Photometer

Spectra
Brightness Spot Meter
Patented
Photo Research Corp.
Burbank
California
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Code 1505-UB
Serial No. 1803
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LENS:
Code LMS-60
Serial No. 1803
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ASSET LABEL:
Elliott Bros (London) Ltd.
Rochester
Division A.E.I. 0161
P.U. No.
Contract
Date
270/850/53

A photoelectric instrument for measuring the luminance of surfaces; it has a telescopic viewing system for imaging the bright surface to be measured on the photo-emissive screen of a photo-multiplier tube, and a separate unit that combines the power supply with the controls and readout meter.

These instruments are used to measure the Luminance of a Display such as a Head Up Display, Head Down Display or a Helmet Mounted Display. The instrument has different apertures and lenses; a Head Up Display is focused at infinity whereas a CRT face or a Head Down Display is a close-up focus.

This photometer is fitted with a close-up lens and, since it has an ISD Asset label on its underside, was probably used to measure the luminance of indicator dials, backlit control panels and alphanumeric readouts.