OPTICAL MEASUREMENT METHOD FOR MATERIAL Russian patent published in 2011 - IPC G01N21/43 

FIELD: physics.

SUBSTANCE: modulation spectroscopy using the r-component linearly polarised radiation is used measure spectra of the angle θ₁, which corresponds to the minimum of the curve of optical radiation reflection coefficient versus angle of incidence, angle θ₂ which corresponds to the flex point of the angular dependence of the reflection coefficient. The angle of incidence on the analysed sample is modulated with amplitude between 0.2 and 2 degrees, which prevents θ₁ and θ₂ distortions associated with nonlinearity of the angular dependence of the reflection coefficient, or the negligible effect of nonlinearity of the angular dependence of the reflection coefficient. Modulation frequency of 5-200 Hz ensures sufficiently high signal/noise ratio for extraction of the useful signal from the noise in order to measure characteristic angles without θ₁ and θ₂ distortions.

EFFECT: high accuracy of measured characteristics and accuracy of information on properties of the material.

5 cl, 5 dwg