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UDT Instruments

For over 40 years UDT Instruments, a Gamma Scientific company, has been trusted by the world’s leading organizations to

provide accurate light measurement systems.


UDT Instruments manufactures precision photometers, radiometers, colorimeters and photosensors for optical measurement applications.


UDT Instruments designs the most accurate photometric filters in the world, with an unsurpassed ability to match the human eye’s sensitivity to color and light intensity. Each sensor includes a NIST-traceable calibration.


High-performance optometers from UDT Instruments can be combined with our integrating spheres and detectors to create complete photometric and radiometric test systems with industry leading accuracy.

UDT Instruments Resources 

If you are unsure what type of system you need for your testing application download our System Configuration Guide. To learn more about Photometry and Radiometry download our free, comprehensive guides.

Products from UDT Instruments


UDT Instruments offers an extensive selection of photometers, lux meters, luminance meters, illuminance meters and optical sensors to meet your photometric test and measurement needs. Combining our wide range of optometers, photometric sensors and accessories, with our state-of-the-art calibration facilities, allows our applications engineers to assemble and configure custom photometer systems for nearly any project.



High-performance radiometers designed to operate as stand-alone instruments or computer-controlled radiometric measurement systems. Available as a flexible, bench-top design with up to four interchangeable detector heads or as a handheld radiometer. Electronic design is based on Gamma Scientific’s TIA-3000 measurement system, which serves as the primary working standards of several National Standards Labs. Laboratory grade accuracy and durability ensures that UDT radiometers will operate in the most rigorous production line environments.

Integrating Spheres

Gamma Scientific and UDT Instruments (a Gamma Scientific Company) offer a range of integrating spheres and sphere systems to meet diverse test and measurement requirements. Specialized configurations and custom designs are also available. Gamma Scientific products are distinguished by their value, providing unmatched design and quality at competitive prices.

Photosensor and Photodetector Solutions from UDT Instruments

UDT Instruments produces precision photosensors for diverse applications and are ideally suited for OEMs and value-added resellers. UDTi photometric sensors provide industry leading accuracy, with an unsurpassed ability to match the human eye’s sensitivity to color and light intensity. Each sensor from UDT Instruments includes a NIST-traceable calibration from our NVLAP accredited laboratory.


Electronic autocollimators from UDT Instruments, a Gamma Scientific company, are compact optical instruments designed for measuring the angular position of reference surfaces. They are used wherever flatness, angle, or parallelism must be measured very accurately.

Position Sensors and Position Sensing Amplifiers

UDT Instruments produces segmented and continuous position sensors as well as position sensing indicators and position sensing amplifiers. These instruments are used to measure a light spot’s movement over wide ranges, as well as nulling and centering operations.

Optical Accessories

Photosensors can be equipped with various types of optical accessories to form sensor head assemblies suitable for diverse types of measurements. UDT Instruments offers a range of preconfigured sensor heads and optical components to enable configuration of custom sensor heads for the measurement of flux, illuminance, irradiance, intensity, luminance, or radiance.

Products from UDT Instruments

  • Display Measurement

  • LED Testing

  • Laser Measurement

  • Photometry

  • Radiometry

  • Fiber Optic Testing

  • Position Sensing

Products from UDT Instruments

The evolution of UDT Instruments can be traced to 1967, when a small group at United Detector Technology (UDT) began manufacturing the first commercially available transimpedance amplifiers for planar-diffused and Schottky barrier silicon photosensors. From there, the group went on to pioneer leading-edge technology for photometers, radiometers, fiber optic power meters, and optical position sensing instruments. By the time the 1980s rolled around, this innovative and highly successful group grew into an autonomous entity known as UDT Instruments (UDTi).The momentum generated by UDTi’s precision photometric instruments ultimately spurred the company to develop an inventive handheld CRT colorimeter for the growing television and computer peripherals markets. UDTi’s SLS 9400 colorimeter has strengthened the company’s position as a leader in precision electro-optic instrumentation. We have continually improved on the SLS 9400, allowing it to continually meet the stringent demands of display calibrations as the industry has transformed into flat-panel and projection displays. Today, UDTi is poised and ready to pursue even greater technological excellence with only one goal in mind: to meet or exceed the ever-changing needs of its customers worldwide.

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