Model 30750 Sample Compartment with fiber bundle, mounted to 70683 PMT HousingUltimate low light level detectors
DC or modulated light detection
High responsivity pulsed event detection from ms down to us
160 nm to 1100 nm models
Photomultiplier Tubes (PMTs) have very low noise levels and are several orders of magnitude more sensitive than any other detector for UV and visible radiation. We offer PMT models with a full range of spectral sensitivities. Components and instruments are available through Newport to create PMT systems supporting DC, modulated and pulsed measurements <10µs. Pulse measurements from microseconds to milliseconds are possible at useful photocurrent levels of 100 µA to 1 mA and above.
With all the choices, it can become confusing deciding on the appropriate PMT for your measurement application. Below we describe the options. If you need further help, or want to validate your choice, please call a Sales Engineer for guidance.
All our PMTs can be used in a pulsed mode or DC. The housing determines the operation. Typical risetimes 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.
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 model LIDA-SRS-KIT .
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 1918-R, 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.
Model 30750 Sample Compartment with fiber bundle, mounted to 70683 PMT Housing
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. Opening your optical set-up while the PMT is biased can easily lead to a need for an expensive replacement tube. Please note the maximum DC anode currents in the Ordering Information Table (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 up to 50x higher currents for short times, as long as average current ratings are not exceeded.
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.
Typical responsivity curves of photomultiplier tubes
Uniformity of response is dependent on PMT housing orientation
To build a complete PMT System, you need:
Photomultiplier Tube
Model 70706 PMT Power Supply
Signal reading instrument, such as Newport\'s power meters or Oriel\'s model LIDA-SRS-KIT Radiometry System
Optional:
70710 Current Preamplifier, which is particularly beneficial with the LIDA-SRS-KIT. 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.
The model 70706 PMT power supply replaces the Oriel legacy 70705.
PMT systems 70107, 70207 and 70690 are no longer offered as a system. However, individual instruments are available to build your own system.
The legacy Oriel 70680 PMT housing was used for DC operation or pulsed systems <10um. The currently offered 70683 PMT housing may be used for DC operation or pulse widths >10um.