Germanium CCDs

Another case which is of increasing importance is where the detector is divided into a large number of well defined pixels of finite size e.g. CCD pixels, discrete scintillator elements, or Germanium detectors). If we assume that all relative positions of the boundaries of the detector pixels and the mask element shadows are equally likely to occur, then a typical value for the sensitivity can be found by considering the coding power of the mask convolved with the detector pixel shape e,g, a square or circular patch). 

The matrix array detector (128 x 128) associates P(VF2-VF3) copolymer with a silicon CCD matrix. This detector made by Thomson-CSF/LCR and TCS has been characterized al room temperature using an IR germanium optics. The following table summarizes the performances of this detector. 

Photomultiplier tubes and CCD detectors are the dominant detectors for Raman spectroscopy. Less common detectors include avalanche photodiodes for specialized applications in the near-infrared, single element photovoltaic detectors such as germanium or InGaAs detectors for FT-Raman measurements, and single element silicon photovoltaic detectors for stimulated Raman measurements. 

A Raman spectrophotometer analyzes the radiation scattered by molecules when they are illuminated with monochromatic exciting radiation. Currently, most Raman spectrometers are either FT instruments equipped with cooled germanium transducers or multichannel instruments based upon CCDs. These transducers, in contrast to photomultiplier tubes, are sensitive to radiation at 785 nm produced by diode lasers, which provide Raman excitation of many compounds without significant fluorescence. CCDs are not sensitive to the 1064-nm radiation from an Nd/YAG laser. 

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