The SH&G VTP is a Visioneering Model III device essentially as described in Willard Allphin's article, “Application procedures for evaluation of veiling reflectances in terms of ESI,” LD&A, Vol. 3, No. 8, August 1973, p. 37.
2.
The BRDF measurements are used by LUMEN II, and are therefore made reguarly as SH&G investigates new tasks.
3.
Determined from operator's manual and physical inspection of the equipment.
4.
National Semiconductor Corp, Linear Data Book, June 1976, page 1-69, data on the LM723 regulator used in the circuit.
5.
Linear Control Systems, Melsa and Schultz, McGraw-Hill, New York, 1969.
6.
A perusal of 'The selection, care, and use of electrical instruments in the photometric laboratory (revision),” prepared by the IES Testing Procedures Committee, Journal of the IES, Vol. 9, No. 2, January 1980, p. 77, suggests that there may be several areas where the system may benefit from further improvement.
