Strahlvergrößerung

Strahlvergrößerung, also known as beam expansion, is an optical process that increases the diameter of a collimated beam of light. This is typically achieved using a system of lenses, often a Keplerian or Galilean telescope arrangement. In a Keplerian system, two convex lenses are used, with the focal point of the first lens coinciding with the focal point of the second lens. In contrast, a Galilean system employs a convex and a concave lens.

The purpose of beam expansion is to reduce the divergence of a light beam, making it more suitable for various applications. For instance, in laser systems, a tightly focused laser beam might diverge too rapidly for its intended use. Expanding the beam decreases its intensity per unit area, which can be beneficial for preventing damage to optical components or for achieving a larger illuminated spot.

Common applications include laser material processing, where a larger beam can provide a wider cutting or engraving area. In microscopy, beam expanders can be used to illuminate a larger field of view. They are also found in optical metrology, interferometry, and in some projection systems. The magnification factor of a beam expander is determined by the ratio of the focal lengths of the lenses used. A higher magnification results in a larger output beam diameter from a given input beam. The quality of the beam expander is crucial to ensure that the output beam remains collimated and free from aberrations.