|
PH-656/PD and FB-5b Self-developing Film Holders (early 1950s) |
|||
|
This film holder is a high range self-developing film dosimeter. The film packets that were used with this system were the Radiac DT-64/PD (0.5 – 25 R) and DT-65/PD (15 – 420 R). The holder is a steel box (1.25” x 2.25” x 0.25”) lined on the top and bottom with 1 mm of lead. It is hinged at one end and latched at the other. The jaws at the latched end of the holder are rounded so that they spread the developing agent over the film when the packet is pulled from the holder. |
 |
||
 |
|||
|
Each film packet consists of three negative emulsion film strips separated from three corresponding positive film sheets by a pod containing the developing solution. When the packet is pulled out of the holder, the pod bursts and the developing solution is spread between the negative strips and the positive sheets. After one minute, the packet is opened and the dose determined by viewing the darkening of the three positive sheets. For the DT-64/PD packet, the positive sheet on the left side is used for low exposures (0.5 to 10 R), the sheet on the right side is used for high exposures (12 to 25 R), and the third, in the center, is a test sheet used to determine that the unit worked properly. The darkening of the two outermost sheets is compared with an adjacent graded scale that employs letters (A to L). The letter corresponds to the exposure. | ||
|
There
are two examples in the collection. One has “U.S. Army” painted on the
side in white letters. The other example has “FB-5b, Polaroid Corp., References Department of the Army Technical Bulletin TB SIG 226,
Radiation Monitoring in Atomic Defense. D. Van Nostrand. 1951. p. 62. |
|||
|
Donated by Ron Kathren |
|||
