A sensor and a method for using the sensor for precise measurement of displacement is disclosed. The sensor comprises a fringe tracking signal processing system which can be used with any type of interferometer to provide high resolution over a large dynamic range of motion. The signal processing is based on phase information from the interferometric signal and the sensor is not sensitive to amplitude changes.

An array of antenna elements is arranged along a common, rotating platform so as to form a pair of mechanically scanned interferometers exhibiting spaced, parallel receiving axes for ranging on a distance emitter. As the receiving lobes of the pair of interferometers scan across the emitter, lobe modulated signals are received having a relative time difference t.sub.21 that varies as a sinusoidal function of time due to the platform's rotation and includes a dc error value due to slight but unav...

Circuitry is provided for detecting threshold crossings of an input signal which is generally sinusoidal or otherwise periodic, but which is subject to either high-frequency noise which would cause erroneous multiple threshold crossings, or low-frequency noise which would cause erroneous failure to detect a threshold crossing. Two detection elements detect the crossing of two different threshold values and produce detection signals reflecting whether the input signal is above or below their thre...

System and method for wavelength discrimination using a DWDM (N+1)-stage cascade tree structure with distributed filtering to provide acceptable optical isolation and acceptable flat-top wavelength response. Each channel has a Mach-Zehnder interferometer (MZI) that provides wavelength discrimination. The input channel includes an inverted Fabry-Perot etalon (FPE) filter or an inverted, non-symmetric MZI filter that helps provide a desired flat-top response. Each channel in a second stage has a s...

An interferometer and method for performing preliminary and main measurements quickly and with high precision are provided. Laser light and white light are successively introduced to the same interferometer booth. Laser light is introduced from a laser light source, and the interference fringe with a reference mirror as a reference is detected using a CCD and a personal computer. By setting the interference fringe to a preset value, the position of a work is adjusted. White light from a halogen ...

An optical translator that includes an interferometer and a plurality of semiconductor optical amplifiers (SOAs) coupled to the interferometer. The at least two of the SOAs receives data and a clock signal. The data is received by the at least two SOAs at different times. A coupler combines each of a respective output of the at least two SOAs to provide output data. The output data is a retimed and a reshaped signal of the data provided to at least one of the plurality of SOAs.

Optical wavelength-division multiplexers and demultiplexers based on Mach-Zehnder interferometers via evanescent coupling through a side-polished fiber port of a fiber.

Optical Mach-Zehnder interferometers and related devices, systems that have at least one fiber integrated or engaged to a substrate fabricated with one or more grooves. An integrated optical monitoring mechanism may be implemented in such devices.

Improved systems, apparatus, and methods for detecting positions of moving stages and a reference position of a beam column are provided. For some embodiments, independent discrete interferometers may be utilized for distance measurements in each axis, rather than a cumbersome monolithic multi-axis interferometer utilized in conventional systems.

Techniques for compensating for geometric effects of beam misalignment in plane mirror interferometers are disclosed.