The present invention comprises: a light source; a generator that generates, from light generated by the light source, a light pulse train in which the carrier waves are coherent, interference between adjacent waveforms is low, and the spatial length of a pulse width is smaller than a depth range of an observation target region in a measurement target; a frequency shifter that converts the frequency of a light pulse train modulated by the generator; a light path length changing unit that changes the light path length of the light pulse train; a light detection unit into which is input the light pulse train output from the light path length changing unit and backwardly scattered waves from the measurement target; a filter that extracts a difference signal output from the light detector and having a shift frequency of the frequency shifter; a demodulator that combines the difference signal extracted by the filter and a reference signal synchronized with the shift frequency of the frequency shifter; and an analyzing unit that analyzes a signal output by the demodulator.

Scatterometry overlay (SCOL) measurement methods, systems and targets are provided to enable efficient SCOL metrology with in-die targets. Methods comprise generating a signal matrix by: illuminating a SCOL target at multiple values of at least one illumination parameter, and at multiple spot locations on the target, wherein the illumination is at a NA (numerical aperture)> yielding a spot diameter<1, measuring interference signals of zeroth and first diffraction orders, and constructing the signal matrix from the measured signals with respect to the illumination parameters and the spot locations on the target; and deriving a target overlay by analyzing the signal matrix. The SCOL targets may be reduced to be a tenth in size with respect to prior art targets, as less and smaller target cells are required, and be easily set in-die to improve the accuracy and fidelity of the metrology measurements.

The present invention discloses a real-time normalization apparatus and method of the PGC demodulation in a sinusoidal phase modulation interferometer. An optical setup containing a measuring interferometer and a monitoring interferometer is constructed. An electro-optic phase modulator is placed in the common reference arm of the two interferometers. High-frequency sinusoidal wave modulation and low-frequency triangular wave modulation are applied to the electro-optic phase modulator at the same time. Sinusoidal modulation is used for generating phase carrier, and PGC demodulation is performed to obtain quadrature signals containing the phase information to be measured. Triangular wave modulation makes the quadrature signals change periodically. Ellipse fitting is performed on the Lissajous figure corresponding to the quadrature signals, and real-time normalization of the PGC demodulated quadrature signals is achieved. By calculating the variation of the phase difference between the two interference signals, the measured displacement is obtained, and nanometer scale displacement measurement is achieved.

A system of super-resolution full-field optical metrology for delivering information on the surface topography of a sample or object on the far-field nanometre scale, including a light source, an interferometer (1a, 1b, 1c, 1d) including a reference arm incorporating a micro bead and a mirror, an object arm including a micro bead similar to the micro bead and arranged in immediate proximity to the surface of the object, receiving structure for capturing the interference figures, and a processor for processing these interference figures in such a way as to produce surface topography information. The light source is temporally coherent or partially coherent. The interferometer and the processor for processing interference figures are designed to reconstruct the surface of the object by phase shifting interferometry.

Aspects of the subject technology relate to particulate matter sensors for electronic devices. A particulate matter sensor may include three lasers, three total-internal-reflection lenses, and three detectors for detecting changes in the operation of the three lasers due to the principles of self-mixing interferometry. The three total-internal-reflection lenses may use internally reflective surfaces to tilt the three beams into three corresponding directions that form an orthogonal basis in the three dimensional space, so that a gas flow speed can be determined while maintaining a small, modular form factor for implementation of the sensor in portable electronic devices.

Techniques for removing interferometry signal phase variations caused by distortion and other effects in a multi-layer stack include: providing an electronic processor sample interferometry data acquired for the stack using a low coherence imaging interferometry system; transforming, by the electronic processor, the sample interferometry data to a frequency domain; identifying a non-linear phase variation from the sample interferometry data in the frequency domain, in which the non-linear phase variation is a result of dispersion introduced into a measurement beam by the test sample; and removing the non-linear phase variation from the sample interferometry data thereby producing compensated interferometry data.

In an optical position measuring device for the interferential determination of the relative distance of two objects which are movable relative to each other in at least one measuring direction, a bundle of rays emitted by a light source is split up into at least two partial bundles of rays, which fall on a grating or a plurality of gratings on separate optical paths and undergo distance-dependent phase shifts as a result. The partial bundles of rays are superpositioned at a mixing grating, whereupon at least three pairs of interfering partial bundles of rays propagate in different directions in space. Via the mixing grating, each pair of interfering partial bundles of rays is focused on a detector element so that at least three position-dependent, phase-shifted incremental signals are detectable via the detector elements.

A method of measuring a polarization response of a sample (1), in particular a biological sample, comprises the steps of generating a sequence of excitation waves (2), irradiating the sample (1) with the sequence of excitation waves (2), including an interaction of the excitation waves (2) with the sample (1), so that a sequence of sample waves (3) is generated each including a superposition of a sample main pulse and a sample global molecular fmgerprint (GMF) wave (E.sub.GMF(sample)(t)), irradiating a reference sample (1A) with the sequence of excitation waves (2), including an interaction of the excitation waves (2) with the reference sample (1A), so that a sequence of reference waves (3A) is generated each including a superposition of a reference main pulse and a reference GMF wave (E.sub.GMF(ref)(t)), optically separating a difference of the sample waves (3) and reference waves (3A) from GMF wave contributions which are common to both of the sample waves (3) and reference waves (3A) in space and/or time, and detecting the difference of the sample waves (3) and the reference waves (3A) and determining a temporal amplitude of differential molecular fmgerprint (dMF) waves (.sub.GMF) (4) each comprising the difference of the sample and reference GMF waves. Futhermore, as a spectroscopic apparatus for measuring a polarization response of a sample (1) is described.

A control device assumes that observation light observed by an imaging device is composite light of primary reflection light and secondary reflection light. The control device acquires three or more samples of a brightness amplitude value of the observation light, calculates a phase error caused by the secondary reflection light using these samples, calculates a corrected phase value by correcting a phase value of the observation light using the phase error, and calculates a three-dimensional position of the measurement point on the measurement object based on the corrected phase value.

An interference measurement device configured to detect a phase from an interference beam between an object beam and a reference beam, includes: a laser beam source; a splitter configured to split an emitted beam from the laser beam source into the object beam and the reference beam; an object beam optical unit configured to make only the object beam incident on a measurement object; a combination unit configured to combine the object beam and the reference beam; a phase element configured to vary mutual relationship in phase between the object beam and the reference beam; and a detector configured to detect the interference beam between the object beam and the reference beam. A signal of a spatial phase variation of the measurement object is directly operated, based on at least two measurement results of an intensity signal with the detector.