Basics of Measurement and Analysis

If the fast axis of a quarter-wave plate is oriented at 45° from 

The relative amplitude diminution (tan upon reflection from the interface can be determined by rotating the analyzer until the photodetector registers minimum intensity. The analyzer orientation, A, will be orthogonal to the direction of vibration, ij/  

The determinations of A and ij/ are made by adjusting the angles of the polarizer and analyzer alternately until the minimum (null) intensity is registered by the photodetector. This is the null method of ellipsometry. 

Alternatively, the polarizer orientation, P, can be chosen to have values from tt/4 to 3n/4) so that A is positive. In this case 

The equations to be used in determining A and ij/ from readings of the null-type ellipsometer with the fast axis of the quarter-wave plate fixed at 45° are summarized in Table 1. 

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