Gershun Irradiance

Measure total incident light and net upward/downward energy flow

When used in pairs,* these collectors measure both the scalar and net planar irradiance. Like HOBI's other light collectors, it is designed for underwater use with HydroRad and HOBI fiber optic cables, but also can be used with other SMA-905 terminated cables.

* a single collector of this type does not provide a meaningful radiometric measurement. For single-collector scalar irradiance measurements, see our Scalar Irradiance collectors.

Measurement

Collectors must be used in pairs, one up and one down. Each connects to a separate radiometer channel or other light-measurement instrument.
Adding the two measurements yields the true scalar irradiance, E₀.
Subtracting the two measurements yields net plane irradiance, E_d− E_u.
Scalar irradiance measurement is the most accurate possible — no self-shading or dead zone as with traditional scalar collectors

Features

Angular response identical in air and water
Use with HydroRad for complete hyperspectral measurements
Totally waterproof when installed on HOBI Labs fiber optic cable
Also compatible with other SMA-terminated cables
All-plastic construction is corrosion-proof

Specifications

Diameter: 6.4 cm (2.5")
Length: 11 cm (4.4") including SMA connector
Weight: 200 g dry, 20 g buoyant when submerged
Usable wavelength range: 380 to 1000 nm
Maximum depth: 200 m