Abstract: A dual-color photographic sensitometer for exposing a piece of test film to a known amount of light of a selectable one of two different colors. The multiple-step density gradient of the sensitometer is uniformly illuminated along its entire length by an electroluminescent lamp comprising a plurality of phosphor segments of varying widths which are electrically connected to form two sets, with each of the segments in each set adapted upon excitation to emit a single color light. The width of each segment of a set is determined in accordance with its distance from the multiple-step density gradient so that the multiple-step density gradient is illuminated substantially uniformly by each segment set.

Abstract: A Geiger-Mueller (GM) tube coincidence loss correction circuit for automatically compensating for the dead time of the GM tube in an analog system so that the reading provided by the meter more accurately reflects the true radiation level. The electrical output pulses from the GM tube are differentiated and provided to a retriggerable one-shot multivibrator circuit which produces in response to each GM tube pulse a corresponding output pulse of predetermined duration greater than the dead time of the Geiger tube. The output pulse signal from the multivibrator circuit advances an analog ratemeter circuit and also effectively disables "time" for the duration of the output pulse by opening an analog switch connected in the discharge path of the integrating capacitor in the ratemeter circuit to maintain constant the charge thereon.

Abstract: A radioactive gas monitor that is adapted to measure total airborne radiation activity over an extended period of time and provide a readout in units that can be directly correlated to the maximum permissible exposure standards established by the federal government. The instrument also includes automatic background count rate subtraction, as well as means for measuring the actual background radiation level and adjusting the subtracted count rate accordingly.