Wavelength selective mirror systems

Claim 1

A system for separating different wavelength bands from a polychromatic beam of radiation having wavelengths which obey optical laws which comprises, a. an optically hollow cube having a diagonal plane chromatic beamsplitter, the two edges thereof coinciding with edges separating four faces of the cube, b. one of said faces being open to an incident polychromatic beam and reflecting interference filters on at least two of the other three faces, each said interference filter passing a different wavelength band of radiation, and reflecting substantially all others, each said wavelength band being about 200 angstroms, and hence being sharply selective for the wavelengths of specific rare earth luminescers, whereby the incoming polychromatic beam is split by the beamsplitter, part being reflected to a first face and part transmitted to a second face of the cube, and each interference filter on the first and second faces reflects a selected portion of the radiation back toward the beamsplitter which transmits and reflects, respectively, at least part of the selected portion of the radiation to the third face of the cube, whereby one wavelength component of the incoming polychromatic beam is largely reflected to the first face where it is passed by the interference filter at that face, another wavelength component is largely transmitted to the second face where it is passed by the interference filter at that face, and a third wavelength component is partially reflected and partially transmitted in substantially comparable amounts toward the first and second faces respectively, where the interference filters reflect the component back toward the beamsplitter, c. a phase retardation plate being placed in the radiation path between the beamsplitter and the first cube face and between the beamsplitter and the second cube face so that on passing through the plate twice the third wavelength component has its polarization altered to reverse its transmission and reflection characteristics on a second encounter with the beamsplitter, thereby causing the third wavelength component of the initial polychromatic beam to be diverted to the third face of the cube, d. the cube being oriented so that the optical axis of the polychromatic beam passing through the beamsplitter strikes the open face of the cube at substantially normal incidence.

Claim 2

A system for separating different wavelength bands from a polychromatic beam of radiation having wavelengths which obey optical laws which comprises, a. an optically hollow cube having a diagonal plane chromatic beamsplitter, the two edges thereof coinciding with edges separating four faces of the cube, b. one of said faces being open to an incident polychromatic beam and reflecting interference filters on at least two of the other three faces, each said interference filter passing a different wavelength band of radiation, and reflecting substantially all others, each said wavelength band being about 200 angstroms, and hence being sharply selective for the wavelengths of specific rare earth luminescers, whereby the incoming polychromatic beam is split by the beamsplitter, part being reflected to a first face and part transmitted to a second face of the cube, and each interference filter on the first and second faces reflects a selected portion of the radiation back toward the beamsplitter which transmits and reflects, respectively, at least part of the selected portion of the radiation to the third face of the cube, whereby one wavelength component of the incoming polychromatic beam is largely reflected to the first face where it is passed by the interference filter at that face, another wavelength component is largely transmitted to the second face where it is passed by the interference filter at that face, and a third wavelength component is partially reflected and partially transmitted in substantially comparable amounts toward the first and second faces respectively, where the interference filters reflect the component back toward the beamsplitter, c. a phase retardation plate being placed in the radiation path between the beamsplitter and the first cube face and between the beamsplitter and the second cube face so that on passing through the plate twice the third wavelength component has its polarization altered to reverse its transmission and reflection characteristics on a second encounter with the beamsplitter, thereby causing the third wavelength component of the initial polychromatic beam to be diverted to the third face of the cube, d. the cube being oriented so that the optical axis of the polychromatic beam passing through the beamsplitter strikes the open face of the cube at substantially normal incidence.