Special Products

Versatile, Broadband Pyroelectric Detectors, 200 kHz Joulemeters and many custom laser instruments.

Position Sensing Detectors

QUAD Detector (Internal detail)
QUAD Detector with QUAD-Track
QUAD-Track (Front Panel)
QUAD-Track (Back Panel)
QUAD Detector
QUAD Detector (Internal detail)


  • Measure, Track and AlignFollow your laser beam wherever it goes
  • 4-Channel DetectorsUnique QUADrant detector technology senses laser beam position with high resolution
  • For CW, Pulsed and High Rep Rate Lasers
    • QUAD-E: Energy per pulse from μJ to mJ
    • QUAD-P: Powers from μW to mW
  • From UV to FIR and THzAbsorbers to cover all sources, from UV to Millimeter wavelengths
  • Large Area Sensors9 mm and 20 mm square detectors
  • Fast USB 2.0 ConnectionEnsures full speed tracking
  • Includes Application SoftwareComplete LabView Application Software included, with many features


The QUAD-4Track is a Laser Position Sensing system designed to support our unique Pyroelectric Quadrant Detectors, QUAD-P and QUAD-E. It is a 4-channel microprocessor-based system that measures the voltage output of each QUAD element and does the math necessary to provide a measurement of the X and Y displacement of a laser beam or image. It is fast and can be used to track, align and/or measure movement in real time, with a resolution of just a few microns!





Number of Channels


Full Scale Ranges (4 Decades) (E / P)


Joulemeter Mode (with QUAD-E)

20 µJ to 20 mJ

Radiometer Mode (with QUAD-P)

200 µW to 200 mW

USB Connection to Computer

YES (USB 2.0 Full Speed)

Power Supply


Power On Light


Detector Input

DB-25 Connector

Detector Analog Output

BNC Connector (0-2 V)

Trigger Input (TTL)

BNC Connector with LED Indicator

Product Number




Our large area Pyroelectric Quadrant Detectors provide unique advantages over other position sensing detectors like Silicon quads or lateral effect photodiodes. They are fast, handle high peak power of pulsed lasers without saturation and respond to lasers across the spectrum, from UV to Far IR and even THz. The QUAD-E is intended for use with pulsed sources at up to 1000 Hz, while the QUAD-P is designed for CW and High Repetition Rate (Quasi CW) sources. Both types of detectors can also be used as standalone units, in an analog mode, for incorporation into your own system application. We can provide a Lemo pigtail cable for this purpose.



The analog output of the QUAD-4Track provides voltage that is directly proportional to the pulse energy or laser power irradiating each QUAD element. When the four voltage outputs are equal, the beam is centered on the QUAD detector. This provides a very useful tool when setting up our QUAD probes with your source for optical alignment.



QUAD-4Track includes powerful, stand alone, LabView Software which is used to control the instrument, process the data, and display X and Y position. It also displays the energy or power of your source and repetition rate. The large graphic in this screen shows the position of the centroid of the beam and tracks its movement in real time. The software includes many handy features like: set boundary, zoom (2X to 128X), set resolution, data logging, and many more. The green line represents the tracking history.



In the measurement screen shown on the left, we are tracking the beam stability of a pulsed Nd:YLF laser at 10 Hz. The resolution was set at 0.001 nm, the boundary is at 20 µm (red circle), and the zoom feature is at 64X. The total energy is 108.5 µJ, the final position of the laser is at -8 µm in X and -8 µm in Y. The green tracking line shows the movement of the laser about the zero position over a few hundred pulses.



We've developed a unique position calibration routine which allows you to calibrate our QUAD-4Track system when working with a uniformly round laser beam. It requires the use of a micrometer-driven linear stage (1-axis only). As you can see from the calibration screen on the left, the procedure involves zeroing the instrument, moving the QUAD probe to nine discrete positions (+2.000 to - 2.000 mm) and then capturing the QUAD readings. It then determines correction coefficients (last column) and applies them to the raw data to arrive at "corrected positions". The QUAD probe is now calibrated!



Another very handy feature is "data logging". This allows you to set up the QUAD-4Track to follow the displacement, energy and/or power of your laser over several minutes, hours or even days. Need to measure the "beam steering" of your laser as it warms up? This is how you do it! Need to measure the beam displacement vs laser repetition rate or energy level? Data logging will help you measure it!