Abstract:
A method of determining induced change of polarization state of light in a polarization element comprising transmitting unpolarized light from a light source at the one end of an optical transmitter waveguide means (21) to polarizer means (31) at the other end; polarizing the unpolarized light by the polarizer means (31); transmitting the polarized light through the polarization element (41, 41A, 41B) using at least one reflective optical element; analyzing the transmitted polarized light from the polarization element by an analyzer means (32); and transmitting the analysed polarized light from the one end of optical receiver waveguide means (22) to a light detector at the other end; wherein the unpolarized light polarized by the polarizer means (31), the polarized light analysed by the analyzer means (32), or both, are non-collimated; and the polarized light in the light path between the polarizer means (31) and the analyzer means (32) is collected and reflected by at least one reflective imaging optical element (51) so that the analyzed light exits the analyzer means (32) from the same side as the unpolarized light enters the polarizer (31). Further, fiber optic sensor devices for determining induced change of polarization state of light in a polarization element, particularly linear birefringence induced by electric voltage, electric field, and mechanical force, and circular birefringence induced by electric current and magnetic field.
Abstract:
PROBLEM TO BE SOLVED: To precisely detect stress of a sample semiconductor wafer, as the absolute value, without rotating the sample or the overall optical system. SOLUTION: A birefringent phase difference is generated when a laser light R is modulated by photo elastic modulation by a PEM (photo elastic modulator) 6, and is detected after passing through a first and a second 1/4 wave plates. The reference signal data thereof are stored in a signal processor. The laser light R of the polarized wave, modulated by the photo elastic modulation by the PEM 6 and passing through the 1/4 wave plates, has the birefringent phase difference, and is transmitted through the semiconductor wafer D having the residual stress. When transmitted through a test piece, the direction of the stress of the test piece is detected when the angle with respect to the linearly polarized light is 0 degrees and 90 degrees. The transmission electric signal thereof is transmitted to an analog/digital converter 16. The signal is inputted into the signal processor, where the transmission signal is generated. The signal processor reads out the stored reference signal data and the transmission signal data, and calculates the reference birefringent phase difference and the absolute value of the birefringent phase difference. COPYRIGHT: (C)2005,JPO&NCIPI