3-Dimensional vision system utilizing coherent optical detection

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:

• 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;
• and
• 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.

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:

• 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.

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:

• 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.