SU1446579A1 - Method of making microlense raster screens - Google Patents

Abstract

The invention relates to optical instrumentation and can be used, in particular, for the manufacture of microlens rasters transmitting volumetric integral or composite images used in duplicating machines for television, film technology, holography, etc. In this case, both positive and negative microlenses can be made with a large curvature of the surfaces and with the high quality of these surfaces. The method includes the following steps. A polished plate made of photosensitive crystallizing glass is exposed through a photomask with opaque discs arranged according to the pattern of rabbits in the raster, and then the exposed interliner regions are crystallized by heat treatment. After crystallization of the surface, the plates are secondarily squeezed and the plate 1 is subjected to ion exchange treatment at a temperature higher than the glass transition temperature in molten salts 5 containing ions of a larger or smaller radius than those originally present in the glass. Conducting an ion exchange treatment leads to the fact that, due to an increase or decrease in the molar volume of the original glass, its non-crystallized regions 6 are pressed above the surface or bend into the volume, forming spherical segments 7. To further increase the curvature of the surfaces of the positive cups, the crystallized interliner layers are etched before ion-exchange areas 3 to a depth of 10-100 microns. In order to give the micro lenses a meniscus shape, one polished surface of the plate is subjected to ion exchange treatment in molten salts containing ions of a larger radius than originally present in glass, and the other polished surface in molten salts containing ions of a smaller radius than the latter. 2 hp f-ly, 7 sp. 1 tab. // aa (l c ate 1

Description

The invention relates to optical instrumentation and can be used, in particular, for the manufacture of transmitting volumetric integral or composite imaging of optical rasters used, for example

 in the field of mobile devices for television, film, holography, etc.

The purpose of the invention is to expand the functional capabilities of the rasters produced by forging the Positive and negative ffiiKpoJiHHS with increasing curvature of their surfaces and improving the quality of these surfaces, as well as additionally increasing the shape of the microlens and making the microlenses the shape of the meniscus.

Figure 1 shows the exposure of a polished plate of photosensitive crystallizing glass.

: through a photo mask with opaque Disks of FIG. 2 - a photo mask with a capr

, the translucent drive w | figure 3 - crystal lysadi. exposed interiizovyz: areas by heat treatment; in FIG. 4, iHoric polishing; Fig. 5 shows the etching of the crystallized surface of the network in Fig. 6 — ion-exchange treatment; 5 in Fig. 7 — the treatment process used for forging the crisp phase of the Oaxi-11Hyro bath;

The method is used as follows.

Plates t are made of a photosensitive crystal glass; its plates are filled and filled to a thickness of 4–8 mm determined by a specified working distance of the raster. The plate is combined with Photomask 2. with an unseen die ¬ s located according to the location of the micro lenses in raster (fig, | and 2).

The unit is rigidly fixed and exposes the glass through a photomask with short-wavelength radiation 5, for example, a laser (% 337 nm). Exposure time 2-30 minutes.

The activating radiation is especially strongly absorbed in the surface layer; therefore, in this case, when the exposed area is thicker, a noticeable weakening of the intensity of short-wavelength radiation through the sample thickness is observed. The consequence of this is uneven.

S

ten

S 0

five

five

0

the degree of crystallization in thickness and, therefore, different parameters of the microlenses obtained on both surfaces of the sample.

To eliminate the effect of attenuating the intensity of the incident radiation, it is possible to use a mirror with an external coating. The mirror is placed behind the exposed plate and is used for additional exposure by reflected radiation.

The overall intensity of the ultraviolet radiation becomes more uniform throughout the sample, and the microlenses obtained from the sides have the same parameters.

After that, the crystallization of the inter-lens regions 3 is carried out, for which the plate 1 is placed in a furnace and the heat treatment is carried out (Fig. 3 and -7). Next, the plate t is removed and secondary polishing of its surfaces is carried out (Figure 4). Plate thickness becomes 2-6 mm.

If the permanent jelly target is to produce positive rabbits with a greater curvature, then the process includes the additional step presented in figure 5, which means that after the second polishing, the plate 1 is immersed in diluted hydrofluoric acid 4. Within 5-1 minutes The process of etching of the crystallized areas of Zr is in progress; the duration of the etching process depends on the required depth of etching (10-100 µm) and is determined experimentally. After the required time has expired, plate 1 is removed from acid 4, washed with water and dried. After that, ion-exchange treatment is carried out at a temperature higher than the glass transition temperature Ta in melts of 5 salts containing ions of a greater or lesser radius than originally present in the glass.

The use of ion-exchange diffusion treatment leads to the fact that unbroken areas of glass b are pressed above the surface or bend into the interior of the volume, forming spherical segments 7.

The spherical segments 7 on the glass surface are formed as a result of ion exchange in the melt 5 salt due to the increase or

reducing the molar volume of the original glass.

During the ion exchange process it is possible to change the height of the spherical segments 7, i.e. the height of the deflection and the curvature of the microlens of this photosensitive glass over a wide range, by changing the whole group of parameters: variations in the composition of the salt melt by the type of cation, variations in the degree of substitution of cations on the surface, variations in the depth of diffuse 1.W (duration of ion-exchange processing). In addition, the height of the segments 7 or the curvature of the micro lenses depends on the thickness of the plate 1 and the radius of the disks of the photo-car 2.

A lithium alumino-silicate system is used as a matrix for photosensitive glass. The role of photosensitive d (5bazok metals capable of colloid formation belongs to metals: gold, silver, copper. Reducing agents are additives of oxides of cerium, antimony, tin.

Compositions of photosensitive glasses that are appropriately used for the manufacture of microlens grows are determined based on the required degree of substitution of the exchanging ions on the surface of the glass, v.e. ultimately, of the desired microlens curvature.

When establishing the mode of ion exchange treatment (temperature and duration), proceed from the following. The duration of the ion-exchange treatment should be such that, for a given melt 5 of salt, a diffusion depth comparable to the required value of the height of the segment 7 (height of the deflection) should be provided. This value, i.e. the duration of the treatment can be calculated by solving the one-dimensional diffusion problem from the end of the cylinder. It should be taken into account that the pro cess of ion exchange treatment and the composition of the melt are similar in the result obtained. The same or similar values of the radii of curvature of the lenses can be obtained by using a melt melt containing a high concentration of exchangeable cations and carrying out ion exchange for a short period of time or vice versa conducting ionic

ditch by the proposed method, the exchange is a long time using

given in the table.

Based on the task of obtaining positive or negative micro lenses, for the selected composition of photosensitive glass, the thickness of the plate 1 and the size of the microlenses set by the corresponding photomask 2 and their curvature (focal distance), the composition of the melt 5 salts for ion exchange, the time and temperature interval of the ion exchange are determined diffusion processing.

The following molten salts are used. To create positive mic35

40

less concentrated decomposing or melting the salt with cations of a smaller p dius.

The temperature of the ion exchange treatment is determined in many respects by the viscosity of the photosensitive glass and can vary over a wider range than with ordinary ion exchange, i.e. The framework of the crystallized part of the glass is reinforcing with respect to the entire glass. In order to ensure the sphericity of curvilinear surfaces, it is necessary to choose a high ion exchange treatment temperature.

Rollins - sodium nitrates or sulfates, g In this case, the viscosity of the glass can be

potassium, rubidi, cesium and mixtures thereof. At the same time, extrusion (swelling) of the uncrystallized sections 6 of the glass surface occurs due to an increase in the molar volume during the exchange of Li ions from glass to ions (K, Rb, Cs.) From the melt. Negative microlenses are obtained when molten salts are used.

50

less than 10 - 10 AND and the forces of surface tension. The limitation of the upper limit of the temperature range of ion exchange is the resistance of the polished glass surface to melt. However, the upper limit of the working temperature interval can be increased when carbon dioxide sparging is used.

nitrates or sulphates of lithium or sodium, the surface of the glass remains

ri and mixtures thereof, when implemented.

The duration and temperature of the ion-exchange treatment largely depends on the composition of the photosensitive exchange: Na (K) ions from glass to Li (Na) ions from the melt. The quantitative composition of the melt 5 SO5

0

less concentrated decomposing or molten salt with cations of a smaller radius.

The temperature of the ion exchange treatment is determined in many respects by the viscosity of the photosensitive glass and can vary within wider limits than with the usual ion exchange, i.e. The framework of the crystallized part of the glass is reinforcing with respect to the entire glass. To ensure the curvature of the curved surfaces, it is necessary to choose a high temperature ion-exchange treatment.

g In this case, the viscosity of the glass can be

50

less than 10 - 10 AND and the forces of surface tension. A limitation of the upper limit of the temperature range of ion exchange is the resistance of the polished glass surface to melt. However, the upper limit of the operating temperature range can be increased by using sparging with carbon dioxide. In this

glass and the size of the workpiece (plate) and determined experimentally.

After the ion exchange treatment has been established, the preform (plate) 1 is placed in the holder, heated until the ion exchange treatment and placed in the melt 5 of the necessary salt. After the time required and sufficient for obtaining a given microlens curvature located on the surface of the plate, the plate 1 is removed from the melt 5 and cooled to room temperature.

To give the micro lenses a meniscus shape, the process of ion-exchange diffusion treatment is carried out as follows. In the first stage, ion exchange is carried out on one side of the plate in the melt containing ions of a smaller radius than in the glass initially present, for example in the lithium nitrate melt, protecting the second side (surface) of the plate, then the plate is removed from the melt, cool and horn shake water. Next, the ion-exchange treatment is carried out from the side of the second surface in the melt containing ions of a larger radius than those originally present in the glass, for example, in the potassium nitrate melt, protecting the first surface, after which plate 1 is melted out of the melt 5, cooled and washed with water.

Example. In order to obtain a Polo Mtelny microlens on the surface of glass, glass 1 of composition 3 (see table) is used to make a plate 1 polished on both sides with a size of 30x30x4 mm. Photomask 2 is a glass cladding made of silicate glass, onto which a pattern in the form of disks of chromium arranged hexagonal is applied. The disk diameter is 500 microns. A laser LGI-21 SL 337 nm is used as a source of short-wave radiation. The laser beam diameter is increased approximately 10 times by using a collimator based on quartz lenses with focal lengths F, 60 mm F2. 613 nm.

Pastine is combined with a photomask and fixed in a holder for carrying out the illumination with laser radiation. The exposure time of plate 1 carried out through photomask 2 is 30 minutes. After that, the plate 1 is removed from the exposure and placed in a muffle furnace. The heat treatment is carried out according to the regime shown in Fig. 7. After this, the furnace is turned off and the plate is subjected to inertial cooling for 8 hours. After cooling, the plate. 1 polished again.

A melt of potassium nitrate salt is melted to carry out ion exchange. Ion exchange is carried out at

600 ° C, which corresponds to the viscosity of the photosensitive glass TO P. P. Plate 1 is fixed in a stainless steel cage. Then the holder with the plate is heated to and lowered

in the melt 5 on the basis of potassium nitrate. The time of ion-exchange diffusion treatment is 2 hours. After the specified time, the holder and plate are removed from the melt and cooled on

Claims (1)

 1. A method of manufacturing glass microlens rasters, including exposing a polished plate of photosensitive crystallizing glass through a photomask, with opaque discs arranged according to the position of the microlens in a raster, and the subsequent crystallization of the exposed interlens regions by thermal processing, characterized in that, in order to expand the functionality of the rasters being produced by forming both positive and negative gdcrolins with an increase in the curvature of their surfaces and an increase in the quality of these surfaces, after crystallization of the surface of the plate it is again polished and subjected to an ion plate 1446579 " exchangeable with terature 3, Pop.1 method, differing in the glass transition temperature of T. crystals and in that it was given to sheg "°" b-m-microlens, S is more or less than the radius than the polished surface of gshastana Initially nDHrVTPTRvmmMa oh. ".-, J .. initially present in the glass. subjected to ion exchange treatment in 2 Method POP.1. I distinguish melts of salts containing ions more and with the fact that, in order to supplement its radius, the origin of Zcy tively increase the curvature of the surface in the glass, and the other poposteostae have a positive microline, interstitial surface, in melts Red ion-exchange treatment of wires containing the ions of the re-etching of the crystallized inter-lens fibers, than the latter. of its radius zones to a depth of 10–100 μm. UUUUI  . / " ftue. f   .. subjected to ion exchange treatment in melts of salts containing bol ions Phie, 2 Fiyo.Z Phie. 5Q - t t, MUH