Photon Counter Measures with Spatial Resolution
Jul 2008Hamamatsu CorporationRequest Info
• 105 to106 gain
• 25 × 25, 50 × 50 or 100 ×100 pixels
• room-temperature operation
The MPPC from Hamamatsu is a multipixel photon-counting device offering spatial resolution by using multiple silicon-based avalanche photodiode (APD) pixels. The APDs operate in Geiger mode, resulting in an optosemiconductor device with good detection efficiency versus number of photons. Other advantages are low-voltage operation and insensitivity to magnetic fields.
The device offers gain on the order of 105 to 106 by taking advantage of the Geiger discharge in the APD. This phenomenon occurs when the detector is operated with a reverse voltage that is higher than the breakdown voltage. The benefit of this high gain is that it allows the detector to output current that is greater than the typical noise floor of the amplifiers used; therefore, it allows the system to detect a lower light level than can sensors using low-gain detectors.
The units also offer an active area of 1 × 1 mm and use individual quenching circuitry for each pixel. Each APD pixel outputs a pulse when it detects a photon within the 270- to 900-nm spectral range, and the signal output of the device comprises the total sum of the outputs from all pixels. Three versions covering this area with 25 × 25, 50 × 50 or 100 × 100 pixels are available, as are two packaging choices, either metal- or ceramics-based.