Optical system for ellipsometry utilizing a circularly polarized probe beam

An ellipsometry apparatus for analyzing a polarization state of an optical device under test by measuring optical parameters of a light beam which experienced a birefringence of the optical device under test, comprising:

• a light source for generating a coherent light beam;
• a first beam splitter for splitting said coherent light beam into two light beams;
• an optical frequency shifter for shifting a frequency of one of said two light beams splitted by said first beam splitter to form a reference light beam;
• a circular polarization converter for circularly polarizing the other of said two light beams splitted by said first beam splitter to form a probing light beam which is a circularly polarized light beam to be applied to the optical device under test;
• a second beam splitter for combining said reference light beam and said probing light beam that transmitted through said optical device under test or reflected back from said optical device under test;
• a birefringence prism for receiving a light beam combined by said second beam splitter and separating polarization components which are perpendicular with each other;
• a photo detector for receiving said polarization components and converting the same to corresponding electric signals;
• an analog-digital converter for converting said electric signals to digital data and storing said digital data in a memory;
• and
• an arithmetic unit for receiving said digital data and calculating an azimuth angle and an ellipticity of said light beam that transmitted through or reflected back from said optical device under test.

An ellipsometry optical system for analyzing a polarization state of an optical device under test by measuring optical parameters of a light beam which experienced a birefringence of the optical device under test, comprising:

• a light source for generating a coherent light beam;
• a first beam splitter for splitting said coherent light beam into two light beams;
• a polarization beam splitter for receiving one light beam of said two light beams splitted by said first beam splitter and for separating said one light beam into two polarization components perpendicular one another;
• a first optical frequency shifter for shifting a frequency of one of said polarization components separated by said polarization beam splitter by .DELTA.F1;
• a second optical frequency shifter for shifting a frequency of the other of said polarization components separated by said polarization beam splitter by .DELTA.F2;
• means for combining said polarization components which are frequency shifted by said first and second optical frequency shifters to form a reference light beam;
• a circular polarization converter for circularly polarizing the other of said two light beams splitted by said first beam splitter to form a probing light beam which is a circularly polarized light beam to be applied to the optical device under test;
• a second beam splitter for combining said reference light beam and said probing light beam that transmitted through said optical device under test;
• a photo detector for receiving a light beam combined by said second beam splitter and converting the same to corresponding electric signals.

An ellipsometry apparatus for analyzing a polarization state of an optical device under test by measuring optical parameters of a light beam which experienced a birefringence of the optical device under test, comprising:

• a light source for generating a coherent light beam;
• a first beam splitter for splitting said coherent light beam into two light beams;
• a polarization beam splitter for receiving one light beam of said two light beams splitted by said first beam splitter and for separating said one light beam into two polarization components perpendicular one another;
• a first optical frequency shifter for shifting a frequency of one of said polarization components separated by said polarization beam splitter by .DELTA.F1;
• a second optical frequency shifter for shifting a frequency of the other of said polarization components separated by said polarization beam splitter by .DELTA.F2;
• means for combining said polarization components which are frequency shifted by said first and second optical frequency shifters to form a reference light beam;
• a circular polarization converter for circularly polarizing the other of said two light beams splitted by said first beam splitter to form a probing light beam which is a circularly polarized light beam to be applied to the optical device under test;
• a second beam splitter for combining said reference light beam and said probing light beam that transmitted through said optical device under test;
• a photo detector for receiving a light beam combined by said second beam splitter and converting the same to corresponding electric signals;
• an analog-digital converter for converting said electric signals to digital data and storing said digital data in a memory;
• and
• an arithmetic unit for receiving said digital data and calculating an azimuth angle and an ellipticity of said light beam that transmitted through or reflected back from said optical device under test.