106 results about "Fizeau interferometer" patented technology

The present invention consists of a technique and device for measuring the thickness variation and shape of wafers or other polished opaque plates. A combination of two improved phase-shifting Fizeau interferometers is used to simultaneously measure the single-sided distance maps between each side of the wafer and the corresponding reference flat, with the thickness variation and shape being calculated from these data. Provisions are made to determine and eliminate the shape and tilt of the reference surfaces, and also to facilitate the correct overlay of the two single-sided measurements for the calculation of thickness variation and shape.

The invention aims to provide a synchronous phase-shifting Fizeau interference device capable of performing real-time high-accuracy measurement on the surface appearance of an object. A synchronous phase-shifting technology is combined with a Fizeau interference method, and the technical problems that the traditional interferometer has low stability and low measurement accuracy and cannot measure objects in real time and the like are solved. The synchronous phase-shifting Fizeau interference device capable of measuring in real time comprises an illumination unit, an interference unit and a synchronous phase-shifting unit. Due to the adoption of a coaxial interference light path, a space-bandwidth product of a charge coupled device (CCD) is fully utilized; and compared with an off-axis light path, the coaxial interference light path has a higher spatial resolution; a flat glass plate in the traditional Fizeau interferometer is replaced by a 1 / 4 wave plate, so that object light and reference light have orthogonal polarization directions, and the compactness of the structure of the device is kept under the synchronous phase-shifting; and moreover, four phase-shifting interference patterns can be obtained through single exposure, and the real-time property of measurement is realized on the premise of guaranteeing a high spatial resolution.

The tilted relationship between the reference and test mirrors of a Fizeau interferometer is used to spatially separate the reflections from the two surfaces. The separate beams are filtered through a spatial polarization element that provides different states of polarization to the beams. The beams are subsequently recombined to form a substantially collinear beam that is processed using a spatial-phase-shift interferometer that permits quantitative phase measurement in a single video frame. Alternatively, two beams with orthogonal polarization are injected into the Fizeau cavity at different angles, such that after reflection from the reference and test optics they are substantially collinear. Unwanted reflections are blocked at the focal plane through the use of a circular aperture. Short coherence length light and a delay line may be used to mitigate stray reflections, reduce measurement integration times, and implement temporal phase averaging.

The invention provides a large aperture non-spherical surface mirror detection system which is characterized in that the detection system comprises a Fizeau interferometer, a small hole filer, a dual-calculation hologram, a non-spherical mirror to be measured, a large five-dimensional adjusting frame and a small five-dimensional adjusting frame; the dual-calculation consists of two image parts: a main hologram and an aligning hologram; the dual-calculation hologram is fixed on the small five-dimensional adjusting frame and is arranged on the large five-dimensional adjusting frame together with the Fizeau interferometer and the small hole filter; the adjusting state of the main hologram can be judged by observing the interference images of the aligning hologram; the relative position of the dual-calculation hologram and the Fizeau interferometer is kept unchangeable on the condition that the main hologram are precisely aligned,; the position of the main hologram corresponding to the non-spherical surface mirror corresponding to the large five-dimensional adjusting frame can be adjusted by adjusting the large five-dimensional adjusting frame; the small hole filter can filtrate the stray light diffracted by the dual-calculation hologram, and the contrast of the interference fringes is improved, thus realizing the high-precision detection of the non-spherical surface mirror to be measured. The detection system provides an effective detection mean for the development of the large-aperture non-spherical surface mirrors and has great application value.

The invention encompasses beam expanders and methods of using such beam expanders. A beam expander according to the present invention may advantageously be used with an interferometer. Beam expanders according to the present disclosure contain at least an input and an output lens, with the output lens having a plano-convex arrangement such that the surface of the output lens is optically flat and can be used as the reference surface in a Fizeau interferometer. The beam expander may also encompass a housing, a partially reflective coating and an anti-reflective coating.

A synchronous phase-shifting Fizeau interferometer comprises a half-wave plate, a focusing lens, a diaphragm, a beam splitter, a first collimating lens, and a birefringent thin-film standard lens, which are arranged sequentially along the beam advancing direction of a linearly polarized laser source, wherein the diaphragm is positioned on the back focus and the front focus of the first collimating lens; a second collimating lens and a synchronous phase shifter are sequentially arranged in a direction perpendicular to the beam advancing direction of the beam splitter; the beam having a surface to be detected on the linearly polarized laser source passes through the emergent direction of the birefringent thin-film standard lens; the birefringent thin-film standard lens is a standard flat panel and has an antireflection film on the incident surface of the standard flat panel and a birefringent thin film and an antireflection film on the emergent surface; and the birefringent thin film has a phase delay of 90 DEG. The synchronous phase-shifting Fizeau interferometer has the advances of no principle return error, long measurement distance, simple structure and easy operation.

The invention discloses a novel spherical absolute measurement system and a method thereof, wherein the system comprises a computer, a light source, a light splitting unit, a filter, a standard object lens, a measured spherical reflecting mirror, an electro-control translation stage and a data acquisition and transmission unit; the method comprises the steps of: at first, adjusting the confocal location of the measured spherical reflecting mirror on the standard object lens by the electro-control translation stage, controlling a Fizeau interferometer by the computer to perform surface detection on the measured spherical reflecting mirror once and then storing the detection data in the computer, then controlling the electro-control translation stage by the computer to enable the measured spherical reflecting mirror to generate, around the focal point, confocal shears of lambda y and lambda y in relation to an optical axis of the interferometer, and using the interferometer to perform two detections respectively and storing the detection data of the two detections in the computer, and separating the surface data of the measured spherical reflecting mirror from errors of system and reference surface by data processing software in the computer among the three detected surface data so as to obtain the absolute surface information of the measured optical mirror surface.

The time delay (and therefore the OPD) between object and reference beams in an interferometer is manipulated by changing the spectral properties of the source. The spectral distribution is tuned to produce a modulation peak at a value of OPD equal to the optical distance between the object and reference arms of a Fizeau interferometer, thereby enabling the use of its common-axis configuration to carry out white-light measurements free of coherence noise. Unwanted interferences from other reflections in the optical path are also removed by illuminating the object with appropriate spectral characteristics. OPD scanning is implemented without mechanical means by altering the source spectrum over time so as to shift the peak location by a predetermined scanning step between acquisition frames. Finally, the spectrum is controlled on a pixel-by-pixel basis to create a virtual surface that matches the profile of a particular sample surface.

The invention provides a large-diameter paraboloidal mirror detecting system, comprising a Fizeau interferometer, a high precision plane reflector, a detected paraboloidal mirror, an electrically controlled translation platform and a computer control system, wherein, the plane deflector realizes autocollimation detection to the central part of the paraboloidal mirror, and then the plane deflector is removed; the electrically controlled translation platform is controlled through the computer to move the Fizeau interferometer, so that reference spheric wave fronts of different curvature radiuses generated by a standard lens can be matched with a corresponding annular region outside the diameter of the plane deflector of a detected paraboloid, and phase data corresponding to resolvable interference fringes can be extracted through Fizeau interferometer data processing software on the computer system; acquired sub-aperture test data can be processed by the annular sub-aperture 'stitching' algorithm, and data acquired from the autocollimation detection of the plane deflector undergoes a full aperture wave front reconstruction to acquire surface shape information of the detected paraboloid. The large-diameter paraboloidal mirror detecting system provides an effective detecting means for the development of a large-diameter paraboloidal mirror and an ultra-large-diameter paraboloidal mirror, and has higher application value.

The invention provides a multiscale quasi-distributed white light interferometric strain measurement device adopting common path compensation and a method thereof. The measurement device comprises a wide band light source, an optical fiber circulator, an adjustable Fizeau interferometer, a lead-in / lead-out optical fiber, an optical fiber sensor array, a photoelectric detector, a band-pass filter and a signal processing unit, wherein the adjustable Fizeau interferometer is composed of a gradient index lens and a movable scanning mirror, the distance between the two devices can be adjusted; the four ports of the optical fiber circulator are separately connected with the wide band light source, the adjustable Fizeau interferometer, the lead-in / lead-out optical fiber and the photoelectric detector closkwise; the other end of the lead-in / lead-out optical fiber is connected with the optical fiber sensor array; and the output end of the photoelectric detector is connected with the signal processing unit through the band-pass filter. By adopting the device and method of the invention, the multiscale quasi-distributed complete common-path optical path matching can be realized; the luminous power attenuation and loss can be reduced, the detectivity can be increased; and the optical structure of the optical system can be simplified, the cost can be reduced and the stability and reliability can be increased.

The invention relates to the technical field of real-time quantitative test and analysis of a surface microstructure in the process of crystal growth by a solution method in the 3-D direction and belongs to a method of real-time observation of water-soluble crystal and organic crystal growing surface microstructures by adopting a laser digital phase-shifting interferometer system device. The invention is characterized in that a Fizeau interferometer is introduced into an interference light path; one of two reference plane mirrors in the Fizeau interferometer is replaced by a growing crystal surface so as to ensure laser reflected by the reference plane mirrors and the growing crystal surface to interfere so as to lead interference fringes to contain information of the crystal growing surface; phase shifting interferometry is applied to extract the information of the crystal growing surface structure and then contour maps and three dimensional perspective images of the crystal growing surface are obtained by computation and analysis of computer software to realize real-time observation. The method has simple and reliable working principle, high degree of automation of used equipment, good real-time observation effect and strong image intuition, which particularly can convert the process of crystal growth to display information in omni direction.

The time delay (and therefore the OPD) between object and reference beams in an interferometer is manipulated by changing the spectral properties of the source. The spectral distribution is tuned to produce a modulation peak at a value of OPD equal to the optical distance between the object and reference arms of a Fizeau interferometer, thereby enabling the use of its common-axis configuration to carry out white-light measurements free of coherence noise. Unwanted interferences from other reflections in the optical path are also removed by illuminating the object with appropriate spectral characteristics. OPD scanning is implemented without mechanical means by altering the source spectrum over time so as to shift the peak location by a predetermined scanning step between acquisition frames. The invention and its advantages are applicable to optical coherence tomography as well as conventional white light interferometry.

A Fizeau interferometer apparatus is used for both low and high interference measurement. When irradiating a reference surface and a sample with a low coherent luminous flux, a path-matching passage divides the low coherent luminous flux into first and second paths, while the optical path length difference between the respective luminous fluxes passed through the two paths equals twice the optical distance between the reference surface and the sample. When irradiating the reference surface and the sample with a high coherent luminous flux, the luminous flux is made incident on the sample side of the path-matching passage at a position coaxial with the low coherent luminous flux.

A method of manufacturing an optical element involves an interferometric test of the optical element using an interferometer system of a Fizeau type combined with principles of white-light interferometry. The optical element is disposed in a cavity between a Fizeau surface and a mirror, and an optical path difference between a back surface of the optical element and the mirror is determined for determining parameters of the optical element, such as a thickness thereof. Measuring light from an optical delay apparatus can be supplied to the Fizeau interferometer through an optical fiber.

The invention discloses a flatness absolute checking method based on oblique incidence. In the method, three groups of wave surface data are obtained by the cavity interference of a Fizeau interferometer and twice oblique incidence measurement; wave surfaces are fitted by using a Zernike polynomial; and the absolute surface shape distribution of the whole plane is obtained by solving a rotating invariant and a rotating dependent variable of the surface to be detected. The invention simplifies the measuring step and shortens the measuring time and can obtain the absolute surface shape distribution of the plane to be detected only by measuring three times without disassembling and assembling a reference transmitting plane and is especially suitable for the surface shape absolute check of a high-reflectivity optical plane.

A wavelength scanning three dimensional morphology measurement system of optical frequency comb reference comprises an optical frequency comb reference tunable light source module and a Fizeau interferometer module, the optical frequency comb reference tunable light source module comprises a femtosecond optical frequency comb, a wavemeter, a tunable laser and a beat frequency detection and locking feedback module, and the femtosecond optical frequency comb provides the optical frequency reference capable of tracing back to an atomic clock. According to the present invention, a set of tunable light source system which can is tunable in a large range and has the very high frequency stability, is realized, a measurement error caused by the light source frequency stability is reduced substantially, and by introducing a Fourier transform phase measurement method in the Fizeau interferometer module, the measurement time is reduced, and the phase measurement precision is improved. The wavelength scanning three dimensional morphology measurement system of the present invention can measure the three dimensional morphology of the surface of an object accurately, does not have the strict requirements and limit for the height variation of the object, realizes the comprehensive measurement precision not more than 20 nanometers, and has the stronger versatility.

The invention relates to a detection device of off-axis parabolic mirror surface shape precision. The detection device is composed of a Fizeau interferometer, a standard spherical mirror, an auxiliary concave spherical column, a base disc, a five-dimensional adjusting frame, a standard plane mirror, a two-dimensional adjusting frame, a supporting fixing bottom plate, a first base and a second base; the Fizeau interferometer is provided with the standard spherical mirror; the standard spherical mirror is a light beam output window of the Fizeau interferometer; the base disc is located below the Fizeau interferometer; the base disc is provided with an off-axis parabolic mirror to be detected and the auxiliary concave spherical column; the base disc is located at the top surface of the five-dimensional adjusting frame; the standard plane mirror is arranged at the bottom surface of the two-dimensional adjusting frame; and the two-dimensional adjusting frame is located above the off-axis parabolic mirror to be detected. With the detection device of the off-axis parabolic mirror surface shape precision of the invention adopted, the surface shape precision of the off-axis parabolic mirror can be accurately and quickly detected.

The tilted relationship between the reference and test mirrors (24,26) of a Fizeau interferometer is used to spatially separate the reflections (R,T) from the two surfaces. The separate beams (R, T) are filtered through a spatial polarization element (32) that provides different states of polarization to the beams. The beams (R,T) are subsequently recombined to form a substantially collinear beam that is processed using a spatial-phase-shift interferometer (44) that permits quantitative phase measurement in a single video frame. Alternatively, two beams (104,106) with orthogonal polarization are injected into the Fizeau cavity (20) at different angles, such that after reflection from the reference and test optics (24,26) they are substantially collinear. Unwanted reflections are blocked at the focal plane through the use of a circular aperture (112). Short coherence length light and a delay line (84) may be used to mitigate stray reflections, reduce measurement integration times, and implement temporal phase averaging.

The invention provides a device and a method for measuring the thermal distortion of a polarized beam splitter mirror. The device comprises a solid laser, a focusing lens, an energy optical fiber, an optical fiber shaping lens group, a beam splitter prism, a transmission plane mirror, a polarized beam splitter mirror, a zero-degree color filter, an attenuation light filter, a Fizeau interferometer and a computer, wherein the laser emitted from the solid laser is coupled to the energy optical fiber through the focusing lens, transmitted into a measuring room through the energy optical fiber, and is further radiated to the surface of the polarized beam splitter mirror in a theta angle through the optical fiber shaping lens group and the beam splitter prism; and the light emitted from the Fizeau interferometer is vertically radiated to the polarized beam splitter mirror through the light attenuation light filter and the zero-degree color filter. The device for measuring the thermal distortion of the polarized beam splitter mirror has the characteristics of simple structure, good stability and strong interference resistance, wavefront distortion of an optical film element under a laser radiation can be measured without contact, and moreover, the measurement can be carried out in continuous, single pulse or repeated pulse laser radiation.

The invention provides a device capable of judging the optical wave deformation direction in an optical homogeneity test with low cost. The optical glass optical homogeneity test device comprises a Fizeau interferometer. A direction determining standard sample is disposed between a beam splitter and a reflector on the Fizeau interferometer. The invention directly arranges the direction determining standard sample between the beam splitter and the reflector on the Fizeau interferometer. The device has the advantages of simple structure, convenient maintenance, low cost and convenient test method and is in particular suitable to test of the large optical glass.

The time delay (and therefore the OPD) between object and reference beams in an interferometer is manipulated by changing the spectral properties of the source. The spectral distribution is tuned to produce a modulation peak at a value of OPD equal to the optical distance between the object and reference arms of a Fizeau interferometer, thereby enabling the use of its common-axis configuration to carry out white-light measurements free of coherence noise. Unwanted interferences from other reflections in the optical path are also removed by illuminating the object with appropriate spectral characteristics. OPD scanning is implemented without mechanical means by altering the source spectrum over time so as to shift the peak location by a predetermined scanning step between acquisition frames. Finally, the spectrum is controlled on a pixel-by-pixel basis to create a virtual surface that matches the profile of a particular sample surface.

An optical device for characterizing a test surface combines a Fizeau interferometer with a polarization frequency-shifting element. Two substantially collinear, orthogonally polarized beams having respective frequencies differing by a predetermined frequency shift are generated by the polarization frequency-shifting element and projected into the Fizeau optical cavity to produce a pair of test beams and a pair of reference beams, wherein the beams in each pair have orthogonal polarization states and have frequencies differing by the predetermined frequency shift. A second, substantially equal frequency shift is introduced in the Fizeau cavity on either one of the pairs of test and reference beams, thereby generating a four-beam collinear output that produces an interferogram without tilt or short-coherence light. The invention may also be implemented by reversing the order of the Fizeau cavity and the polarization frequency-shifting element in the optical train.

The invention discloses an optical heterogeneity measurement device and method based on a dual wavelength fizeau interferometer. With the dual wavelength fizeau interferometer, interferograms of a reference light wave and a light wave reflected by the front surface of a to-be-tested flat mirror are sequentially collected, and wavefront aberration data [delta]W11(x,y) and [delta]W21(x,y) corresponding to wavelengths [Lambda]1 and [Lambda]2 are obtained by first phase shift measurement; interferograms of the reference light wave and a light wave passing through the to-be-tested flat mirror and reflected by the rear surface of the to-be-tested flat mirror are collected, and wavefront aberration data [delta]W12(x,y) and [delta]W22(x,y) corresponding to the wavelengths [Lambda]1 and [Lambda]2 are obtained by phase shift measurement; and a difference value is calculated by the wavefront aberration data corresponding to the wavelengths obtained by two-stepped measurement, and the optical heterogeneity of the to-be-tested flat mirror is obtained. The invention does not require a standard reflector, and completely eliminates influences of the surface shape of the standard reflector on measurement results. The measurement steps are simple, and the defects that the traditional absolute measurement method has tedious steps and is vulnerable to air disturbance are tackled.

The invention relates to a Fizeau interferometer with simultaneous phase shifting. Reflections (R, T) from two surfaces are separated by the inclining relation between referring and testing lenses (24, 26) of the Fizeau interferometer in space; the separated light beams (R, T) are filtered through a space polarization element (32) which provides different polarization states for the separated light beams (R, T); the separated light beams (R, T) are combined again later to form an approximately collinear light beam, and the collinear light beam is processed by a space phase interferometer (44) which is permitted to carry out quantitative phase measurement in a single video frame. The Fizeau interferometer is selectively provided with two orthorhombic and polarized light beams (104, 106) which enter a Fizeau cavity (20) at different angels so as to be approximately collinear after being reflected from the referring and testing lenses (24, 26). Needless reflections are obstructed on a focal plane by utilizing a circular hole (112), and light with short coherence length and a delay line (84) can be used for reducing scattering, decreasing measuring integral times and carrying out temporary phase average.

The invention discloses a compound-system Doppler anemometry laser radar. The laser radar is the compound-system Doppler anemometry laser radar in which a coherent detection method and a direct detection method are combined. The laser radar can be used for the fields of laser detection, atmosphere detection and photoelectric detection, and the technology is different from the stripe imaging technology based on a Fiso interferometer and adopted by ALADIN at low altitude and the double-edge technology based on a Fabry-Perot etalon and adopted at high altitude. According to the technical scheme,a coherent detection method is adopted at the low altitude and the direct detection method is adopted at the high altitude for measuring a wind field, wind field detection coverage at the height of 0-30 km, the advantage of high background noise resistance of the coherent detection technology can be fully exerted in low-altitude detection, detection under the shot noise extreme can be achieved, and the advantage of higher detection precision is achieved.

The invention provides a sectorial off-axial aspheric surface stitching measurement system, comprising a Fizeau interferometer, a detected sectorial off-axial aspherical mirror, an electrically controlled translation platform and a computer control system, wherein, the electrically controlled translation platform is controlled through the computer to move the Fizeau interferometer, so that reference spheric wave fronts of different curvature radiuses generated by a standard lens can be matched with a sectorial region corresponding to the detected sectorial off-axial aspheric surface, and phase data corresponding to resolvable interference fringes can be extracted through data processing software of the Fizeau interferometer installed on the computer system; acquired sub-aperture test data undergo a full aperture wave front reconstruction by an expanded annular sub-aperture 'stitching' algorithm, thereby acquiring surface shape information of the detected aspheric surface. The sectorial off-axial aspheric surface stitching measurement system can realize low cost detection for the sectorial off-axial aspheric surface of appropriate deviation without a special auxiliary optical element, and has higher application value.

An optical device for characterizing a test surface combines a Fizeau interferometer with a polarization frequency-shifting element. Two substantially collinear, orthogonally polarized beams having respective frequencies differing by a predetermined frequency shift are generated by the polarization frequency-shifting element and projected into the Fizeau optical cavity to produce a pair of test beams and a pair of reference beams, wherein the beams in each pair have orthogonal polarization states and have frequencies differing by the predetermined frequency shift. A second, substantially equal frequency shift is introduced in the Fizeau cavity on either one of the pairs of test and reference beams, thereby generating a four-beam collinear output that produces an interferogram without tilt or short-coherence light. The invention may also be implemented by reversing the order of the Fizeau cavity and the polarization frequency-shifting element in the optical train.

The time delay (and therefore the OPD) between object and reference beams in an interferometer is manipulated by changing the spectral properties of the source. The spectral distribution is tuned to produce a modulation peak at a value of OPD equal to the optical distance between the object and reference arms of a Fizeau interferometer, thereby enabling the use of its common-axis configuration to carry out white-light measurements free of coherence noise. Unwanted interferences from other reflections in the optical path are also removed by illuminating the object with appropriate spectral characteristics. OPD scanning is implemented without mechanical means by altering the source spectrum over time so as to shift the peak location by a predetermined scanning step between acquisition frames. The invention and its advantages are applicable to optical coherence tomography as well as conventional white light interferometry.

The present invention relates to a spectral domain optical coherence tomography apparatus having an endoscopic small-sized probe, and more particularly, to a technology imaging an external shape or an internal structure of a sample by a non-contact and non-invasive method by applying an optical coherent fiber bundle probe attached with a lens to Michelson interferometer or a Fizeau interferometer.