CONTINUOUS OPERATION. Irradiate the IR indicator with long-wave UV-A light. Especially fluorescent lamps with black glass pistons work well as UV sources for suppressing visible light parts. Not suitable are IR light radiating UV lamps such as mercury vapor lamps, which operate with an enclosed glow spiral because the spiral emits strong IR rays. For UV-A lamps without black glass we recommend UG 1 from SCHOTT as prefilter. The sensitivity of the IR indicator IR-IA3 is widely controllable by the UV light intensity. High IR intensities can be dissolved by strong UV radiation, low IR light needs comparatively weak UV radiation. The UV intensity can be varied simply by changing the distance between the UV light source and the phosphor screen. The rise time depends, like the IR intensity, on the UV irradiation density. Strong UV light results in time constants in the millisecond range. With extreme weak lightning (and corresponding high IR sensitivity - observation in the darkness) some minutes may pass for the build-up of a stationary picture.
INTEGRATING OPERATION. The highest IR sensitivity is obtained after switching off the UV irradiation. In this case the IR indicator continues to emit green light for a while (phosphorescence). IR irradiation causes an extinction of the phosphorescence. The degree of extinction does not only depend on the IR intensity, but also on the irradiation time. A limit is given here only by the finite duration of phosphorescence. It should be regarded that even IR parts of the surrounding light show a clearly visible effect. Therefore - and also because of the lower phosphorescence light yield - the room needs to be darkened for this operation.
CAUTION. Don't touch the fluorescent layer with your fingers.
Cleanse only with a clean nylon brush.
Short-wave UV irradiation shortens the life of the IR indicator
and may harm your eyes.
To avoid eye damage from laser beams always use laser safety goggles!