Apparatus for measuring transmissivity of patterned glass substrate
An apparatus for measuring transmissivity of a patterned glass substrate. A beam radiator radiates a laser beam. A collimation lens collimates the laser beam radiated from the laser beam radiator. A beam expander expands a size of the laser beam collimated by the collimation lens. A detector has a light-receiving section, which receives the laser beam that has passed through the patterned glass substrate after having been expanded by the beam expander. A measuring instrument measures a transmissivity of the patterned glass substrate using the laser beam received by the detector.
1. A method for measuring transmissivity of a patterned glass substrate, comprising:
radiating a laser beam having a size, at a single wavelength of 550 nm;
collimating the laser beam with a collimation lens;
expanding the size of the collimated laser beam;
passing the expanded laser beam through a glass substrate having a plurality of pattern units on which the expanded collimated laser beam is incident;
receiving, at a detector having a light-receiving section at least twice as large as a size of the expanded laser beam that is incident on the patterned glass substrate, the expanded laser beam that is passed through the patterned glass substrate; and
measuring transmissivity of the patterned glass substrate based on the received laser beam;
wherein the detector is 5 mm or less from a rear end of the patterned glass substrate.
2. The method of claim 1 , wherein the collimated laser beam is expaned to such a size that the expanded laser beam can be incident on at least 10 pattern units of the patterned glass substrate.
3. The method of claim 1 , further comprising reflecting the laser beam off of a mirror into the collimation lens.
4. The method of claim 3 , further comprising using a noise filter to remove noise from the reflected laser beam.