Optical image scanner with beam stabilization

Claim 2

Apparatus for optically scanning a region, comprising optical objective means for mutually imaging said region and a primary image, optical scanning means movable with respect to said optical objective means for producing and periodically moving a scan image corresponding to at least an elongated strip of the primary image, said scan image moving periodically in a scan direction longitudinal of the strip, means for moving said optical scanning means with respect to said optical objective means field means fixed with respect to said optical objective means for selecting an effective radiation beam corresponding to an elemental area of said moving scan image, aperture means for defining the aperture of the effective radiation beam, the position of the effective radiation beam at said objective means varying with the movement of said scan image, optical relay means for mutually imaging said elemental image area or an optical conjugate thereof and a radiation terminus, said optical relay means including beam deflecting means positioned optically substantially at said elemental image area or an optical conjugate thereof and movable with Respect to said optical objective means for veriably deflecting the radiation beam in a plane optically parallel to said scan direction and means for controlling the movement of said beam deflecting means in such time relation to the movement of said optical scanning means that the effective radiation beam between said radiation terminus and said beam deflecting means is substantially stationary with respect to said optical objective means.

Claim 3

Apparatus according to claim 1 wherein said radiation terminus comprises a source of radiation which traverses the apparatus in the direction from the radiation terminus toward said region to be scanned.

Claim 4

Apparatus according to claim 1 wherein said radiation terminus comprises radiation transducer means responsive to radiation which traverses the apparatus in the direction from said region to be scanned toward the radiation terminus.

Claim 5

Apparatus according to claim 1 in which said aperture means comprise beam limiting means positioned between said radiation terminus and said beam deflecting means.

Claim 6

Apparatus according to claim 4 including a pointing mirror mounted for rotational movement adjacent an optical conjugate image of said beam limiting means between said objective means and said region to be scanned.

Claim 7

Apparatus according to claim 1 wherein said objective means produce spherical aberration substantially independent of said variation of the beam posittion at the objective means, said system including image corrective means between said radiation terminus and said beam deflecting means for compensating said spherical aberration.

Claim 8

Apparatus according to claim 6 wherein said image corrective means comprise a figured optical reflective element mounted in approximately on-axis relation to the radiation beam.

Claim 9

Apparatus according to claim 6 wherein said optical relay means comprise a generally spherical concave relay mirror, said image corrective means comprising figuring of the surface of said relay mirror.

Claim 10

Apparatus according to claim 8 wherein said aperture means comprise means adjacent said relay mirror for defining the beam aperture.

Claim 11

Apparatus according to claim 1 wherein said objective means comprise substantially spherically curved reflective means having a center of curvature, said system including image corrective means mounted substantially at an optical conjugate of said center of curvature between said radiation terminus and said beam deflecting means for compensating the spherical aberration due to said reflective means.

Claim 12

Apparatus according to claim 10 wherein said aperture means comprise beam limiting means at an optical conjugate of said center of curvature, said apparatus including a pointing mirror mounted adjacent said center of curvature for rotational movement.

Claim 13

Apparatus for optically scanning a region comprising optical objective means for mutually imaging said region and a primary image, aperture means for defining the aperture of the radiation beam, the principle rays for respective points of said image varying in direction progressively across the image, optical scanning means movable with respect to said optical objective means for producing and periodically moving a scan image corresponding to at least an elongated strip of the primary image, said scan image moving periodically in a scan direction longitudinal of the strip, means for moving said optical scanning means with respect to said optical objective means, field means fixed with respect to said optical objective means for selecting an effective radiation beam corresponding to an elemental area of the moving scan image the principal ray for the selected radiation varying in direction in accordance with the direction of the principal ray for the corresponding point of the primary image, optical relay means for mutually imaging said elemental image area on an optical conjugate thereof and a radiation terminus, said optical relay means including beam deflecting means positioned optically substantially at said elemental image area or an optical conjugate thereof and movable with respect to said optical objective means for variably deflecting the selected radiation beam in a plane optically parallel to said scan direction, and means for controlling the movement of said beam deflecting means in such time relation to the movement of said optical scanning means that the principal ray for the deflected radiation has substantially constant direction.

Claim 14

Apparatus for optically scanning a region comprising optical objective means for mutually imaging said region and a primary image, aperture means for defining the aperture of the radiation beam, the principle rays for respective points of said image varying in direction progressively across the image, optical scanning means movable with respect to said optical objective means for producing and periodically moving a scan image corresponding to at least an elongated strip of the primary image, said scan image moving periodically in a scan direction longitudinal of the strip, means for moving said optical scanning means with respect to said optical objective means, field means fixed with respect to said optical objective means for selecting an effective radiation beam corresponding to an elemental area of the moving scan image the principal ray for the selected radiation varying in direction in accordance with the direction of the principal ray for the corresponding point of the primary image, optical relay means for mutually imaging said elemental image area on an optical conjugate thereof and a radiation terminus, said optical relay means including beam deflecting means positioned optically substantially at said elemental image area or an optical conjugate thereof and movable with respect to said optical objective means for variably deflecting the selected radiation beam in a plane optically parallel to said scan direction, and means for controlling the movement of said beam deflecting means in such time relation to the movement of said optical scanning means that the principal ray for the deflected radiation has substantially constant direction.

Claim 15

Apparatus according to claim 12 wherein said beam deflecting means comprise reflective surface means mounted for rotational oscillation about an axis transverse of the radiation beam.

Claim 16

Apparatus according to claim 12 wherein said beam deflecting means comprise support means journaled on an axis effectively perpendicular to the direction of scan of said primary image and carrying a plurality of peripherally mounted reflective means for successively intercepting and variably deflecting the radiation beam in response to support rotation.

Claim 17

Apparatus according to claim 14 including means for limiting the effective apertures of said reflective means such that the radiation beam is effectively blanked between beam reflections by successive reflective means.

Claim 18

Apparatus according to claim 12 wherein said optical scanning means include at least one orthogonal reflector assembly mounted for periodic movement along the length of said primary image to offset a progressively varying elemental area of the same to a substantially stationary with respect to said optical objective means position.

Claim 19

Apparatus according to claim 12 wherein said beam deflecting means produce a periodic focal variation, said optical scanning means including a circular array of optical devices mounted for coaxial rotation with respect to an array axis in such position that the devices successively scan the primary image, said optical devices being mounted at a radius from said array axis selected to substantially compensate said focal variation.

Claim 20

Apparaatus according to claim 17 wherein said optical devices comprise orthogonal reflector assemblies.

Claim 21

Apparatus according to claim 12 wherein said primary image lies in a generally arcuate surface with radius of curvature Ro, said optical scanning means comprise a circular array of orthogonal reflector assemblies mounted for coaxial rotation at a radius R1 from an array axis in position to successively scan the primary image, said beam deflecting means comprise a circular array of mirrors mounted for coaxial rotation in timed relation to said scanning means in position to successively intercept and variably deflect the radiation beam, said mirrors producing a periodic focal variation, and the value of R1/Ro differs from 1/2 by an amount selected to substantially compensate the focal variation due to said mirrors.

Claim 22

Apparatus according to claim 19 wherein said beam deflecting mirrors are plane mirrors facing radially outwardly and mounted at a radius R2, and said radius R1 is substantially equal to Ro/(2 + R2/Ro).

Claim 23

Apparatus according to claim 19 wherein said orthogonal reflector assemblies and said mirrors are mounted for coaxial synchronous rotation approximately at a common radius Ro/3, and said mirrors are convexly curved with a radius of curvature substantially equal to Ro/2.

Claim 24

Apparatus according to claim 12 wherein said optical scanning means comprise a circular array of orthongonal reflector assemblies mounted for coaxial rotation with respect to an array axis in position to move successively along the length of said primary image and to transfer the same to said moving scan image, and optical means for mutually imaging said scan image and a moving intermediate image, said apparatus including a plurality of sHield means mounted in coaxial relation to said circular array for intercepting and effectively blanking the radiation beam adjacent said intermediate image during intervals between successive scans.

Claim 25

Apparatus according to claim 14 wherein said radiation terminus comprises radiation transducer means, said apparatue including means for producing a synthetic calibration scene optically positioned laterally adjacent said radiation terminus and for projecting calibration radiation via said relay means to a scene image optically positioned laterally adjacent said scan image, at least one of said shield means comprising optical means for effectively scanning said scene image and for returning calibration radiation via said relay means to said radiation terminus for calibartion thereof.

Claim 26

Apparatus according to claim 23 wherein said at least one shield means comprises an assembly of three mutually orthogonal plane reflectors.

Claim 27

Apparatus according to claim 24 wherein said scene image comprises a linear array of elementary image areas representing different calibration levels extending generally parallel to said scan image and laterally offset therefrom, said reflector assembly transferring the elementary image areas successively to the elemental area of the intermediate image selected by said field means.