Imaging system

Claim 3

A method according to claim 1, wherein the two-dimensional array is a staring focal plane array.

Claim 4

A method according to claim 1, further including the detection of a particular target when in the wide field of view mode, and consequently switching to the narrow field of view mode during which the target is tracked by continuous adjustment of the position of the image on the array so that the target image is not lost.

Claim 5

A method according to claim 3, wherein the tracking of the target is carried out by the same apparatus which causes the scanning movement in the wide field of view mode.

Claim 6

Imaging apparatus comprising a two dimensional array of elements operable selectively in a wide or a narrow field of view mode, each element storing an electrical signal representative of the time-integrated intensity of the light incident on it, scanning means for causing the array to scan swaths of an object along respective columns of the array, drive means for the array, and means responsive to the output of the array to provide an image of the scanned object, wherein, in the wide field of view mode of operation, the scanning means causes the array to scan the object, and the drive means periodically shifts the stored electrical signals simultaneously in the direction of the scan from each element to its neighbour for continued time-integration, and provides, at the output of the array, the stored electrical signal from the end element of each column of the array, the average speed at which the signals progress along the array being equal to the speed of the image scan whereby smearing of the image is minimised, and each successive output signal of a column being representative of the intensity of radiation from a different portion of the object time-integrated by all the elements in succession, and wherein, in the narrow field of view mode, the scanning means ceases the regular scan of the image and the drive means causes the elements to perform a time-integration over a stare period substantially greater than the period between successive simultaneous shifts in the wide field of view mode, and causes the stored signals then to be read-out from all the elements.

Claim 7

Imaging apparatus comprising a two dimensional array of elements operable selectively in a wide or a narrow field of view mode, each element storing an electrical signal representative of the time-integrated intensity of the light incident on it, scanning means for causing the array to scan swaths of an object along respective columns of the array, drive means for the array, and means responsive to the output of the array to provide an image of the scanned object, wherein, in the wide field of view mode of operation, the scanning means causes the array to scan the object, and the drive means periodically shifts the stored electrical signals simultaneously in the direction of the scan from each element to its neighbour for continued time-integration, and provides, at the output of the array, the stored electrical signal from the end element of each column of the array, the average speed at which the signals progress along the array being equal to the speed of the image scan whereby smearing of the image is minimised, and each successive output signal of a column being representative of the intensity of radiation from a different portion of the object time-integrated by all the elements in succession, and wherein, in the narrow field of view mode, the scanning means ceases the regular scan of the image and the drive means causes the elements to perform a time-integration over a stare period substantially greater than the period between successive simultaneous shifts in the wide field of view mode, and causes the stored signals then to be read-out from all the elements.

Claim 8

Imaging apparatus according to claim 5, comprising: target detection means responsive to the output of the array to determine the presence or absence of a target and to set the mode of operation of the array to the wide or the narrow field of view mode in accordance with that determination.

Claim 9

Imaging apparatus according to claim 5, comprising: target tracking means operable in the narrow field of view mode to provide target co-ordinates to the scanning means to cause the scanning means to follow the target if the target moves relative to the remainder of the object, the scanning means otherwise holding the image stationary relative to the array.

Claim 10

Imaging apparatus according to claim 7, wherein the two-dimensional array is a staring focal plane array.

Claim 11

Imaging apparatus according to claim 5, wherein the array is a CCD array.

Claim 12

Imaging apparatus according to claim 9, in which the array is an IRCCD array.

Claim 13

Imaging apparatus according to claim 5, in which the scanning means comprises a mirror driven by a motor.

Claim 14

Imaging apparatus according to claim 11, wherein the scanning means operates in the wide field of view mode to rotate the mirror such as to cause the regular scanning of the image, and alternatively in the narrow field of view mode to move the same mirror intermittently such as to follow the target.