Light irradiation apparatus

A light irradiation apparatus comprising:

• a light source generating ultraviolet light;
• a polarizer polarizing the ultraviolet light generated in the light source;
• and
• a filter, separate from the polarizer, blocking off the polarized light from the polarizer except an effective wavelength band of light for a photo alignment,
• wherein the filter includes a high pass filter blocking off a short wavelength band of light and a low pass filter blocking off a long wavelength band of light,
• wherein the short wavelength band is in a wavelength range below 250 nm,
• wherein the long wavelength band is in a wavelength range above 300 nm,
• wherein the polarizer includes a plurality of quartz plates,
• wherein the polarizer has an extinction ratio range of 34:1˜20:1,
• wherein a collimator is configured between the filter and a substrate to guide the light from the filter toward a substrate,
• wherein the light source includes a lamp having a high peak value within the effective wavelength band of about 200 nm˜330 nm.