Über die Verwendung von Wechsellicht bei thermischen Strahlungsempfängern
The author shows by simple calculations that the radiation sensitivity of thermal receivers becomes about four times smaller if one operates the receiver with alternating light instead of constant light. But the smaller disturbances of the alternating light method and the possibility of using electronic amplifiers yield practically the same limit of accuracy as the method of constant light. The author gives some relations among the heat capacity, the heat transfer and the modulation frequency of resistance bolometers which should be attended to obtain the optimal sensitivity. This limit is still smaller for the alternating light method in comparison with constant light, where the thermal motion of the electrons dominates. Assuming plausible conditions for the band-width of the alternating light and the time of measure for constant light the accuracy of the alternating light bolometer becomes still diminished by the factor 5. So one concludes that the smallest detectable amount of radiation in relation to the disturbances is about 20 times smaller in the case of modulated light.
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