Laser crystallizing apparatus

A laser crystallizing apparatus comprising:

• a first light source unit configured to emit a first input light having a laser beam shape and a first polarized state;
• a second light source unit configured to emit a second input light having a laser beam shape and the first polarized state;
• a first input polarization rotator configured to convert the first input light into a second polarized state different from the first polarized state;
• a second input polarization rotator configured to maintain the first polarized state of the second input light;
• a first output polarization rotator configured to convert the second polarized state of the first input light passing through the first input polarization rotator into the first polarized state;
• a second output polarization rotator configured to maintain the first polarized state of the second input light passing through the second input polarization rotator;
• an optical system configured to convert the first input light and the second input light, which pass through the first and second output polarization rotators, into an output light;
• a stage on which a target substrate is seated and onto which the output light is directed;
• a polarization plate configured to block one of, and transmit another of, the first input light having the second polarized state, which passes through the first input polarization rotator, and the second input light having the first polarized state, which passes through the second input polarization rotator;
• and
• a monitoring unit configured to measure a laser beam quality by using the light passing through the polarization plate.

A method for crystalizing amorphous silicon, comprising:

• emitting a first laser beam from a first laser beam emitter;
• emitting a second laser beam from a second laser beam emitter;
• splitting the first laser beam into a first sub-beam and a second sub-beam;
• splitting the second laser beam into a third sub-beam and a fourth sub-beam;
• calculating a beam quality from one of the first sub-beam and the third sub-beam;
• directing the second sub-beam and the fourth sub-beam through an optical system;
• and
• crystalizing amorphous silicon using an output of the optical system.