Abstract

In a spacelab experiment the shadow profile of a metallic alloy sphere of 8 mm diam. shall be imaged by means of LED illumination (640 nm) and backlight reflectors, using telecentric optics. The direction of the incident light does not meet the condition for direct reflection at the plano reflector surface; thus the reflectors must either have diffuse reflexion (model: white paper), act as diffractive elements with the correct blaze angle or consist of micro surfaces that are oriented in space to meet the condition for direct reflection.

© 1998 Optical Society of America