A telescope produces multiple video outputs representing coregistered images in multiple spectral bands that can range from ultraviolet through far infrared. Although the overall function of the telescope is partly equivalent to that of a color television camera equipped with telescopic lenses, its basic optical configuration differs from that of a color television camera, and it is designed for different applications. In the original intended application, the telescope will be used in research on remote optical detection of stress in plants. By suitable choice and placement of optical components, as described below, the telescope can readily be configured for other special applications.

The Portable Multispectral Telescope produces multiple video images of the same scene in different spectral bands. The telescope could readily be configured for more, fewer, or different spectral bands.

Light from the scene under observation enters the telescope along an input telescopic optical path that is common to the multiple output paths (see figure). The input telescopic optical path includes lenses 1 and 2. (As used here, "lenses" is shorthand for optical subsystems that could, optionally, comprise single- or multiple-element lenses or multiple-lens subsystems.) Lens 1 focuses the light to a real image on a reticle, which serves as a common alignment reference for the multiple spectral images. Lens 2 then expands and collimates the light. The collimated beam then enters an assembly of beam splitters, filters, and a mirror. The portion of the collimated beam emerging through each filter in this assembly contains only light in one of the desired spectral bands. A lens on the optical path for each spectral band focuses the collimated light onto the array of photodetectors in a video camera that is dedicated to producing the video image for that band.

Although the configuration shown in the figure is for three spectral bands, other configurations with fewer or more spectral bands could be chosen. The input beam could be split and filtered as many times as needed, subject only to the practical limitation imposed by finitude of the available luminous flux. Lenses, beam splitters, filters, and video cameras can be off-the-shelf or custom-designed, as needed, for imaging in specified spectral bands.

This work was done by Bruce A. Spiering of Stennis Space Center.

This invention is owned by NASA, and a patent application has been filed. Inquiries concerning nonexclusive or exclusive license for its commercial development should be addressed to

the Patent Counsel
Stennis Space Center; (228) 688-1929

Refer to SSC-00048

NASA Tech Briefs Magazine

This article first appeared in the June, 1999 issue of NASA Tech Briefs Magazine.

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