| 摘要 |
PURPOSE:To enable the highly accurate control of an narrow band oscillation excimer laser for a long time, by making the oscillation bandwidth narrow, by arranging a wavelength selection element, applying an etalon or diffraction grating type spectroscope to a wavelength detector, and performing the feedback control of a selected wavelength. CONSTITUTION:The resonator of a narrow band oscillation excimer laser is constituted by arranging a wavelength selection element 2 and a laser chamber 3 between a rear mirror 1 and a front mirror 5. A wavelength detector 8 detects the respective wavelengths of a reference light and a laser beam whose bandwidth is made narrow, and the detected outputs are delivered to a wavelength controller 9, which calculates the absolute value of the laser beam whose bandwidth is made narrow, according to the wavelength of a reference light, and calculates the difference between a set wavelength and a laser beam whose bandwidth is made narrow. In order to change the selection wavelength of the wavelength selection element 2 by the amount of the above-mentioned difference, a signal is sent from the wavelength controller 9 to a wavelength selection element driver 10, which makes the wavelength selection element 2 change the selection wavelength. |
