| 摘要 |
<p>A retardation plate (10) comprises a birefringent crystal plate (12), which has an entry face (13) and an exit face (15) for incident and emerging light, respectively. The crystal plate (12) consists of an alkaline-earth metal fluoride, in particular of fluorspar. Its optical axis (11) is aligned at least approximately in the direction of the <110> crystal axis or of a principal crystal axis equivalent thereto. A form-birefringent dielectric layer structure (14, 16) is applied to the entry and/or exit face (13, 15). It may, for example, be a periodic sequence of at least two layers (161, 162, .... 166) with alternating refractive indices. The retardation plate (10) is suitable for ultraviolet light, and it permits a large range of angles of incidence.</p> |
