Compare Model Drawings, CAD & Specs Availability Price
185 to 870 nm photomultiplier tube model 77341
Photomultiplier Tube, 185-870 nm Range
In Stock
In Stock
400-1100 nm photomultiplier tube model 77343
Photomultiplier Tube, 400-1100 nm Range
In Stock
In Stock
160 to 900 nm photomultiplier tube (PMT) model 77348
Photomultiplier Tube, 160-900 nm Range
In Stock
In Stock
185 to 850 nm photomultiplier tube (pmt) model 77360
Photomultiplier Tube, 185-850 nm Range
In Stock
In Stock



Photomultiplier Tube Physics

Schematic of a photomultiplier tube.

In a photoemissive detector, light interacts directly with the electrons in the detector material. An absorbed photon frees an electron and the surplus energy gets converted into kinetic energy of an electron. Electrons with enough kinetic energy escape from the surface. The electrons emitted in this way produce the cathode photocurrent in photomultiplier tubes. An applied voltage causes the electrons to flow toward the anode, creating a current that can be proportional to light intensity over 6 to 8 orders of magnitude. The electron multiplier part of a photomultiplier tube amplifies the photocurrent by secondary emission. This is a low noise process which produces currents that are orders of magnitude larger than the initial photocurrent. Photomultipliers are more sensitive than any other detector in the near UV and visible regions.

The figure shows a schematic depiction of an end-on tube. Our side-on tubes have similar components arranged in a much tighter geometry which makes packaging easier and removes some of the environmental sensitivities of these superb detectors. The end-on tubes have larger and more uniform photosensitive areas; side on tubes have faster rise times and reach higher responsivities since most of them use opaque photocathodes, thus avoiding the optical losses associated with the semitransparent photocathodes of the end-on tubes.

Build an entire system with Newport products

To build a complete PMT System, you need:

  • Photomultiplier Tube 
  • PMT Housing Model 70683 or 70693
  • PMT Power Supply Model 70706
  • Signal reading instrument, such as Newport's power meters or Oriel's model LIDA-SRS-KIT Radiometry System

Optional current preamplifier facilitates use of lock-in digital amplifier

The 70710 Current Preamplifier is particularly beneficial with the LIDA-SRS-KIT Radiometry System. The current output from the PMT is converted into a voltage output, which allows users to take advantage of the wider voltage dynamic range of the lock-in digital amplifier.

Housing compatible with various PMTs and detection instruments

For low noise DC operation or pulsed operation <10 µs, Oriel offers the 70683 PMT housing. It includes a high voltage cable for use with Oriel's model 70706 PMT power supply and a low-noise BNC signal cable. The output from the PMT may be read by a lock-in digital amplifier, such as Oriel's LIDA-SRS-KIT Radiometry System. The model 70693 PMT Housing includes all of these items, as well as an interface module allowing signals to be read by many of Newport's popular power meters. The 70693 is compatible with power meters 1936-R and 2936-R. This module may be removed at any time, allowing the signal to be read by Oriel's lock-in digital amplifier if desired.

Ultimate low light level detectors

High responsivity pulsed event detection from ms down to µs, our PMTs function from 160 nm to 1100 nm. Components and instruments are available through Newport to create PMT systems supporting DC, modulated and pulsed measurements <10 µs. Pulse measurements from microseconds to milliseconds are possible at useful photocurrent levels of 100 µA to 1 mA and above. Please note the maximum DC anode currents (averaged over any 30 time interval), and make sure they are not exceeded in your standard set-up. For pulsed applications you can draw up to 50x higher currents for short times, as long as average current ratings are not exceeded. PMTs can be damaged by exposure to excessive light levels in the presence of bias voltage. This is due to anode damage by high current densities. Because the photocathodes of PMTs are very light sensitive, their noise behavior is negatively affected by exposure to strong light, even in the absence of bias voltage, and may take some time to recover once they are screened from light. Typically, more than half an hour is required for recovery. You may need several hours to return to the lowest noise levels. Opening your optical set-up while the PMT is biased can easily lead to a need for an expensive replacement tube.

DC or modulated light detection

All our PMTs can be used in a pulsed mode or DC. The housing determines the operation. Typical rise times and electron transit times (the delay due to the finite time needed for electrons to transverse the multiplier chain) for all PMTs are listed in the specification table. These times are a function of bias voltage and/or the voltage divider network. They get shorter at higher bias voltages. You need to balance the desire for fast response with the increased noise levels at high biases.