Patent ID: 7075648
Filing Date: 2006-07-11
Classification: G01J

Abstract:
1. A system comprising: a light source configured to transmit light along a light transmission axis a polarizer located along the light transmission axis, the polarizer having a polarization transmission direction substantially perpendicular to the light transmission axis; an analyzer located along the light transmission axis, the analyzer having a polarization transmission direction substantially perpendicular to the light transmission axis, the analyzer being configured to rotate about the light transmission axis; a first waveplate interposed between the polarizer and the analyzer, the first waveplate being located along the light transmission axis, the first waveplate having a slow axis, the slow axis of the first waveplate being substantially perpendicular to the light transmission axis, the first waveplate being configured to rotate about the light transmission axis, the combination of the rotating of the first waveplate and the rotating of the analyzer resulting in extinction of light being transmitted through the analyzer; a second waveplate interposed between the polarizer and the analyzer, the second waveplate being located along the light transmission axis, the second waveplate having a slow axis, the slow axis of the second waveplate being substantially perpendicular to the light transmission axis; and a camera configured to capture images projected by the light being transmitted along the light transmission axis.