Bidirectional transmittance distribution function, BTDF, measurements of low scatter optical materials require low scatter beam dumps to dissipate energy when the measurements are made at angles away from the specular beam. Many laboratories use beam dumps without knowing their scatter characteristics. We have made BRDF measurements at 0.6328 μm of beam dumps consisting of painted glass test tubes and a stack of razor blades. Low reflectivity flat surfaces, including Martin Black, Nextel Suede Coating, black felt and anodized aluminum were also measured. Results show that when compared with the BRDF measured for a flat surface coated with Martin Black, test tubes with low reflectivity black paint offer 1.5 to 2 orders of magnitude improvement. For flat surfaces, the BRDF of black felt is within a factor of 2 or 3 of that from Martin Black. When using the best performing beam dump, measurements verify that scatter from the beam dump can corrupt transmissive sample data at large angles in a manner not predicted by instrument signature measurements.

Date Published: 1 January 1987
PDF: 5 pages
Proc. SPIE 0818, Current Developments in Optical Engineering II, (1 January 1987); doi: 10.1117/12.967469

Published in SPIE Proceedings Vol. 0818:
Current Developments in Optical Engineering II
Robert E. Fischer; Warren J. Smith, Editor(s)