Avalanche photo diode

Nuclear scattering is counted by two avalanche photo diode (APD) detectors. The detector for NIS (Fig. 9.1) is located close to the sample. It counts the quanta scattered in a large solid angle. The detector for NFS is located far away from the sample. It counts the quanta scattered by the nuclei in the forward direction. These two detectors follow two qualitatively different processes of nuclear scattering ... 

FIGURE 10.10 An experimental system of tip-enhanced CARS microscopy. See the text for detail. ND nentral-density filter, P polarizer, DM dichroic mirror, BE beam expander, BS beam splitter, APD avalanche photo diode. 

Figure 7.27 Confocal Raman microscope spectrometer. The sample is illuminated by a laser light reflected on a dielectric mirror (DM) combined with a highly selective Notch filter. The Raman signals scattered from the sample are detected by highly selective avalanche photo diodes (APD) or via a monochromator on a CCD detector. The sample is scanned in two or three dimensions and the...

Acceptor channel emission filter (e.g. FIQ620/30M, Chroma Technology Corp., USA) Avalanche photo diode detectors, (e.g. SPCM-AQR-15, Perkin Elmer Optoelectronics, USA)... 

Figure 8. Photon-pair correlation analysis of single molecule emission, (a) The temporal separation of photon pairs can be analyzed by a Hanbury-Brown and Twiss experiment, where the fluorescence photon flux is divided by a 50/50 beamsplitter and detected by two avalanche photo diodes (APDs). By delaying the arrival time of signals from one detector, simultaneous photon events can be detected if the delay time is known, (b) Photon-pair correlation analysis of - 1000 molecules of Rhodamine 6G probed individually by the setup shown in (a). Single fluorescent molecules can only emit one molecule at a time (photon antibunching), which results in an anti-correlation of photon events for times shorter than the fluorescence lifetime. By fitting such a histogram, the fluorescence lifetime and the number of molecules probed in the excitation spot can be extracted. For an increasing number of molecules, the dip at time zero begins to become less well expressed, because the probability for simultaneous photon emission increases.

The single photon detector - typically an avalanche photo diode (APD) driven in counting mode- detects the arrival of fluorescence photons. The recorded photon trace is finally evaluated according to the chosen FFS method, i.e. the sequence of detection events is numerically processed for yielding information about the investigated sample. 

The alignment of discrete detectors for each input is no less a difficult task than the source assembly problem. The extra traces associated with connecting discrete field effect transistors (FETs), PIN diodes, or avalanche photodiodes leads to degradation of signal, lower reliability, and greater cost. The integration of photo FETs onto the IC does provide a way to simplify the detector side of the problem, unfortunately at the... 

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