Patent ID: 6853442

Claim:
A projection exposure apparatus, comprising: a continuous emission excimer laser, having a resonator, for providing laser light; an illumination optical system for receiving the laser light from the continuous emission excimer laser and for illuminating a pattern of a reticle with the laser light; a projection optical system, comprising a lens system made of a substantially single glass material, for projecting the illuminated pattern of the reticle onto a substrate; an injection laser for injecting light into the resonator of said continuous emission excimer laser, wherein a design wavelength of the injection laser is equal to a design wavelength of the continuous emission excimer laser; a wavemeter for measuring the wavelength of the laser light from said continuous emission excimer laser and for producing a signal; and changing means for changing a resonator length of said continuous emission excimer laser on the basis of the signal from said wavemeter so that the wavelength of the laser light from said continuous emission excimer laser becomes equal to the design wavelength of the continuous emission excimer laser.