Method for changing the cross section of a laser beam
AssigneeThe United States of America as represented by the United States Department of Energy
InventorsWilliam C. Sweatt, Lynn Seppala
Life of this patent
Estimating the term…
Abstract
A technique is disclosed herein in which a circular optical beam, for example a copper vapor laser (CVL) beam, is converted to a beam having a profile other than circular, e.g. square or triangular. This is accomplished by utilizing a single optical mirror having a reflecting surface designed in accordance with a specifically derived formula in order to make the necessary transformation, without any substantial light loss and without changing substantially the intensity profile of the circular beam which has a substantially uniform intensity profile. In this way, the output beam can be readily directed into the dye cell of a dye laser.
Claims17
A laser beam reshaping system comprising a mirror having a laser beam reflective surface for converting an incident laser beam having a circular cross-section to an output beam having a polygonal cross-sectional shape at a distance L from said surface, said mirror defining a mirror plane and an axis Z normal to said mirror plane, each point on said reflective surface being described by an equation
- W.sub.m (r,.beta.)=k.sub.m R.sup.2 /L (r/R).sup.m cos(m.beta.)
- where m equals the number of sides of said polygonal cross-sectional shape, W is the deviation of said reflective surface from said mirror plane along said Z axis, R is the radius of said incident beam, r and .beta. are the cylindrical coordinates of said points on said mirror plane, and k.sub.m is an empirically selected variable.
A laser beam reshaping system comprising:
- a laser emitting a laser beam having a circular cross-section;
- and
- a mirror positioned to receive the laser beam and having a laser beam reflective surface for converting the laser beam to an output beam having a polygonal cross-sectional shape at a distance L from said surface, said mirror defining a mirror plate and an axis Z normal to said mirror plane;
- and
- a collimating element positioned the distance L from the mirror plane, the collimating element collimating the polygonal cross-sectional shape of the output beam;
- and
- wherein each point on said reflective surface is described by an equation
- W.sub.m (r, .beta.)=k.sub.m R.sup.2 /L(r/R).sup.m cos(m.beta.)
- where m equals the number of sides of said polygonal shape, W is the deviation of said reflective surface from said mirror plane along said Z axis, R is the radius of said incident beam, r and .beta. are the cylindrical coordinates of said points on said mirror plane, and K.sub.m is an empirically selected variable.
A method for reshaping a laser beam comprising:
- providing an incident beam having a circular cross-section;
- reflecting said incident beam on a reflective surface, the reflective surface producing an output beam having a polygonal cross-sectional shape at a distance L from the reflective surface, wherein each point on said reflective surface is described by an equation
- W.sub.m (r,.beta.)=k.sub.m R.sup.2 /L(r/R).sup.m cos(m.beta.)
- where m equals the number of sides of said polygonal shape, W is the deviation of said reflective surface from a mirror plane along an axis normal to the mirror plane, R is the radius of said incident beam, r and .beta. are the cylindrical coordinates of said points on said mirror plane, and K.sub.m is an empirically selected variable;
- and
- positioning a collimating element at the distance L from the reflective surface to receive the output beam having the polygonal cross-sectional shape.
Dependencies are inferred from the claim text.