Hybrid lenses, in which surfaces include diffractive optical elements, can be used for reducing color separation caused by chromatic aberration of the projector lens in projection-type headlamps. In optics, a lens which includes a DOE is called a hybrid lens. By combining refraction and diffraction effects, the depth of the focus difference across the wavelength range can be compressed. The reason chromatic aberration can be corrected by using a DOE is that lens materials have a positive Abbe number, and DOE structures have a negative Abbe number. It should be noticed that chromatic aberration cannot be corrected perfectly because the wavelength dependence of lens powers of refraction and diffraction are different Generally, hybrid lenses can be made more easily with plastic rather than glass. However, in the case of plastic, lens performance can change dramatically with temperature because the refractive index of optical plastics change and plastics expand considerably as temperature changes. Usually these two properties of the material cancel, even in the case of a hybrid lens, though it is not perfect. In this study, the effect of the change of these properties with temperature on performance of a hybrid lens was simulated, and the simulated data was compared to the measured data. The purpose of this report is to compare the change of lens performance with temperature through simulation and experiment.
Study of temperature dependence of plastic hybrid lenses for projection-type headlamps
2009
10 Seiten, 12 Bilder, 5 Quellen
Conference paper
English
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