Photometers, Radiometers, and Photodetectors

Photometers, Radiometers, and Photodetectors

Luminosity, luminance, illuminance, intensity, radiant, and irradiance measurement   

Photometers, Radiometers, and Photodetectors   

Gamma Scientific's UDT Instruments division offer a broad selection of systems for photometry - the measurement of the intensity of light, and radiometry - the measurement of its power. These include both benchtop and handheld instruments, as well as an extensive range of photodetectors for a variety of light measurements. UDT Instruments have the capability to measure:

  • Photometry
    • Luminous Flux - Lumen (lm)
    • Luminous Intensity - Lumens per steradian (lm sr-1)
    • Illuminance - Lumens per sq. metre (lm m-2)
    • Luminance - Candela per sq. metre (cd m-2)
  • Radiometry
    • Radiant Flux - Watts (W)
    • Radiant Intensity - Watts per steradian (W sr-1)
    • Irradiance - Watts per sq. metre (W m-2)
    • Radiance - Watts per steradian per sq. metre (W sr-1 m-2)
 Photometric and/or Radiometric Systems
UDT TIA-3000 Measurement System

TIA-3000 Measurement System

The TIA-3000 is UDT Instruments' flagship laboratory system.

With TE-cooled silicon or InGaAS detector-based absolute standards for capturing a wide range of quantities, the TIA-3000 can be configured with photometric or radiometric correction filters, flat response filters, trap detectors, and ANVIS-compatability filters to provide precision measurements in all applications.

UDT flexOptometer Benchtop SystemflexOptometer Benchtop System

Based on the TIA-3000, UDT Instruments has designed the flexOptometer to operate as a stand-alone or computer-controlled photometric or radiometric measurement system depending on configuration.

Available with a single head, or up to four interchangeable detector heads, the flexOptometer is ideal in production line environments.

UDT Model 471 Handheld SystemModel 471 Handheld System

The Model 471 handheld can be supplied as either a photometer or radiometer. It has been designed to be used for measurements in the laboratory or field and features high-accuracy, wide dynamic range, plus a high-speed update rate and large calibration capacity.

All calibrations are traceable to the National Institute of Standards Technology (NIST).

 Photometer systems  Radiometer systems

uLUM-MF - Multi-function Photometer System
The uLUM-MF is a powerful and flexible system for research labs, metrology centres, and other laboratories that must provide a diverse range of photometric measurements. It combines a four-channel benchtop optometer with four different types of photometric sensors to provide measurement capability in each of the following fundamental measurement geometries: Luminous Flux (lumens); Illuminance (lux); Luminous Intensity (candela); Luminance (nit; cd/m2).

uRAD-E - Irradiance Meter
This irradiance meter system combines a broadband silicon sensor with a benchtop optometer to provide simple and accurate measurement of irradiance. The system’s calibration is programmed into the benchtop optometer. Measurement results are displayed by the optometer in units of Watts per square meter (W/m2), and digital data can be acquired directly via PC.

uNIT-LL - Handheld Luminance Meter
The uNIT-LL handheld combines a photopic sensor with a fixed-focus lens (LumiLens™) to provide non-contact measurement of an area on the display surface. Spot size is dependent working distance, which ranges from 17 mm to infinity. This system is suitable for Luminance, Contrast Ratio, and Gamma (Grey Scale/EOTF) tests and measurements.

uRAD-LL - Handheld Radiance Meter
This handheld radiance meter combines a filtered silicon sensor with a fixed-focus lens to provide non-contact radiance measurement of an area on the surface of an extended source. Spot size is dependent the working distance, which ranges from 17 mm to infinity.


uLux - Illuminance Meter
The uLux meter uses a high-performance photopic sensor with an optical diffuser to provide simple and accurate measurements of illuminance in units of lux or lumens per square metre. The diffuser provides a cosine correction to make the sensor’s illuminance response nearly independent of the direction of incidence.


TIA-LUX - Illuminance Meter Testing Sytem
Highly accurate and stable illuminance measurements – even at very low light levels - can be made using tihs Gamma Scientific combination of a high-quality photopic sensor with a thermo-electric stabilisation system and a state of the art transimpedance amplifier - see below. A number of metrology institutes currently use the TIA-LUX as a physical standard.

Transimpedance Amplifier
The TRAMP (current-to-voltage) transimpedance amplifier, from UDT Instruments, provides a low input impedance to accurately measure the short circuit current of phototransducers. It is available as a stand-alone unit for use with silicon and germanium photodetectors, vacuum photodiodes, and photomultiplier tubes.



UDT Instruments offers a wide range of NIST-traceable radiometric sensors and photometric sensors for illuminance or irradiance measurements. Each type of sensor can be combined with various types of optical adaptors to form sensor head assemblies suitable for measurements of flux, intensity, luminance, or radiance.
For more information, please contact us or visit the Gamma Scientific website by using the link below.

UDT Radiometric & photometric sensors

Gamma Scientific website.

Product Code: Gamma Scientific Photometers, Radiometers, and Photodetectors

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