US 5,396,282 AGranted

Image mapping radiometer with a band-to-band registration device

AssigneeNEC Corporation

InventorKazuhiro Ogikubo

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Abstract

An image mapping radiometer mounted on a craft flying an orbit above an object zone. The radiometer includes main optics having in the visible field thereof a unit object zone defined by the swath width over the object zone and a distance in the direction of orbit, and a plurality of linear photoelectic detectors each being assigned to one of a plurality of observation spectral bands and located in the focal plane of the main optics, thereby sequentially imaging the unit object zone. A correcting section has correction optics for projecting a correction pattern onto the photoelectric detectors so as to correct the band-to-band registration, i.e., the positional deviation between the elements of the detectors. A movable mirror is provided for selecting either of the main optics and correction optics. When the correction pattern is projected, a lattice pattern having a pitch different from the element pitch is generated on the light-sensitive surfaces of the detectors. The correction is effected by calculating the output signal levels of the detectors associated with the projected image on the basis of a vernier principle.

Claims12

Dependent claims

An image mapping radiometer mounted on a craft flying over an object zone of the ground surface along an orbit having a predetermined relation with said object zone, and comprising first optics having in a visual field thereof a unit object zone defined by a predetermined width of said object zone and a distance in a flying direction of said craft and capable of dividing light rays of a frequency range including visible rays and infrared rays from said unit object zone into rays of a first spectral band and rays of a second spectral band and focusing said rays onto a first and a second focal plane, respectively, and first and second photoelectric transducer means located in said focal plane and each comprising an array of photoelectric transducer elements for detecting a radiance distribution of said rays of respective one of said first and second spectral bands in said focal plane, thereby sequentially picking up optical images in said first and second spectral bands of said unit object zone entering said visual field as said craft flies, said radiometer comprising:

correction pattern forming means comprising light source means for providing a light source, diffusing means for making uniform the light source of the light source means, and a movable mirror selectively movable into an optical path defined by the first optics, said correction pattern forming means forming on the first and second photoelectric transducer elements an optical image of a correction pattern in the form of a stripe pattern for determining whether or not said photoelectric transducer elements of said first and second photoelectric transducer means are aligned with each other in the first and second focal planes;
and
optical path switching means for controlling movement of said movable mirror into the optical path.

A image mapping radiometer mounted on a craft flying over an object zone of the ground surface along an orbit having a predetermined relation with said object zone, and comprising optics having in a visual field thereof an elongate unit object zone defined by a predetermined width of said object zone and a distance in a flying direction of said craft and extending in a direction of said width and capable of dividing light rays of a frequency range including visible rays and non-visible rays from said unit object zone into rays of a first spectral band and rays of a second spectral band and focusing said rays onto, respectively, a first and a second focal plane as a first and a second elongate optical image, and first and second optical transducer means respectively located in said first and second focal planes and each comprising a plurality of photoelectric transducer elements linearly arranged at a predetermined element pitch along associated one of said first and second optical images to convert said associated one of said first and second optical images to an electric signal, thereby sequentially picking up, as said craft flies, said optical images in said first and second spectral bands of said unit object zone as a series of said optical images corresponding to said unit object zone, said radiometer comprising:

optical image forming means for selectively forming an optical image of a repetitive stripe pattern having a pattern pitch and a width having a predetermined relation with the element pitch at a position where the first and second photoelectric transducer means are located, so that deviations of said first and second photoelectric transducer means from corresponding positions in said first and second focal planes may be detected,
the optical image forming means including light source means for providing a light source, and diffusing means for making uniform the light source of the light source means;
and
means for calculating the deviations in response to outputs of the first and second photoelectric transducer means when said stripe pattern is formed.

1 more element

Dependencies are inferred from the claim text.