PURPOSE: To make an inspecting operation in a short time even if an error generating part is in an oscillator or an optical path duct by dividing an inspection range into plural groups such as an oscillator, an optical path duct, and a process head.
CONSTITUTION: An optical system means is divided into plural groups and each optical system means of the respective plural groups is provided with an optical path control means capable of inspection of the part generating an error in a direction of an optical axis direction of a laser beam 3. For example, if there is an abnormal state in the measured value in the first measuring point 13 of an optical axis of the inspection He-Ne laser from the first projection point 12, it can be made clear that a guide mirror 5 is an error generating part of the optical axis. Similarly if the abnormal value is measured in the second measuring point 15 of the optical axis of the gas from the second projection point 14, a guide mirror 8 or a converging lens 9 is an error generating part. For the inspection inside an oscillator 1, an image of Moire' fringe of the He-Ne laser beam from a projection hole 11 is measured at the output terminal 2 and if an abnormal value is detected, it is made clear that the error generating part is a guide mirror or a resonator mirror and etc. in the oscillator 1.
UENO MANABU
ANDO TAKASHI
MATSUNAGA MASAYUKI
MITSUBISHI ELECTRIC CORP