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Photon Counting PMT Detection System

Self contained PMT housing for quantitative spectroscopy and imaging low light measurements

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, PMTs are durable, long-lived, and economical.

HORIBA provides a simple, self contained PMT housing that operates in either analog or photon counting modes with the flick of a switch. This ambient PMT housing is ideal for standard side-on PMTs that are used from 185 to 900 nanometers. It has a very low dark count for a non-cooled PMT housing providing a dark count of only ~ 50 to 500 counts per second (cps) depending on the PMT selected.

Segment: Scientific

Division: Custom Spectroscopy Solutions

Manufacturing Company: HORIBA Scientific

Features
Specifications

Key Benefits

Compact Size
Inexpensive
Operates in Analog or Photon Counting Modes
Detection from 185 to 900 nm
Complete Package
LCD display of output signal
Easy to Use

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 low 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 NIR Detection?

For NIR detection beyond 900 nm please take a look at our CoolOne cooled PMT housing for photomultiplier detection from 185 to 1,200 nm and also our InGaAs detectors for detection from 0.8 to 1.9 μm.

The HORIBA ambient PMT housing includes the following

On/off switch
Complete analog and photon counting circuitry
Analog or photon counting mode/output switch
Line voltage power supply
High voltage power supply
LCD display of PMT high voltage or measured analog signal
Signal out BNC connection
High voltage adjustment knob
External high voltage control input BNC connection (for optional external control)
RF shielded case
Internal socket for most 1 1/8-inch side-on photomultiplier tubes

HORIBA's photomultiplier detection system is very convenient and easy to use. It is built as a complete unit using modern design techniques and components. Everything needed to quantitate the intensity of light is packaged into a compact, attractive housing that attaches conveniently to your experiment. There are no unsightly boxes for power supplies or a multitude of cables tangled on your bench-top. The system incorporates a high voltage supply, all detector electronics, and the controls in a compact, attractive housing that also contains the PMT. You have a choice of standard PMTs to choose from or you can select from any other 1 1/8-inch side-on photomultiplier tubes that operate from -200 to -1,100 Volts DC. The PMT high voltage is shown on a digital display on the housing or you can select to show the actual analog signal from the PMT with just a flip of a switch. The high voltage can be adjusting manually or controlled externally with a signal at the “External Voltage Control” BNC. Power is delivered from an external AC adapter that is included.

Controls

All controls and displays are available on the front and side of the OBB PMT housing.

Control Specifications
	Display	LCD display of high voltage or signal
	Controls	On/Off switch Analog/Digital Mode switch Voltage/Signal Display switch Voltage Adjust potentiometer Analog Gain selection Analog Time Constant selection Analog Offset
	BNC Connectors	Signal Out External Voltage Control

Physical Specifications

Dimensions (WxDxH)	4 x 4 x 8 inches
Weight	4 lbs

High Voltage Power Supply Specifications

Input	± 15 VDC, 250 mA
High Voltage	-200 to -1,100 VDC manually adjustable LCD displays actual cathode voltage
External High	0 to +5 VDC (0 = -200 V, 5 = -1,100 V)
Voltage Adjust	Continuously adjustable
Input Regulation	± 0.05% max. (for 15 V ± 1 V input).
Load Regulation	± 0.05% max.
Ripple	100 mV p-p max.
Temperature Coefficient	± 0.01% max. (+5 to 40°C)
Drift	± 0.03%/hr. max. (after 15 minute warm-up)

Analog Mode Specifications

Gain Settings:	1 µA = 1 V 0.1 µA = 1 V 0.01 µA = 1 V 0.001 µA = 1 V
Time Constant Settings: (with Corresponding Analog Frequency)	0.05 msec (20 KHz) 0.5 msec (2 KHz) 5 msec (200 Hz) 50 msec (20 Hz) 500 msec (2 Hz)
Offset Correction:	± 50 nA
Signal Output on BNC connector:	Analog voltage

Photon Counting Mode Specifications

Linear Dynamic Range:	5 orders of magnitude*
Dead Time:	250 ns
Signal Output on BNC connector:	TTL

* Linear dynamic range of the OBB photon counting PMT housing. The intensities were produced by attenuating the fluorescence emission of a fluorescein sample with neutral density filters.