Patent ID: 6563847
Filing Date: 2003-05-13
Classification: H01S

Abstract:
A laser optical system, comprising:a multiline laser source that emits a laser beam having a plurality of peak wavelengths, each peak wavelength having a beam diameter as emitted; an imaging optical system that converges said laser beam emitted from said multiline laser source to form beam spots of respective peak wavelengths or an object surface; and a correcting optical system that adjusts the magnification of the beam diameters of respective peak wavelengths in accordance with the magnitude of the respective peak wavelengths, before said laser beam is incident on said imaging optical system, so as to make the imaging optical system form beam spots of substantially the same diameter for at least two selected peak wavelengths, wherein said correcting optical system satisfies the following condition (1): Î»AÎ»B<Ï‰Aâ€²Ï‰Bâ€²<(Î»AÎ»B)3(1)where &lgr;A and &lgr;B are said selected peak wavelengths and &ohgr;â€²A and &ohgr;â€²B are diameters of said peak wavelengths of said laser beam as the peak wavelengths are incident on said imaging optical system at said selected peak wavelengths &lgr;A and &lgr;B, wherein the ratio &ohgr;â€²A/&ohgr;â€²B of the diameters of said selected peak wavelengths is a predetermined diameter ratio defines the adjustment of the magnification of the beam diameters before said laser beam is incident on said imaging optical system, and the square root of the ratio of the two selected peak wavelengths defines a lower acceptable level of beam spot difference as formed by the imaging optical system, while the cubed square root of the ratio of the two selected peak wavelengths defines an upper acceptable level of beam spot difference as formed by the imaging optical system.