CHARGING. Charge IR indicator in daylight or fluorescent light prior to use and recharge when sensitivity drops after IR illumination or self discharge. The duration of recharging depends on the intensity of the exciting light. When charging with sun light it takes several seconds; with moderate twilight it might be several minutes. Especially when charging with incandescent bulbs, it should be regarded that a full charge can only be obtained with IR free excitation light, because the IR part leads to a simultaneous discharge during excitation. To separate IR part from the excitation light, the filter BG39 from SCHOTT has been proven useful. As optimal excitation source we recommend the fluorescent lamp DULUX S 9W/71 Blue from OSRAM, which can be used without any filter.
INDICATOR OPERATION. The indicator operation corresponds to a discharge of the energy storing phosphor. The discharge is controlled by IR radiation and is shown as a bright-red emission, whose strenght is proportional to the intensity of the IR light. The light yield during the discharge is not constant, but decreases continuously at constant IR radiation. The discharge duration is inversely proportional to the radiant intensity of the stimulated bright-red light. The rise and fall time of the bright-red emission lies in the nanosecond range. To separate unwanted visible parts of the radiation to be examined, the filters RG780 to RG1000 from SCHOTT are recommended. Is the IR source too weak, shield surrounding light. The infrared indicator can be used transmissive as well as reflective. The coarse-grained front side is significantly more sensitive for incident IR radiation then the fine-grained back side.
SELF DISCHARGE. As every energy store, the infrared indicator IR-B1 shows a self discharge, which can be observed as an extremely weak emission of bright-red light. It takes several months for a (nearly) complete self discharge; the saturation charge holds some ten minutes.
CAUTION. Card may break when bent. Cleaning with a moist cloth. Only use isopropyl alcohol or water.
To avoid eye damage from laser beams, always use laser safety glasses.