Error analysis of null ellipsometry with depolarization.
Null ellipsometry is analyzed for components with depolarizations for unpolarized incident light. Serious imperfections include sample depolarization D < 0.2, misalignment (deltaC < 2 degrees) and off-quarter-wave retardance (deltatau < 5 degrees) of the compensator. The four-zone null positions are derived analytically to the second order of serious imperfections and are also simulated based on Mueller matrices with depolarization. Errors of all four-zone nulls increase with increasing D. Depolarizations of all components except the analyzer cause errors to the nulls. The errors associated with D always couple with the second order of deltaC and deltatau and are enhanced by csc(2) 2psi. These divergent errors limit the applicable region of null ellipsometry where the errors in psi and D are within 0.1 degrees, and the simulation agrees well with the analytic solutions.
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Physics Branch, Research and Technology Group, Weapons Division, Naval Air Warfare Center, China Lake, California 93555-6001, USA. neesf@navair.navy.mil