Broadband and wide field angle compensator

An ellipsometer, comprising:

• an illumination source configured to generate non-collimated, polychromatic illumination light directed toward a sample;
• a parallel plate compensator configured to transmit an amount of the illumination light, wherein the rotatable compensator comprises,
• a first birefringent plate having a front surface, a back surface, an optic axis oriented in a plane parallel to the front and back surfaces within a manufacturing tolerance, and a thickness of less than five hundred micrometers;
• a second birefringent plate having a front surface, a back surface, an optic axis oriented in a plane parallel to the front and back surfaces within the manufacturing tolerance, and a thickness of less than five hundred micrometers, wherein the first birefringent plate and the second birefringent plate are oriented such that their respective optic axes are aligned approximately perpendicular to one another;
• and
• a first optically isotropic plate in optical contact with the front surface of the first birefringent plate,
• an analyzer configured to extract a polarization state from the amount of light transmitted through the parallel plate compensator;
• and
• a detector configured to measure an intensity of an amount of light transmitted through the analyzer at different wavelengths throughout a wavelength range of interest that includes ultraviolet wavelengths.