JP4458394B2 - Creation method to create an optical master using non-interfering light - Google Patents

Description

[0001]
(Background of the Invention)
[0002]
(1. Field of the Invention)
[0003]
The present invention relates to an improved, faster and more reliable method for creating irregular pattern holes in a suitable master for making photoformed diffusers and similar optical members.
[0004]
(2. Examination of related technology)
[0005]
Conventionally, interference lasers are used to make optical products such as light-shaping diffusers. As shown in FIG. 1, a photosensitive medium 4 such as a photoresist is recorded by exposing it to interference (laser) light 1 applied from a krypton laser through a spatial filter 2 and a diffuser 3. The diffuser 3 is a diffuser, holographic, lenticular or acetate diffuser, or ground glass prerecorded in the recording setup of FIG.
[0006]
A preferred method and apparatus for making such a diffuser is disclosed in U.S. Pat. No. 5,365,354, “Grin type diffuser based on volume holographic material”, U.S. Pat. No. 5,534,386, coherent. Homogenizers and holographic diffusers made with light "and US Pat. No. 5,609,939“ Field screens made with coherent light ”, which are mass-produced diffusers and replicas of these diffusers. It relates to a method for recording such an optical product. Each of these U.S. patents provides background and known examples of the present invention. US patent applications related to these include: US patent application Ser. No. 08 / 595,307 “LCD with light source distribution and shaping device”, US Pat. Application Ser. No. 08 / 601,133 “Liquid crystal with collimated background and non-lambertene diffuser. US Patent Application No. 08 / 618,539 “Method of Manufacturing Liquid Crystal Display System”, US Patent Application No. 08 / 800,872, “Method of Manufacturing Duplicates and Compositions Used With It”, and US Patent Application No. 09 / 052,586 Issue "How to make a duplicate while preserving the master". All of these US patent applications are owned by the assignee of the present invention and are shown as background and known examples of the present invention, but the present invention is not limited thereto.
[0007]
According to the methods shown by these patents, both the inner surface and surface structure called “speckle” that diffuses light with a higher efficiency, uniformity and controlled means that could not be achieved by the conventional method are contained in the photosensitive medium 4. Can be made. As fully described in the above patent, the size and shape of the speckle recorded in the photosensitive medium can be controlled, and thus the angle of the output light from the diffuser can be controlled after development. The diffuser made by the method of the above patent is extremely useful as a viewing screen and homogenizer with a myriad of uses.
[0008]
For mass production, the surface structure remaining in the photosensitive medium 4 after processing is utilized. After exposing the photosensitive medium for a preferred time, it is processed to make a master. A first generation sub-master or replica of epoxy or other synthetic resin is made from the master by adding epoxy to the surface of the master, spreading evenly on the master, and releasing the epoxy from the master after the epoxy is cured. Sequential generation submasters are created from the previous generation submaster by the above process. Each successive generation of submasters causes a change (usually a decrease) in the aspect ratio of the surface structure features due to shrinkage.
[0009]
The above known example has a number of drawbacks. First, the overall size of the diffuser that can be made is limited by the strength of the laser used and the sensitivity of the photosensitive medium. Secondly, in the known example, 2.7 Joules / cm to obtain a favorable exposure ² An interference light source that produces an extremely high energy density on the order of As a result, as shown in FIG. 2, it was considered that many small sub-masters were connected to each other to create a large seamless master. It was extremely difficult to do.
[0010]
In addition, when making a large master diffuser, the corner area will be perforated with respect to the central area, resulting in an undesirable non-uniform pattern. Finally, the photoresist reacts slowly to light, and the conventional system is extremely sensitive to vibration and motion due to the need to physically separate the light source, diffuser and photosensitive medium as shown in FIG. . Even if the vibration is very slight, a phase change occurs in the interference light source, and undesirable aberrations occur in the master. The size of this aberration may exceed the size of the speckle, making the master unusable. It is difficult or impossible to record speckles of extremely small size due to vibration and other drawbacks of the recording method. For example, in order to produce a diffuser having an extremely wide output in the horizontal direction and an extremely narrow output in the vertical direction, the speckle recorded in the photosensitive medium must be extremely small (and large in the vertical direction). (The light output distribution from the diffuser is inversely proportional to the speckle size and the light distribution in the diffuser). For example, to triple the horizontal output angle, the speckle size needs to be reduced to one third.
[0011]
Furthermore, traditionally it is necessary to make separate masters for diffusers with special angular outputs, requiring a large library of masters with different angular outputs. For example, different masters are desired to achieve 10 ° × 10 ° circular output, 10 ° × 15 ° elliptical output, and the like. To make these masters, it is necessary to use the recording setup shown in FIG. As mentioned above, this recording process is slow and susceptible to vibrations and other effective inhibition factors.
[0012]
It would be highly desirable to have a method for creating a large inexpensive inexpensive master that is not affected by vibration.
[0013]
(Summary and purpose of the invention)
[0014]
It is a primary object of the present invention to provide an improved method of making a master having a plurality of randomly distributed speckles suitable for making a photoformed diffuser. Another object of the present invention is to obtain a simple and reliable method for creating a large seamless master. Another object of the present invention is to obtain a method for forming a large-sized light-forming diffuser inexpensively and completely uniformly so as not to be sensitive to vibration and movement. Yet another object of the present invention is to provide a method for making a master that makes the angular spread of the light output from the light shaping diffuser desirable without using many successive generations of submasters. To get.
[0015]
In the present invention, the above object can be achieved by a method using non-interference light to record a desired speckle pattern in a photosensitive medium. In the present invention, the film is exposed to one actual speckle pattern or one made by a computer. The film is exposed by a standard interference laser setup as shown in FIG. 1 where the film is replaced with a photosensitive medium 4, or a computer driven imagesetter driven by a number of random sequences that randomly expose the film with dots. After exposure, the film is developed and placed in contact with a photosensitive medium such as standard photoresist and exposed to non-interfering light so that the speckle pattern in the film is exposed to the photosensitive medium. The speckle structure in the photosensitive medium is used as a master for making sequential submasters and final diffuser products.
[0016]
In the present invention, the film is exposed in an image setter corresponding to a pseudo-random sequence obtained from a maximum length shift register realized by hardware or software. This pseudo-random sequence is used by the image setter's raster image processor to control the irregular distribution or emission characteristics of the laser or the "dots" of the film. Film exposed dots are made to resemble the speckle recorded within the standard setup of FIG.
[0017]
Also, in the present invention, a highly sensitive millimask film can be exposed in a standard interference laser setup where the millimask film is replaced by a conventional photosensitive medium. In this case, the speckle is recorded in the film in a short time, has little sensitivity to vibration, and has a high resolution.
[0018]
If a particularly small feature size is desired in the film, for example if a diffuser with a large angular output is desired, the film obtained by any of the above methods can be reduced (or by using standard light reduction techniques). (Enlarge) This reduced or enlarged film is then contact copied onto a photosensitive medium, such as photoresist, or used in a stepper to obtain a second film having smaller sized dots, then photoresist with non-interfering light, etc. Used in a stepper to make a contact copy on top or to expose a photoresist in the stepper.
[0019]
In the present invention, the drum in the deformed image setter is further covered with a photosensitive medium such as a photoresist, and the film is completely unnecessary by exposing with a imagesetter laser. Unexposed photoresist on the drum is removed by standard etching techniques, and then the drum itself is etched with an irregular dot pattern. This drum is then preferably used in a continuous process to emboss or stamp an epoxy or other layer on plastic or other sheets.
[0020]
In the present invention, a collimated UV, excimer or electron beam source is used to expose a sandwiched photoresist on chrome on glass using a pseudo-random dot pattern. Unexposed photoresist is etched away, and then the chrome is etched away to create a dot pattern in the chrome.
[0021]
The diffuser made by the method of the present invention can be large enough to be used for front and rear projection screens, fluorescent lamp screens, highway and advertising signs, and the like. According to the present invention, it is inexpensive and fast turnaround (approximately 48 hours from the first concept of master creation), and an inexpensive non-interfering light source such as a standard arc lamp can be used to expose the photoresist material. Results in large scale diffusers that are completely insensitive and restorative, large elliptical or circular diffusers that produce angular output of any shape, linear or circular gradients, or variable direction Has the ability to create a unique diffuser pattern that exhibits elliptical properties. Still other advantages of the present invention will be readily apparent to those skilled in the art.
[0022]
Other objects and features of the present invention will become apparent from the following description of the drawings. However, the following description and preferred embodiments of the present invention are not intended to limit the present invention. It goes without saying that the present invention can be variously changed or increased without departing from the spirit of the present invention.
[0023]
DETAILED DESCRIPTION OF THE INVENTION
[0024]
(A. Film recording in imagesetter )
[0025]
In the preferred embodiment of the present invention, an imagesetter is utilized to create a high resolution master for forming the master. Imagesetters are known in the photographic arts that use their capabilities to form high resolution masks on photographic film and are typically used for high resolution color printing. Preferred imagesetters for use in the present invention include those produced by Agfa and Hellinetronic.
[0026]
An image setter is typically an image to be recorded based on the supply of unexposed film, a recording surface support or holder such as a drum to support the material during exposure, instructions from a dedicated laser image processor or “RIP” An image exposure system for forming the image. Image exposure systems use one or more lasers or other light sources. For example, a film such as a Kodak 2000 series film is scanned with a beam and exposed to form a latent image on the material. The film is then removed from the imagesetter for the next process.
[0027]
FIG. 3 shows the imagesetter 10. The film 12 is supported by a capstan roller, a flat plate, a cylindrical drum platen or other support surface 14 as shown in FIG. A scanning exposure system 16 for film exposure includes an optical system for focusing a light or light source 18 such as a laser mounted at a predetermined distance from the support surface 14 and a light beam 22 from the light source 18. 20 and a beam deflecting device for scanning the beam across the film 12. The scanning exposure system is moved along the CC line of the drum having the support surface 14 by a precision linear drive mechanism, while the film 12 is held in position. As the scanning exposure system moves, a laser or other light source is emitted to expose the exposed area of the film in response to a command made by the RIP.
[0028]
In the present invention, the basic feature to be recorded on the film is shown as “dodd”, but this need not be circular, but may be oval, rectangular or other shapes. Large features such as an elliptical structure can be created by combining multiple adjacent dots. The dots correspond to “speckle” in the prior art and are combined as needed to achieve with a diffuser having the desired angular output. It will be described below whether or not a dot located at a special position on the master is determined by a pseudo random sequence.
[0029]
(▲ 1 ▼ Generation of a favorable pattern for diffuse light )
[0030]
FIG. 4A shows a regular, periodic diffraction grating with rectangular holes. FIG. 4B shows a diffraction pattern when the diffraction grating is illuminated with white light. FIG. 5A shows a regular, periodic diffraction grating with circular holes. FIG. 5B shows the result of the diffraction pattern. Since these diffraction patterns are regularly repeated, each light wave exhibits a fixed phase relationship with respect to the others. Thus, there are certain directions in which the light waves interfere constructively and destructively, resulting in a diffraction pattern. The purpose of making the diffuser is to prevent the generation of such a diffraction pattern and to uniformly diffuse the light output.
[0031]
FIG. 6A shows an irregular row of rectangular holes. FIG. 6B shows the resulting white light diffraction pattern. FIG. 7A shows an irregular array of circular holes. FIG. 7B shows the resulting white light diffraction pattern and a series of concentric rings surrounding the white center desk. As shown, the irregular array of holes produces a more diffuse diffraction pattern than the pattern output from the periodic array. However, the diffusion pattern still exists. This pattern is due to the use of a somewhat interfering white light source. If a completely incoherent light source is used, the diffusion pattern is uniformly diffused. Instead, this pattern is erased when the hole is blurred to remove sharp edges. Thus, in general, the masks that are desired to make the diffuser preferable will have irregular disorder features that do not have sharp edges.
[0032]
Such a pattern depends on the size of the mask. Corresponding It can be obtained from an imagesetter by creating a mask code based on a pseudo-random sequence of lengths. The pseudo-random sequence is created by a shift register that can be executed by software or hardware. A functional diagram of the hardware implementation is shown in FIG. 8, which includes a shift register 80 and an OR gate 90 connected in a feedback manner. Preferably, the shift register is made by software and the stock image setter RIP _S Can be used instead of bespoke hardware. Since hardware is maximally available for special applications and is therefore generally fast, hardware implementation is preferred when speed is most important. An example of a preferred source code for creating a pseudo-random sequence in C language is as follows.
[0033]
#define mask 0x80000057
static unsigned long ShiftRegister = 1;
void seed # LFSR (unsigned long seed)
[
if (seed = = 0) / * avoid calamity * /
seed = 1;
ShiftRegister = seed;
]
int modified # LFSR (void)
[
if (ShiftRegister & 0x00000001) [
ShiftRegister = (ShiftRegister ^ mask)>> 1) |
0x8000000;
return 1;
] else [
ShiftRegister>> = 1;
return 0;
]
]
[0042]
(▲ 2 ▼ Feature formation to shape light )
[0043]
In general, the feature size and shape define the angular output pattern of light from the light shaping diffuser. The angular distribution of light is controlled by the Furanel diffraction equation. The angle r corresponding to the curvature r of the predetermined circular hole and the wavelength λ of the light is
[0044]
sinθ = 1.22 λ / 2r
[0045]
It is.
[0046]
Elliptical features with aligned axes are often used for shaping the output pattern of light-shaping diffusers. An elliptical feature having a horizontal major axis produces an output pattern that is elongated in the vertical direction, ie, rotated 90 ° with respect to the major axis of the elliptical diffuser feature. The speckle recording method for producing the desired light angular distribution from the light-shaping diffuser is shown in detail in the U.S. patents listed in the related prior art section.
[0047]
(▲ 3 ▼ Determining the number of features )
[0048]
After calculating the hole size and shape, it is necessary to determine how to create these features from a collection of dots. Each of the basic features is indicated by one binary bit.
[0049]
The basic feature size is determined by several factors. First, the program language indicating the print process determines the display accuracy of the print command. The preferred embodiment uses a Postscript language. One PostScript point is 1 / 72th of an inch, so 1 inch is 25,400 microns and the Postscript point is 352,78 microns. 0.0001 or 0.035 inch postscript can be calculated. This level of accuracy is sufficient for the optical application of the present invention. Other print programming languages are used to indicate the features with sufficient accuracy as will be apparent to those skilled in the art. Furthermore, in any optical system, the feature size is limited by diffraction and lens aberrations as will be apparent to those skilled in the art.
[0050]
It is necessary to superimpose several features to prevent the appearance of a periodic composition within the space between features. A uniform overlap of 0.75 of the space between features (on the order of approximately √2) is sufficient to ensure sufficient overlap to prevent uniform areas that do not contain features.
[0051]
The number of features for a master in a given area is determined as follows:
[0052]
Feature density x film area = number of features
[0053]
A sufficiently long pseudo-random sequence in which features are randomly distributed is defined as follows.
[0054]
In (number of features) / In 2 = bit
[0055]
Here the bits are the number of bits in the shift register needed to create a random sequence of sufficient size to cover the entire area of the film to be exposed. In general, a 128 bit long register is sufficient for any application.
[0056]
(▲ 4 ▼ Create master )
[0057]
After the film is exposed as described above, the film can be developed by standard development techniques to be negative.
[0058]
As shown in FIG. 9, the negative 23 functions as a mask 23 in a standard contact copying process by placing the mask 23 on a photoresist or similar photosensitive medium. The photoresist 24 is disposed on a substrate as a photolithographic plate 25 made of glass, but a preferable plastic material may be used. This mask 23 is fixed on the photolithographic plate 25 as shown in FIG. 9 by a clamp, a cover sheet, or a vacuum action.
[0059]
As shown in FIG. 9, the combination of the mask and the photoresist plate is exposed with a non-interference light source 26, and the mask pattern is exposed on the photoresist. Preferably, the light source is a non-parallel UV light source having an output of 300 to 500 watts and a wavelength range of 365 to 400 nm. This light source should have the same size as the size of the sheet film that shines and diffuses uniformly, and the sheet film to be exposed. A good example of a sufficiently diffusive light source is a large fluorescent lamp. When scanning uniformly over the surface to be exposed, a smaller light source is used.
[0060]
The diffuse light source blurs the boundary between the light and dark parts. The feature with very sharp edges produces non-diffused light with a diffractive pattern such as the bulleye or ring pattern shown in FIG. Variations include several other ways to obtain blurred features if a preferred diffuse light source is not available. One is to make successive generations of masters from the first generation master to eliminate the sharp edges of features. Another variation is to adjust the imagesetter so that it is slightly out of focus. Another possibility to blur feature edges is due to the linear chemical process of the film and / or photoresist. The straight line process involves changing the intensity of development to obtain a straight line change between black and white.
[0061]
(B. Recording film in standard laser recording setup )
[0062]
In the second embodiment using a film, the master of the present invention uses the recording setup shown in FIG. 10 and speckles on the semiconductor flat film 31 like an 8E56 mm mask instead of the photoresist / glass plate of FIG. Make by recording. The film is exposed by interfering light from laser 28 that passes through diffuser 30. Since the film 31 has high photosensitivity, it is desired to expose for several seconds unlike the few minutes in the case of a photoresist. The resulting film is used as a mask in a standard contact recording process as shown in FIG. 9 for recording features on the photoresist plate after exposure with non-interfering UV light in the manner described above. Since the millimask film is in physical contact with the photoresist by a vacuum or a clamping mechanism, the exposure time can be increased as much as necessary without causing stability problems in conventional methods. Therefore, a deep aspect ratio structure can be recorded in the photoresist using an extremely long exposure time.
[0063]
(C. Shrink film )
[0064]
Using the contact copying shown in section A and B above, the size between the film negative and the photoresist coated plate is always 1: 1. It is difficult to obtain feature sizes below about 5 microns using simple contact coating techniques. For dots of 4 microns or less, a light reduction technique is used as shown in FIG. First, the exposed film 32 is made using the techniques described above or other preferred techniques. This film is then developed and the size of the dot record on the film is reduced by a standard photo reduction camera 34. This film is then contact-copied to a photoresist or the like as shown in FIG. Further, the reduced (or enlarged) second film is exposed again using the reduced film as a mask in the stepper shown in FIG. This second film is then contact copied to photoresist or the like. In a modification, a stepper having a first or second film may be used as a mask, and this film may be stepped along the separated points of the photoresist in each step to expose the photoresist. As shown in FIG. 12, the stepper includes an ultraviolet ray source 36 having a shutter, a magnifying mask 37 generally having an actual size of 5 times, a 1/5 reduction lens 38, and a precision XY movable stage 40. The photoresist 39 is placed on the stage 40, the stage 40 is moved, the shutter is opened, and the selected area of the photoresist is exposed with UV light through the mask 37 within the “step”.
[0065]
The hole size can change the angular spread of the diffuser without the need to optically shrink and record a new master to determine the angular spread of the light output from the diffuser. As the feature size is reduced, the angular spread of the output increases proportionally. For example, if the feature size is reduced to 1/10, the angle is increased 10 times. Therefore, as shown in FIG. 13, when the circular angle output of the unreduced film is 9 °, the angle output is increased to 90 ° by reduction by 1/10. In this case, the angular spread of the master can be adjusted by optical reduction or enlargement.
[0066]
As shown in FIG. 14, the feature shape can be changed by using an anamorphic lens in the stepper that distorts horizontal or vertical magnification. The preferred optical technology allows feature sizes and shapes to be obtained from a single mask, thus creating a custom light-shaping diffuser where a change in the recording setup of FIG. The process can be very simple.
[0067]
(D. Etching of metal drum without filter )
[0068]
In the third filmless embodiment, instead of recording features on the film fixed on the surface of the drum, the dot pattern display speckle is directly recorded on the surface of the metal drum coated with a layer of photoresist. Use a deformed imagesetter. As shown in FIG. 15, the photoresist coating drum 41 is exposed by a laser 42 that scans all the drums in the image setter 43. This drum 41 is then removed from the imagesetter 43 and processed by standard etching techniques. First, the unexposed photoresist on the surface of the drum is etched with a photoresist developer using standard materials and processes. This unexposed surface is then further etched with nitric acid to cause the metal to etch the pattern.
[0069]
The photoresist is then removed using a solvent. The drum 44 obtained as shown in FIG. 16 is a master that can be used to emboss a seamless light-forming drum of unlimited length. The diffuser can be embossed on epoxy 45 or other plastic resin attached to the plastic substrate 46. The drum 44 is wrapped with a substrate 45 coated with an epoxy 41 to obtain an imprint of a diffuser and exposed with a UV light source 47 to cure the epoxy. The light source 47 is a non-parallel UV light source having an output of 300 to 500 watts and a wavelength range of 365 to 400 nm.
[0070]
(E. Excimer laser or electron beam recording )
[0071]
Using a UV excimer laser or electron beam as a light source, it is also possible to obtain a small feature size without reducing the photo. When a UV excimer laser is used, a feature size as small as about 7 microns can be obtained. As a modification, a smaller dot size of 1 micron or less can be obtained using an electron beam. As shown in FIG. 17, the process uses a glass sheet 50 and deposits a first layer of chrome 49 on the glass sheet, and then deposits a first layer 48 of photoresist on the first layer 49 of chrome. Including that. Computer generated pseudo-random features can be recorded in the photoresist using a UV excimer laser source 51 and / or an electron beam source. The pseudo-random feature is created in a maximum length shift register as described above that is used to modulate the laser source 51 when the photoresist 48 is exposed. The unexposed photoresist is then etched away using a standard process, and further etched with nitric acid or the like to etch away the chrome metal layer. The remaining photoresist is then washed away with solvent. The resulting dot size is much smaller than that from the film process described above, but excimer lasers and electron beams are much more expensive.
[0072]
The best embodiments of the present invention have been described above, but the present invention should not be limited to these detailed descriptions, specific examples, and preferred embodiments. It goes without saying that the present invention can be variously increased / decreased and changed without departing from the spirit of the present invention.
[0073]
Many other modifications can be made as described above without departing from the spirit of the invention. The scope of this change will be made clear by the claims.
[Brief description of the drawings]
The clear concept, benefits and characteristics of the present invention and the operation of the construction of a typical mechanism according to the present invention will be made clearer with reference to the examples. The embodiments illustrated in the accompanying drawings are not limiting and constitute a part of the detailed description.
FIG. 1 is an explanatory diagram of a conventional recording method for a photosensitive medium having speckles.
FIG. 2 is an explanatory diagram of a conventional method for creating a large master from a number of sub-masters.
FIG. 3 is an illustration of a side view of a preferred imagesetter for carrying out the method of the present invention.
FIG. 4A is an explanatory diagram of a regular periodic lattice of rectangular holes.
FIG. 4B is an explanatory diagram of a diffraction pattern obtained by illuminating the grating with white light.
FIG. 5A is an illustration of a regular periodic grating of circular holes.
FIG. 5B is an explanatory diagram of a diffraction pattern obtained by illuminating the diffraction pattern of FIG. 5A with white light.
FIG. 6A is an explanatory diagram of an irregular row of rectangular holes.
FIG. 6B is an explanatory diagram of the obtained white light diffraction pattern.
FIG. 7A is an explanatory diagram of irregular rows of circular holes.
FIG. 7B is an illustration of a white light diffraction pattern having a series of concentric rings around a white center plate.
FIG. 8 is a functional diagram of a preferred apparatus for creating the pseudo-random sequence of the present invention.
FIG. 9 is an explanatory view of contact copying of a film on a photoresist.
FIG. 10 is an explanatory diagram of a standard laser recording setup using a millimask film.
FIG. 11 is an explanatory diagram of film reduction.
FIG. 12 is an explanatory diagram of a stepper mask.
FIG. 13 is an explanatory diagram of an angular spectrum output enlarged from 9 ° to 90 ° by reducing the dot size by 1/10.
FIG. 14 is an explanatory diagram of a recording setup for changing the shape of angle output using an anamorphic lens in a stepper.
FIG. 15 is an explanatory diagram of a filmless recording setup using a photoresist on a metal drum.
FIG. 16 is an explanatory diagram of a continuous or discontinuous drum press.
FIG. 17 is an explanatory diagram of an electron beam or excimer laser recording setup.

Claims (10)

(1) Obtain an irregular random speckle pattern using a shift register (80) for creating a pseudo-random sequence having a length corresponding to the size of the mask (23),
(2) The photographic film (12) is exposed by modulating the laser light from the light source (18) with the speckle pattern,
(3) Developing the photographic film (12) exposed by the laser beam,
(4) Place the exposed photographic film (12) in contact with the photoresist,
(5) In order to record an irregular and irregular speckle pattern as an irregular and irregular surface structure in the photosensitive medium, the photoresist is removed from the non-interfering light source (26) via the developed photographic film (12). A method for producing a master optical surface diffuser comprising the step of exposing with non-interfering light. (1) Using a shift register (80) to create a random pattern feature corresponding to the size of the mask (23),
(2) Make a random pattern mask by recording the characteristics of the random pattern in the mask (23),
(3) Cover the photoresist with this random pattern mask,
(4) exposing the coated photoresist with incoherent light from an incoherent light source (26);
A method for producing a master optical surface diffuser, comprising a step of transferring features of the random pattern from a mask to the photoresist as a random surface structure. (1) Place the film (12) on the print drum of the imagesetter (10),
(2) Create a pseudo-random sequence corresponding to the size of the mask (23) using the shift register (80),
(3) The film (12) is exposed with interference light from an interference light beam source (18) to form a mask (23) with the pseudo-random sequence,
(4) Remove the exposed film from the print drum,
(5) Develop this film to make a negative,
(6) Place this negative adjacent to the photoresist (24);
(7) Exposing the photoresist (24) by moving the non-interfering light source (26) through the negative,
(8) A method for producing a master surface diffuser comprising: developing the exposed photoresist (24) to record the pseudorandom sequence as a pseudorandom surface structure in the photoresist (24).   4. The method of claim 3, further comprising the step of reducing the negative in a high resolution reducer.   4. The method of claim 3, wherein the reduced negative is used as a stepper mask.   4. A method according to claim 3, characterized in that the non-interfering light source (26) is a diffuse light source. (1) Using the shift register (80) to provide irregular random features corresponding to the size of the diffuser (30) that do not repeat itself beyond an area equal to the size of the diffuser (30). Made in the diffuser (30),
(2) exposing the film (12) with light from a spatial filter (29) and an interfering light beam source (18) that passes through a diffuser (30) with irregularly random features;
(3) Developing the exposed film,
(4) Obtain a film obtained by reducing the developed film using a high resolution reducer,
(5) Place the reduced film on the photoresist (24),
(6) exposing the photoresist (24) with non-interfering light from a non-interfering light source (26) through the developed film;
(7) developing the exposed photoresist (24) and recording irregular random features as irregular random surface structures in the photoresist (24); How to make. (1) coating glass (50) with a layer of chrome (49);
(2) coating the chrome (49) layer with a photosensitive medium;
(3) using a shift register (80) to create a pseudo-random amplitude used to create the mask (23) having a size corresponding to the size of the mask (23);
(4) exposing the photosensitive medium with interference light from an interference light beam source (18) that has passed through the computer-generated mask (23) to produce a photosensitive medium exposed portion and a non-exposed portion;
(5) The unexposed portion of the photosensitive medium is removed by etching to expose a part of the chrome layer (49),
(6) etching the exposed chrome layer portion in a manner that does not affect the unexposed chrome layer portion;
(7) A method for producing a metal master surface diffuser comprising: removing a remaining photosensitive medium from an unexposed chrome layer portion to form an etched layer of chrome (49). (1) using a shift register (80) to create a pseudo-random pattern feature used to create a pseudo-random pattern mask (23) corresponding to the size of the mask (23);
(2) Create a pseudo-random pattern mask (23) using the imagesetter (10) to record the features of the pseudo-random pattern in the mask (23),
(3) Cover the photoresist with the pattern mask,
(4) exposing the photoresist by non-interfering light (26) passing through the pattern mask (23) to transfer the features of the pseudo-random pattern to the photoresist;
(5) A method for producing a master surface diffuser comprising the step of etching the photoresist in order to produce the characteristics of the pseudo-random pattern in the photoresist. The method of claim 9 , wherein the photoresist is coated on a drum.

Images