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.
In many consumer and professional plastic lenses have potential applications because of cost, weight and aspherical shape. However they suffer from a big disadvantage: large amount of focal shift as function of temperature. In particular for bar code scanners, focal shifts due to temperature changes have huge impacts on the function of the scanner. One possibility to improve the temperature behavior of such lenses is to turn them into so- called hybrids: a combination of a refractive and a diffractive surface. This way a temperature compensation can be achieved that reaches the level of glass lenses. In this paper design and manufacturing considerations for such a lens will be given. This includes proper material choice and mechanical design. The lens is temperature compensated over a range from -230 degrees-+60 degrees C. Operating at 650 nm and having a focal length of 4 mm, makes it extra difficult to produce such a lens with sufficient image quality and diffraction efficiency. Results from the design will be compared with measured values from an injection molded sample of the designed lens. Quality parameter such as wavefront quality, focal shift with temperature and diffraction efficiency will be given.
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