Fast Acting Optical Deflection
Rept. no. 3 (Final) Dec 1989-Mar 1991,
UNIVERSITY COLL OF NORTH WALES BANGOR SCHOOL OF ELECTRONIC ENGINEERING SCIENCE
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The spectral transmittance has been studied with sinusoidal phase transmission gratings with 600 lines per mm and of varying groove depths from 637nm to 776nm in order to obtain minimum optical transmission in the wavelength range of 500nm to 1000nm. All the gratings were formed on photo-resist materials on glass substrates using a holographic technique. A high degree of attenuation of the zero order beam over a small wavelength range is attainable with a single sinusoidal transmission grating of an appropriate groove depth, min at which the transmittance is minimum, being proportional to the magnitude of the groove depth. A superposition of two crossed gratings of two dissimilar groove depths either on two different glass substrate or on a single substrate can provide a very low optical transmittance in the band 400-1000nm although the visibility through such a system is poor.