Two-dimensional optical scan system using a counter-rotating disk scanner
View Patent ↗A counter-rotating disk scanner together with another scan mechanism provides two-dimensional optical scanning. The counter-rotating disk scanner includes counter-rotating scan disks that implement the scanning action as they rotate through an optical axis of the system.
1. A two-dimensional optical scan system for scanning a bundle of rays, the bundle of rays propagating along an optical axis of the scan system, the scan system comprising:
a counter-rotating disk scanner for scanning the optical axis along a first direction,
the counter-rotating disk scanner comprising a first scan disk and a second scan disk wherein:
each scan disk has a rotational axis and a plurality of facets that rotate around the rotational axis;
facets on the first scan disk have corresponding facets on the second scan disk;
the first and second scan disks counter-rotate so that corresponding facets rotate through the optical axis in synchronization; and
the optical axis is scanned along the first direction by the corresponding facets rotating through the optical axis; and
a scan mechanism optically coupled with the counter-rotating disk scanner for scanning the optical axis along a second direction that is cross to the first direction.
2. The scan system of claim 1 wherein:
the rotational axes of the two scan disks are offset from each other;
the optical axis is incident on the scan disks at a point located between the two rotational axes; and
the first direction is approximately parallel to the tangential direction of the scan disks.
3. The scan system of claim 1 wherein:
the facets on the first and second scan disks include lens-like scan components; and
the scan components on the first scan disk have approximately the same optical power as the corresponding scan components on the second scan disk.
4. The scan system of claim 3 wherein the difference in optical power between corresponding scan components compensates for a spacing between the scan disks.
5. The scan system of claim 3 wherein at least a majority of facets on each scan disk includes a lens-like component with negative power.
6. The scan system of claim 3 wherein at least one of the facets on at least one of the scan disks includes an aspheric surface.
7. The scan system of claim 6 wherein the aspheric surface corrects for aberrations introduced by rotation of the facet through the optical axis.
8. The scan system of claim 3 further comprising:
a pre-scanner lens group that corrects for optical power introduced by the lens-like scan components.
9. The scan system of claim 3 further comprising:
a pre-scanner lens group that corrects for aberrations introduced by the facets when the facets are in a neutral rotational position.
10. The scan system of claim 1 wherein the facets on the scan disks comprise injection molded plastic.
11. The scan system of claim 1 wherein a majority of facets on the first scan disk are the same and a majority of facets on the second scan disk are the same.
12. The scan system of claim 1 wherein facets on the first scan disk introduce a first scan line bow and corresponding facets on the second scan disk introduce a second scan line bow that counteracts the first scan line bow.
13. The scan system of claim 1 wherein the scan mechanism comprises:
either a piezo-electric scanner or a galvanometer-based scanner.
14. The scan system of claim 1 wherein the scan mechanism comprises:
a polygon scanner.
15. The scan system of claim 1 wherein the scan mechanism comprises:
a second counter-rotating disk scanner.
16. The scan system of claim 1 wherein the first direction is a fast scan direction and the second direction is a slow scan direction.
17. The scan system of claim 1 wherein the first direction is a slow scan direction and the second direction is a fast scan direction.
18. The scan system of claim 1 wherein the counter-rotating disk scanner is a reflective counter-rotating disk scanner.
19. The scan system of claim 1 , further comprising:
an optical source for generating an optical beam along the optical axis.
20. The scan system of claim 19 wherein:
the rotational axes of the two scan disks are offset from each other;
the optical beam is incident on the scan disks at a point located between the two rotational axes; and
the first direction is approximately parallel to the tangential direction of the scan disks.
21. The scan system of claim 19 wherein:
the facets on the first and second scan disks include lens-like scan components; and
the scan components on the first scan disk have approximately the same optical power as the scan components on the second scan disk.
22. The scan system of claim 19 wherein facets on the first scan disk introduce a first scan line bow and corresponding facets on the second scan disk introduce a second scan line bow that counteracts the first scan line bow.
23. The scan system of claim 19 wherein:
the scan mechanism comprises either a piezo-electric scanner or a galvanometer-based scanner;
the scan mechanism is located upstream of the disk scanner; and
the disk scanner scans the optical beam in a fast scan direction and the scan mechanism scans the optical beam in a slow scan direction.
24. The scan system of claim 23 further comprising:
a pre-scanner lens group located between the scan mechanism and the disk scanner; and
a post-scan imaging lens group located downstream of the disk scanner.
25. The scan system of claim 24 wherein:
the facets on the first and second scan disks include lens-like scan components;
the scan components on the first scan disk have approximately the same optical power as the corresponding scan components on the second scan disk; and
the pre-scanner lens group corrects for optical power introduced by the lens-like scan components.
26. The scan system of claim 24 wherein the pre-scanner lens group corrects for aberrations introduced by the facets when the facets are in a neutral rotational position.
27. The scan system of claim 24 wherein the facets include aspheric surfaces that correct for aberrations introduced by rotation of the facets through the optical beam.
28. The scan system of claim 19 wherein:
the scan mechanism comprises a polygon scanner;
the polygon scanner is located upstream of the disk scanner; and
the polygon scanner scans the optical beam in a fast scan direction and the disk scanner scans the optical beam in a slow scan direction.
29. The scan system of claim 24 wherein the post-scan imaging lens group corrects for aberrations introduced by rotation of the facets through the optical beam.
30. The scan system of claim 29 further comprising:
a pre-scanner lens group located between the polygon scanner and the disk scanner; and
a post-scan imaging lens group located downstream of the disk scanner.
31. The scan system of claim 30 wherein:
the facets on the first and second scan disks include lens-like scan components;
the scan components on the first scan disk have approximately the same optical power as the corresponding scan components on the second scan disk; and
the pre-scanner lens group corrects for optical power introduced by the lens-like scan components.
32. The scan system of claim 30 wherein the pre-scanner lens group corrects for aberrations introduced by the facets when the facets are in a neutral rotational position.
33. The scan system of claim 30 wherein the facets include aspheric surfaces that correct for aberrations introduced by rotation of the facets through the optical beam.
34. The scan system of claim 30 wherein the post-scan imaging lens group corrects for aberrations introduced by rotation of the facets through the optical beam.
35. The scan system of claim 29 further comprising:
an astigmatic lens group located upstream of the polygon scanner; and
an astigmatic relay lens group located between the polygon scanner and the disk scanner.
36. The scan system of claim 35 wherein the astigmatic lens group focuses an input optical beam to a line focus on the polygon scanner, wherein the line focus is focused along the slow scan direction and is collimated along the fast scan direction.
37. The scan system of claim 36 wherein the astigmatic relay lens group collimates the optical beam along both the slow scan and fast scan directions.
38. The scan system of claim 35 further comprising:
a pre-scanner lens group located between the astigmatic relay lens group and the disk scanner for compensating for optical power introduced by the disk scanner.
39. The scan system of claim 38 wherein the pre-scanner lens group corrects for monochromatic aberrations introduced by the disk scanner in a neutral rotational position.
40. The scan system of claim 35 wherein the disk scanner includes aspheric surfaces that correct for dynamic off-axis aberrations introduced by rotation of the disk scanner.
41. The scan system of claim 35 further comprising:
an imaging lens group located downstream of the disk scanner for projecting an image to be displayed.
42. The scan system of claim 41 wherein the imaging lens group corrects for dynamic chromatic aberration introduced by rotation of the disk scanner.
43. The scan system of claim 35 wherein the optical source generates multiple optical beams for simultaneously displaying multiple scan lines.
44. The scan system of claim 29 further comprising:
an astigmatic lens group located upstream of the polygon scanner for focusing an input optical beam to a line focus on the polygon scanner, wherein the line focus is focused along the slow scan direction and is collimated along the fast scan direction;
an astigmatic relay lens group located between the polygon scanner and the disk scanner, for collimating the optical beam along both the slow scan and fast scan directions;
a pre-scanner lens group located between the astigmatic relay lens group and the disk scanner for compensating for optical power introduced by the disk scanner and further for correcting monochromatic aberrations introduced by the disk scanner in a neutral rotational position; and
an imaging lens group located downstream of the disk scanner for projecting an image to be displayed and further for correcting dynamic chromatic aberration introduced by rotation of the disk scanner.
45. The scan system of claim 19 further comprising:
an f-theta lens group located downstream of the disk scanner and downstream of the scan mechanism.
46. The scan system of claim 19 wherein the optical source generates multiple optical beams.
47. The scan system of claim 1 further comprising:
a detector having a field of view along the optical axis.
48. The scan system of claim 47 wherein:
the rotational axes of the two scan disks are offset from each other;
the field of view is incident on the scan disks at a point located between the two rotational axes; and
the first direction is approximately parallel to the tangential direction of the scan disks.
49. The scan system of claim 47 wherein:
the facets on the first and second scan disks include lens-like scan components; and
the scan components on the first scan disk have approximately the same optical power as the scan components on the second scan disk.
50. The scan system of claim 47 wherein facets on the first scan disk introduce a first bow and corresponding facets on the second scan disk introduce a second bow that counteracts the first bow.
51. The scan system of claim 47 wherein the counter-rotating disk scanner is a reflective counter-rotating disk scanner.
52. The scan system of claim 47 further comprising:
a pre-scanner lens group located downstream of the disk scanner for compensating for optical power introduced by the disk scanner and further for correcting monochromatic aberrations introduced by the disk scanner in a neutral rotational position.
53. The scan system of claim 47 wherein the disk scanner includes aspheric surfaces that correct for dynamic off-axis aberrations introduced by rotation of the disk scanner.
54. The scan system of claim 47 further comprising:
an imaging lens group located upstream of the disk scanner for correcting dynamic chromatic aberration introduced by rotation of the disk scanner.