摘要 |
This invention relates to a device for use when evaluating optical signals by means of a chopper (2, 2'), i.e. a rotating shutter, and a photodetector (6, 6') for detecting the signal transmitted through the chopper (2, 2'). In order to improve the evaluation of the incident signal the opaque part (3, 3') of the chopper is provided with a reflective surface (7) to utilize also the optical signal falling on the opaque part (3, 3'). An additional photodetector (9, 9') has been arranged for detecting this reflected optical signal. In order to reduce the energy losses and in this way increase the amplification of the optical signal the device also comprises an optical element in the form of a glass prism (10, 10') in which one and the same surface is utilized both for transmitting and reflecting the optical signal.
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