Light measurement

Optical radiometry is the science of light measurement, spanning across the ultraviolet, visible and infrared regions of the electromagnetic spectrum. Photometry is the subset of radiometry dedicated to the measurement of visible light as it is perceived by the average human eye.
International Light Technologies (ILT) has been the most respected name in research oriented light measurement for 40 years. They offer a variety of modular light meters. Optical radiation is perhaps the most difficult form of energy to measure accurately. Light energy is distributed over wavelength, position, direction, time and polarization.

A light meter or a radiometric light measurement system must be designed to measure the distribution of energy over one parameter while holding all others constant. In addition to high levels of measurement uncertainty, the field of radiometry and photometry has been characterized by confusion of terminology, symbols, definitions and units. International Light Technology’s goal is to provide customers with light measurement solutions to these problems by offering a comprehensive line of accurate modular light meters, i.e. radiometers and photometers. There are many (low-cost) instruments called radiometers on the market, which were designed to measure power from a light source with a constant known spectrum. These give erroneous results when measuring any other radiation.

The extremely flexible light measuring system concept of International Light Technology is based on a choice of suitable radiometer display devices and a wide range of different detectors. As a special feature the detector head allows a custom-designed modular configuration by using special matched filters and input optics.


For some years now, so-called audience scanning laser shows have been used in show business, involving the public. This is accompanied by an increased risk of eye damage to the audience. Light meters help to minimize this risk and there are many more applications ...


The ILT350 Spectroradiometer is a low cost, easy-to-use lux and color measurement spectroradiometer with NIST-traceable and ISO 17025-accredited calibration.

The device comes with a built-in 12mm-diameter cosine-correcting receptor and a magnetic protective cover. ILT350 has three measurement speeds: fast (0.5 s), slow (2.5 s), and auto (0.5 – 27 s), depending on light intensities. Data is provided in 1 nm increments.

Spectral bandwidth is approx. 2.5 nm (half bandwidth) with ±0.3 nm wavelength accuracy. The internal memory can store up to 100 files and export data into both Excel and Word formats.


The ILT2400 is the most advanced hand-held light meter and optometer on the market today. ILT’s Accuspan software automatically sets the averaging while rapidly measuring over 8 decades of light intensities.

The internal software allows customers to capture a peak as brief as 100 μs and to store up to 16 readings per second. The color display works in both landscape and portrait mode.


The ILT800 CureRight is a feature-rich profiling UV radiometer that delivers unmatched flexibility and capability.  The ILT800 Radiometer meets a broad range of applications across a variety of light measurement needs.  The system has been designed with the varying needs of its users in mind, and can be configured and customized to your unique environment.


The ILT950 is equally at home on the production floor as well as in the laboratory combining high performance, accuracy, ease of use, and a wide array of features all in a rugged, compact, portable design.

The excellent performance of the ILT950 has been improved further with the addition of a new machined optical bench for reduced stray light and improved thermal stability.

The ILT950 and ILT950UV spectroradiometers also now use the new higher pixel SONY CCD array for improved performance including nearly 50% more sensitivity over the entire spectral region, and higher S/N ratio increased from 200:1 to 300:1 with larger quantum well depth.

These improvements combined with the new features in our powerful SpectriLight III software, including PAR μmol/m²/s, metamerism, and baseline overlay comparisons, make the ILT950 a top performer in the CCD array spectroradiometer market.


The ILT560 comes with a SMA905 receptor as standard, allowing it to be used with all of the ILT950 spectroradiometer accessories including the R4 Right angle adapter, mini and standard diffusers, fiber optics, 2, 5 and 10 inch integrating spheres.

Standard and optional accessories can be combined to allow measurement of total flux, irradiance, radiance, colorimetry, luminance, illuminance and more.


The ILT1000 is a broad and versatile UV, VIS and IR datalogging optometer with NIST-traceable ISO 17025 ccredited calibrations. System configurations are based on the industry standard ILT1700 research radiometer/photometer detectors, filter/optics and calibrations. The ILT1000 was designed with OEM and custom configurations in mind and can easily accommodate most solid state detectors, 1/2” and 1” optical filters and a vast selection of input optics.

The ILT1000 is capable of measuring over six decades of light intensity and providing direct readout in W, W/cm², Lux, Fc, Lumens, cd/m², cd, W/sr, W/sr/cm² and more. On board data storage allows continuous monitoring at customer specified sampling rates using the “set it and forget it” datalogging.


The ILT5000 Research Radiometer is “The ILT1700 for the 21st Century” improving on the industry standard with rapid measurements (up to 100 Hz), a broader dynamic range (100fA to 1mA), extensive supporting software apps, wireless communication, internal data storage, and a 4-20 mA output. The broad linear dynamic range of the ILT5000 and the SMA input connector allow the meter to also serve as a broadrange, highly sensitive and accurate picoammeter.


The ILT5000-P Picoammeter brings sensitive electrical current measurement capabilities into the 21st century with its broad dynamic range, multi-unit monitoring software and advanced auto-ranging capabilities.

The ILT5000-P Stand-Alone Picoammeter boasts a very broad dynamic range from 1 mA to 100 fA with 1 fA of resolution. The built in Accuspan™ control software eliminates harmful /error inducing range changing spikes and samples at a rapid rate of over 50,000 samples per second. The picoammeter silently changes from femtoamps to milliamps with no clicking sounds, no dials and no range buttons to change. Accuspan can be set to automatic, or fixed ranges using the programmable controls in Datalight II.


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