| 摘要 |
PURPOSE:To improve an excimer laser of this design in performance by a method wherein the intensity component of light rays penetrated through a cell is observed through a spectrograph, the light rays and small band laser rays emitted from a laser oscillator are made to be alternately incident on the spectrometer, and a laser oscillation wavelength is optionally controlled to be fixed close to an absorption line of the wavelength component of the light rays observed by the spectrometer on the basis of the absorption line. CONSTITUTION:A first shutter 5 is closed, a second shutter 7 is opened, and light rays from a background light source are made incident on a cell 8. The cell 8 enables the incident light rays to be incident on a spectrometer 10 absorbing only light rays of specified wavelength close to an oscillation wavelength of an excimer laser oscillator 1 with an absorbent provided inside the cell 8, a spectral waveform is detected by an image sensor 11, and the position P1 of a known absorption line serving as a reference is determined on the image sensor 11 after separation through the spectrometer 10. Then the shutter 7 is closed and the shutter 5 is opened, laser rays emitted from an oscillator 1 are made incident on the spectrometer 10 through the intermediary of an optical converging device 9, a position P2 of the laser rays is detected the same as above, and an oscillation wavelength is controlled so as to make K.(P2-P1), a reduced value of (P2-P1) expressed in term of wavelength, equal to the difference between a wavelength lambda1 of the absorption line and a laser wavelength lambda2. |
