Jadak PHOTO RESEARCH A-TAKT V-7HS, Руководство пользователя

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Chapter 3
– Theory of Operation
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Chapter - 3 T
HEORY OF
O
PERATION
The A-TAKT V-7HS are true Spectroradiometers. It collects the optical radiation (light) through the
objective lens. The signal then passes through the aperture (hole) in the aperture mirror to the diffraction
grating (see Figure 6). The grating breaks up the light into its component wavelengths much like a prism
turns white light into a rainbow. A broad band source of light such as the sun emits radiation at all
wavelengths throughout the visible spectrum. When the diffraction grating is exposed to this type of light,
it will refract the light at several angles thus creating a dispersed spectrum much like a rainbow. Similarly,
if the grating is exposed to a source such as a laser which emits a nearly monochromatic wavelength of
light, only the wavelength(s) of the laser will be refracted.
FIGURE 5
– SPECTRUM MEASURED BY THE V-7HS
The measurement wavelength range is 380 nanometers (nm) (violet) to 780 nm (deep red)
– the visible
band of the electromagnetic spectrum (see Figure 5).
The diffracted spectrum is then dispersed onto the detector. The detector is comprised of 512 individual
elements. Thus, each of the detector elements samples a unique color.
During a measurement, the diffracted optical radiation (light) is sampled for a period of time determined
by the Adaptive Sensitivity™ algorithm. Adaptive Sensitivity automatically determines the correct
integration (exposure) time on the detector based on the available signal. Following the light
measurement, a measurement of the dark current of the detector is made for the same length of time that
was used for the light measurement. The dark measurement is then subtracted from the light
measurement yielding the contribution of light for each detector element.
380 nm 500 nm 600 nm 780 nm.