| 摘要 |
PROBLEM TO BE SOLVED: To provide a controller for the light quantity of a laser beam with which the quantity of the laser beam is monitored and controlled by forming a beam splitter without using such a high-functional film as a multi-layer film of dielectric material and by utilizing S-polarization reflection resulting from the refractive index which a substrate itself has. SOLUTION: A half-mirror 102c is formed on a side of a glass substrate of the beam splitter 102, the substrate face of the glass substrate is formed to have a predetermined refractive index, and the half-mirror is arranged in the optical path of an emitted light beam from a laser beam source 101 so that a part of the laser beam emitted from the laser beam source 101 is reflected from the substrate face of the glass substrate 102a of the beam splitter 102 and led to a photodetector 106. Thus, a part of the laser beam given by the reflection from the substrate face of the glass substrate 102a is received by the photodetector 106 for detecting the light quantity and the light quantity is detected. |
