Thin - Film Measurement Instrument
System is based on optical reflection principles. Optical fiber probe carries the light, reflected light is carried back to Siphotodiode/CCD array sensors. Thickness is measured based on sinusoidal waves. Multiple layers are differentiated based on absorption maxima. W light source, optical fiber reflection probe, 512 element photodiode array, electronics, interface, windows based s/w are being supplied. Wavelength can be chosen by the user vis or NIR depanding on the absorbance of sample. In case if the sample is completely opaque in the visible region NIR is chosen so that some amount of light reaches bottom layer allowing sensor to analyse reflected light from both the layers.
n & k
It is possible to get n & k for all the wavelengths (450-950nm). One can plot n & k vs. Wavelength and also get the values in tabular form.
Roughness
It is also possible to measure the roughness.
Requirement of film
The film needs to be smooth, shiny, and translucent for it to work.
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