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This is one of a set artifacts that typify the infrared detectors those used by astronomers from the 1940's into the 1960's. This small glass tube is an infrared photocell manufactured in 1946 by Robert Cashman of Northwestern University. The tube is coated on part of the interior face with a very thin evaporated layer of lead sulfide (PbS). The conductivity of the coating is modified by impinging infrared photons. This change in conductivity, when amplified by appropriate electronic circuits, is a direct measure of the intensity of the infrared radiation. Detectors such as this were used for studies of the infrared spectra of stars by Cashman and his collaborator Gerard Kuiper. The set of detectors was donated to NASM in 1994 by Dale P. Cruikshank.

 Display Status

This object is not on display at the National Air and Space Museum. It is either on loan or in storage.
Object Details
Country of Origin United States of America Type INSTRUMENTS-Scientific Manufacturer Robert Cashman
 Dimensions 3-D: 8.6 × 1.3 × 1.3cm (3 3/8 × 1/2 × 1/2 in.)
Storage: 13 × 10.2 × 1.9cm (5 1/8 × 4 × 3/4 in.)
 Materials Glass
Steel
Lead Sulfide
 Inventory Number A19940241001 Credit Line Gift of Dale P. Cruikshank Data Source National Air and Space Museum Restrictions & Rights Usage conditions apply
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