Purpose. For measuring the refractive indices of dielectric samples.
Application area. Laser spectroscopy.
Advantages. Small sample area required for measurement (equal to the cross-section of the laser beam that can be focused); possibility of measurements on curved sample surfaces; wide range of refractive indices that can be measured (1.3-2.5).
Description. For measuring the refractive indices of dielectric substrate samples, a nonlinear phenomenon of formation of periodic structures (PS) in a thin photosensitive AgCI-Ag film deposited in vacuum on the substrate is used due to excitation of the limiting waveguide mode in the film by a laser beam. PS is induced by an s-polarized beam at an angle of incidence. After the PS is formed, the diffraction angle from the PS corresponding to the autocollimation condition is measured. Then the refractive index of the substrate is calculated.