3-Dimensional vision system utilizing coherent optical detection
First Claim
1. A vision system for determining characteristics of a target comprising:
- optical source means for providing a source light beam which is linearly polarized in a first orientation;
beam splitter means for splitting said source beam into a target beam and a reference beam both of which are linearly polarized in said first orientation;
quarter wave plate means for converting said target beam to circular polarization in a first rotational direction and directing said target beam toward the target, and for receiving a return light beam reflected from said target which is circularly polarized in a second rotational direction opposite to said first rotational direction, said quarter wave plate means converting said return light beam to linear polarization in a second orientation perpendicular to said first orientation;
retroreflector means for converting said return light beam which is linearly polarized in said second orientation to linear polarization in said first orientation and for reflecting said return beam;
detector means for optical heterodyne detection of said reference and return beams which are both linearly polarized in said first orientation, and for providing an output signal including information about saidscanning means for scanning said target beam across said target; and
processing means for controlling said scanning.
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Accused Products
Abstract
A three-dimensional optical scanning vision system capable of producing high-resolution images in real-time includes an optical source for producing a source light beam. The source light beam is directed to a beam splitter which splits it into a local oscillator beam and a signal beam. The local oscillator beam is directed toward a photodetector, while the signal light beam is directed toward a target. Light reflected from the target is received by the beam splitter and directed toward a retroreflector which returns the beam to the beam splitter interface. Quarter wave plates and the retroreflector insure that the return light beam and the local oscillator beam are collimated and have the same polarization state. Mixing of the local oscillator beam and the return light beam occurs at the beam splitter interface, thus providing coherent optical detection by the photodetector. The photodetector thus provides an output signal providing a high degree of information about the target. The system also includes scanner optics to scan the signal light beam across the target. A processor is also included for outputting a three-dimensional image of the target, and for controlling the scanner optics.
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Citations
22 Claims
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1. A vision system for determining characteristics of a target comprising:
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optical source means for providing a source light beam which is linearly polarized in a first orientation; beam splitter means for splitting said source beam into a target beam and a reference beam both of which are linearly polarized in said first orientation; quarter wave plate means for converting said target beam to circular polarization in a first rotational direction and directing said target beam toward the target, and for receiving a return light beam reflected from said target which is circularly polarized in a second rotational direction opposite to said first rotational direction, said quarter wave plate means converting said return light beam to linear polarization in a second orientation perpendicular to said first orientation; retroreflector means for converting said return light beam which is linearly polarized in said second orientation to linear polarization in said first orientation and for reflecting said return beam; detector means for optical heterodyne detection of said reference and return beams which are both linearly polarized in said first orientation, and for providing an output signal including information about said scanning means for scanning said target beam across said target; and processing means for controlling said scanning. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. An optical apparatus for splitting a source light beam which is linearly polarized in a first orientation into a target beam and a reference beam, and ensuring that a return light beam reflected from a target is linearly polarized in said first orientation, said apparatus comprising:
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beam splitter means for splitting said source beam into said target beam and said reference beam both of which are linearly polarized in said first orientation, quarter wave plate means for converting said target beam to circular polarization in a first rotational direction and directing it toward said target, and receiving said return light beam reflected from said target which is circularly polarized in a second rotational direction opposite to said first rotational direction, said quarter wave plate means converting said return light beam to linear polarization in a second orientation perpendicular to said first orientation, retroreflector means for converting said return beam which is linearly polarized in said second orientation to linear polarization in said first orientation and directing said return beam along an optical axis coincidental with an axis of said reference beam. - View Dependent Claims (11, 12, 13, 14, 15)
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16. An optical apparatus for splitting a source light beam which is linearly polarized in a first orientation into a reference beam and a target beam, and for ensuring that a return light beam reflected from a target is linearly polarized in said first orientation, comprising:
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beam splitter means for splitting said source beam into said reference beam and said target beam, both of which are linearly polarized in said first orientation, and for directing said reference beam along an optical detection axis; first quarter wave means for converting said target beam to circular polarization in a first rotational direction, and for converting said return light beam, which is circularly polarized in a second rotational direction opposite to said first rotational direction, to linear polarization in a second orientation perpendicular to said first orientation; said beam splitter means reflecting said return beam after it has passed through said first quarter wave means; second quarter wave means for converting the reflected return beam to circular polarization in said second rotational direction; retroreflector means for receiving said reflected return beam after it has passed through said second quarter wave means and retroreflecting it along said optical detection axis;
the retroreflected return beam being circularly polarized in said first rotational direction; andsaid second quarter wave means converting the retroreflected return beam to linear polarization in said first orientation to cause optical heterodyne mixing of said retroreflected return and reference beams along said optical detection axis. - View Dependent Claims (19, 20, 21, 22)
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17. An optical apparatus for splitting a source light beam which is linearly polarized in a first orientation into a reference beam and a target beam, and for ensuring that a return light beam reflected from a target is linearly polarized in said first orientation, comprising:
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beam splitter means for splitting said source beam into said reference beam and said target beam, both of which are linearly polarized in said first orientation, and for directing said reference beam in a first direction along an optical detection axis; first quarter wave means for converting said target beam to circular polarization in a first rotational direction, and for converting said return light beam, which is circularly polarized in a second rotational direction opposite to said first rotational direction, to linear polarization in a second orientation perpendicular to said first orientation; said beam splitter means reflecting said return beam after it has passed through said first quarter wave means in a second direction along said optical detection axis; second quarter wave means for converting the reflected return beam to circular polarization in said second rotational direction; retroreflector means for receiving said reflected return beam after it has passed through said second quarter wave means and retroreflecting it along said optical detection axis in said first direction, the retroreflected return beam being circularly polarized in said first rotational direction; said second quarter wave means converting the retroreflected return beam to linear polarization in said first orientation to cause optical heterodyne mixing of said retroreflected return and reference beams along said optical detection axis in said first direction.
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18. An optical apparatus for splitting a source light beam which is linearly polarized in a first orientation into a reference beam and a target beam, and for ensuring that a return light beam reflected from a target is linearly polarized in said first orientation, said apparatus comprising:
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beam splitter means for splitting said source beam into said reference beam and said target beam, both of which are linearly polarized in said first orientation, and for directing said target beam toward said target along an optical target axis and for transmitting said reference beam along an optical detection axis; first quarter wave means for converting said target beam to circular polarization in a first rotational direction, and for converting said return light, which is circularly polarized in a second rotational direction opposite to said first rotational direction, to linear polarization in a second orientation perpendicular to said first orientation; said beam splitter means transmitting therethrough said return beam after it has passed through said first quarter wave means; second quarter wave means for converting the transmitted return beam to circular polarization in said second rotational direction; retroreflector means for receiving said transmitted return beam after it has passed through said second quarter wave means and retroreflecting it along said optical target axis, the retroreflected return beam being circularly polarized in said first rotational direction; and said second quarter wave means converting the retroreflected return beam to linear polarization in said first orientation, optical heterodyne mixing of said return and reference beams taking place along said optical detection axis.
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Specification