Caterpillar Tractor Co.

Simon L Engel

Preston Lee Gale

Glenn H Lenzen, Jr

Laurence R Peters

Robert A McFall

A method of heat treating a bore in a workpiece to increase its surface hardness is disclosed, including shaping an annular laser beam emanating from a source into an elongated focal pattern to provide a more evenly distributed energy level in cross section, directing the elongated focal pattern generally axially inwardly toward the bore, reflecting the elongated focal pattern from a mirror arrangement substantially transversely upon a surface of the bore to provide an instantaneously more uniformly hot heating zone thereat, and effecting relative motion between the workpiece and the mirror arrangement so that the bore is progressively scannably heat treated to minimize heating of the entire workpiece.

Method and apparatus for heat treating an internal bore in a workpiece

A method of focussing a laser beam having a ring-shaped cross-section to provide a depth of focus for use in cutting and the like, in which the laser beam is converged to and through a focus by reflection from a concave mirror, and in which the diverging laser beam emanating from the focus is passed into an axicon having a substantially cylindrical inner reflective surface for reflecting the diverging laser beams back to an elongated focus. In its apparatus form, focussing means is provided together with a substantially cylindrical axicon positioned to intercept said diverging laser beam and to bring it back to a focus along an extended axis. The cylindrical axicon is preferably formed from a pair of telescoped tubular members having a closed annular space therein for receiving a cooling fluid, with the inner cylinder having its inner surface highly polished and/or coated with some material to minimize the absorption of the incident laser beam.

Method and apparatus for focussing laser beams

Apparatus for shaping a laser beam having a substantially ring-shaped cross-section in order to provide even heat distribution at a work station and to adjust the operational size of the beam at said station, comprising a cylindrical reflector positioned to receive and reflect the laser beam and direct the laser beam toward a work station with the beam laterally converged so as to provide a more concentrated even energy distribution at the work station. In a preferred form, the mirror is positioned to be at a focal distance from the work station and has adjusting means for adjusting the mirror to accommodate variations in focal length caused by different work pieces and to allow operation slightly away from focal length, if desired. The preferred form also comprises a second cylindrical reflector adjustably positioned to converge the laser at right angles to the first direction of convergence whereby the length of image of the laser on the work piece may also be adjusted. The cylindrical cross-sections should be conic sections and preferably are circular with the degree of curvature being rather small so as to have rather long focal lengths. In an alternate form, means are also provided to vibrate the beam whereby the image may be caused to oscillate at the work station and to cover a larger fixed area of operation.

Laser beam shaping arrangement

An apparatus for modulating a high energy beam such as a laser beam comprising a rotor having a plurality of circumferentially spaced selectively shaped openings formed in a periphery thereof and adapted to rotate in the path of said high energy beam for permitting modulated portions of said beam to pass through to a work piece. Impeller blades are integrally formed on the rotor to provide a supply of cooling air that is pumped axially inward and directed radially outward through a space between the rotor and end shroud positioned thereover. The shroud contains a plurality of vanes formed to direct the cooling air against the peripheral portion of the rotor exposed to the laser beam to effect cooling thereof. The periphery is also provided with a reflective surface adapted to reflect the impinging portions of the beam to a beam trap to reduce the heating effect of the beam on the rotor.

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Mountain View, CA, United States of America

Simon L Engel