Light source system and polarization angle adjusting method

A light source system, comprising:

• a light source, configured to emit an original light beam, wherein the original light beam has an original polarization angle;
• an amplifying module, including reflective mirrors and configured to amplify the original light beam and generate a forward beam for hitting a target, wherein the forward beam has a forward polarization angle that is equal to the original polarization angle;
• an optical isolator, disposed between the light source and the amplifying module;
• and
• a polarization measurement and monitoring device, configured to measure a first polarization angle of a first return beam and adjust a second polarization angle of a second return beam, wherein the first return beam is reflected from the target, and the second return beam is emitted from the amplifying module;
• wherein the polarization measurement and monitoring device further includes a phase adjusting module, the phase adjusting module includes a reflective phase retarder and is configured to adjust the second polarization angle according to the forward polarization angle and the first polarization angle, so that an optical isolator is able to block the second return beam from entering the light source.

A polarization angle adjusting method, comprising:

• emitting an original light beam by a light source;
• amplifying, by an amplifying module, the original light beam to generate a forward beam for hitting a target, wherein the target reflects a first return beam after being hit, and the forward beam has a forward polarization angle;
• providing a first polarization measurement module to receive the first return beam so as to measure a first polarization angle of the first return beam;
• providing a second polarization measurement module to receive a second return beam so as to measure a second polarization angle of the second return beam, wherein the second return beam is emitted from the amplifying module toward the light source;
• and
• controlling a phase adjusting module to adjust the second polarization angle according to the forward polarization angle and the first polarization angle.