DOE-based systems and devices for producing laser beams having modified beam characteristics

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 (L1), 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 L1 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 M1;
• and
• a second fixed spatial-frequency diffractive optical element (DOE), mounted in said module housing, having a beam expansion factor M2,
• wherein the collimated laser beam exiting said collimating lens L1 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 L1, 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 L1 and through said module;
• and wherein the total beam-shaping factor (M=M1M2) for the laser beam producing module is less than unity, and the laser beam leaving said collimating lens (L1) is compressed in one dimension, and has a circularized beam aspect-ratio, minimized or reduced to zero beam dispersion, and corrected astigmatism.