Gossen Mavomonitor Manual de usuario descargar pdf (Pagina 6)

6 GOSSEN Foto- und Lichtmeßtechnik

4 Functioning and Circuitry

The instrument essentially comprises the sensor

containing the silicon photocell and the correction

filters and the instrument itself. In an integrated

(IC) operational amplifier the short-circuit current

of the photocell, which is located directly at the

input to the op amp, is measured. This kind of

short-circuit current measurement has the advan-

tage of low dependency on temperature and pro-

ducing a linear result. Range selection is done by

means of the selector slider switch. Sensors can

be interchanged by means of the “sensor match-

ing” circuit in conjunction with the potentiometer

control in the sensor. This circuit also generates

the voltage level for the recorder output.

5 What is Luminance?

This is the amount of light as registered by the

eye. Luminance thus expresses the brightness of

a surface. The luminance in a certain direction is

the density of the illumination emitted from the

light-source surface, i.e. the quotient of the illumi-

nance J in the direction concerned and the illumi-

nating surface area A • cos ε.

The unit of measurement of luminance is the can-

dela per square centimeter = cd/cm²

or for very low luminance levels cd/m² (the former

unit was: “Apostilb” (1 asb = 0.31831 cd/m²)).

Also used:

1 fL (footlambert) = 3.426 cd/m²

1 cd/ft² (candela per square foot) = 10.76 cd/m²

A • cos ε

Probe

(7)

cd/m²

Segment test

Probe

Adaptor

Power Supply

Battery Monitoring

Segment test

Analogue

Digital

Converter

Batt.

Recorder Output Store

1 2 3 4 5 6 7 8 9 10 11 ... 15 16

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Gossen Mavomonitor Manual de usuario Pagina 6

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