Patent ID: 7443587

Claim:
A laser beam production module for producing a laser beam having a desired beam aspect-ratio, a minimized or reduced to zero beam dispersion, and corrected astigmatism, said laser beam producing module comprising: a module housing; a visible laser diode (VLD), mounted within said module housing, for producing a laser beam from its junction having divergent and elliptical beam characteristics; a collimating lens (L 1 ), mounted in said module housing, spaced from said VLD by a distance D, for collimating the laser beam as it is transmitted through said collimating lens L 1 and through components in said module; a first fixed spatial-frequency diffractive optical element (DOE), mounted in said module housing, having a beam expansion factor M 1 ; and a second fixed spatial-frequency diffractive optical element (DOE), mounted in said module housing, having a beam expansion factor M 2 , wherein the collimated laser beam exiting said collimating lens L 1 is transmitted through said first DOE, and the collimated laser beam exiting said first DOE is transmitted through said second DOE, and wherein: (a) the collimating lens has a downstream focus location, in the direction of said collimating lens L 1 , that is calculated to adjust or eliminate astigmatism in the beam propagating beyond the second DOE; (b) for the calculated downstream focus location, D is selected to provide a desired beam spot size, thereby determining an upstream focus location for the lens, in the direction of said VLD; and (d) the focal length of the collimating lens is selected according to the upstream and downstream focus locations, whereby the collimated laser beam exiting said second DOE exits has a controlled beam aspect-ratio, a minimized or reduced to zero beam dispersion, and corrected astigmatism; and wherein said laser beam is transmitted through said collimating lens L 1 and through said module; and wherein the total beam-shaping factor (M=M 1 M 2 ) for the laser beam producing module is less than unity, and the laser beam leaving said collimating lens (L 1 ) is compressed in one dimension, and has a circularized beam aspect-ratio, minimized or reduced to zero beam dispersion, and corrected astigmatism.