Photometry is the radiometric measurement of light as perceived by the human eye. A photopic filter passes the wavelengths of light in proportion to the eye's response. International Light's proprietary photopic filters consist of several elements designed so as to match the CIE photopic response curve to better than 1% at all wavelengths. Most safety regulations for measurement of illumination are photopic measurements and require the integration of a photopic filter in the system.

The IL1710 research photometer is renowned for its unmatched, sensitivity and dynamic range. The handheld IL1410 photometer is the industry standard for on-site photometry. International Light offers a complete range of illuminance and luminance probes. Any of the probes listed below can be incorporated into an IL1700 or IL1400 based system.

FLASH PHOTOMETRY APPLICATION:

The IL1711 Flash Photometer System is unique in its abilility to integrate intense flashes as brief as 5 microseconds without saturating the detector, while autoranging over 7 decades! Since the human eye is 5 times more sensitive to a flashing source than to a steady light, we designed our flash measurement system to measure both the flash integral (cd^*s), lm^*s/ft², lux^*s), and the flash effective intensity (effective cd) of xenon flash lamps and most other types of flashing devices.

Fresnel lenses are often used to concentrate the a flash in the horizontal plant. It is necessary to measure these lenses from a substantial distance to determine the proper effect of the optical system as it is normally viewed, making the total measurable energy for a short duration flash quite small. The high gain lens assembly increases the signal 30 times, improving the range down to 20 millicandela at a distance of over 25 feet from flash sources with an on time between 6 microseconds and 10 milliseconds.