WI41/G Luminous intensity standard lamp – Reference light source for testing photometers

The main area of application for the WI41/G luminous intensity standard lamp is the calibration of photometers, tristimulus colorimeters, and retroreflectometers which are used in a photometric laboratory. They are ideal for all applications where maximum precision and stability are a top priority with minimum measurement uncertainty for the calibration artifacts used.

WI41/G luminous intensity standard lamp

The WI41/G lamp provides approx. 250 cd in luminous intensity at a color temperature of 2856 kelvin (illuminant A), which is recognized as the reference color temperature for photometers. A special socket is used to provide reproducible positioning of the lamp, e.g. on an optical bench or a goniometer sample table.


  • Luminous intensity of approx. 250 cd at 2856 kelvin (illuminant A)
  • Rated voltage 31 V (maximum), rated current 6 A
  • PTB calibration certificate
  • Measuring uncertainty of calibration according to PTB calibration certificate approx. 0.6%
  • Recommended calibration interval: 6 hours operating time or 2 years

Ordering information

Order numberDescription
ACS-600WI41/G luminous intensity standard lamp including PTB calibration certificate and case for storage and transport