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1954-55 Theatre Catalog, 12th Edition, Page 308 (272)

1954-55 Theatre Catalog, 12th Edition
1954-55 Theatre Catalog
1954-55 Theatre Catalog, 12th Edition, Page 308
Page 308

1954-55 Theatre Catalog, 12th Edition, Page 308

place. Of course, certain restrictions on thickness of the layer, particle size compared to lenticle size and composition for the retention of 3-D characteristics must be evaluated before a selection is made of a particular substance.

An element containing such a coating is illustrated in Figure 10. This may be regarded as one segment of the Astrolite screen. It is noticed from a comparison of this figure with a wholly specular element that the uniformity of reflectivity is still present, this state

FIGURE 11 (above. left) is an enlargement at a screen section to podrav the particle distribution. Figure 12 (above, right) is cm enlargement of

IE]. being indicated by the length of the reflected rays A and B. But, in addition to these major rays, 21 series of less intense redections are created by the particles and these diverging beams tend to spread out the light energy past the normal optical boundary of the element.

Figure 11 is a shadowgraph showing the distribution of these fine particles when viewed under high magnification. An upper limit on the magnitude of any particle is approximately 0.1 that

' I l

,y i p. 600 509 400 300 zoo loo 0. +100 204: 300 400 psoo.609 7o.


of the size of the lenticle. This, of course, is easily understood when consideration is given to the effects produced by a particle of the same order of magnitude as the element. In such a case, the lenticle curvature would have little influence on the distribution of reflected light, and consequently the entire screen would approximate a completely diffusing surface. Figure 12 shows the enlarged section of a finished screen and the embossing details which spread the light uniformity throughout the theatre.


The test of whether or not the above theories work out in practice is to perform a photometric analysis on a finished sample of Astrolite. If the controlled diffusion principle is operating as one would expect, the brightness gain should remain relatively Hat when leaving the axis in a lateral direction and then gradually taper off reaching a value of standard white. As is shown in Figure 13, this is actually the situation that exists with Astrolite. The magnitude of the brightness gain and the angular spread of light may be controlled by varying the embossing techniques and this factor affords a means whereby any desired type screen may be produced.

screen section to show lenticular pattern. Figure 13 (below) is a chart showing the brightness gains of a sample Astrolite motion picture screen.


1954-55 Theatre Catalog, 12th Edition, Page 308