The Xenon lamp for either direct sample illumination or for use with an monochromator. It is the major light source used with photoelectric spectrometer.
It mostly used with an elliptic reflector which generates a white light beam converging into a single focal point about 20 cm from the lamp output window. This way one can vary light intensity density by changing sample distance from the lamp.
Due to an reflector engulfing the lamp, the setup has very good efficiency. Up to 70% of emitted radiation is captured by the reflector and directed at an illuminated sample.
The unit provides also three types of stabilization: electric current, electric power and light intensity stabilization. The light intensity stabilization mode helps the long term (order of hours) stability of the output beam. It also reduces the warm up time to about 3 minutes as compared with 30 minutes or longer in the current stabilization mode.
The lamp can be used with various filters. With an Air Mass filter it can serve as a solar simulator.
The plot shows the difference in light intensity evolution in two available stabilization modes. The current in the current stabilization regime is kept constant with about 0.0025 % accuracy. Despite
of that, the light intesity changes significantly over time (black line) due to temperature and pressure changes within the xenon bulb.
The light intensity stabilization eliminates the long term drift
in the light output and makes it stable just 3 minutes after the lamp is switched on.
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