An interferometer which comprises: (1) a single, coherent light source; (2) a first converging lens positioned on the optical axis of said coherent light source; (3) a beam-splitting arrangement positioned on said optical axis and spaced from said first converging lens by a distance greater than the focal length of said lens; (4) a second converging lens positioned on said lens; (4) a second converging lens positioned on said optical axis to receive and to focus the two beams emanating in use fr...

A Mach Zehnder interferometer with arms of equal length is formed between two optic fibres. This is achieved by locating the lightly tensioned fibres in a generally parallel configuration and forming optical couplings between them at points which lie on the center-line of the configuration. Preferably the couplings are formed by a fused biconical tapering technique.

Interferometers for precise determination of lengths and more particularly, a highly sensitive interferometer which can produce interference fringes one fringe separation of which corresponds to .lambda./2N (.lambda. is a wavelength of an incident light and N is an integer which is 2, 3, 4 . . . ). The interferometer comprises light emitting means at least one beam splitting means, retroreflecting optical means and bilateral reflecting optical means. Two embodiments of the beam splitting means a...

This invention involves an interferometer arranged to measure the distance to a movable object. The interferometer includes a main wave guide for radiating electromagnetic waves towards the object and for receiving the electromagnetic wave after reflection from the object, and a secondary wave guide system, including detectors coupled to the main wave guide in order to receive components of both the radiated and reflected waves. By appropriate positioning of the coupling between main and seconda...

Methods and systems for determining information about the incident angle of a beam are disclosed, the method including directing a beam having an s-polarized component and a p-polarized component to reflect from an interface at a non-normal angle, where the non-normal reflection introduces for each component a phase change upon reflection that is different for each component, and measuring an optical interference signal related to the phase change between the components of the reflected beam.

An X-ray interferometer comprises a plane film of material of low X-ray absorption coefficient, a first surface facing one side of the film, and a second surface facing the other side of the film and substantially opposite the first surface, the first and second surfaces being of high X-ray absorption coefficient and being relatively inclined at a small angle, arranged so that when a beam of X-rays is incident on the film at a glancing angle in the plane in which the small angle of relative incl...

An acoustic or ultrasonic device includes two ultrasonic energy transmission paths having substantially identical transmission characteristics for a neutral condition of the device. One or both of the transmission paths include path altering structure(s) or coating(s) for changing the transmission characteristics of one or both of the paths in response to a physical phenomenon to be sensed or monitored. The paths have input transducers coupled thereto for transmitting ultrasonic energy into the ...

A device for counting fringes produced by an interferometer. An interferometer with a single photomultiplier is used to determine the magnitude and direction of motion of an object to a digital sensitivity of one-eighth of a wavelength. By an electronic squaring technique the digital sensitivity of the device can be increased to one-sixteenth or one thirty-second of a wavelength.

An interferometer for detecting the velocity of small particles in a fluid includes relatively static means comprising a source of coherent radiation and a beam splitter means mounted in a fixed relationship for directing beams of coherent radiation from the source along two predetermined paths comprising a test path which will pass through the fluid under test and a reference path, and a scattering means mounted in the reference path for scattering the radiation in that path into a plurality of...

The tilt-compensated interferometers of the present invention are novel variations of Michelson's interferometer that use tilt- and shear-compensation to provide excellent photometric accuracy even when there are imperfections in the scanning motion used to produce variation of path difference. The tilt-compensation mechanism of the present invention consists of antiparallel reflections from a beamsplitter element and a roof reflector element, which elements are held rigidly in alignment. Severa...