Abstract: Techniques include converting an original or source image into a computer image file that uses guide curves to provide for a cutting of that image onto a surface of a material. One or more techniques comprise a process of converting the image into a computer image file, such as by pixelating or rasterizing the image. The process then controls a CNC knife to cut the surface of the material at different locations, different angles, different depths, and different range of motion, based on the processing of the computer image file, thereby creating the original image, or a very close replica, on the surface of the material. By deviating the cut lines from each other, the intensity of the image can be varied.

Abstract: A optical measurement apparatus includes: an optical system which generates a pupil image of a measurement target, using light; a polarization generator which generates a polarized light from the light; a self-interference generator which generates a plurality of beams divided from the pupil image, using the polarized light, and causes the plurality of beams to interfere with each other to generate a self-interference image; and an image analysis unit configured to extract phase data from the self-interference image, and to move the measurement target to a focus position on the basis of the phase data.

Abstract: Disclosed are a distance image acquisition apparatus and a distance image acquisition method capable of achieving high distance measurement accuracy and omitting wasteful imaging or calculation. The distance image acquisition apparatus (10) includes a distance image sensor (14), a drive mode setting unit (20A), a distance image generation unit (20B), a pulse light emission unit (22), and an exposure control unit (24). The exposure control unit (24) controls emission and non-emission of pulse light emitted from the pulse light emission unit (22) according to a drive mode set by the drive mode setting unit (20A), and controls exposure in the distance image sensor (14). The distance image generation unit (20B) performs calculation processing of a sensor output acquired from the distance image sensor (14) according to the drive mode set by the drive mode setting unit (20A) to generate a distance image corresponding to a distance of a subject.

Abstract: An optical system for measuring a parallelism of rays of a light emitter and virtual imaging distances (VIDs) of the light emitter, the optical system including an enclosure, a pair of apertures, and a lens system disposed between the front and rear end of the enclosure, wherein a first and second of the apertures allows a first and second set of rays into the enclosure to be disposed through the optical lens system to be cast on an imaging plane as a first and second spot, respectively, wherein a parallelism of the sets of rays is based on a correspondence of a distance between the spots with a distance between sets of rays and a VID of the light emitter is based at least in part on an offset of the imaging plane from the lens system focus position when the light emitter is not optically disposed at infinity.

Abstract: A spectrometry device 1 includes: a collimating optical system 15 configured to collimate object light from a measurement point a on a sample S; a photodetector 21 having a light-receiving face in which a plurality of pixels are arrayed in a predetermined direction; a conjugate plane imaging optical system 11 provided between the sample and the collimating optical system to form a plane optically conjugate with respect to a surface of the sample; an amplitude-type diffraction grating 1 disposed on the conjugate surface and having a light incident face on which the object light is incident or a light emission face from which the object light is emitted, the light incident face or the light emission face being formed by a light-shielding member made of a material having a light shielding rate higher than that of silicon in a wavelength band of the object light and provided with a plurality of openings, an optical path length differentiating optical system 16 configured to divide collimated object light into a f

Abstract: A system for evaluating the surface of a tire (10) comprises: a region (21) for entry of the tire into the system, a capture region, and an exit region (22), distinct from the entry region, means for moving (23) and for holding a tire in position, means for illuminating the tire allowing the illumination of a sidewall of the tire and of the crown of a tire in the capture region, means for acquiring a visual image of the tire in the capture region, and means for processing the acquired image, at least one acquisition means being installed on a shaft that is movable with respect to the tire installed in the capture region.

Abstract: A method for 3D surface imaging of an object, comprising generating a sinusoidal pattern from an input beam; projecting the sinusoidal pattern onto the object; acquiring deformed structured images from the object; reconstructing and displaying the surface of the object in real-time. A system comprises an device encoding an input beam with a structured pattern; a filter configured to spatially filter the encoded beam; a projector lens projecting the structured pattern onto the object; a high speed camera acquiring a structured pattern deformed by the 3D surface of the object; a graphic processing unit; and a CoaXPress interface transferring data acquired by the camera to the graphic processing unit; the graphic processing unit reconstructing and displaying the 3D surface of the object in real-time.

Abstract: A system for providing a virtual distance of a device under test, the system including a light source, a wedge shear plate including a first surface, a second surface and a wedge angle, wherein the second surface is disposed at the wedge angle with respect to the first surface and the wedge shear plate is configured to be disposed between the device under test and the light source, a first detector configured for receiving a first interference pattern formed as a result of the light source being disposed through and reflected by the first surface and the second surface of the wedge shear plate and a second detector configured for receiving a second interference pattern formed as a result of the light source being disposed through and reflected by the first surface and the second surface of the wedge shear plate.

Abstract: The present disclosure relates to methods for evaluating features of objects such as liquid droplets and surfaces. More particularly, the present disclosure relates to methods for measuring features such as the contact angle and the thickness of an object such as a liquid droplet or a fingerprint as well as related compositions for evaluation.

Abstract: A simultaneous phase-shift point diffraction interferometer and method for detecting wave aberration. The interferometer comprises an ideal spherical wave generation module, an optical system to be measured, an image plane mask, a polarization phase shift module, a two-dimensional polarization imaging photodetector and a data processing unit. Single photodetector is adopted to realize simultaneous detection of more than three phase shift interference patterns, and has the advantages that environmental interference suppression, a flexible optical path, high measurement accuracy, and calibration of system errors of the interferometer may be realized.

Abstract: An interference imaging device includes a light interference generator that includes: a light wave splitter configured to reflect a part of incident light and to allow a remaining part of the incident light to pass through; a phase modulator configured to modulate a phase of incident light that has passed through the light wave splitter; and a reflector configured to reflect the phase-modulated incident light from the phase modulator so that the reflected, phase-modulated incident light overlaps with incident light that has been reflected by the light wave splitter.

Abstract: This interference image imaging apparatus includes a first optical member (21) and a second optical member (22), and has a first portion (8) for transmitting a first bundle of rays (7) to change a direction of outgoing light with respect to incident light, and a second portion (10) for changing a phase of second bundle of rays (9) with respect to the first bundle of rays (7).

Abstract: Methods and systems for detecting and classifying defects based on the phase of dark field scattering from a sample are described herein. In some embodiments, throughput is increased by detecting and classifying defects with the same optical system. In one aspect, a defect is classified based on the measured relative phase of scattered light collected from at least two spatially distinct locations in the collection pupil. The phase difference, if any, between the light transmitted through any two spatially distinct locations at the pupil plane is determined from the positions of the interference fringes in the imaging plane. The measured phase difference is indicative of the material composition of the measured sample. In another aspect, an inspection system includes a programmable pupil aperture device configured to sample the pupil at different, programmable locations in the collection pupil.

Abstract: An interference image acquisition apparatus includes a light source, a beam splitter, a second reflection mirror, an imager, and a first reflection mirror. A cell is placed on one side of a transparent material, and the first reflection mirror is placed on the other side of the transparent material. In a two-beam interferometer, an optical path difference between an optical path length of a first light beam reflected by the first reflection mirror and an optical path length of a second light beam reflected by the second reflection mirror is set to a coherence length of light output from the light source or less. The imager acquires an interference image in a state in which the cell is placed at a position conjugate to an imaging plane in a first optical system between the imaging plane and the first reflection mirror.

Abstract: A device is provided for determining an orientation of an optical device of a coherence tomograph. The device has an optical reference geometry, a deflection optics configured to direct an optical measuring beam reflected by the optical device onto the optical reference geometry, and an evaluation unit configured to determine a distance between a first reference plane and at least one second reference plane of the optical reference geometry in order to determine the orientation of the optical device.

Abstract: A measurement system includes a light source configured to emitting a source light, a detection platform configured to support a reference sample and a test sample; a light guiding element on an optical path of the source light; and a detector. The detection platform is configured to synchronously move the reference sample and the test sample on a same surface of the detection platform. The light guiding element is configured to divide the source light into a measurement light and a reference light and guide the measurement light to the test sample, and the reference light to the reference sample. The measurement light reflected by the test sample and the reference light reflected by the reference sample are combined as an interference light. The detector is configured to receive the interference light and obtain optical information of the test sample according to the interference light.

Abstract: A computer-implemented method for identifying mechanical parameters of an object subjected to mechanical stress is provided. The method comprises a step of acquiring, by an imaging means, images of the object taken before and during the application of the mechanical stress, three steps of calculating the effects due to the stress carried out either on the basis of the modeling of the recorded images or on the basis of a theoretical mechanical modeling of the stress, a step of defining a functional equal to the difference between the two models and a last step of minimizing said functional so that the experimental model is as close as possible to the theoretical mechanical model. Additional measurements make it possible to refine the method.

Abstract: Systems and methods for computationally simulating and optimizing shearography systems are provided. The systems and methods for simulation and optimization avoid ray tracing, and, instead, implement a phase screen approach to image computation. The systems and methods include physics-based surface texture and surface motion simulations, the application of phase screens to computer-generated simulations of shearographic remote sensing, and the inclusion of de-polarization due to multiple scattering and birefringence at a surface being imaged. The systems and methods include further greatly optimize diffraction computations by treating an optical transfer function (OTF) of an arbitrary aperture as a sum of separable OTFs.

Abstract: A laser shearography testing system for non-destructively testing a component includes a component heating sub-system coupled to the component. The component heating sub-system excites the component into a loaded state by passing an electric current through the component. A resistivity of the component causes the component to internally and uniformly heat as the electric current passes through the component.

Abstract: Auto-alignment beam tracking apparatus and methods. In one example, an auto-alignment beam tracking system includes an optical train that receives an auto-alignment beam, a linear detector array including a plurality of photosensitive detectors each configured to measure intensity of electromagnetic radiation incident thereon, and a lateral shearing interferometer positioned between the optical train and the linear detector array. The optical train is configured to direct the auto-alignment beam to the lateral shearing interferometer. The lateral shearing interferometer is configured to produce an interference pattern at the linear detector array from the auto-alignment beam, wherein changes in the intensity measured by the plurality of photosensitive detectors over time corresponding to a lateral shift of the interference pattern on the linear detector array indicate an angular tilt of the auto-alignment beam.

Abstract: Interference fringes in a bullseye pattern are produced by a measurement module by interfering a flat reference beam with a spherical beam reflected by a sphere connected to the tip of a probe in point contact with a test object. The bullseye interferogram is registered at a detector and analyzed conventionally to produce a position measurement of the tip of the probe. A beam correction module is used to align the bullseye interferogram with the illumination axis of the measurement module. By combining at least three such measurement modules in a coordinate measurement machine, the three-dimensional position of the probe and of its point contact with the test object can be obtained from analysis of the bullseye interferograms registered by the detectors with high precision and greatly reduced Abbe error.

Abstract: A collimation evaluation device includes a first reflection member, a second reflection member, a screen, and a housing. A first reflection surface of the first reflection member and a first reflection surface of the second reflection member face each other and are parallel to each other. Further, interference fringes are formed on the screen by light L12 reflected on the first reflection surface of the first reflection member and a second reflection surface of the second reflection member and light L21 reflected on a second reflection surface of the first reflection member and the first reflection surface of the second reflection member, and collimation of incident light is evaluated on the basis of a direction of the interference fringes.

Abstract: A first reflection member, when light is incident, reflects a part of the light by a first reflection surface, reflects light transmitted through the first reflection surface by a second reflection surface, and emits reflected light components in an opposite direction. The second reflection member, when light emitted from the first reflection member is incident, reflects a part of the light by a first reflection surface, reflects light transmitted through the first reflection surface by a second reflection surface, and emits reflected light components. Interference fringes are formed on a screen by light reflected on the first reflection surface of the first reflection member and the second reflection surface of the second reflection member and light reflected on the second reflection surface of the first reflection member and the first reflection surface of the second reflection member.

Abstract: An example system determines biomechanical properties of eye tissue. The system includes a confocal microscopy system configured to scan the incident light across a plurality of cross-sections of the tissue. The incident light is reflected by the plurality of cross-sections of tissue as scattered light. The system includes a spectrometer to receive the scattered light and provide spectral information for the scattered light. The system includes processor(s) to determine a Brillouin frequency shift from the spectral information and to generate a three-dimensional profile of the corneal tissue according to the Brillouin frequency shift. The three-dimensional profile provides an indicator of one or more biomechanical properties of the tissue. The spectrometer includes a multipass optical device that generates an interference pattern from the scattered light. The interference pattern provides the spectral information for the scattered light.

Abstract: A method for optically acquiring a wind turbine for monitoring purposes with the aid of an aircraft, in particular a manned or unmanned rotorcraft, which has at least one camera installed thereon, wherein the wind turbine comprises a plurality of rotor blades, the surface of which is scanned within the scope of the method.

Abstract: A pulse compressor for compressing a laser pulse in a laser device using a chirped pulse amplification method includes two identically shaped diffraction gratings arranged parallel to each other with their respective grating surfaces facing each other and a total reflection mirror for receiving a laser pulse through the diffraction grating and returning it back to the same gratings. Each diffraction grating is a reflective blazed diffraction grating having grooves with a sawtooth-shaped section covered with a reflective Au coating on their surface, with the blaze angle determined so that, at the wavelength of the laser pulse to be used, the incident angle of a laser pulse entering the pulse compressor and first order diffracted light form a relationship of mirror reflection with the groove slope and so that a predetermined level of diffraction efficiency is obtained.

Abstract: A system and method are presented for generating shearograms from raw specklegram images which may, for example, be collected from airborne or other mobile shearography equipment. The system and method is used to detect and characterize buried mines, improvised explosive devices (IEDs), and underground tunnels, bunkers, and other structures. Amongst other purposes, the system and method may also be used for rapid scanning of ship hulls and aircraft for hidden structural defects, rapid pipeline inspection, and non-contact acoustic sensing for in-water and underground sources.

Abstract: The invention relates to a deformable mirror comprising a deformable membrane (2) having a reflecting face (3) and being mounted on a support provided with at least one actuator designed to deform said membrane (2), said actuator comprising at least one movable member (7) fixed to the membrane (2) via an adhesive joint (8) and having a main body (11) located away from the adhesive joint (8), said body being extended by an active part (12) that penetrates said adhesive joint (8) partly or completely in such a way that the adhesive spreads over the concealed face (4), parallel to the reflecting face (3), and adheres at least partly to the side wall (14) of said active part (12), this part (12) forming a tip (32) limiting the bonding footprint on said reflecting face (3). Deformable mirror for adaptive optics.

Abstract: Polarization-based coherent gradient-sensing systems and methods for measuring at least one surface-shape property of a specularly reflective surface are disclosed. The method includes: reflecting a first circularly polarized laser beam from a sample surface to form a second circularly polarized laser beam that contains surface-shape information; converting the second circularly polarized laser beam to a linearly polarized reflected laser beam; directing respective first and second portions of the linearly polarized reflected laser beam to first and second relay assemblies that constitute first and second interferometer arms. The first and second relay assemblies each use a pair of axially spaced-apart gratings to generate respective first and second interference patterns at respective first and second image sensors. Respective first and second signals from the first and second image sensors are processed to determine the at least one surface-shape property.

Abstract: The present invention includes an illumination source, at least one illumination symmetrization module (ISM) configured to symmetrize at least a portion of light emanating from the illumination source, a first beam splitter configured to direct a first portion of light processed by the ISM along an object path to a surface of one or more specimens and a second portion of light processed by the ISM along a reference path, and a detector disposed along a primary optical axis, wherein the detector is configured to collect a portion of light reflected from the surface of the one or more specimens.

Abstract: In one embodiment, a method comprises projecting, from a projector, a diffused on an object. The method further includes capturing, with a first camera in a particular location, a reference image of the object while the diffused is projected on the object. The method further includes capturing, with a second camera positioned in the particular location, a test image of the object while the diffused is projected on the object. The method further includes comparing speckles in the reference image to the test image. The projector, first camera and second camera are removably provided to and positioned in a site of the object.

Abstract: Some systems described herein include a frequency dependent phase plate for generating multiple phase-contrast images of a sample, each from a different frequency range of light, each phase-contrast image for frequency range of light formed from light diffracted by the sample interfered with undiffracted light that has a frequency-dependent baseline relative phase shift from the phase plate. In some embodiments, the multiple phase-contrast images may be used to generate a quantitative phase image of a sample. The phase-contrast images or the produced quantitative phase image may have sufficient contrast for label-free auto-segmentation of cell bodies and nuclei.

Abstract: A communication network, wherein the network includes a plurality of communication elements that function as transmitters and/or receivers, in particular base stations and operating nodes being associated to at least one of the base stations, wherein the communication between the transmitters and the receivers is performed by way of generating and transmitting signals based on a multi-carrier modulation with a number of N subcarriers around a carrier frequency fc, is characterized in that the communication elements are configured to perform, upon receiving a transmitted signal, a sub-sampling of the received signal, wherein only a predetermined number of the inner-most subcarriers around the carrier frequency fc are employed for data reconstruction. Furthermore, a respective method for operating a communication network is described.

Abstract: Provided is an operating method of a measuring apparatus measuring a wavefront of a target. The operating method includes measuring a measurement wavefront on the basis of the wavefront of the target, measuring reference slope information and first to third slope information respectively corresponding to a reference direction and first to third directions on the basis of the measurement wavefront, obtaining first to third rotation angles on the basis of the measured reference slope information and first to third slope information, and outputting a wavefront of which an error is corrected, which is generated by rotation errors on the basis of the obtained first to third rotation angles, wherein the first to third rotation angles are differences in angle between the reference direction and the first to third directions.

Abstract: Methods and apparatus for pixel multiplication in optical imaging systems. In one example, an expanded optical point spread function, referred to as a code spread function, is used to phase modulate an incident electromagnetic wavefront, and digital processing, including correlation techniques, are used to filter and process the modulated wavefront to recover sub-pixel information from an image produced by the wavefront on a pixilated detector array.

Abstract: An arrangement and a method are provided for robust interferometry for detecting distance, depth, profile, form, undulation, flatness deviation and/or roughness or the optical path length in or on technical or biological objects, including in layered form, or else for optical coherence tomography (OCT), with a source of electromagnetic radiation and with an interferometer, in particular also in the form of an interference microscope, having an object beam path and having a reference beam path, in which an end reflector is arranged, and a line-scan detector for detecting electromagnetic radiation in the form of at least one spatial interferogram.

Abstract: A focusing device that includes a differential interference prism used in differential interference observation in a focusing detection optical system includes: a light source that emits light with which a measurement surface of an observation sample is irradiated; a photo detection unit that detects light from the measurement surface; a focusing detection unit that detects an error signal near a focusing point of the measurement surface on the basis of an output signal from the photo detection unit; and a condition changing unit that changes an acquisition condition of the error signal.

Abstract: A method for qualifying optics (16; 14, 16) of a projection exposure tool (10) for microlithography. The optics include (16; 14, 16) at least one mirror element (14-1 to 14-7, 16-1 to 16-6) with a reflective coating (52) disposed on the latter. The method includes: irradiating electromagnetic radiation (13, 42) of at least two different wavelengths onto the optics (16; 14, 16), a penetration depth of the radiation into the coating (52) of the mirror element varying between the individual wavelengths, taking an optical measurement on the optics (16; 14, 16) for each of the wavelengths, and evaluating the measurement results for the different wavelengths taking into consideration a respective penetration depth of the radiation into the coating (52) of the mirror element for each of the different wavelengths.

Abstract: The present invention relates to a portable industrial instrument for performing, in an integrated and two-way manner, an interferometric fringe projection and shearography, on a object to be tested, so that, when the two-way interferometer (1) is associated with the coherent or quasi-coherent projection device (2), the instrument is able to measure the 3D shape of the object by interferometric fringe projection, also known as moiré method, and, when the two-way interferometer (1) is associated with the recording or imaging device (4), the instrument is able to perform shearographic measurements on the object, the direction of the traversing light beam in the interferometer (1) being reversed when shifting from one measurement configuration to the other one.

Abstract: A tire inspection machine includes an incoming conveyor adapted to transport tires to the machine and also align the tires in a transverse direction. An inspection table of the machine includes a table conveyor system that is responsive to a controller. The table and table conveyor are together arranged to permit scanning of both sidewall portions of a tire disposed thereon. A sensor detects a longitudinal position of the tire and stops the table conveyor when the tire is longitudinally aligned. A controller operates the table conveyor based on the longitudinal position of the tire.

Abstract: A shearography system that operates while moving at significant speeds over a surface is disclosed. Two lasers are utilized and the distance between the two lasers is adjusted based on the altitude of the aircraft on which the shearography equipment is located, the speed of the aircraft, the distance between two lasers in the shearography equipment lasers, and the time difference between the laser pulses from each of the two lasers. The adjustment of the distance between the two lasers causes the angles of incidence and reflection to be the same for two sequential images and permits the moving shearography to work.

Abstract: A transmitted wavefront measuring method comprises the steps of emitting light 101 from a light source 100 onto an object to be measured 120 to receive interfering light transmitted through the object and a diffraction grating 130 on a light receiving portion 140 disposed at a predetermined distance from the diffraction grating to measure an intensity distribution of the interfering light T10, performing a Fourier transform of the intensity distribution to calculate a frequency distribution T20, and obtaining a transmitted wavefront of the object based on a primary frequency spectrum in the frequency distribution T30 to T90. The step of obtaining the transmitted wavefront comprises the steps of performing an inverse Fourier transform of the primary frequency spectrum with reference to a grating frequency of the diffraction grating to calculate a complex amplitude of the interfering light T60, and obtaining the transmitted wavefront based on the complex amplitude T90.

Abstract: An active imaging system includes a laser transmitter configured to emit light in a plurality of beamlets. A sensor is configured to receive light from the beamlets. A processor is communicably coupled to the sensor and configured to compute images of objects illuminated by the beamlets.

Abstract: The invention allows a shearography system to successfully sense ground/surface vibrations while moving at aircraft speeds and altitudes. This is done by effectively making stationary the apparent location of a coherent laser beam illuminating an area on the ground/surface, and also effectively making stationary the apparent location of the aperture of an optical receiver which acquires pairs of sequential images captured and used for shearography. A different laser is used for capturing each of the two images, and the distance between the two lasers is adjusted based on a number of operational parameters. The adjustment of the distance causes the apparent locations of the transmitter and a receiver sub-aperture to remain the same and permits the moving shearography to work.

Abstract: A method and apparatus for the remote nondestructive evaluation of an object such as a wind turbine blade involves applying mechanical and/or thermal stress to the object and then scanning the object using long-range thermographic and/or laser interferometric imaging. The laser interferometric imaging is preferably performed by a long range shearography camera capable of imaging deformation derivatives at long distances coupled with a blade stressing mechanism incorporating either thermal or internal blade pressurization for the purpose of detecting remotely and at high speed, changes in the structural integrity of an installed wind turbine blade.

Abstract: An interrogation apparatus and method use a partial shear optical interference apparatus to interrogate the optical properties of an array of target specimen probe volumes as compared to an array of reference sample probe volumes. The apparatus produces a formatted probe beam that contains a partially sheared probe beam pair that is formatted into an array of completely sheared probe beam pairs. Target specimen probe volumes and reference sample probe volumes are suitably organized and exposed to the array of completely sheared probe beam pairs.

Abstract: A method and apparatus for the remote nondestructive evaluation of an object such as a wind turbine blade involves applying mechanical and/or thermal stress to the object and then scanning the object using long-range thermographic and/or laser interferometric imaging. The laser interferometric imaging is preferably performed by a long range shearography camera capable of imaging deformation derivatives at long distances coupled with a blade stressing mechanism incorporating either thermal or internal blade pressurization for the purpose of detecting remotely and at high speed, changes in the structural integrity of an installed wind turbine blade.

Abstract: Systems configured to generate output corresponding to defects on a specimen and systems configured to generate phase information about defects on a specimen are provided. One system includes an optical subsystem that is configured to create interference between a test beam and a reference beam. The test beam and the reference beam are reflected from the specimen. The system also includes a detector that is configured to generate output representative of the interference between the test and reference beams. The interference increases contrast between the output corresponding to the defects and output corresponding to non-defective portions of the specimen.

Abstract: A method of flattening a deformable mirror (DM) such as a piezoelectric DM to correct for distortion includes inputting an incident light beam into a reference beam optical path while blocking the DM response, recording a flat wavefront (?n, R) as a reference wavefront from a reference mirror, blocking the reference beam to obtain a DM response, activating a close-loop mode of DM Control Software and computing iterations until a difference between the reference wavefront and the DM response is minimized, recording a wavefront created by the DM (?n, DM) and the corresponding voltage vector (Vn) applied to the DM; and applying a voltage vector to the DM to thereby flatten the DM and correct for the distortion. The method is useful in an application such as for ground-to-space links at Short Wave Infrared (SWIR) wavelengths.

Abstract: A wavefront-aberration-measuring device measures wavefront aberration of a to-be-tested optical system and includes a diffraction grating that splits light transmitted through the optical system, a detecting unit that detects interference fringes produced by beams of the split light, an arithmetic unit that calculates the wavefront aberration from the detected interference fringes, an image-side mask insertable into and retractable from an image plane of the optical system, and an illuminating unit that incoherently illuminates the image-side mask. The image-side mask has an aperture with a diameter larger than ?/2NA, where ? denotes a wavelength of the illuminating unit and NA denotes a numerical aperture of the to-be-tested optical system. The arithmetic unit calculates the wavefront aberration of the optical system from the interference fringes detected with the image-side mask being retracted from the image plane and the interference fringes detected with the image-side mask being in the image plane.