Thickness measurements can be performed when thickness data is
selected. If a transparent material is within the measurement volume of
the chromatic optical probe, the white light spot is focused on both the
two surfaces of the measured object. The reflected light is more intense
for the two wavelengths in focus on the two surfaces. Reflected light is
spectrally analyzed and the spectral response is constituted of two peaks
centered on focused wavelengths. Considering the refractive index of the
object, one can determine the thickness of the object at the spot light
location. This thickness data is calculated and transmitted to host
computer at up to 4KHz frequency. See Fig. 2-4.
Fig. 2-4: Chromatic measurement principle, thickness measurement
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