| 摘要 |
<p>A multi spectral window, transparent to a large range of wavelengths, is made of two materials, both transparent from 0.4 to 13 microns. The first material has good mechanical rigidity, and the second, which encloses the first, and is pref. in direct contact with it, has good resistance to natural agents. The first material is pref. a monocrystal of an alkali halide, partic. NaCl or KCl, in the form of a parallel sided sheet. The second material is pref. an organic polymer film, partic. polyethylene terphthalate, and it pref. has a refractive index intermediate between the first material and air. Enclosure of the first material by the second can be done under vacuum, or by heavy shrinkage in an oven. The window solves the problem, more easily than other methods, at providing a material simultaneously transparent to visible, near infra-red, and middle infra-red wavelengths. It can thus be used for laser telemetry, missible guiding, thermal image systems, laser illuminators, etc.</p> |
