For personnel working in radiation areas, Direct Reading Dosimeters provide an accurate and instantaneous indication of accumulated exposure. This instrument is accurate to 10 % of True Dose.

There is less than 2% leakage per 24 hours and the dosimeters are hermetically sealed. Resembling fountain pens in size and appearance, they contain a quartz fiber electrometer and compound microscope. The fiber is set at zero with a battery operated charger. As X- or gamma rays strike the charged fiber the scale is moved up in proportion to the radiation exposure.