51 results about "Phase shifting interferometry" patented technology

An in vivo method of characterizing dynamic tear films has been developed using a near infrared phase-shifting interferometer. This interferometer continuously measures light reflected from the tear film, allowing precision analysis of the dynamic surface topography. Movies showing the tear film behavior may be generated along with quantitative metrics describing the tear film surface as it changes in time.

The invention relates to an on-line detection method for detecting the wave aberration of a projection objective of a photoetching machine. The on-line detection, revising, and controlling are done to the wave aberration of the projection objective by integrating an interferometer device on the photoetching machine. The interferometer device is a point-diffraction interferometer or a slit-diffraction interferometer and is provided with two measuring modules: a PSI measuring module and an FTM measuring module. The PSI measuring module adopts phase shifting interferometry with high measuring precision and is mainly used to detect the error calibration in an interferometer device system; the FIM measuring module adopts fourier transform method to treat with interference fringes with high measuring speed, and is mainly used to on-line detect and control the wave aberration of the projection objective. The method improves the measuring precision without reducing the measuring speed, and improves the measuring precision and reproducibility of the interferometer device by adopting a higher quality spherical reference wave to calibrate the systematic error caused by each component of the interferometer device without reducing the contrast ratio of the interference fringes.

The invention discloses an optical freeform surface interference detection system. A point light source array is adopted to generate a multi-field-of-view sloped wavefront to illuminate a measured optical freeform surface, the point light sources located on the optical axis are always lit up as reference light, and according to the phase-shifting interferometry, subregion wavefront data are recovered from a multi-field-of-view interferogram; a standard spherical surface is used for calibrating the positional relation between CCD (Charge Coupled Device) pixels and the multi-field-of-view interferogram, the position of the multi-field-of-view interferogram is shifted when the optical freeform surface is measured, and wavefront slope information is obtained from the offset; and according to the slope information and multi-field-of-view subregion wavefront data, the surface form information of the measured surface is reconstructed. A controllable point light source array-lighting scheme is generated according to the characteristics of the measured surface, and the system can cover a variety of test objects (convex-concave aspheric surfaces and freeform surfaces). The invention overcomes the defects of simplicity and high cost of the conventional freeform surface detection method, the defect of great error caused by the non-common path in the conventional detection method and the defect of high displacement precision requirement of the subaperture method.

An in vivo method of characterizing dynamic tear films has been developed using a near infrared phase-shifting interferometer. This interferometer continuously measures light reflected from the tear film, allowing precision analysis of the dynamic surface topography. Movies showing the tear film behavior may be generated along with quantitative metrics describing the tear film surface as it changes in time.

The invention relates to a coaxial Fizeau synchronous phase shifting interferometer capable of adjusting extended light illumination and belongs to the field of an optical interference measuring device. The coaxial Fizeau synchronous phase shifting interferometer comprises an extended light source assembly, a fronting Michelson type interferometer assembly and a Fizeau main interferometer. In the invention, the fronting interferometer assembly is adopted to generate two illumination light waves of orthogonal polarization state; polarization phase shifting interferometry between a measured surface and a reference surface is realized through match of spatial coherence of the fronting interferometer and the main interferometer; and an additional fringe is removed by using the characteristic of a short coherent optical length of an extended light source space. The coaxial Fizeau synchronous phase shifting interferometer has the characteristics of long measuring distance, continuous and adjustable contrast ratio, continuous and adjustable coherent optical length, easy operation, lower error requirement on a high frequency surface shape of the reference surface and the like; and the coaxial Fizeau synchronous phase shifting interferometer can be used in the fields of high precision detection of an optical element, optical element on-line detection and super-smooth surface detection and the like.

Device and method for wavefront measurement of an optical imaging system by means of phase-shifting interferometry, having a mask structure (6a) to be arranged on the object side, and / or a grating structure (7a) to be arranged on the image side. The object-side mask structure includes one or more one-dimensional mask structure patterns, and the image-side grating structure includes one or more two-dimensional grating structure patterns. Alternatively, conversely, the mask structure includes one or more two-dimensional patterns, and the grating structure includes one or more one-dimensional patterns. Additionally or alternatively, a pupil position offset caused by a lateral relative movement of the mask structure and detector element can be taken into account by back calculating the interferogram, respectively recorded by the detector element, using an associated phase-shift characteristic, or by a computational correction of wavefront derivatives, obtained from the recorded interferograms, in the direction of lateral movement. The method and / or the device can by used, for example, for determining aberration in the case of high-resolution projection objectives of microlithography exposure machines using shearing or point interferometry.

In certain aspects, disclosed methods include combining reference light reflected from a reference surface with test light reflected from a test surface to form combined light, the test and reference light being derived from a common source, sinusoidally varying a phase between the test light and reference light, where the sinusoidal phase variation has an amplitude u, recording at least one interference signal related to changes in an intensity of the combined light in response to the sinusoidal variation of the phase, determining information related to the phase using a phase shifting algorithm that has a sensitivity that varies as a function of the sinusoidal phase shift amplitude, where the sensitivity of the algorithm at 2 u is 10% or less of the sensitivity of the algorithm at u.

A system and method for analyzing the dynamics of fluid layers on contact lenses utilizes phase shifting interferometry to quickly and accurately model the time-evolution of the fluid layers. The system and method are utilized for in vitro studies.

The present invention provides a phase-shifting interferometry (PSI) method and corresponding system including: (i) recording an interferogram for each phase in a sequence of phases between test light reflected from a test surface and reference light reflected from a reference surface, the interferograms defining an interferometry signal for each of different transverse locations of a cavity defined by the test and reference surfaces; (ii) calculating an initial phase map for the cavity based on at least some of the recorded interferograms; (iii) calculating an estimate for each of at least some of the phase shift increments based on the initial phase map and at least some of the recorded interferograms; and (iv) calculating an improved phase map based on the calculated estimates for the phase shift increments and at least some of the recorded interferograms.

The present invention relates to a method of compensating a fringe order error in white-light phase-shifting interferometry, including: an interference signal acquisition step, an index determination step, and a real position calculation step. The interference signal acquisition step includes acquiring at least two color interference signals, using a color camera, from among a red interference signal, a green interference signal, and a blue interference signal. The index determination step includes determining a position where a phase difference between the at least two interference signals reaches a minimum value as an index of the zero order interference signal position. The real position calculation step includes determining, as a zero order interference signal measured position, a position corresponding to the index of the zero order interference signal position from among positions where interference signals are measured from black-and-white interference signals acquired through a black-and-white camera, and calculating a zero interference signal real position where the intensity of light is a maximum value by adding or subtracting a phase value of the zero order interference signal measured position to or from the zero order interference signal measured position.

The invention relates to a device for detecting a precision wafer based on parallel optical flat splitting polarized beam and phase-shifting interferometry. The device comprises a light source, a spatial filter, a beam expander, a polarizer, a depolarizing dispersion prism, a parallel optical flat, a quarter-wave plate and an analyzer, wherein the light source, the spatial filter, the beam expander and the polarizer are arranged on a first optical axle in sequence, the analyzer, the quarter-wave plate, the depolarizing dispersion prism, the parallel optical flat and the surface of an externalobject to be measured are arranged on a second optical axle in sequence, and the first optical axle is perpendicular to the second optical axle.

A system of super-resolution full-field optical metrology for delivering information on the surface topography of a sample or object (6) on the far-field nanometre scale, comprising a light source (2), an interferometer (1a, 1b, 1c, 1d) comprising a reference arm incorporating a microbead (9) and a mirror (10), an object arm including a microbead (7) similar to said microbead (9) and arranged in immediate proximity to the surface (22) of the object (6), receiving means (5) for capturing the interference figures, and means for processing these interference figures in such a way as to produce surface topography information. The light source (2) is temporally coherent or partially coherent. The interferometer and the means for processing interference figures are designed to reconstruct the surface of the object (6) by phase shifting interferometry.

The invention relates to a method for analyzing the surface profile of the object to be measured, which relates to a method for obtaining the surface profile of the object to be measured by analyzing the interference intensity, and uses a spectroscopic interferometer combined with a broadband light source (white light) to perform analysis. The analysis method of the present invention combines the vertical scanning interference analysis algorithm and the phase analysis algorithm to describe the surface profile of the object to be measured, and has high measurement resolution. In addition, the analysis method of the present invention can analyze the phase and contour information of the object to be measured with only one piece of interference intensity data. Only in the vertical scanning interferometry mode can the phase and profile information of the object under test be obtained. Therefore, the analysis method of the present invention can further shorten the time required for measurement, and can be applied to the occasion of on-line product quality inspection.

The invention discloses a dual-wavelength phase-shift interference-based method for measuring optical heterogeneity, wherein according to dispersion characteristics of a material, an interferometer which comprises two lasers with different optical wavelengths or a wavelength tunable laser is adopted, and refractive index heterogeneity of a sample to be measured under optical waves of two wavelengths is considered as the same as optical heterogeneity to be measured of the sample to be measured; a phase-shift interferogram of the sample to be measured under the optical waves of the two wavelengths before being put into the interferometer, and a phase-shift interferogram of the sample to be measured under the optical waves of the two wavelengths after being put into the interferometer are obtained by using phase-shifting interferometry;and physical light wave phase difference of the sample to be measured under the optical waves of the two wavelengths before / after being put into the interferometer is obtained by using a phase-shift interference phase recovery algorithm, and then the optical heterogeneity of the sample to be measured is obtained. According to the dual-wavelength phase-shift interference-based method for measuring the optical heterogeneity, system errors are automatically eliminated, the sample to be measured does not need to be adjusted during a process of measuring, no special requirements for surface shape, parallelism and machining accuracy of a front and a rear surfaces of the sample to be measured exist, thus the dual-wavelength phase-shift interference-based method for measuring the optical heterogeneity is a genuine absolute measuring method and has high measuring accuracy.

The invention discloses an interferometric phase microscopy one-step imaging system and method based on two-step phase shift, and adopts the technical scheme that based on a typical Mach-Zehnder interference light path, lateral displacement beam splitting mirrors are adopted to perform light splitting on sample light and reference light respectively, a wave plate is utilized as a phase shifter, and two interference figures can be acquired at the same time through single exposure, and phase imaging can be realized quickly through corresponding phase recovery operation, and a spatial form structure of a phase body is further deconstructed. The interferometric phase microscopy one-step imaging system and method are suitable for all interferometric phase microscopy imaging systems, such as traditional coaxial interference, off-axis interference and slight off-axis interference, and have high practical value and wide application prospect in the aspect of phase microscopy, particularly in the field of application and identification of biological cell morphology.

The invention discloses a single-black-and-white CCD phase-shift dual-wavelength interferometric method based on a specific phase shift amount, which includes step 1: constructing a co-path coaxial dual-wavelength interference system, and injecting lasers with two wavelengths of wavelength λ1 and λ2 into the interferometric In the system, adjust the lasers with two wavelengths to form an interferogram along the exact same path; second: adjust the parameters of a single black and white CCD to simultaneously collect two wavelengths of the interferogram; third: use a single black and white CCD to collect the dual waves generated by two wavelengths at the same time Long phase-shift interferogram; 4: From the collected dual-wavelength phase-shift interferogram, separate two sets of single-wavelength phase-shift interference signal images that eliminate the background; 5: Separate two sets of single-wavelength phase-shift interference signal images Carry out normalization processing; Sixth: Calculate the single-wavelength package phase diagram under the wavelengths λ1 and λ2, Seventh: Calculate the synthetic wavelength phase of the wavelengths λ1 and λ2, so as to obtain the surface three-dimensional topography information of the object to be measured. The method is simple and easy to implement.

The invention discloses a secondary confocal measurement method and device based on phase-shifting interference. In the device, a laser emits a linearly polarized beam, which becomes an approximate ideal plane wave after passing through a collimating beam expander group; After one-half of the wave plate, it becomes a circularly polarized beam; it is divided into two beams by the beam splitter, the first beam is transmitted by the beam splitter, reflected by the mirror, reflected by the beam splitter, and converged by the second pinhole and detected by the collecting objective lens. A point detector composed of detectors; the second beam of light is reflected by the beam splitter, converges on the measurement surface through the detection focusing objective lens and the beam splitter, is reflected on the measurement surface, passes through the detection focusing objective lens, and converges on the point detector through the collecting objective lens; the first The micro-driver is used to drive the mirror to change the phase difference between the reference light and the measurement light to realize phase-shifting interference; the initial position of the measurement point is the first confocal state. The invention also discloses a secondary confocal measurement method based on phase-shifting interference.

The invention relates to a phase shifting interferometry-based sphere diameter absolutely-precise measuring system and a method thereof. The phase shifting interferometry-based sphere diameter absolutely-precise measuring system comprises a tunable laser, a polarization-maintaining optical fiber system, a laser frequency locking system, a laser frequency tracing system and a sphere diameter interferometer which are mutually connected. According to the invention, the method which is used for interfering phase control based on frequency scanning by the tunable laser is adopted, thus the phenomena of mechanical vibration and nonlinearity caused when piezoelectric ceramic is used for interfering phase control are avoided and the accuracy for phase shift control is enhanced; a Fabry-Perot cavity is additionally adopted, the outputted laser frequency is locked at a transmission peak of the Fabry-Perot cavity, and then an assumption of equally-spaced phase shift required by an asynchronous sampling phase shift algorithm is strictly ensured and the calculating accuracy of the phase shift algorithm is enhanced; and in addition, the femtosecond optical frequency combing system-based laser frequency tracing system is further adopted, the output laser frequency of the tunable laser can be traced to the microwave frequency standard, thus a diameter measuring result of a sphere to be measured has metrological significance.