Abstract: An apparatus is described for automatically shifting a lens of a laser focussing optical system, the lens undergoing translational motion along an optical axis, being moved by at least one motor which carries out rotational movement. This rotational movement is converted by a linkage into translational movement to shift the lens.

Abstract: 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.

Abstract: The present invention provides a method and apparatus for controlling laser power, using at least two Brewster windows which are aligned along an axis which is parallel to the direction of the laser beam and which are rotatable around said axis, wherein the first Brewster window is rotated in one direction and the second Brewster window is rotated in the opposite direction. Preferably, both Brewster windows only have to rotate each through +/−45° to control transmission of the laser beam from maximum to minimum.

Abstract: The present invention provides a method and apparatus for controlling laser power, using at least two Brewster windows which are aligned along an axis which is parallel to the direction of the laser beam and which are rotatable around said axis, wherein the first Brewster window is rotated in one direction and the second Brewster window is rotated in the opposite direction. Preferably, both Brewster windows only have to rotate each through +/−45° to control transmission of the laser beam from maximum to minimum.