and the image elements are provided substantially in registration with the light control optics such that at least two light focusing directions are provided.

14. A light control material as described in Claim 10 wherein the image elements are located between the focusing optics and the light control optics.

15. A light control material as described in Claim 10 wherein the image elements are positioned on the side of the focusing optics opposite the light control optics.

16. A light control material as described in Claim 10 wherein the image elements are positioned on the side of the light control optics opposite the focusing optics.

17. A light control material as described in Claim 1 wherein the focusing optics comprises an outer optic layer and the light control optics comprise an inner optic layer. 18. A light control material as described in Claim 1 wherein the focusing optics comprise an inner optic material and the light control optics comprise an outer optic material, said focusing optics including a reflective layer for receiving light passed through the light control optics and reflecting the light back through the light control optics. 19. A light control material as described in Claim 4 wherein the substrate is comprised of a light absorbing layer and a reflective material covers selected portions of the light absorbing layer thereby forming the bright zones. 20. A light control material as described in Claim 1 wherein for each of said focusing elements there are a plurality of said bright zones, said bright zones having predetermined sizes and shapes, each bright zone of said plurality of bright zones being separated by at least one of said dark zones such that a pattern of said bright zones and said dark zones is provided, wherein each of said bright zones provides a field of view and wherein said predetermined sizes are selected for controlling the fields of view provided by the bright zones. 21. A light control material as described in Claim 20 wherein said bright zones incorporate curved surfaces.

22. A light control material as described in Claim 20 wherein each of said dark zones constitutes a light trap.

23. A light control material as described in Claim 20 wherein the light control optics further include a reflective layer for reflecting light at the bright zones.

24. A light control material according to Claim 20 wherein the dark zones are covered with a reflective layer.

25. A light control material as described in Claim 24 wherein the dark zones comprise tapered elements having large aspect ratios such that light entering the dark zones is reflected within the dark zones until virtually all of the light has been absorbed.

26. A light control material as described in Claim 21 wherein said curved surfaces are cylindric-shaped surfaces.

27. A light control material as described in Claim 21 wherein said curved surfaces are substantially ellipsoid- shaped surfaces. 28. A light control material as described in Claim 25 wherein said tapered elements are created by reactive ion etching a polymer.

29. A light control material as described in Claim 21 wherein said curved surfaces brightness enhance an image being illuminated thereby.

30. A method for creating a light control structure, said method comprising the steps of: applying a first layer of liquid photopolymer to a first side of a transparent substrate; imprinting a focusing optic pattern in said first layer of liquid photopolymer; subjecting said transparent substrate having said focusing optic pattern imprinted thereon to ultraviolet light such that said first layer of liquid photopolymer having said focusing optic pattern imprinted therein hardens and bonds with said transparent substrate; —— applying a second layer of liquid photopolymer to a second side of said transparent substrate; imprinting a light control optic pattern in said second layer of liquid photopolymer; subjecting said transparent substrate having said focusing optic pattern bonded thereto and said light control optic pattern imprinted thereon to ultraviolet light such that said second layer of liquid photopolymer having said light control optic pattern imprinted therein hardens and bonds with said transparent substrate such that an embossed light control structure is created.

31. A method for creating a light control structure according to Claim 30 wherein the first layer of liquid photopolymer is applied to the first side of the transparent substrate by rolling the transparent substrate over a roller having liquid photopolymer thereon. 32. A method for creating a light control structure according to Claim 30 wherein the second layer of liquid photopolymer is applied to the second side of the transparent substrate by rolling the transparent substrate over a roller having liquid photopolymer thereon.

33. A method for creating a light control structure according to Claim 30 wherein the focusing optic pattern is imprinted in the first layer of liquid photopolymer by rolling the transparent substrate having the first layer of liquid photopolymer thereon over a roller which carries a master of the focusing optic pattern such that the master comes into contact with the first layer of liquid photopolymer thereby imprinting the focusing optic pattern in the first layer of liquid photopolymer. 34. A method for creating a light control structure according to Claim 30 wherein the light control optic pattern is imprinted in the second layer of liquid photopolymer _tby rolling the transparent substrate having the focusing optic pattern bonded thereto and having the second layer of liquid photopolymer thereon over a roller which carries a master of the light control optic pattern such that the master comes into contact with the second layer of liquid photopolymer thereby imprinting the light control optic pattern in the second layer of liquid photopolymer. 35. A method for creating a light control structure according to Claim 33 wherein, prior to the . step of applying the second layer of liquid photopolymer, a laser scale detection unit determines the scale of the focusing optic pattern. 36. A method for creating a light control structure according to Claim 34 wherein, after the step of imprinting the light control optic pattern in the second layer of liquid photopolymer, a laser scale detection unit determines whether the focusing optic pattern and the light control optic pattern match in scale.

37. A method for creating a light control structure according to Claim 35 wherein said roller is a thermosiphon which can be maintained at a substantially constant temperature and wherein a control unit controls the temperature of the thermosiphon. 38. A method for creating a light control structure according to Claim 36 wherein said roller is a thermosiphon which can be maintained at a constant temperature and wherein a control unit controls the temperature of the thermosiphon.

.39. A method for creating a light control structure according to Claim 37 wherein the laser scale detection unit sends information concerning the scale of the focusing optic pattern to the control unit which controls the temperature of the thermosiphon in accordance with said information.

40. A method for creating a light control structure according to Claim 38 wherein the laser scale detection unit sends information concerning the scale of the focusing optic pattern and the scale of the light control optic pattern to the control unit which controls the temperature of the thermosiphon in accordance with said information. 41. A method for creating a light control structure according to Claim 30 wherein the step of imprinting a focusing optic pattern in said first layer of liquid photopolymer is accomplished by rolling the transparent substrate having the first layer of liquid photopolymer thereon over a first thermosiphon which is at a first temperature and wherein the step of imprinting a light control optic pattern in said second layer of liquid photopolymer is accomplished by rolling the transparent substrate having the focusing optic pattern and the second layer of liquid photopolymer thereon over a second thermosiphon which is at a second temperature, wherein said first thermosiphon carries a master of the focusing optic pattern and wherein said second thermosiphon carries a master of the light control optic pattern and wherein a control unit controls the first and second temperatures in accordance with information received from a scale detection unit to produce a focusing op ic pattern and a light control pattern, each of which are of a predetermined scale.