US 8,045,175 B2 · Equal-path interferometer

Abstract

An optical assembly for use in an interferometer is provided. The optical assembly includes first and second partially reflective surfaces positioned along an optical axis and oriented at different non-normal angles to the optical axis. The second partially reflective surface is configured to receive light transmitted through the first partially reflective surface along the optical path, transmit a portion of the received light to a test object to define measurement light for the interferometer and reflect another portion of the received light back towards the first partially reflective surface to define reference light for the interferometer. The reference light makes at least one round trip path between the second and first partially reflective surfaces.

Claims51

Dependent claims

An optical assembly for use in an interferometer, the optical assembly comprising:

first and second partially reflective surfaces positioned along an optical axis and oriented at different non-normal angles to the optical axis,
wherein the second partially reflective surface is configured to:
i) receive light transmitted through the first partially reflective surface along the optical path;
ii) transmit a portion of the received light to a test object to define measurement light for the interferometer;
and
iii) reflect another portion of the received light back towards the first partially reflective surface to define reference light for the interferometer, wherein the reference light makes at least one round trip path between the second and first partially reflective surfaces.

3 more elements

An interferometry method comprising:

positioning first and second partially reflective surfaces along an optical axis;
orienting the first and second partially reflective surfaces at different non-normal angles relative to the optical axis;
transmitting light through the first partially reflective surface along a direction parallel to the optical axis to the second partially reflective surface;
at the second partially reflective surface, transmitting a first portion of the light to a test object to define measurement light, and reflecting a second portion of the light back towards the first partially reflective surface to define reference light;
and
at the first partially reflective surface, reflecting a portion of the second portion of the light towards the second partially reflective surface such that the reference light makes at least one round trip path between the second and first partially reflective surfaces.

3 more elements

Dependencies are inferred from the claim text.

Equal-path interferometer

Life of this patent

Equal-path interferometer

Life of this patent

Abstract

Claims51