| 摘要 |
PURPOSE:To lower coherence in terms of space and time of a laser beam by a method wherein an optical system used to connect a cross-sectional shape of the beam is installed between a laser source and a first reflection member. CONSTITUTION:Optical systems 5a, 5b used to convert a cross-sectional shape of a beam are installed between a laser source 1 and a first reflection member 6. In this case, wavelength-narrowing elements 3a, 3b used to narrow a spectral width of the laser beam may be installed on a light path between the first reflection member 6 and a second reflection member 4. It is preferable that the first reflection member 6 is composed of an aggregate of a plurality of optical rods, of different lengths, which are arranged in parallel with a light-path direction of the beam; at least one end face of the plurality of optical rods is used as a reflecting face having a transmissive property; the aggregate as a whole is used as a stepped mirror. Thereby, the beam is expanded inside a resonator; it is possible to prevent an increase in coherence in terms of space and time by an expansion of the cross-sectional shape of the beam. |
