Abstract: An spectrophotometer system (100) separately images rays of optical radiation in a plurality of wavelength bands from a distant object into a plurality of distinct wavelengths simultaneously and projects the separate images upon a detector (124). Each distinct wavelength is within a corresponding one of the plurality of wavelength bands. The apparatus includes a lens system comprising an objective lens (104), first and second field lenses (108, 116), a collimating lens (118), and a re-imaging lens (120) all disposed coaxially with respect to each other along an optic axis (110). The objective lens (104) and the first field lens (108) coact to cause rays of optical radiation emitted by the object to form an image at a first focal plane. An aperture (112) at the first focal plane passes rays of the optical radiation corresponding to a predetermined portion of the object. The second field lens (116) causes rays from the image at the first focal plane to form an image at a second focal plane.

Abstract: An imaging spectrometer that includes a mask (214) that has an array of n rows (302) and n columns (304) of transmissive elements (306) for transmitting the light from a plurality of locations of an image and of opaque elements (308) for blocking light from a plurality of locations of the image. The transmissive and opaque elements are arranged in a Hadamard pattern having rows (and columns) that are different cyclic iterations of an m-sequence. A grating (110) disperses the transmitted light from the transmissive elements (306) in a linear spatial relationship in a predetermined relationship to the wavelength of the transmitted light. A detector array (406) has a plurality of detector elements (408) arranged in a row to receive the dispersed transmitted light from the grating (110). Each detector element (408) provides an intensity signal indicative of the intensity of the light impinging thereon.

Abstract: Optical radiation generated by an auroral event is gathered by a fish-eye optical objective (12, 21, 22) and focussed by a telecentric lens (23) to a focal region where a two-passband filter (24) is located. The filter (24) passes two narrow bands of optical radiation, each band of which is centered on a specified wavelength. Rays in the two specified wavelengths are passed by a condenser lens (25) and a collimator lens (26) through an aperture stop in which a blocking filter (27) is located. The blocking filter (27) comprises two side-by-side half-size filters, each of which transmits a corresponding one and suppresses the other of the two specified wavelengths. A prism (28) diffracts rays each of the specified wavelengths by a different amount so that separated images in the two specified wavelengths are formed. A reimaging lens (29) relays the separate images to correspondingly different portions of a detector (30).