| 摘要 |
An apparatus and method for controlling the power of a laser beam is described. In one embodiment a rotatable Brewster element, rotated by a drive means, is disposed in the propagation path of a laser beam and is aligned along the an axis parallel to the direction of propagation of the laser beam. At least one stationary Brewster element is also disposed in the propagation path of the laser beam. Measuring means is provided to determine the power of the laser beam downstream of the rotatable Brewster element and to generate an actual power value. A control means receives the actual power value from the measuring means, compares it with the desired power value, and provides a control signal for the drive means. The drive means rotates the rotatable Brewster element in response to the control signal in order to minimize the difference between the actual power value and the desired power value. According to the invention, the rotatable Brewster element thus is used as an adjuster in a control loop for controlling the power of a laser beam.
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