Photosynthetically Active Radiation (PAR) Sensor

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The PAR Irradiance Sensor has been designed for the measurement of Photosynthetically Active Radiation. 

 

It is ideally suited to monitoring marine photosynthesis, where the prime concern is to quantify the amount of PAR available. It is designed to be moored, profiled or deployed in towed vehicles (AquaShuttle, NνShuttle & SeaSoar) and can be used to measure both upwelling and downwelling light and also as an on-deck reference.

Applications and Features
Applications
  • For the measurement of Photosynthetically Active Radiation.
  • It is ideally suited to monitoring marine photosynthesis, where the prime concern is to quantify the amount of PAR available.
  • Designed to be moored, profiled or deployed in towed vehicles (AQUAshuttle, NνShuttle & SeaSoar)
  • Can be used to measure both upwelling and downwelling light and also as an on-deck reference.
  • Compatible with Chelsea's range of Fast Repetition Range fluorometers (including the FASTtrackas and newly launched FASTocean).

 

Features
  • Logarithmic 6 Decade Range
  • (1 + Cos ø)/2 Response
  • Relative Spectral Sensitivity flat to + 3% from 450-700nm, down 8% of 400nm & 36% at 350nm
  • PTFE 2ττ Scalar Collector
  • Angular Detection Range +130o from normal incidence
  • Protective cover when not in use
Integral sensor within the FASTocean system
 
Description

The Chelsea Technologies Group PAR (Photosynthetically Active Radiation) Scalar Quantum Irradiance Sensor was designed at Plymouth Marine Laboratory to assist the study of marine photosynthesis, where the prime concern is to quantify the amount of PAR available.

 

With the use of logarithmic amplication, the sensor covers a range of 6 orders of magnitude. This has the advantage of avoiding setting up the sensor range for the expected signal level for different ambient conditions which can be tedious and can produce calibration errors between ranges. The sensor's simple construction consists of a hollow PTFE 2ΤΤ collector supported by a clear acetal dome diverting light to a filter and photodiode from which a (1 + Cos Θ) /2 response is obtained.

 

The sensor's input (7 to 20 Vdc) and output (0 to 5V range covering 3000 to 0.002μ Em-25-1) lend for ease of integration to standard oceanographic data acquisition systems. A depth rating of 1000 metres is achieved using a stainless steel outer casing, which also provides a mounting plate for clamping to either a profiling cage or towed vehicle. Due to the sensitivity of the collector dome itself, a cover is provided to protect the sensor when not in use.

 
Specification
Dimensions
Length 130 mm
Diameter 50mm
Material PTFE, Acetal and Stainless Steel
Weight
In air 0.85 kg
In water 0.5 kg
Operating Depth 1000m
Supply Voltage 7-20VDC
Connector VSG-4-BCL (others on request)
Output 0 to 5V
Range 2000-0.002μE.m-2.5-1 (E=6.023 x 1023 quanta)
 
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