The present invention relates to an apparatus and a method for measuring a thickness and a refractive index of a multilayer thin film using an angle-resolved spectral interference image according to polarization. More specifically, the present invention relates to an apparatus for measuring a thickness and a refractive index of a multilayer thin film using an angle-resolved spectral interference image according to polarization in an apparatus for measuring a thickness and a refractive index of a measurement object coated with the multilayer thin film, the apparatus including: an illumination optical module having a light source emitting light; a first beam splitter configured to reflect some of the light emitted from the illumination optical module; an objective lens configured to input some of the light reflected from the first beam splitter to the measurement object constituted by the multilayer thin film and reflect the remaining light to a reference plane to form interference light on a back focal plane; a second beam splitter in which interference light where the reflected light incident and reflected to the measurement object interferes with the reflected light reflected from the reference plane is incident, wherein some of the interference light is reflected and the remaining interference light is transmitted; a first angle-resolved spectral image acquiring unit configured to receive interference light reflected from the second beam splitter and first-polarize the interference light located in the back focal plane of the objective lens to acquire a first polarized interference image; and a second angle-resolved spectral image acquiring unit configured to receive interference light transmitted from the second beam splitter and second-polarize the interference light located in the back focal plane of the objective lens to acquire a second polarized interference image.

A time-domain or frequency domain including a sample light path between a source interface and a detector interface, a reference light path between the source interface and the detector interface, and a photonic integrated circuit, wherein the reference light path is at least partially separate from the sample light path, wherein the sample light path comprises a forward sample light path between the source interface and a sample interface, and a backward sample light path between the sample interface and the detector interface, wherein the forward sample light path and the backward sample light path are at least partially provided by the photonic integrated circuit, and wherein the photonic integrated circuit comprises an integrated sample-side polarization beam splitter arranged in the forward sample light path and the backward sample light path.

The invention relates to a device for measuring a substrate for semiconductor lithography with a reference interferometer for ascertaining the change in the ambient conditions, wherein the reference interferometer comprises a means for changing the optical path length of a measurement section of the reference interferometer, wherein the means is configured to bring about a change in the refractive index.

Furthermore, the invention relates to a method for correcting cyclic error components of a reference interferometer, wherein the reference interferometer comprises a means for changing the optical path length of a measurement section of the reference interferometer, comprising the following method steps: starting up the reference interferometer, continuously detecting measurement values of the reference interferometer, changing the optical path length of the measurement section of the reference interferometer until a path length change of at least one quarter of the wavelength of the reference interferometer is detected, determining the cyclic errors on the basis of the continuously detected measurement values of the reference interferometer, and correcting the current measurement values ascertained by the reference interferometer on the basis of the cyclic errors ascertained.

Provided is a shape measurement system in order to perform three-dimensional measurement corresponding to a measurement object having various shapes, which includes a measurement probe, a probe tip, and a processor. The probe tip includes an optical element that is configured to irradiate an object with measurement light and a cylindrical unit that is configured to lock the optical element. The processor is configured to calculate an optical path length from the optical element to an object based on reflected light of the measurement light with which the object is irradiated; and calculate a three-dimensional shape of the object based on the input information and the optical path length.

The present disclosure provides an OCT imaging system having a variety of advantages. In particular, the OCT system of the present disclosure may provide a more intuitive interface, more efficient usage of controls, and a greater ability to view OCT imaging data.

A transient digital moire phase-shifting interferometric measuring device and method for a surface shape of an optical element solves a defect that an instantaneous vibration resistance needs to be sacrificed for a measurement range when using a two-step carrier splicing method, and expands the measurement range of a digital moire phase-shifting method while retaining instantaneous anti vibration characteristics of the digital moire phase-shifting method. The transient digital moire phase-shifting interferometric measuring device includes a light source, a beam splitter, a reference lens, a first polarization grating, a measured lens, a second polarization grating, a first imaging objective lens, a first camera, a second imaging objective lens and a second camera. Different carriers are loaded through a spectral performance of a polarization grating, and the polarization grating is used to separate two beams of an interference light, and two actual interference patterns are obtained at a same time.

The invention provides an Optical Coherence Tomography (OCT) system capable of acquiring two orthogonally polarized depth scans from a target such as the fingerprint region of a finger. In the preferred embodiment the birefringence of tissue components and, optionally, other aspects of the target are measured in order determine a characteristic of the target, such as whether it is real of fake finger.

A heterodyne one-dimensional grating measuring device and measuring method thereof, including a light source, a reading head, a photoelectric receiving module, and a signal processing system. The light source is configured to generate two linearly polarized lights having characteristics of overlapping, polarization orthogonal, and fixed frequency difference. The reading head is configured to receive two beams of polarized lights and be respectively incident on a surface of a moving measuring grating to generate a +1-order diffracted light and a −1-order diffracted light. The photoelectric receiving module is configured to receive the +1-order diffracted light and the −1-order diffracted light to form two paths of beat frequency signals. The signal processing system is configured to perform differential calculation on the two paths of the beat frequency signals to realize a displacement measurement of single diffraction of the measuring grating for four-fold optical subdivision.

An interferometric distance-measurement device includes a multi-wavelength light source which provides a beam having at least three different wavelengths. An interferometer unit splits the beam into measuring and reference beams. The measuring beam propagates in the direction of a measuring reflector movable along a measuring axis and undergoes a back-reflection, and the reference beam propagates in the direction of a stationary reference reflector and undergoes a back-reflection. The back-reflected measuring and reference beams interfere with each other in an interference beam. A detection unit splits the interference beam such that several phase-shifted partial interference signals result for each wavelength. A signal processing unit determines absolute position information regarding the measuring reflector from the partial interference signals of different wavelengths and an additional coarse position signal.

Interferometric systems and methods for measuring rotational movement are described. In one implementation, an interferometer for measuring rotational movement includes a housing and a light source within the housing configured to project coherent light toward a non-coded surface of an object. The interferometer further includes at least one optical element configured to modify the projected coherent light in a manner accounting for a rotation of the object. The interferometer also includes at least one sensor within the housing including at least one light detector configured to detect reflections of the modified projected coherent light from the opposing non-coded surface as the object rotates relative to the housing. The interferometer further includes at least one processor configured to receive input from the at least one sensor and determine an amount of rotation of the object around the at least one rotational axis.