Averaging Screen-Illumination Readings

In obtaining the total output of a projector, or the total illumination which falls on a projection screen, it is customary to read the incident intensity at selected points in the illuminated area. These readings are then averaged by a suitable weighting formula to give the average over the face of the screen. This paper discusses some of the more commonly used formulas, considers their relative accuracy and the effects of various screen aspect ratios on the results obtained with them. It also analyzes various types of errors on the basis of an idealized distribution pattern which experience has shown checks closely with practical results.

Print ISSN

0361-4573

Published

1958-03

Content type

Original Research

DOI

10.5594/J11171