Abstract: An illumination device for microscopes is detachably connected to the microscope and has at least one unconventional illumination source such as an LED, laser or the like. The microscope has an operating control for adjusting the brightness of the illumination, and the brightness of the unconventional illumination source is adjusted by means of this operating control.

Abstract: Apparatus and method are disclosed for controlling the spatial beam position of laser beams, e.g., in a laser exposure device, using a position detector for determining the current (actual), beam position and a control element for determining the control quantity based on the difference between the actual and the desired beam position. An actuator that moves an optical element, which in turn guides the laser beam, is provided for changing the beam position. The actuator includes a controllable heating element that is connected to a position-determining actuator element, for moving the actuator element and, thus, the optical element, through thermal expansion due to heating of the actuator element.

Abstract: For measuring a laser frequency electronic signals can be generated by means of optical interferometers, especially Michelson, Mach-Zehnder and Fabry-Perot interferometers. These signals present profiles with a variation of the laser frequency which are practically identical but shifted in phase by 90°. It is common to generate such phase-shifted signals for frequency measurement in various systems, e.g. by means of a sigmameter, which present, however, disadvantages on account of the great number of the necessary high-quality optical components. The inventive method is based on the analysis of transmission and reflection signals of a Fabry-Perot interferometer (FPI) wherein the signals are obtained from two component beams (PBA and PBB) which are passed through slightly different path lengths within the interferometer.