Measurement of optical parameters of crystalline samples using reflected light

摘要

The polarization state of the beam reflected by the crystalline surface of the sample (P), is altered. It is analyzed using a beam-splitter and plane- or focusing mirrors (S1, S2, S3). The beam splitter transmits a fraction of incident light exhibiting linear polarization in the required direction for measurement. The reflected fraction of the beam has differing polarization. The apparatus includes analyzers processing data simultaneously from the separated beams, which determine the RAS parameters from the fraction reflected by the splitter, and the reflectivity parameters from the fraction transmitted by the splitter. Preferred Features: The splitter is a beam-splitting polarization prism (P2). To measure polarization-dependent optical parameters of beams reflected by static crystalline samples, the apparatus includes in addition, a photoelastic modulator (PEM). The analysis unit processes data to determine real and imaginary parts of RAS spectra includes a plane mirror, spherical mirror, monochromator, detector and lock-in amplifier tuned to the PEM-modulation. The plane and spherical mirrors focus the transmitted split beam onto the monochromator and the light leaving is intercepted by detectors. The lock-in technique analyses real and imaginary parts of RAS spectra. Apparatus used, and a variant are further detailed.