Silicon photodiode detector

This interferometric dilatometer consists of a rather simple and small Michelson interferometer, in which the two arms are parallel, and of a 4He cryostat, in which the sample to be measured is hold. The sample is cooled to 4 K, and data are taken during the warm up of the cryostat. The optical path difference between the two arms depends on the sample length hence a variation of the sample length determines an interference signal. The Michelson interferometer consists of a He-Ne stabilized laser (A = 0.6328 xm), two cube corner prisms, a beam splitter, three mirrors and a silicon photodiode detector placed in the focal plane of a 25 mm focal length biconvex lens (see Fig. 13.1). 

The first measurement we make when starting a fluorescence study is not usually a fluorescence measurement at all but the determination of the sample s absorption spectrum. Dual-beam differential spectrophotometers which can record up to 3 absorbance units with a spectral range of 200-1100 nm are now readily available at low cost in comparison to fluorimeters. The wide spectral response of silicon photodiode detectors has made them preeminent over photomultipliers in this area with scan speeds of a few tens of seconds over the whole spectral range being achieved, even without the use of diode array detection. 

Spectrophotometric analyses were carried out using a Biochrom Model Libra S12 UV/Visible Spectrophotometer, equipped with tungsten halogen and deuterium arc light sources with a single solid state silicon photodiode detector, and operating software. 

Meissner et al. (1988a, 1988b) used an IR-sensitive silicon photodiode detector, which revealed, in addition to the TL emission of CaF2 Tm in the visible, TL emission at 800 run. The IR TL exhibited the same TL peaks as the visible TL but at higher intensities. The increase in the TL intensities in the IR was by factors of 24, 16 and 6 for the 100, 150 and 240°C peaks, respectively. The same investigators (Jacob et al. 1990) have verified that the visible and IR TL peaks are related to the same trapping levels. 

Figure 5.16. Radiant sensitivity of a large area silicon photodiode detector.

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