OBB Light Detector

CoolOne™ Dual Mode, Analog/Photon Counting, Thermo-Electrically Cooled Photomultiplier Detection System

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Cooled PMT Housing
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NIR Photon Counting Detection to 1,010 nm
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Detect Single Photons (switch positions)
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Operates in Analog or Photon Counting Modes
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Compact Size
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Complete Detection Sub System
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Easy to Use

For spectroscopy and microscopy experiments in the UV/Vis/NIR region of the spectrum, a photomultiplier tube (PMT) is the ideal detector for quantitative low light level measurements. A PMT is extremely sensitive, with very wide dynamic range so it can also measure high levels of light. PMT’s are also very fast so rapid changes in optical signals can be reliably monitored. As a practical matter, PMT’s are durable, long-lived, and economical.

Photomultiplier tubes can be cooled to reduce thermal background noise (also referred to as the dark count), and hence lower the detection limit of the PMT to very low levels for extreme low light level single photon counting detection. Cooling the PMT also allows for detection further into the NIR because NIR PMT’s by their nature are much more thermally sensitive and are not suitable for use with non cooled PMT housings.

Optical Building Blocks is pleased to introduce the CoolOne™ dual stage thermo-electrically cooled PMT housing that operates in either analog, photon counting or direct out modes with the flick of a switch. This cooled PMT housing is ideal for standard side-on PMTs that are used from 185 to 1,200 nanometers and provides a very low dark count of only a few counts per second (cps) depending on the PMT selected.

PMT’s are better than photodiodes and APD’s for low light detection

Although the quantum efficiency (QE) of a PMT is less than that of a silicon photodiode or avalanche photodiode (APD), a PMT has a much lower limit of light detection due to the high current amplification (~ 107) of the electron multiplier in the PMT. It is because of this large gain and low noise that a PMT provides significantly better low light sensitivity than a photodiode or APD.

Looking for a different type of detector?

For a less expensive non-cooled PMT housing that operates from 185 to 900 nm please take a look at our ambient PMT housing. For NIR detection from 0.8 to 1.9 μm please take a look at our InGaAs detectors.

The OBB CoolOne™ detection system consists of the following

  1. CoolOne™ Housing
  • Two stage, thermo-electrically air cooled PMT housing
  • Internal socket for most 1 1/8-inch side-on PMT’s



  1. CoolOne™ HV Supply
  • High voltage adjustment  with LCD display of HV
  • Indicator lights for In temperature range and Overheating
  • AC Adapter



  1. CoolOne™ Multi-Mode Electronics Module. This is an optional electronics module. If you already have detection electronics, you could use what you have instead of this module and feed the signal from the PMT housing into your own box.
  • CoolOne™ Multi-Mode Electronics Module
  • Output switch to select analog, photon-counting or direct out detection modes
  • Complete analog and photon counting circuitry
  • BNC connectors for PMT In, Analog Out, Photon-Counting Out

OBB’s CoolOne™ detection system is very convenient and easy to use. It incorporates modern design techniques and components. You have a choice of standard PMT’s to choose from or you can select from any other 1 1/8-inch side-on photomultiplier tubes that operates in the range from -150 to -1,250 Volts DC. The PMT high voltage is shown on a digital display on the HV supply. The high voltage can be adjusted manually or controlled externally with a signal at the “External Voltage Control” BNC on the multimode electronics module. Power is delivered from an external AC adapter that is included.

OBB has a policy of continuous product development and reserves the right to amend part numbers, descriptions and specifications without prior notice.

More Cooled PMT Housing Information




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HORIBA Scientific
Optical Building Blocks
3880 Park Avenue
Edison New Jersey

Tel: 732-494-8660
Fax: 732-623-8129