US 12,000,698 B2
Polarization-separated, phase-shifted interferometer
Noah Gilbert, Waltham, MA (US); and Joshua Brown, Newton, MA (US)
Assigned to Massachusetts Institute of Technology, Cambridge, MA (US)
Filed by Massachusetts Institute of Technology, Cambridge, MA (US)
Filed on Jan. 10, 2022, as Appl. No. 17/572,353.
Claims priority of provisional application 63/157,913, filed on Mar. 8, 2021.
Prior Publication US 2023/0160682 A1, May 25, 2023
Int. Cl. G01B 9/02001 (2022.01); G01B 9/02 (2022.01); G01B 9/02055 (2022.01); G01B 11/24 (2006.01)
CPC G01B 9/0201 (2013.01) [G01B 9/02051 (2013.01); G01B 9/02067 (2013.01); G01B 11/2441 (2013.01); G01B 2290/70 (2013.01)] 18 Claims
OG exemplary drawing
 
1. An interferometric measurement apparatus comprising:
a light source to generate a reference beam in a first polarization state and a sample beam in a second polarization state orthogonal to the first polarization state and having a fiber-coupled phase modulator to shift a phase of the reference beam with respect to the sample beam;
a beam collimator including at least one lens arranged to receive light from a fiber exiting the light source and produce a first beam intensity at an edge of an exit pupil of the beam collimator that is at least 50% of a second beam intensity at a center of the exit pupil; and
an interference head to receive the reference beam and the sample beam from the beam collimator and to interfere the sample beam with the reference beam after propagating the reference beam along a first optical path and the sample beam along a second optical path in the interference head.