The standard use of the parameter σ for the rms surface roughness of optics has obscured the fact that the effective surface roughness is a function of both the measurement wavelength and bandwidth. A more appropriate method for the flowdown of surface specifications from stray light requirements is presented. Acceptance test methods for validating surface properties of optics using a Zygo NewView Profilometer are also discussed.

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Non-sequential ray tracing for stray light analyses have demonstrated value, but are over-constrained when high sampling and speed are both needed. In cases where real geometry and mechanical surface properties are critical, such analyses are certainly required. But the goal of these analyses is often to attempt to approach the performance that would be achieved if only the optics contributed scatter and only through the sequential optical path. In other words, optical element scatter is the limiting case for system performance. An analysis technique is therefore presented that enables approximate but rapid sequential stray light estimates through deterministic modeling. Results of correlation to nonsequential analyses demonstrate the large range of applicability of this approach. Examples of parametric studies show the value of rapid paraxial estimates for understanding system performance sensitivities.

BATC has developed a new stray light test facility (SLTF) and performed initial tests demonstrating its capabilities. The facility interior is nearly all black and is a Class 5 cleanroom. Coupled with a double cylindrical chamber that reflects the specular light away from the instrument under test, the stray light control in the facility is excellent. The facility was designed to be able to test a wide variety of instruments at a range of source angles from in-field to large off-axis angles. Test results have demonstrated PST performance below 1E-9.