Photometry involves the measurement of electromagnetic radiation in terms of luminous power – that is, its capacity to stimulate the human visual system and to be perceived as light. Different applications require different types of measurements, and therefore, different types of photometric instruments (photometers).
Photometric quantities include: luminous flux – in lumens (lm), luminous intensity (lm/sr), illuminance (lm/m2) and luminance (lm/m2sr).
- Luminous Flux Measurements (in units of lumens) are performed with a luminous flux meter. This type of testing is typically used for characterizing the total output of sources such as: LEDs, Lamps and Fiber-Optic Illuminators
- Illuminance Measurements (in units of lux) are performed with a lux meter. This involves the measurement of the amount of luminous flux incident upon a surface, per unit area. Such measurements are important in the following fields: Architectural and Medical
- Luminous Intensity Measurements (in units of candela) are performed with an instrument that may be described as a luminous intensity meter or a candela meter. This type of testing is typically used for characterizing the output of a relatively small source in a particular direction. Typical devices under test include: LEDs, Automobile Headlamps and Signal Lamps
- Luminance Measurements (in units of nits, or candela per square meter) are performed with a luminance meter. This involves measuring the light emitted in a particular direction by a given spot on the surface of a relatively large, or extended source. Typical devices under test include: Computer Monitors, Television Screens, Avionics Displays and other Electronic Displays
UDT Instruments, a division of Gamma Scientific, 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.
Specifying a photometric system is best approached in three steps. First, evaluate the source to determine which measurement technique best applies. Then, select a detector and optical system (detector head) that suit the measurement. And finally, match the detector head to the particular electronics which provide the most effective user interface for the application.
How to Specify a Photometric System
Photometer and Photometry Resources from Gamma Scientific
Gamma Scientific Photometers and Photometric Sensors
Multi-Function Photometer System: uLUM-MF
The uLUM-MF is a powerful and flexible system for research labs, metrology centers, and other laboratories that must provide a diverse range of photometric measurements. This bundle combines a four-channel benchtop optometer with four different types of photometric sensors, to provide measurement capabilitiy in each of the following fundamental measurement geometries: Luminous Flux (lumens); Illuminance (lux); Luminous Intensity (candela); Luminance (nit; cd/m2).
The model 471 handheld photometer is designed to be used for photometric measurement in the laboratory or field testing environment. It features high-accuracy measurements, wide dynamic range, high-speed update rate and a large calibration capacity. All calibrations are traceable to the National Institute of Standards Technology (NIST).
Detector-based absolute standards for capturing a wide range of measurements. Configurations include thermo-electrically cooled silicon and indium gallium arsenide (InGaAs) detectors with options for photometric correction filters, flat-response filters, trap detectors and ANVIS-compatibility filters. Standard calibrations, directly traceable to NIST, are available for any configuration of the TIA-3000 from Gamma Scientific’s world-renowned standards lab.
TRAMP Transimpedance Amplifier
The UDT Instruments Tramp is a transimpedance amplifier (current-to-voltage) instrument which provides a low input impedance to accurately measure the short circuit current of phototransducers such as silicon and germanium photodetectors, vacuum photodiodes and photomultiplier tubes.
flexOptometer Benchtop Photometer
High-performance photometer designed to operate as a stand-alone instrument or computer-controlled photometric measurement system. Available with a single head, or up to four interchangeable detector heads. 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 the flexOptometer will operate in the most rigorous production line environments.
Photosensor and Photodetector Solutions from UDT Instruments
UDT Instruments produces precision photometric sensors 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.
Lux Meter: uLux Illuminance Meter
This lux meter bundle combines a high-performance photopic sensor with an optical diffuser to provide simple and accurate measurement of illuminance in units of lux (lx), or lumens per square meter. The diffuser provides a ‘cosine correction,’ making the sensor’s illluminance response nearly independent of the direction of incidence.
Luminance Meter: uNIT-LL Handheld Luminance Meter with LumiLens™
This bundle combines a photopic sensor with a fixed-focus lens 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 the following types of test and measurements: Luminance; Contrast Ratio; Gamma (Gray Scale/EOTF).
TIA-LUX Illuminance Meter Testing System
This bundle combines a high-quality photopic sensor with a thermo-electric stabilization system and a state of the art transimpedance amplifier to provide highly accurate and stable illuminance measurements – even at very low light levels. This Gamma Scientific technology has been adopted for use as a physical standard by prestigious national metrology institutes (NMI’s).
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, as well as the following optical components to enable configuration of custom sensor heads for the measurement of flux, illuminance, irradiance, intensity, luminance, or radiance.
