illuminance & luminance photometers

Irradian L202 PhotometerPhotometers are designed to measure light as seen by the human eye. Edaphic Scientific’s range of photometers are supplied from Irridian, the world leading manufacturer of scientific, medical, industrial, and office light sensing technology.


  • L201: digital, portable and measures illuminance in lux
  • L202: digital, portable and measures illuminance in lux and screen luminance in cd
  • L203: digital, portable and measures luminance incidence, illuminance in lux, and luminous intensity in cd

specification sheets and manuals

L201 Spec Sheet & Manual

L202 Spec Sheet & Manual

L203 Spec Sheet & Manual


further information

Irradian L203 PhotometerAll of our photometer instruments are comprised of a hand held display unit and a detector / amplifier assembly with connecting cable. The sensor is a large area silicon photodiode with excellent linearity and long-term stability.

The Irradian photopic filter set housed in the detector, and fitted in front of the silicon detector gives a response which closely matches the human eye response outlined by the CIE V-lambda curve. This precise colour correction gives high accuracy of photometric measurements from light sources with different spectral distributions.

For illuminance measurements, the cosine corrected diffuser, which is fitted to the detector assembly, will integrate light from all sources in the hemisphere in front of the detector.

Before leaving the factory, every single instrument is individually calibrated to read directly in lux or candelas.


illuminance versus luminance measurements

Irradian L201 PhotometerIlluminance is the measurement of photometric light per unit area, lumens per square meter, lux, or lumens per square foot, footcandle. For most applications the measurement plane is horizontal and a cosine corrected diffuser is fitted to the front of the detector assembly. If the working surface is not horizontal, then placing then placing the detector on, or parallel to, the worktop is a more representative measurement of the illuminance.

Luminance (lumens per steradian per unit area) or brightness is the photometric measurement of the response from viewing an illuminated object or self-luminous source. Luminance measurements are typically performed with an integrating sphere (see image to the right).

Irradian Integrating Sphere

If you need to measure the luminance of a small area contact us for the special Spot Measuring Accessory.


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