Interferometry system having a dynamic beam steering assembly for measuring angle and distance

An interferometry system comprising:

• an interferometer which during operation directs a measurement beam along a measurement path contacting a measurement object, separates the measurement beam into m portions, and recombines at least a part of one of the portions with each of the remaining m−1 portions to form m−1 overlapping pairs of exit beams, the interferometer comprising a beam steering assembly having a beam steering element and a positioning system to orient the beam steering element, the beam steering element positioned to direct the measurement beam to the measurement object and receive the m separated portions, the measurement beam and each of the m separated portions contacting the beam steering element;
• a control circuit which during operation causes the positioning system to reorient the beam steering element in response to a change in angular orientation of the measurement object;
• and
• an angle measurement system which during operation calculates the change in angular orientation of the measurement object based on at least one of interferometric signals derived from the m−1 overlapping pairs of exit beams and the reorientation of the beam steering element.

An interferometry system comprising:

• an interferometer which during operation directs two measurement beams along corresponding measurement paths contacting a measurement object and combines the measurement beam to form an overlapping pair of exit beams, the interferometer comprising a beam steering assembly having a beam steering element and a positioning system to orient the beam steering element, the beam steering element positioned to direct the two measurement beams to the measurement object, the two measurement beams contacting the beam steering element;
• a control circuit which during operation causes the positioning system to reorient the beam steering element in response to a change in angular orientation of the measurement object;
• and
• an angle measurement system which during operation calculates the change in angular orientation of the measurement object based on at least one of an interferometric signal derived from the overlapping pair of exit beams and the reorientation of the beam steering element.

An interferometry system comprising:

• an interferometer which during operation receives an input beam, splits the input beam into a measurement beam and m reference beams, where m is an integer greater than 1, directs the measurement beam along a measurement path contacting a measurement object, separates the measurement beam into m portions, and combines each of the m portions of the measurement beam with a corresponding one of the m reference beams to form m overlapping pairs of exit beams,
• a beam steering assembly having a beam steering element and a positioning system to orient the beam steering element, the beam steering element positioned to direct the input beam and the m overlapping pairs of exit beams, the input beam and the m overlapping pairs of exit beams contacting the beam steering element;
• a control circuit which during operation causes the positioning system to reorient the beam steering element in response to a change in angular orientation of the measurement object;
• and
• an angle measurement system which during operation calculates the change in angular orientation of the measurement object based on at least one of interferometric signals derived from the m overlapping pairs of exit beams and the reorientation of the beam steering element.

An interferometry system comprising:

• an interferometer which during operation receives an input beam, splits the input beam into two measurement beams, directs the measurement beams along respective measurement paths contacting the measurement object, and combines the measurement beams to form an overlapping pair of exit beams,
• a beam steering assembly having a beam steering element and a positioning system to orient the beam steering element, the beam steering element positioned to direct the input beam and the overlapping pair of exit beams, the input beam and the overlapping pair of exit beams contacting the beam steering element;
• a control circuit which during operation causes the 0positioning system to reorient the beam steering element in response to a change in angular orientation of the measurement object;
• and
• an angle measurement system which during operation calculates the change in angular orientation of the measurement object based on at least one of an interferometric signal derived from the overlapping pair of exit beams and the reorientation of the beam steering element.

An interferometry system comprising:

• an interferometer which during operation directs a measurement beam along a measurement path contacting a measurement object, separates the measurement beam into first and second portions, directs the first and second portions along separate paths, and subsequently recombines the first and second portions with each other to form at least one overlapping pair of exit beams, the interferometer comprising a beam steering assembly having a beam steering element and a positioning system to orient the beam steering element, the beam steering element positioned to direct the measurement beam to the measurement object and subsequently receive the measurement beam from the measurement object, the measurement beam thereby twice contacting the beam steering element, after which the interferometer separates the measurement beam into the first and second portions;
• a control circuit which during operation causes the positioning system to reorient the beam steering element in response to a change in angular orientation of the measurement object based on at least one interferometric signal derived from the at least one overlapping pair of exit beams;
• and
• an angle measurement system which during operation calculates the change in angular orientation of the measurement object based on the reorientation of the beam steering element.

An interferometry method comprising:

• directing a measurement beam along a measurement path contacting a measurement object;
• combining at least a portion of the measurement beam with another beam to form an overlapping pair of exit beams;
• using an electronic control system to redirect the measurement beam in response to a change in the angular orientation of the measurement object based on a servo signal derived from at least a portion of the overlapping pair of exit beams;
• and
• calculating the change in angular orientation based on at least one of an interferometric signal derived from the overlapping pair of exit beams and the redirection of the measurement object.