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The design and operation of a near-angle scatterometer that measures the total integrated scatter (TIS) from bare and coated diamond-turned surfaces are described. The scatterometer is designed to make TIS measurements from 0.06 out to 4 deg from the specular beam. Both bare and coated diamond-turned surfaces generated on two different machines were measured. The effect of machine control on minimizing near-angle scatter is discussed.

An investigation was conducted to develop a set of criteria that would allow the typical user to preselect a diamond-turning tool for the most critical optical finishing operations. A wide variety of tools used in this study had their edge quality evaluated by Nomarski and scanning electron microscopy methods, and the diamond crystal orientation and quality were determined by Laue x-ray methods. One of the tools was subjected to a long-term machining test to evaluate the tool wear process and to correlate the wear observed with changes in the scattering properties of the surface.