Metrology of injection-molded optical components with multiple optical functions

摘要

Abstract: A well-known advantage of injection molded plastic optical components is the possibility of integration of an optical function and a mechanical mount. The optical part can be positioned accurately with respect to well-defined references of the mechanical mount. The optical function does not have to be restricted to one optical surface. In principle any combination of lenses, mirrors and/or beam splitters is possible. The metrology of these combined optical functions is often not trivial. Commercial available measuring equipment in general has difficulties when the different optical functions are tightly toleranced with respect to each other and when less common types of optical surfaces are involved. In this paper three examples of multi function optical components are presented. One of these examples, a double mirror, is elaborated in detail in terms of metrology. The orientation of both mirrors with respect to the mechanical references is tightly toleranced. The same holds for the orientation of the mirrors with respect to each other. The shape of one of the mirrors is so accurate that the reflected wave front is diffraction limited. The other mirror is an off axis paraboloid. The specially developed measurement tool, based on the autocollimator principle, the obtainable measurement accuracies and the calibration procedure will be described. Also the product accuracies realized with injection molding of this component in mass production will be presented.!4