Pulsed spectroscopy with spatially variable polarization modulation element

A method of ellipsometrically measuring a sample, the method comprising:

• turning on and off a broadband electromagnetic beam to produce a pulsed electromagnetic beam to be incident on a sample;
• polarizing the pulsed electromagnetic beam prior to being incident on the sample;
• producing a spatially dependent relative phase difference between the electric field components of the pulsed electromagnetic beam in a first direction;
• polarizing the pulsed electromagnetic beam after a spatially dependent relative phase difference is produced;
• filtering the wavelengths of the pulsed electromagnetic beam spatially in a second direction that is perpendicular to the first direction;
• and
• detecting the intensity of the polarized pulsed electromagnetic beam at a plurality of positions as a function of the spatially dependent relative phase shift in the first direction and the wavelengths in the second direction.

An apparatus for measuring a characteristic of a sample, the apparatus comprising:

• a flash bulb light source that can be turned on and off to produce a pulsed electromagnetic beam with multiple wavelengths;
• a polarizer in the path of the pulsed electromagnetic beam, wherein the polarized pulsed electromagnetic beam is incident on the sample;
• means for producing a spatially dependent phase shift in the pulsed electromagnetic beam, the means for producing a spatially dependent phase shift producing a phase shifted beam wherein the phase shift is spatially dependent along a first direction;
• means for polarizing within the path of the phase shifted beam, the means for polarizing producing a polarized phase shifted beam;
• means for dispersing the wavelengths of the expanded pulsed electromagnetic beam along a second direction, the means for dispersing the wavelengths being in the path of the expanded pulsed electromagnetic beam;
• and
• means for measuring the intensity of the polarized phase shifted beam as a function of phase shift in the first direction and as a function of wavelengths in the second direction, the means for measuring being in the path of the polarized phase shifted beam.