Handheld Photometers and Radiometers

We offer two high-accuracy handheld optometers for use in laboratory settings or field environments. Both instruments are compatible with the full range of UDT Instruments sensor heads and are calibrated in our ISO-17025 accredited laboratory.

Each handheld optometer measures the photocurrent produced by a photometric or radiometric sensor, applies a predefined electro-optical calibration factor, and displays the result in optical units.

A photometer system is built by coupling an optometer to a photometric sensor; a radiometer system is built by coupling an optometer to a radiometric sensor.


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System Configuration Guide

Learn how to configure a photometer or radiometer system to meet your testing requirements with this free guide from Gamma Scientific.


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Guide to Photometry

What’s in the Guide?

  • Definitions of the most important terms in photometry
  • Photometric to radiometric conversion factors
  • How to specify a photometer system
  • Photometric quantity units, symbols and abbreviations


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Guide to Radiometry

What’s in the Guide?

  • Definitions of the most important terms in radiometry
  • How to specify a radiometer system
  • Radiometric quantity units, symbols and abbreviations
  • Calibration by transfer of standards


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Model S471 Portable Optical Power Meters


The Model S471 is a high-quality handheld optical power meter, ideal for all your photometric, radiometric and fiberoptic measurement needs. The S471 is designed to be used in a laboratory setting or field environment. The Model S471 is microprocessor controlled and has three measurement data-presentation options: direct display measurement with analog bar; RS-232 computer interface and analog voltage input.

In addition to its exceptional technical and functional characteristics, this system is fully compatible with all UDT Instruments sensor heads in any configuration. All calibrations are traceable to the National Institute of Standards and Technology (NIST).


  • High-accuracy measurements
  • Wide dynamic range
  • Computerized high-speed update rate
  • Programmable averaging readings in low pass or boxcar average
  • Large calibration capacity
  • Large monochrome LCD graphics/backlit
  • Calibration data/accessories information display
  • Long operational battery life or direct external power
  • Simple touch keypad
  • Portable and durable
  • Optional USB to serial bridge converter
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Model S450 Portable Optical Power Meters


The UDTi S450 is a handheld Energy / Power optical power meter designed for laboratory or field environments. Key to the Model S450 is ultra-high sensitivity, sophisticated microprocessor control and three data-presentation options: direct display measurement with analog bar, RS-232 computer interface and programmable analog voltage output.

Compatible with the full range of UDT Instrument sensor heads, the Model S450 is easily configured as a high-performance radiometer, photometer or Energy meter with seven measurement decades.



  • Compact and light-weight
  • Portable and durable
  • High-accuracy
  • Wide dynamic range
  • Measures in Power or Energy Mode
  • Electronic temperature-drift compensation
  • High sampling rates
  • Programmable low pas or boxcar averaging
  • Large calibration capacity
  • Calibration data and accessories information center
  • RS-232 or optional USB computer interface
  • Simple touch keypad controls
  • Icon driven menus
  • Large backlit LCD graphical display
  • Rechargeable NiMH battery or AC power
Download Data Sheet
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