Method of making speckle-diffuser

FIELD: optical engineering.

SUBSTANCE: method is based upon exposure of parts of light-sensitive medium by speckle pattern and subsequent processing of the medium. Exposed parts of light-sensitive medium have central and surrounding peripheral areas; the parts overlap each other with their peripheral areas. Exposure in central area is equal to preset value and exposure in peripheral area decreases linearly from preset value at its boundary with central area till zero at the boundary of exposed part. Shape, sizes and mutual disposition of exposed parts are chosen to provide constant exposition on whole surface of light-sensitive medium is constant and equals to preset value after process of exposure is finished. Indicatrix of diffusion is provided to be constant along the whole surface of speckle-diffuser at big sizes of speckle-diffuser.

EFFECT: improved efficiency.

3 cl, 6 dwg

 

The invention relates to optical instruments, and more specifically to a light diffusers and projection screens.

There are different types of light diffusers and projection screens, the purpose of which is the scattering of light falling on them in a certain solid angle. One of the types of light diffusers and projection screens form a speckle diffusers [1]. Speckle diffuser is a diffuser of light, and whose refractive index or elevation or both of these parameters describes the intensity distribution of the scattered beam of coherent light. The distribution of the intensity of this light beam has a patchy structure, spots which are called speckles. There are several ways of making the speckle diffusers. There is a method, according to which the photosensitive medium is recorded intensity distribution of the coherent light scattering, for example, frosted glass [2]. Then, the photosensitive medium is subjected to processing, leading to change its index of refraction, relief in accordance with the local intensity distribution of the light. Known methods, according to which first, by exposing the photosensitive medium diffused beam of coherent light and its subsequent processing is made matrix with rolespec cone. Then use this matrix to plastic medium is extruded relief speckle-cone [3], or the terrain is copied from the matrix during curing applied to the matrix layer of epoxy resin [4]. The known method according to which first, by exposing the photosensitive medium diffused beam of coherent light is produced mask, the transmittance of which is described by the distribution of intensity of scattered coherent light [4]. Then, the contact mask is copied onto a photosensitive medium in its coverage of incoherent light. A known method of manufacture, in which, proceeding from a specific indicatrix of scattering speckle diffuser is calculated on a computer, its microstructure, which is then formed by point-by-point exposure of the photosensitive medium. Describes the known methods are not suitable for the manufacture of speckle diffusers large sizes, with the size of the diagonal of about or more than one meter required when creating projection screens. Thus, the process of exposing the photosensitive medium by a beam of coherent light scattered frosted glass and covering the whole of its area, with larger photosensitive medium and frosted glass exposed to the effects of vibration and air flow, lubricating the recorded intensity distribution of the light is Difficult to ensure the necessary uniformity of illumination of the light-sensitive environment on the edges and especially the corners. The method consisting in calculating the microstructure speckle diffuser and subsequent point-by-point exposure of the photosensitive medium, with larger speckle diffuser inefficient.

A known method of manufacturing the speckle diffuser large size that is closest to the technical nature of the proposed, according to which the mask image, the transmission of which is described by the distribution of intensity of scattered coherent light is projected by the lens on the light-sensitive environment [4]. The image of this mask exhibited different parts of the photosensitive medium located so that they cover the entire surface of the photosensitive medium. This method requires high precision moving table on which the photosensitive medium relative to the projection lens. If the amount of movement greater than the size of the mask image, between two adjacent exposed areas of the photosensitive medium gap occurs where exposure environment is missing. Through such sites speckle diffuser light will not be scattered. If the amount of movement is smaller than the size of the mask image, two adjacent exposed area of the photosensitive medium are superimposed on each other. In the area of overlay exposure twice previshayuschii on the remaining surface of the photosensitive medium, which leads to overexposure of light-sensitive environment and to the appearance of the light passing through the speckle diffuser without scattering. The lens, projecting the mask image should be no aberration of the lens, which distorts the shape of the mask image, which leads either to the imposition of adjacent exposed areas of the light-sensitive environment, or to the emergence of a gap between them. The disadvantage of this method is that since the movement of the table with the photosensitive medium to long distance, approximately equal to the size of the photosensitive medium, is carried out with some degree of error, and the projection lens has some distortion, the speckle diffuser will always have a place or imposition of adjacent exposed areas, or education between the cracks, making the indicatrix of scattering data on areas other than the scattering phase function on the remaining surface speckle diffuser. To reduce the area of these plots is necessary to use more accurate and therefore more expensive equipment.

The purpose of the present invention consists in the manufacture of speckle diffuser, scattering indicatrix which is constant over the entire area of the speckle of the diffuser, and in reducing the cost of manufacturing the speckle diffuser. This objective is achieved in that the exposed areas of svetosavlje the Noah environment are superimposed on each other so the total exposure time at any point on the photosensitive medium is equal to the specified value. To obtain a permanent exhibition on the entire area of the photosensitive medium exhibited the plot has two regions: Central, within which the exposure is constant and equal to the given value, and peripheral located around the Central region. Exposure within the peripheral area is linearly decreased from the predetermined exposure values on the inner boundary of the peripheral region, coincident with the boundary of the Central region, to zero on the outer boundary of the peripheral region, coinciding with the boundary of the exposed area. The exposed parts are of such shape and size and are arranged so that a peripheral region adjacent the exposed areas overlap each other. The distribution of exposure within the exposed areas leads to a small deviation of the exposure of the photosensitive medium from the set value with a small error relative location of the exposed areas or small change in their form. If the photosensitive medium has a flat surface, all exposed parts are identical and have the shape of a hexagon. The Central region of the exposed area where the exposure is constant and equal to C is aceniu, has the shape of a rectangle. The peripheral region of the exposed area forms part of the site not included in the Central region. Four sides of the exposed area of the parallel sides of the Central region and are located at the same distance from them. The ends of two of the four sides coincide at one point, the ends of the other two of the four sides are the same at a different point. Four other end of these four sides are the points of intersection of straight lines, on which lie the four sides, with straight lines, which are the sides of the rectangle bounding the inner region of the exposed area. The remaining two sides of the exposed area is formed by two straight line segments, closing the perimeter of the exposed area. The exposed areas are arranged in such a way that their boundaries overlap the boundaries of the inner region adjacent parcels. When these conditions peripheral region adjacent the exposed areas overlap each other.

In the manufacture of speckle diffuser large size of the spherical shape of the exposed areas of the photosensitive medium are in the form of a spherical hexagon. Four sides of the exposed area lie on the meridians and Parallels of the sphere, the ends of two of these four sides are the same in one the point, the ends of the other two of the four sides are the same at a different point. Four other end of the data of the four sides of the exposed area are at the point of intersection of the meridians and Parallels, which are the four sides, with meridians and Parallels, which are the sides of a spherical rectangle that forms the Central region of the exposed area. The remaining two sides of the exposed area is formed by two arcs of great circles, closing the perimeter of the exposed area. The exposed areas located on the same Parallels have the same dimensions and distribution of exposure. The exposed areas have such dimensions and are arranged so that their boundaries overlap the boundaries of the inner regions of adjacent parcels. When these conditions peripheral region adjacent the exposed areas overlap each other.

Figure 1. The exposed area of the photosensitive medium when the flat shape of the surface and the distribution schedule of the exposition in section AA section.

Figure 2. Positioning of four of the exposed areas on the flat surface of the photosensitive medium.

Figure 3. The compound exhibited an area of flat light-sensitive environment that occur after sequential exposure of the four it is Astrov.

Figure 4. The exposed area of the photosensitive medium when the spherical shape of its surface.

Figure 5. Positioning of four of the exposed areas on the surface of the photosensitive medium spherical shape.

6. Composite exposed area of the photosensitive medium when the spherical shape of the surface that occurs after sequential exposure of the four areas.

The exposed part of the surface of the photosensitive medium with the flat shape of its surface are presented in figure 1, where 1 is the Central region of the exposed area, 2 - peripheral region. This figure shows a graph of the distribution of exposure in the cross-section AA of the exposed area, where E0- set the exposure value. Figure 2 presents the mutual arrangement of four of the exposed areas on the flat surface of the photosensitive medium. The exposed areas of overlap their peripheral areas. In zones 3 overlap two peripheral areas, in zones 4 - three of the peripheral area. The total exposure time at those points in zones 3 through which you can spend straight lines crossing the Central region 1 exposed areas, such as in the Central regions, and equal to the value of E0. This follows from the fact that the sum of the linear zavisimost is her exposure from the coordinates on the surface of the photosensitive medium is a linear function of the coordinates. If this linear function of the coordinates equal to the value of E0in two different points, then it is equal to the same value and the segment of the straight line connecting these points. In zone 4, the total exposure time is equal to E0because each of these two zones, the exposure time is a linear function of the coordinates, takes the value of E0at the boundaries of the zones. Figure 3 presents the composite exposed area of the light-sensitive environment that occur after sequential exposure of the four areas considered. In the Central area 5 of this composite plot of the exposure equal to the value of E0in the surrounding peripheral region 6 exposure time decreases linearly from F0to zero on the boundary. Having similarly exhibited additional areas, you can get exposure equal to E0on the flat photosensitive environment of any size. It is essential that a small deviation of positions of the exposed areas and their shape causes a small deviation of the exposure from the setpoint. This deviation is smaller, the greater the width of the peripheral region 2 (figure 1) exhibited plots. Due to this, the indicatrix of scattering speckle diffuser, obtained by this method is less sensitive to errors relative position and shape of the exposed students who tcov.

The exposed area of the photosensitive medium when the spherical shape of its surface when the lower side of the plot is situated near the equator of the sphere, are presented in figure 4, where 1 is the Central region of the exposed area, 2 - peripheral region. The exposed area is a spherical hexagon bounded by two meridians 7, 10, two parallel spheres 9, 12 and two arcs 8, 11 large circles. The Central area 1 display area where the exposure time is equal to the given value of E0is a spherical quadrangle, bounded by two meridians and two Parallels. Area 2 - peripheral region, where the exposure time decreases linearly from the values of E0on the border with the Central region to zero at the boundary of the exposed area. The end of the arc 9 is the point lying on the Meridian, which is the left lateral side of the Central region 1. The end of the arc 7 is at a point lying on the same parallel of latitude, which is the upper side of the Central region 1. Similarly, the determined position of the ends of the arcs 10, 12 in the bottom right corner of the exposed area. 4 shows the mutual arrangement of four of the exposed areas on the spherical surface of the photosensitive medium. In zones 3 are superimposed two peripheral areas in zones 4 - three of the peripheral area. The total exposure time at those points in zones 3 through which you can spend arcs of the great circles that intersect the Central region 1 of the exposed sections, the same as in the Central regions areas and equal to the value of E0. In zones 4 exposure time equal to the value of E0because it is equal to this value at the boundaries of these zones. Having similarly exhibited additional areas, you can get the set exposure value E0on the entire surface of the sphere, except for two areas in the vicinity of the two poles of the sphere. Figure 6 presents the composite exposed area of the photosensitive medium spherical shape that occur after sequential exposure of the four areas considered. In area 5 of this composite plot of the exposure equal to the value of E0in the surrounding peripheral region 6 exposure time decreases linearly from F0to zero on the boundary.

The described distribution of the exposure, the exposed areas of the photosensitive medium can be obtained by setting the optical filter with variable transmittance close to the photosensitive medium when the lighting environment of the scattered coherent light, or by applying such a filter close to the mask, the transmittance of which OPI is ivalsa intensity distribution of the scattered coherent light and the image which is projected onto the photosensitive medium.

Sources of information

1. U.S. patent No. 5609939 on March 11, 1997, MCI G 03 B 21/60.

2. U.S. patent No. 4336978 on June 29, 1982, MKI G 02 B 5/02.

3. U.S. patent No. 5534386 from July 9, 1996, MCI G 03 H 1/32.

4. U.S. patent No. 6303276 B1 October 16, 2001, MCI G 03 H 1/32.

1. A method of manufacturing the speckle diffuser, consisting in successive exposure areas photosensitive medium scattered coherent light or image, the intensity distribution corresponding to the intensity distribution of the scattered coherent light, and post-processing of the photosensitive medium, changing its refractive index, surface relief in accordance with the magnitude of the local exposure, characterized in that the exposed areas of the photosensitive medium consisting of the Central and surrounding peripheral areas overlap each other with their peripheral areas, the exposure time in the Central region is equal to the given value, the exposure in the peripheral region decreases linearly from the setpoint on the border with the Central region to zero at the boundary of the exposed area, the shape, size and arrangement of the exposed areas is such that after exposure exposure on the whole surface of the photosensitive medium is constant and equal to C is aceniu.

2. A method of manufacturing a speckle-diffuser according to claim 1, characterized in that when the flat surface shape of the light-sensitive environment of the exposed areas have the shape of a hexagon, four sides of which are parallel to the sides of the Central region having a rectangular shape, and are located at the same distance from the ends of two of the four sides coincide at one point, the ends of the other two of the four sides are the same at another point four other end of these four sides are the points of intersection of straight lines, on which lie the four sides with straight lines, which are the sides of the rectangle bounding the Central region of the exposed plot the remaining two sides of the exposed area, formed by two straight line segments, closing the perimeter of the exposed area, the exposed areas are arranged in such a way that their boundaries overlap the boundaries of the inner regions of adjacent parcels.

3. A method of manufacturing a speckle-diffuser according to claim 1, characterized in that when the spherical shape of the surface of light-sensitive environment of the exposed areas have the shape of a spherical hexagon, four sides of which lie on the meridians and Parallels of the sphere, the ends of two of the four sides coincide at one point, the ends of the other two of these the four sides are the same at another point four other end of these four sides are the points of intersection of the meridians and Parallels, which are the four sides, with meridians and Parallels, which are the sides of a spherical quadrilateral bounding the Central region of the exposed area, the other two sides of the exposed area is formed by two arcs of great circles, closing the perimeter of the exposed area, the exposed parts are of such a size and are arranged in such a way that their boundaries overlap the boundaries of the inner regions of adjacent parcels.



 

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