A novel variation of Michelson's interferometer uses tilt- and shear-compensation optics to allow various mirror motions to produce variation of path difference. The tilt-compensation mechanism consists of two complementary reflections from a single plane mirror and, in some cases, the beamsplitter, to produce a beam having a constant angle of propagation, typically the same as the input beam. Using a retroreflector to invert the image of a single plane mirror or a sequence of plane mirrors befo...

Classical distance measuring optical interferometer systems determine the desired measured distance by measuring phase differences between two light waves; two light waves are needed to uniquely determine distance and direction of motion. A third light wave is used for making the system insensitive to variations in brightness of the light source. This invention provides a distance or optical phase decoding system having three output light waves that uses all of the available light for the measur...

There is disclosed an adjustment structure for use in initially aligning the two arms of an interferometer, by varying slightly the angular position of mirror surfaces. Two "wedge" elements are used behind the mirror, each of which is independently rotatable about an axis perpendicular to the face of the mirror. In order to provide ideal lubrication between the relatively movable flat engaging surfaces, a solid layer of a low friction polymer is used, preferably polytetrafluoroethylene.

The invention generally is accomplished by a casting of a liquid metallo-organic ceramic precursor solution to form a layer on a substrate. This layer is then heated to a low temperature to create an amorphous layer. Then a selected area is heated to a high temperature by localized heating to create a patterned area of polycrystalline ceramic having electro-optic properties.

A reflector system for Michelson interferometers comprises: a beam splitter arranged in the measurement ray path, which splits the measurement beam path into two split ray paths; a first mirror arrangement in each split ray path reflecting parallel to the incident ray; and at least one second mirror reflecting parallel to the incident ray, which is arranged in the ray path reflected from one of the first mirror arrangements and is coupled to the beam splitter, a partially transparent reflector s...

In general, in one aspect, the invention features a method for determining the location of an alignment mark on a stage including measuring a location, x.sub.1, of a stage along a first measurement axis using an interferometer, measuring a location, x.sub.2, of the stage along a second measurement axis substantially parallel to the first measurement axis, and determining a location of the alignment mark along a third axis substantially parallel to the first measurement axis based on x.sub.1, x.s...

Beam shear can be reduced in an interferometric system by conditioning an input beam prior to directing the input beam to an interferometer. Accordingly, apparatus and methods for conditioning an interferometer input beam are disclosed.

A retroreflector has three mutually-orthogonal reflective surfaces arranged around an optical axis. The reflective surfaces stop short of the optical axis to provide a central region of the retroreflector which transmits incident light and a peripheral region of the retroreflector which retroreflects incident light. When the reflector is used in a Jamin-type interferometer with another reflector, this enables the interferometer to be used for measuring displacement between the reflectors. In the...

Compact, high performance, scanning heterodyne optical interferometers for interferometric phase-based measurement and a host of other applications are introduced. An in-line, almost common-path optical interferometer design offers robustness to externally induced phase noise via mechanical vibrations, thermal effects, and other environmental effects. Several instrument designs are disclosed for both transmissive and reflective interferometry. These interferometers use acousto-optic devices or B...

An optical device has at least one waveguide with at least one adjacent resonator, where the distance between the resonator and the waveguide can be controllably adjusted to change the optical coupling between the resonator and the waveguide. When implemented as part of an interferometer, the ability to adjust the waveguide/resonator distance--and thereby the optical coupling between them--provides a mechanically tunable interferometer.