| 摘要 |
A highly accurate thermoelectrically controlled radiant energy detector achieving sufficient measurement stability to permit it to monitor the radiant energy output of a calibrated standard instrument, such as a luminance/illuminance source, which is to generate a standard quantity of radiant energy to be used, e.g., in the field testing and calibration of photometric instruments. The radiant energy detector provides a highly stable and drift free photometric measurement using a silicon photovoltaic detector arranged to receive radiant energy upon a sensitive surface thereof and to emit an electrical output signal related to the magnitude of incident radiant energy. A thermally conductive member, such as a mounting block, carries the light detecting element, and temperature sensing means, such as the semiconductor junction of a transistor, is in thermal communication with the conductive member. Controllable heat emitting means, such as another transistor, also is in thermal communication with the conductive member and a feedback circuit responds to the temperature sensing means for controlling the heat emitting means to maintain the conductive member and the light detecting element carried thereby at a constant temperature elevated above ambient temperature, e.g., 40 DEG C. The relationship between incident radiant energy and electrical output of the light detecting element remains substantially invariant, e.g., with a drift of approximately only 1% per year. Spectral response is stabilized and sensitivity is improved. Accordingly, the radiant energy detector and monitored radiant energy source allow highly accurate field or laboratory measurement and calibration to take place.
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