DESIGN, FABRICATION AND TESTING OF KINOFORM LENSES

摘要

Fresnel lenses are a type of lens that eliminates the bulk of a conventional lens by collapsing the lens thickness while retaining the curvature necessary for focusing. Figure 1 shows the Fresnel lens equivalent of a conventional lens. For a rotationally symmetric lens, the discontinuities or grooves formed when collapsing the lens are annular. This produces a much thinner lens, particularly for large apertures.rnThe advantages of a Fresnel lens are that more light is transmitted due to lower absorption and dispersion. With more uniform thickness a Fresnel lens is typically easier to replicate by molding. For these reasons Fresnel lenses are being considered for improved laser scanning systems.rnFresnel lenses are intended as purely refractive lenses. A kinoform lens combines refractive and diffractive properties of Fresnel lenses and zone plates to produce an efficient diffractive lens that can focus as well as cancel chromatic aberration.