IM-235/PD Pocket Dosimeter (ca. 1980s)
The IM-235/PD is a military direct reading pocket dosimeter that measures gamma ray and X-ray exposures in the 0-200 mR roentgen range. The IM-235 is similar to the IM-9/PD except that the latter only responds to gamma rays while the IM-235 responds to both gamma rays and X-rays. The first reference I have for the IM-235 is the 1987 version of the List of Military and Civil Defense Radiac Devices which mentions the IM-235, the 235A and the 235B.
The following photo shows, from the top down, the IM-235, IM-235A and IM-235B. None of the three carries information about the manufacturer.
Size: 0.5” diameter and 4” long
Weight: ca. 1 oz.
Manufacturers: Victoreen Instrument Company, Dosimeter Corp and Physiotechnie.
Defense Nuclear Agency List of Military and Civil Defense Radiac Devices HQDNA (AR) 3M Revised, August 1987.