Importance

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Abstract

Two concave spherical metal mirrors are used to scan a continuous wave laser beam for heat treating of metals. The mirrors are rotated in opposite directions and each is tilted at a small angle with respect to its axis of rotation. The frequencies of rotation of the mirrors are made constant by a precision timing drive linkage which also allows for phase adjustment. The beam deflection from an individual mirror describes an ellipse, but the deflection when added to that from the second mirror with the proper phase relationship to the first is a straight line. The input laser beam, which is too large in diameter for heat treating, is made to converge by the two mirrors, oriented so as to compensate for astigmatism. Spot size and scan width are adjustable over a wide range, as is scan frequency, which is equal to mirror rotational frequency. The scan produces a uniform, time-averaged distribution of power on the work piece.

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First Claim