Diffuser radiation patterns over a large dynamic range. 1: Strong diffusers.
Theoretical computations are presented for the far-zone radiation patterns from strong diffusers having a normally distributed height profile and different autocorrelation functions for the surface height. Diffusers having two scales of roughness are also analyzed. Data are presented from ground-glass and acid-etched-glass diffusers using a scatterometer that permits measurements over an entire hemisphere with a dynamic range of 6-8 orders of magnitude. For the ground glass, excellent agreement is obtained using an autocorrelation function that is conical for small spatial offsets; this is consistent with our physical expectation based on the need for a rapid fall-off in surface correlation, due to the jagged nature of the surface relief. For the acid-etched case, excellent agreement is found using an autocorrelation function that is paraboloidal for small spatial offsets. Remote sensing of surface roughness and surface correlation are seen to be practical and accurate.
Shirley
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George
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