Patent ID: 6935757

Claim:
A spectroscopic multi-band direct vision prism system comprising: a plurality of at least two prismatic elements including a first prismatic element having an incident face corresponding to the incident face of the multi-band direct vision prism system and a second prismatic element having an emergent face corresponding to the emergent face of the multi-band direct vision prism system, each prismatic element of the plurality of prismatic elements having (i) a refractive index, (ii) a first face through which constituent wavelengths of a polychromatic light column enter that prismatic element, (iii) a second face through which constituent wavelengths of the polychromatic light column exit that prismatic element and (iv) an apex angle defining the angle at which the second face is disposed with respect to the first face, the first face of each prismatic element being disposed at a predetermined tilt angle with respect to a common optical axis, wherein at least two of the prismatic elements have different refractive indices and (i) the refractive indices, (ii) the apex angles and (iii) the tilt angles are selected such that a single wavelength within each of at least two predetermined energy bands within a polychromatic light column propagating parallel to an incident axis and incident upon the incident face of the direct vision prism system emerges from the emergent face of the direct vision prism system with no net angular deviation with respect to the incident axis and such that wavelengths other than the undeviated wavelength within each predetermined energy band are measurably dispersed in order to facilitate spectral analysis; wherein one of the prismatic elements comprises a material selected from a first set of materials consisting of (i) sapphire, (ii) spinel, (iii) lithium fluoride, (iv) beryllium oxide, (v) aluminum nitride, (vi) magnesium oxide, (vii) magnesium fluoride, (viii) barium fluoride, (ix) lead fluoride, and (x) cesium bromide and another of the prismatic elements comprises a material selected from a second set of materials consisting of (a) zinc sulfide, (b) thallium bromoiodide, (c) zinc selenide and (d) silver chloride.