Beam expander with variable magnification.

摘要

PURPOSE: To obtain a decolorzing zoom beam expander which is useful to expand the parallel beam from a laser by including three compound lens constituent elements having colors corrected individually. CONSTITUTION: First and second compound lens constituent elements 10 and 12 form a divergent lens group and a 3rd compound lens constituent element 14 form a collimator. The compound lenses 10, 12, and 14 have their colors corrected individually, so various lights differing in wavelength are expanded and then focused by an objective at the same time. Here, the compound lens 10 is fixed and the compound lenses 12 and 14 can move to and away from the compound lens 10 and are mutually movable.