PAR Irradiance Sensor

Highly sensitive irradiance measurements to 1000 m water depth.

Gather highly sensitive data on light irradiance with the Chelsea PAR sensor. With a depth rating of 1000 m, the PAR sensor can be fitted to profiling systems or oceanographic moorings to get a complete picture of the photic zone. The long term calibration stability and titanium corrosion-resistant housing make it ideal for long term deployments on vehicles or wider instrumentation systems in all water environments.

How does it work?
Light is efficiently collected by a PTFE 2p Scalar Collector, supported by a clear acetal dome, and is directed onto a photodiode via a filter from which a (1+cosӨ)/2 response is obtained. With use of logarithmic amplification

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PAR irradiance sensor - highly sensitive irradiance measurements to 1000 m water depth

Features & Applications


  • High sensitivity
  • Long term calibration stability
  • Logarithmic 6 Decade range
  • Wide angular detection range
  • 1000 m depth rating
  • Corrosion resistant housing


  • Sea-truthing of satellite data
  • Oceanographic and environmental studies
  • Referencing primary productivity measurements
  • Referencing in situ fluorometer measurements


Size Ø 50 mm x 130 mm
Material PTFE, Acetal and Stainless Steel
Weight 0.85 kg in air/0.5 kg in water
Max operating depth 1000 m
Input voltage 7-20 V
Output 0-5 Vdc
Range 3000 to 0.002µEm-2s-1 (E=6.023 x 1023 quanta)
Relative spectral Flat to ±3% from 470-700 nm, down
Sensitivity 8% of 400 nm and 36% at 350 nm
Angular detection range ±130° from normal incidence
Operating temperature -2 °C to +32 °C
Storage temperature -40 °C to + 70 °C
Connector VSG-4-BC

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