Abstract

The simplification of the traditional Fourier transform system by using a dichromated gelatin off-axis hololens has been described.¹ In the new system a hololens and an achromatic imaging lens of small aperture were used in place of the three large achromatic Fourier transform lenses in the old system, thus upgrading the quality and brightness of the processed image. In the past year, two improved instruments have been constructed. The new instruments have in common a 150-W bromide-tungsten lamp as a light source, an achromatic imaging lens (40-mm diameter, 325-mm focal length), a holographic element astigmatic at 488 nm, and an input image of 4-in. by 5-in. transparency. The new instruments project the image onto a piece of ground glass to display a transmitted image, its magnification is 2, and the maximal observed image is 8-in. by 10-in. In weakly illuminated laboratory conditions, the color image can be observed through the ground glass, having 10-lines/mm resolution. The miniature pseudocolor reader weighs <30 lb and costs no more than $500. The instruments can be used for density coding pseudocolor image processing and phase transparency pseudocolor image display.

© 1985 Optical Society of America