Jeulin 545 017 Mode D'emploi page 9

Geology
Radiation meter
Ref :
545 017
1. Principle and description
1.1
The theoretical study shows that the response of the radiation meter is proportional to
luminance of the target along the line of sight, in other words the intensity radiated along this
direction per apparent unit area of the target.
steradian and per square meter.
The luminance of a surface varies with the wavelength  of the radiation. Therefore, we
need to define the spectral luminance L() for a given wavelength.
It is important to know that, if the surface aimed at by the radiation meter is uniform, the
result of the measurement (allowing for precision) is independent of:
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Therefore, luminance is a fundamental magnitude in remote detection.
The reflectance R of a surface is the quotient of the reflected radiating power and the
received radiating power. Therefore, it is between 0 and 1 but it is often expressed as a
percentage.
environment. It is the basis for recognition of substances. Radiation metering can be used
to make a quantitative determination. Spectral reflectance R() is the reflectance defined for
each wavelength.
With a constant illumination of the target, the following are compared for a given spectral
band and for the same line of sight:
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The JEULIN radiation meter is capable of measuring the reflectance of any object towards
which it is aimed.
ENGLISH
Principle
the distance from the radiation meter to the surface,
the dimensions of the observation field,
Unlike luminance, reflectance is a magnitude that is characteristic of the
the luminance L of the substance studied,
the luminance L0 of a matt white surface (= white reference) with a known reflectance (for
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example, 180 g/m of matt white Canson paper with reflectance of about 0.92 for the
wavelength range from 400 to 1100 nm).
Luminance is expressed in Watts per
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