Apparatus for measuring birefringence without employing rotating mechanism

Claim 1

An apparatus for measuring a birefringence of an object, comprising: a light source for emitting onto the object a first linearly polarized laser beam, transmitted in a z-axis direction and having an optical frequency (f1), an optical electric field of which is an x-axis direction, and a second linearly polarized laser beam, progressing along the same optical path as the first laser beam and having an optical frequency (f2), an optical electric field of which is in a y-axis direction perpendicular to the x-axis direction; a difference cycle generating means for generating a difference cycle alternating signal of a difference frequency of f=f1-f2; an optical separating means for separating laser beams from the first and second laser beams which have transmitted through the object from each other at an approximate constant ratio irrespective of polarized direction thereof; a first analyzer for transmitting therethrough only one of the laser beams separated by the optical separating means and polarized by about 45° with respect to the x-axis; a first photodetector for detecting the laser beam transmitted through the first analyzer; a second analyzer for transmitting therethrough only an other beam of the laser beams separated by the optical separating means and polarized in the x-axis direction or the y-axis direction; a second photodetector for detecting the laser beam transmitted through the second analyzer; a multiplier for calculating a first product (q) of the difference cycle alternating signal (f) and a first signal (a) received and detected by the first photodetector and a second product (s) of the difference cycle alternating signal (f) and a second signal (b) received and detected by the second photodetector; and a calculating means for calculating a birefringence amount (d) of the object and a direction (c) of a lag-phase axis or that of an advance-phase axis based on the first product (q) and the second product (s) output from said multiplier.

Claim 2

An apparatus for measuring a birefringence of an object, comprising: a light source for emitting onto the object a first linearly polarized laser beam, transmitted in a z-axis direction and having an optical frequency (f1), an optical electric field of which is an x-axis direction, and a second linearly polarized laser beam, progressing along the same optical path as the first laser beam and having an optical frequency (f2), an optical electric field of which is in a y-axis direction perpendicular to the x-axis direction; a difference cycle generating means for generating a difference cycle alternating signal of a difference frequency of f=f1-f2; an optical separating means for separating laser beams from the first and second laser beams which have transmitted through the object from each other at an approximate constant ratio irrespective of polarized direction thereof; a first analyzer for transmitting therethrough only one of the laser beams separated by the optical separating means and polarized by about 45° with respect to the x-axis; a first photodetector for detecting the laser beam transmitted through the first analyzer; a second analyzer for transmitting therethrough only an other beam of the laser beams separated by the optical separating means and polarized in the x-axis direction or the y-axis direction; a second photodetector for detecting the laser beam transmitted through the second analyzer; a multiplier for calculating a first product (q) of the difference cycle alternating signal (f) and a first signal (a) received and detected by the first photodetector and a second product (s) of the difference cycle alternating signal (f) and a second signal (b) received and detected by the second photodetector; and a calculating means for calculating a birefringence amount (d) of the object and a direction (c) of a lag-phase axis or that of an advance-phase axis based on the first product (q) and the second product (s) output from said multiplier.