Optical scanning apparatus incorporating counter-rotation of elements about a common axis by a common driving source

Abstract

An optical scanning apparatus embodied in a gyroscopic missile seeker to provide a rosette scan pattern of the field of view. A single driving motor is employed with a traction drive assembly to produce the necessary counter-rotation of scanned elements and thereby effect the rosette scan pattern.

We claim: 
     
       1. An optical scanning apparatus including: means providing a concave primary mirror disposed to focus an image within the field of view of said primary mirror at a central optical axis;   detector means disposed on said optical axis for receiving said focused image and responsively outputting an electrical signal;   means providing a secondary mirror interconnected with and displaced from said primary mirror on said optical axis to direct said focused image towards said detector means;   means for rotating said primary and secondary mirror providing means at a first rate and direction about said optical axis;   means intermediate said secondary mirror and said detector means for optically relaying said directed focused image to said detector means; and   means connected to said providing means for responsively rotating said optical relaying means about said optical axis at a rate that is directly proportional to said first rate and in a direction that is opposite to the rotation of said rotational direction of said primary and secondary mirror providing means.   
     
     
       2. A scanning apparatus as in claim 1, wherein said secondary mirror contains a flat non-focusing reflective surface that is slightly canted with respect to the optical axis and provides a primary conical scan of images to said detector means. 
     
     
       3. An optical scanning apparatus as in claim 2 wherein said primary and secondary mirror providing means, said optical relay means and said optical relay rotating means are gimbal mounted to move about a central point at which said detector means is located and maintain the focus of said image at said detector means. 
     
     
       4. An apparatus as in claim 3, wherein said optical relay rotating means includes a traction drive mechanism to communicate counter-rotational forces from said rotating primary and second mirror providing means to said optical relay means so as to rotate said optical relay means in a direction opposite to the rotational direction of said primary and secondary mirrors. 
     
     
       5. An apparatus as in claim 4, wherein said rotating optical relay means effects a rosette scan pattern of images over said field of view onto said detector. 
     
     
       6. An apparatus as in claim 5, .Iadd.further including a flat secondary relay mirror on said optical axis, .Iaddend.wherein said optical relay means includes an apertured relay mirror, .[.a flat secondary relay mirror.]. and a set of relay lenses mounted on said optical axis, wherein said apertured relay mirror reflects said image from said secondary mirror means to said flat secondary relay mirror where it is focused at a point preceding said relay lenses; said relay lenses function to convey the image at said point to said detector means. 
     
     
       7. An apparatus as in claim 6, wherein said aperture relayed mirror is slightly canted with respect to said optical axis and is rotated by said optical relay rotating means at said proportional rate in a direction that is opposite to the rotational direction of said primary and second mirrors to effect a secondary conical scan of images in concert with said primary conical scan to produce a rosette scan pattern of images over said defined field of view. 
     
     
       8. An optical scanning apparatus for providing a rosette scan pattern of focused images over the field of view of said apparatus, including: a focused primary mirror for defining said field of view;   a secondary mirror means in the optical path established by said primary mirror for conically scanning said defined field of view at a first rate and direction of rotation;   optical relay means in said optical path adjacent said secondary mirror means for conically scanning said defined field of view at a second rate of rotation that is directly proportional to said first rate and in a rotational direction opposite to said first direction of rotation; and   a single motor means for producing the rotation of said secondary means and the counter-rotation of said relay means.   
     
     
       9. An optical scanning apparatus as in claim 8, wherein said primary mirror means, secondary mirror means and optical relay means are gimbal mounted. 
     
     
       10. An optical scanning apparatus as in claim 9, wherein said motor means functions to rotate said primary mirror means and said secondary mirror means at said first rate and includes a traction drive means between said secondary mirror means and said optical relay means to responsively rotate said optical relay means in said opposite direction.