| 摘要 |
PURPOSE:To make it possible to perform stable output measurement without changing the beam characteristics and without the effect of fluctuation in oscillating frequencies in measuring at an attenuation factor of 1% or less, by selecting the specified relationship with regard to the thickness of parallel plates (t), the diameter of an incident laser beam phi, the refractive index of the parallel plates (n), and a Brewster angle phiB. CONSTITUTION:A beam splitter 1 has the two plates, which are in parallel each other, and the reflected beams are emitted from both plates. A numeral 6 is the reflected light from the incident surface of the beam splitter 1, and a numeral 9 is the reflected light from the output surface. The two beams of the reflected light 6 and 9 are inputted to a beam output meter 2. The coherent length of the laser light is sufficiently long and usually sufficiently larger than the plate thickness (t) of the beam splitter 1. Therefore, the two beams of the reflected light yield mutual interference. When the thickness (t) of the beam splitter 1 is selected so as to satisfy the expression in the Figure, the interference between the two beams does not occur, and the beam intensity can be measured regardless of the fluctuation of the frequency. |
