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Single Photon Counting Modules (SPCM) for Confocal Microscopy

SPCM-AQRH is a self-contained module that detects single photons of light over the 400 nm to 1060 nm wavelength range - a range and sensitivity that often outperforms a photomultiplier tube. The SPCM-AQRH uses a unique silicon avalanche photodiode (SLiK) with a circular active area that achieves a peak photon detection efficiency of more than 65 % at 650 nm over a 180 μm diameter. The photodiode is both thermoelectrically-cooled and temperature-controlled, ensuring stabilized performance despite ambient temperature changes.

  • The SPCM performs well in a variety of applications including:
  • Particle Sizing
  • Confocal Microscopy
  • Astronomic Observations
  • Optical Range Finding
  • ultra-sensitive Fluorescence
  • Quantum Communications.

The product is available as a single-channel unit in different performance classifications and in a four-channel array format, the SPCM-AQ4C, a module containing four APDs with a single power supply and four individual outputs.

Count speeds exceeding 20 million counts per second (Mc/s) are achieved by the SPCM-AQRH-1X module (> 30 million counts per second on some models). There is a “dead time” of 35 ns between pulses but other values can be set at the factory. As each photon is detected, a TTL pulse of 2.5 Volts (minimum) high in a 50Ω load and 15 ns wide is output at the rear BNC connector. To avoid a degradation of the module linearity and stability, a case temperature between 5°C and 40°C should be maintained.