Method and apparatus for analyzing optical characteristics of optical medium and method for production monitoring

An apparatus for analyzing an optical medium, comprising:

• a light source;
• an input unit allowing at least three input light beams from the light source, differed from each other in a polarization state, to enter a surface of an optical medium from a direction inclined by a polar angle θ (0°<θ<90°) with regard to the surface;
• a detection unit detecting polarization states of output light beams from the optical medium, corresponded to the input light beams;
• and
• a calculation unit determining the Jones matrix M which can satisfy the equation (1) below with polarization vectors of the input light beams and polarization vectors of the correspondent output light beams:
• (
• Es
• ′
• Ep
• ′
• )
• =
• Q
• ′
• ×
• M
• ×
• Q
• ×
• (
• Es
• Ep
• )
• (
• 1
• )
• where, Es and Ep are polarization vectors of s-polarization and p-polarization of an input light, respectively;
• Es′ and Ep′ are polarization vectors of s-polarization and p-polarization of a correspondent output light beam, respectively;
• Q is a dynamics matrix expressing changes in a polarization state of a input light beam going into an optical medium from the air;
• and Q′ is a dynamics matrix expressing changes in a polarization state of an output light beam going from the optical medium into the air.

A method for production monitoring of an optical medium comprising:

• illuminating an optical medium, having an input surface and an output surface of light, with at least three input light beams differed from each other in a polarization state, respectively from a direction inclined by a polar angle θ (0°<θ<90°) with regard to the input surface;
• obtaining polarization states of output light beams coming out from the output surface, corresponded to the input light beams;
• determining the Jones matrix M which can satisfy the equation (1) below with polarization vectors of the input light beams and polarization vectors of the output light beams:
• and
• monitoring a shift from an ideal value of at least one parameter which determines the Jones matrix M:
• (
• Es
• ′
• Ep
• ′
• )
• =
• Q
• ′
• ×
• M
• ×
• Q
• ×
• (
• Es
• Ep
• )
• (
• 1
• )
• where, Es and Ep are polarization vectors of s-polarization and p-polarization of an input light beam, respectively;
• Es′ and Ep′ are polarization vectors of s-polarization and p-polarization of an output light beam, respectively;
• Q is a dynamics matrix expressing change in a polarization state of an input light beam going into an optical medium from the air;
• and Q′ is a dynamics matrix expressing change in a polarization state of an output light beam going from the optical medium into the air.