A new type of automatic ellipsometer based on a phase-shifting technique is described, where an electrooptic modulator made of ADP (ammonium dihydrogen phosphate) crystals is used for phase shifting; thus we call it the phase-shifting ellipsometer. The light source is a 5 mW He-Ne laser. The intensities changed as the phase retardation Gamma was shifted by 0, pi/2 and pi. The design, alignment, and calibration of the system are discussed in detail. Once the optical system is aligned, all components are free from mechanical movement, hence the precision is high. The accuracy of the results has been evaluated, and the errors introduced on Psi and Delta are <0.032 degrees and 0.19 degrees, respectively. The inaccuracy of the phase shift can only introduce an error on Delta, and the degree of error on Delta is the same as that on Gamma, so it is very easily to modify.
JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS SHORT NOTES & REVIEW PAPERS