A measuring assembly for the frequency-based determination of the position of a component, in particular in an optical system for microlithography, includes at least one optical resonator, which has a stationary first resonator mirror, a movable measurement target assigned to the component, and a stationary second resonator mirror. The second resonator mirror is formed by an inverting mirror (130, 330, 430, 530), which reflects back on itself a measurement beam coming from the measurement target.

Methods, devices and systems are described that use a combination multiple light sources having different coherence lengths to measure surface characteristics of an object. One example system includes a two laser sources configured to operate at a first and a second center wavelength, a broadband source configured to operate at a range of wavelengths outside of the operating range of the at least two lasers, a phase mask array and a color filter arranged, respectively, to impart different phase delays and provide spectral filtering corresponding to the emitted radiation from the sources. A pixelated sensor device is positioned to simultaneously measure intensity values associated with a plurality of interferograms formed due to interference of light from the light sources after propagation through the phase mask array and the color filter. The measured intensity values enable the determination of surface characteristics of the object.

An interferometer having a fundamental beam generator, a first second harmonic generator, a waveplate, a second second harmonic generator, a harmonic separator, and a polarizing beam splitter, mounted uniaxially, (i.e., the components are aligned along one optical axis), wherein the interferometer is adapted to change a diameter of a beam to match a diameter of a sample, and to change the diameter of the beam back to its original diameter.

A blade tip measurement system includes a case and a blade that rotates within the case, the blade having an outer blade tip surface that has a clearance distance from an inner surface of the case. A light source emits light along an optical path that is directed toward the outer blade tip surface by a lens, and the outer blade tip surface reflects the light back along the optical path. An optical interferometer generates an interference pattern using the reflected light, and a photoreceiver receives the interference pattern. A complex logic device determines the clearance distance of the blade tip surface from the inner surface of the case based on the interference pattern. The interferometer may be a Fabry-Perot optical interferometer formed using a window positioned between the lens and the blade tip surface, or a Michelson interferometer formed using a reference optical path. The system may alternatively include an optical time of flight measurement of the blade tip clearance. The system further may include an abradable substrate having an optical fiber array of optical fibers at different depths, whereby the blade tip clearance is determinable based on which of the optical fibers are abraded as the blade tip rotates.

An adjustable beam directing optical system for a focused laser differential interferometer (FLDI) instrument according to various aspects of the present technology may include an optical half waveplate to achieve an incident linear polarization orientation with equal components of laser intensity aligned to the vertical and horizontal axis of the optical system, and an optical prism for splitting these components of an incident laser beam into two orthogonally-polarized beams equally about an optical axis of the FLDI instrument. A series of beam realignment devices positioned downstream of the optical prism are configured to selectively direct each beam to a predetermined location.

A calibration method includes the steps of placing a structure to be measured at a first position, measuring a first distance from a laser interferometer to a reflector, and measuring first coordinates of a body to be measured, moving the structure to be measured to a second position, measuring a second distance from the laser interferometer to the reflector and measuring second coordinates of the structure to be measured with the coordinate measuring apparats, while the structure to be measured is at the second position, determining a scale error of the reference instrument, mounting the reference instrument, measuring the interval between objects to be measured, and calculating a calibration value of the interval between the objects to be measured.

A laser device includes a laser configured to generate laser light and a laser control module configured to receive at least a portion of the laser light generated by the laser, to generate a control signal and to feed the control signal back to the laser for stabilizing the frequency, wherein the laser control module includes a tunable frequency discriminating element which is preferably continuously frequency tunable, and where the laser control module is placed outside the laser cavity.

A system for interrogating an interferometer. The system comprises an optical signals generation system for concurrently generating a plurality of optical signals that each have a modulation parameter that the other of the plurality of optical signals do not have. The optical signals generation system is for optically coupling each of the plurality of optical signals to a plurality of optical ports of the interferometer for ingress of the plurality of optical signals into the interferometer. The system comprises an interferometer output processing system. Also disclosed herein is an interferometric system and a method for interrogating an interferometer.

A truncated non-linear interferometer-based atomic force microscope (AFM) includes an input port and a non-linear amplifier that renders a probe beam and a conjugate beam. The AFM includes local oscillators having a relationship with the probe beam and the conjugate beam. The displacement of the AFM's cantilever is transduced by the probe beam, and/or the conjugate beam or their respective local oscillators. The AFM's phase-sensitive detectors detect a phase modulation between the respective local oscillators and the probe beam and the conjugate beam. The detected phase modulation corresponds to the change in phase. The AFM's circuitry measures phase signals that are indicative of the cantilever displacement. The resulting measurement signals exhibit a quantum noise reduction in either the intensity difference or phase sum quadrature.

An interferometer having a fundamental beam generator, a first second harmonic generator, a waveplate, a second second harmonic generator, a harmonic separator, and a polarizing beam splitter, mounted uniaxially, (i.e., the components are aligned along one optical axis), wherein the interferometer is adapted to change a diameter of a beam to match a diameter of a sample, and to change the diameter of the beam back to its original diameter.