Spectra Pritchard photometer
Date: circa 1980
Inventory Number: 2004-1-0214a
Classification: Photometer
Dimensions:excluding cord: 14.5 × 58.1 × 23.6 cm (5 11/16 × 22 7/8 × 9 5/16 in.)
Accessories: Two instructions manuals: SPECTRA PRITCHARD PHOTOMETER, MODEL 1980A, CONDENSED OPERATING INSTRUCTIONS; INSTRUCTION AND MAINTENANCE MANUAL FOR SPECTRA PRITCHARD PHOTOMETER, Model 1980A. Both in gray archival box, C2-H1
Description:
This photometer encloses a patented optical system that was used to measure with great precision the attributes of light-color intensity. The dial on the side of the instrument rotates a filter turrets through which the light to be analyzed passes before hitting a photomultiplier tube. The photometer is equipped with an eyepiece (to determine the intended target) and an objective lens, over which has been added a glass filter.
A sticker mentions the following information: Calibrated on 8-13-85 / by SC / Due 2-13-86.
All the technical details of this instrument and its accessories can be found online
here.
Signedunder instrument: PHOTO RESEARCH DIVISION, KOLLMORGEN CORPORATION
FunctionUsed by Land for his experiments with color vision (Retinex theory). It was also most likely used in Land's famous lectures on the same topic.
The photometer was used to measure the flux, one wave band at a time, coming to the eye from a specific area of a colorful panel dubbed "Mondrian" by Land.
Primary SourcesEdwin H. Land, "The Retinex Theory of Color Vision," Scientific American 237 (1977): 108-128.
Edwin H. Land, "Recent Advances in Retinex Theory and Some Implications for Cortical Computations: Color Vision and the Natural Image," Proceedings of the National Academy of Sciences of the United States of America 80 (1983): 5163-5169.
Edwin H. Land, "An Alternative Technique for the Computation of the Designator in the Retinex Theory of Color Vision," Proceedings of the National Academy of Sciences of the United States of America 83 (1986): 3078-3080.
ProvenanceThis object belonged to Edwin H. Land and came from the Rowland Institute, Harvard University. Gift of the Edwin H. Land Family.