The Cooling of Film and Slides in Projectors

A heat-absorbing filter is of primary importance for cooling film or slides, and experimental results are given of the performance of various types. A good filter, combined with a more powerful lamp, allows the screen illumination to be doubled without affecting the film. A study of the heat flow within the film during exposure leads to estimates of the efficacy of methods of film cooling which may be used in the future. The theory of cooling slides shows that best results are given by blowing air at very high velocities across the slide, to remove the “blanket” of stagnant air adhering to the surfaces. A practical slide cooler is described, and its performance figures given.

Print ISSN

0898-042X

Published

1951-05

Content type

Original Research

DOI

10.5594/J06318