In general, in a first aspect, the invention features a method that includes using an interferometry assembly to provide three different output beams, each output beam including an interferometric phase related to an optical path difference between a corresponding first beam and a corresponding second beam, each first beam contacting a measurement object at least once, monitoring the interferometric phases for each of the three different output beams, and deriving information about variations in...

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.

An interferometer includes a two-frequency laser and a polarizing beam splitter (PBS) that separates a heterodyne beam from the laser into separate beams having different the frequencies and orthogonal polarizations. Optical fibers conduct the separate beams to a beam combiner for interferometer optics. The PBS and/or the beam combiner can use a coating to reflect one linear polarization and transmit an orthogonal linear polarization. To improve extinction ratios in the PBS or the beam combiner,...

The position of an original plate stage for moving an original plate and the position of a substrate stage for moving a substrate are measured by using an original plate laser interferometer and a substrate laser interferometer, respectively. While control is performed on the basis of the measured values, the pattern of the original plate is transferred onto the substrate by scan exposure by moving the original plate stage and the substrate stage in a scan direction. The measurements of the stag...

An interferometer system includes an optical radiation source, an optical circulator connected between the optical radiation source and a sample location for transmitting optical radiation from the optical radiation source to the sample location, an output of the optical circulator connected to direct optical radiation to an optical detector. Various embodiments of such a system are possible. A method of performing OCDR or OCT imaging of a sample which involves the steps of: (a) producing low co...

An apparatus and method for measuring absolute measurements having two measuring interferometers and a tunable laser emitting a laser beam. The two measuring interometers each have their own measuring lines and are supplied with the beam from one and the same laser. A reference line is established from the arithmetic sum or difference of the two measuring lines and is maintained at a constant value.

An integrated optical head has first and second channels forming an interferometer. A electro-optically phase-shiftable waveguide channel is associated with one of the first and second channels of the interferometer for electro-optical phase shifting of one channel with respect to the other channel. The interferometer is formed on a silicon substrate and the phase-shiftable waveguide channel is formed of Langmuir-Blodgett thin-film electro-optic polymers described on the silicon substrate.

The present invention provides a multi-functional separator which may be used as a demultiplexer or as a multiplexer in wavelength division multiplexed optical communication systems. The preferred embodiment of the multi-functional separator includes a first polarization beam splitter, a non-reciprocal rotator; a reciprocal rotator, a second polarization beam splitter, and a non-linear interferometer. Each of the polarizing input and polarizing output ports includes an optical fiber, a collimato...

An optical apparatus functioning either as a multiplexer or a demultiplexer, including: a first polarization beam splitter (PBS); a second PBS optically coupled to the first PBS along an axis of the apparatus; a half-wave plate optically coupled between the first and second PBS; a common optical port optically coupled to the first PBS at a face intersecting the axis; a first non-common optical port optically coupled to the first PBS at a face not intersecting the axis; a second non-common optica...

The present invention provides a multi-functional separator which may be used as a demultiplexer or as a multiplexer in wavelength division multiplexed optical communication systems. The preferred embodiment of the multi-functional separator includes a first polarization beam splitter, a non-reciprocal rotator; a reciprocal rotator, a second polarization beam splitter, and a non-linear interferometer. Each of the polarizing input and polarizing output ports includes an optical fiber, a collimato...