Abstract: The present disclosure provides a portable apparatus for detecting early crop diseases based on spatial frequency domain imaging. The apparatus includes an end cover, a spatial frequency domain imaging apparatus, a dark box body, a telescopic section, and an opening-and-closing apparatus connected in sequence. The detection method includes: putting a crop sample to be detected into the dark box body from a bottom; projecting structured light of sine grey scale patterns with different spatial frequencies to the crop sample; after the sine gray scale pattern is switched each time, acquiring, by a camera, a diffuse reflection image of a surface of the crop sample once; after capturing all diffuse reflection images, performing uniformity correction on the images, demodulating the images, and extracting an alternating current component; and inputting an alternating current component image to a trained disease detection model, and determining whether the crop sample has a disease.

Abstract: A method for providing an object distance of a device under test (DUT) using a system including a first lens, a second lens, an optical pinhole disposed between the first lens and the second lens, a detector, a pair of gratings disposed between the second lens and the detector, the detector configured for receiving a Moiré pattern formed as a result of light from of the DUT being disposed through the first lens, the optical pinhole, the second lens and the pair of gratings, the method including obtaining the Moiré pattern using the detector and determining the object distance based on the Moiré pattern and one or more properties of the pair of gratings.

Abstract: The present invention relates to a device for measuring an optical element comprising: a. a light source, b. a measurement structure which illuminated by the light of the light source and has areas of different transmissivity, c. an optical imaging system for converting light transmitted by the measurement structure into a collimated measuring beam which is directed onto the optical element, and d. a sensor for detecting a reflection of the measuring beam generated on the optical element for detecting a transmission of the measuring beam passing through the optical element. According to the invention the light source has a plurality of light segments, wherein the device further comprises a control unit which is designed for independently controlling the plurality of light segments. The invention further relates to a corresponding method for measuring an optical element.

Abstract: An optical system configured to measure a raised or receded surface feature on a surface of a sample may comprise a broadband light source; a tunable filter configured to filter broadband light emitted from the broadband light source and to generate a first light beam at a selected wavelength; a linewidth control element configured to receive the first light beam and to generate a second light beam having a predefined linewidth and a predetermined coherence length; collimating optics optically coupled to the second light beam and configured to collimate the second light beam; collinearizing optics optically coupled to the collimating optics and configured to align the collimated second light beam onto the raised or receded surface feature of the sample, and a processor system and at least one digital imager configured to measure a height of the raised surface or depth of the receded surface from light reflected at least from those surfaces.

Abstract: Disclosed is an apparatus for testing a camera module, and the apparatus for testing the camera module according to the disclosure includes a socket section configured to settle the camera module thereon; a movable unit-pattern chart lens section comprising a housing, a light source unit provided inside the housing and emitting light toward the camera module, and a chart disposed below the light source unit inside the housing and formed with a unit pattern; a first actuator configured to actuate the movable unit-pattern chart lens section; a second actuator configured to actuate the socket section; and a test image capturer configured to obtain a test image from images captured while actuating the movable unit-pattern chart lens section or the socket section based on actuation of the first actuator or the second actuator.

Abstract: A lens matching apparatus and a lens matching method are provided. In the method, respective modulation transfer function (MTF) values corresponding to multiple focus lengths of each lens are obtained, a maximum MTF value among the focus lengths of each lens is determined, and lenses are classified according to the maximum MTF value. Each MTF value is determined based on at least one first pixel having maximum light intensity and at least one second pixel having minimum light intensity. Accordingly, the lenses with the same clearness may be classified into the same group, so as to improve image-stitching and speed up the image-stitching.

Abstract: A Bayesian model for predicting spectacle independence of one or more IOLs based on pre-clinical data (e.g., visual acuity value for one or more defocus values) of an IOL. The Bayesian model is trained to assign appropriate weights for different combinations of defocus values.

Abstract: A method of characterizing an imaging system includes generating a plurality of point spread function (“PSF”) samples using the imaging system, each PSF sample representing a response of an imaging system to a point illumination source, each PSF sample comprising one or more pixel values. The method also includes co-registering the pixel values contained in each of the plurality of PSF samples to form an oversampled point spread function (“PSF”) population; resampling the oversampled PSF population to uniform spacing to form a PSF image; slicing the PSF image in an evaluation direction to form a slice of the PSF image; and evaluating the slice to determine a value of a resolution metric of the imaging system that is specific to the evaluation direction.

Abstract: A method of improving a network-based marketplace system with referral-service functionality is disclosed. One or more notifications are received from a client device of a first user of a plurality of users. The one or more notifications include an authorization from the first user to make a payment to complete a purchase of an item included in a listing posted on the network-based publication system. The one or more notifications also include a referral code associated with the authorization. The payment is received from the first user into a holding account. Based on the referral code, a second user of the plurality of users is identified as a referrer of the purchase. The payment is divided into a plurality of payments to be made to a seller of the item as a purchase fee and to be made to the referrer of the purchase as a referral fee.

Abstract: A system for producing an image includes a MW (microwave) transmitter, configured to transmit a MW towards an object, and a MW receiver, configured to detect a MW signal received from the object. A processor is programmed to produce an image of the object by compensating both phase shifts and amplitude losses for frequency dependency in a plurality of detected MW signals.

Abstract: A 3D test chart, an adjusting arrangement, a forming method, and an adjusting method thereof are disclosed. The 3D test chart provides a plurality of test patterns arranged at different depths. When testing a photographic arrangement, the photographic arrangement is only required to move for one time or even does not need to be moved, so as to obtain an image containing information of different depths, so that the testing and adjusting process of the photographic arrangement can be easily achieved.

Abstract: A hyperspectral imaging spectrophotometer and system, with calibration, data collection, and image processing methods designed to match human visual perception and color matching of complex colored objects.

Abstract: An example non-transitory machine-readable storage medium encoded with instructions executable by a processor is provided. The machine-readable storage medium includes instructions to identify fiducials on a target comprising multiple sample areas, instructions to determine positions of the fiducials in relation to the multiple sample areas, and instructions to detect a different region of interest (ROI) associated with each of the multiple sample areas based upon the positions. The machine-readable storage medium further includes instructions to calculate an optical performance metric based upon the ROI associated with each sample area, and instructions to determine a text resolution based upon the optical performance metric.

Abstract: A method for detecting defects in computer software code comprises: preprocessing a code to check; generating an SEG for the code to check, wherein the SEG includes nodes, data dependency edges and control dependency edges that connect the nodes, wherein, the nodes include value nodes and operator nodes, the value nodes including terminal value nodes representing unknown values or constants generated outside a function, and non-terminal value node representing values generated within the function, wherein each non-terminal value node is associated with a unique memory location, and wherein the data dependency edge is a directed edge connecting a value node to another value node that has a direct data dependency relationship with the value node, and traversing the SEG in a depth-first way backward from a null pointer node in a lowest level of the SEG and generating a bug report when a defect is found.

Abstract: To provide an image display device configured to more faithfully display a projection image on a region where a physical quantity change has occurred. An image display device of the present invention includes a flow rate sensor and a screen on which an image from a projector is projected, and a control is performed such that the image is projected on the screen so as to include a position of the flow rate sensor that has detected the physical quantity change, and the image changes corresponding to a measured value change of the flow rate sensor. Preferably, a plurality of the physical quantity detection units are disposed, and the control is performed such that the image changes corresponding to the measured value changes in the respective physical quantity detection units.

Abstract: A test system is provided. Said test system comprises a device under test, a measurement equipment, and a remote source simulator. In this context, the remote source simulator is adapted to simulate a remote video source, wherein the remote video source is adapted to transmit a video comprising at least one detection pattern to the device under test. Furthermore, the device under test is adapted to display the video. In addition to this, the measurement equipment is adapted to detect the at least one detection pattern with respect to the device under test and to determine the number of detection patterns having been received by the device under test.

Abstract: Hyperspectral imaging sensors that can readily switch between multiple common aperture imagers, and are more compact and lightweight than previous hyperspectral sensor designs.

Abstract: An optical inspection device includes: an LED; a chart; a collimator; and a mirror. The LED irradiates the chart with light to deliver light rays to the collimator as on-axis light rays. This allows a pattern on the chart to be projected onto a center of an image sensor through the collimator and an optical system under inspection. The mirror reflects light rays delivered to the mirror through the collimator among the on-axis light rays. This allows the pattern on the chart to be projected onto a periphery of the image sensor through the optical system under inspection.

Abstract: An apparatus, system, and method to characterize a focal plane array. The apparatus includes a speckle field source to generate and emit a plurality of uniform speckle fields, a diamond-shape aperture, and a pedestal to mount the focal plane array at a predetermined distance from the aperture. The diamond-shape aperture shapes the uniform speckle fields from the speckle field source so that the uniform speckle fields have a desired power spectral density at the focal plane array. The desired power spectral density has recoverable aliased regions out to two times the Nyquist frequency of the focal plane array. The system includes a controller to characterize, by computing a modulation transfer function, the focal plane array based on the desired power spectral density of the uniform speckle fields impinging on the focal plane array.

Abstract: Techniques using small form factor infrared imaging modules are disclosed. An imaging system may include visible spectrum imaging modules, infrared imaging modules, illumination modules, and other modules to interface with a user and/or a monitoring system. Visible spectrum imaging modules and infrared imaging modules may be positioned in proximity to a scene that will be monitored while visible spectrum-only images of the scene are either not available or less desirable than infrared images of the scene. Imaging modules may be configured to capture images of the scene at different times. Image analytics and processing may be used to generate combined images with infrared imaging features and increased detail and contrast. Selectable aspects of non-uniformity correction processing, true color processing, and high contrast processing, may be performed on the captured images. Control signals based on the combined images may be presented to a user and/or a monitoring system.

Abstract: Methods and systems for solving measurement models of complex device structures with reduced computational effort and memory requirements are presented. The computational efficiency of electromagnetic simulation algorithms based on truncated spatial harmonic series is improved for periodic targets that exhibit a fundamental spatial period and one or more approximate periods that are integer fractions of the fundamental spatial period. Spatial harmonics are classified according to each distinct period of the target exhibiting multiple periodicity. A distinct truncation order is selected for each group of spatial harmonics. This approach produces optimal, sparse truncation order sampling patterns, and ensures that only harmonics with significant contributions to the approximation of the target are selected for computation.

Abstract: A lens meter includes a measurement optical system that projects measurement light to a test lens, and receives the measurement light which has passed through the test lens, a control part that calculates an optical characteristic value of the test lens based on the received measurement light, and controls the measurement optical system, a display part that displays the optical characteristic value by control of the control part, and an imaging part that obtains a lens image of the test lens, wherein the control part generates a mapping image showing distribution of the optical characteristic value of the test lens based on the optical characteristic value and position information of a measurement position of the optical characteristic value, generates a superimposed image in which the mapping image is superimposed onto the lens image, and displays the superimposed image on the display part.

Abstract: An optical imager design that is capable of imaging a common scene to two or more optical systems, and is more compact in physical size and superior in throughput than previous designs is disclosed.

Abstract: Provided are a mobile terminal testing device for and a mobile terminal testing method of enabling a user to easily recognize a change in the testing result data in each domain in a case where testing result data indicating a result of testing a mobile terminal is displayed with two domains. A three-dimensional display screen 40 on which the testing result data indicating a result of testing the mobile terminal is displayed in a three-dimensional graph that uses the first domain and the second domain, a first display screen 41 on which the testing result data is displayed in a graph that uses the first domain, and a second display screen 42 on which the testing result data is displayed in a graph that uses the second domain are displayed on a display device.

Abstract: An imaging system with real-time digital testing capabilities verifies the functionality of image processing circuitry used to process pixel data signals read out from a pixel array during imaging operations. Image processing circuitry may process a data frame read from an imaging array that includes multiple regions of imaging and non-imaging data. Digital test patterns may be generated to test the functionality of specific image processing blocks. Test patterns may correspond to or represent imaging data or non-imaging data from regions of the output readout frame. A checksum generator generates a test pattern checksum for output of a subset of the image processing blocks that were provided with a given test pattern. The test pattern checksum may be compared to a predetermined checksum of the output of properly functioning image processing blocks provided with test patterns equivalent to the given test pattern.

Abstract: A method for ascertaining distortion properties of an optical system in a measurement system for microlithography is provided, wherein the optical system images at least one structure to be measured into a measurement image.

Abstract: A system for quickly measuring and displaying in real-time a variety of performance characteristics of IR optical components such as lenses, or the like. The system is video based and is under the control of a computer which uses a windowing software program to provide the user with a graphical user interface by which the various components of the system and test lenses may be characterized and operated on through functions available via the interface. The system has features for compensating for the presence of IR background radiation that may be present during a measurement cycle and for drift in the video imager. Thermal management features are included to minimize IR background.

Abstract: Super-resolution observation apparatus includes excitation light irradiation unit for irradiating excitation light intended to excite a sample on the sample, excitation light modulation unit for modulating a spatial intensity distribution of the excitation light on the sample, enlarged image forming unit for forming an enlarged image of the sample at an image position from observation light generated by irradiating the excitation light on the sample, image capturing unit for converting a spatial intensity distribution of the enlarged image into digital image data, and super-resolution processing unit for generating a super-resolution image where a super-resolution frequency component higher than a cutoff frequency of the enlarged image forming unit is made visible from one or a plurality of pieces of the digital image data.

Abstract: A lens assembly testing method includes: providing a lens assembly having a first lens and a second lens placed on the first lens; determining whether a modulation transfer function value of the lens assembly is in a predetermined range; if not, separating the first lens and the second lens, and forming a first coating layer and a second coating layer on the first lens to obtain a coated first lens with a number of dots; capturing two images of the coated first lens; attaching the coated first lens on the second lens, and capturing another two images of the coated first lens; determining an actual moving distance of a chosen dot using a 3D-Digital image correlation method according to the four images; adjusting a size of the first lens according to the actual moving distance; and displaying the adjusted size of the first lens to a user.

Abstract: A lens assembly testing method includes: providing a lens assembly having a first lens and a second lens placed on the first lens; determining whether a modulation transfer function value of the lens assembly is in a predetermined range; if not, separating the first lens and the second lens, and forming a first coating layer and a second coating layer on the first lens to obtain a coated first lens with a number of dots; capturing two images of the coated first lens; attaching the coated first lens on the second lens, and capturing another two images of the coated first lens; determining an actual moving distance of a chosen dot using a 3D-Digital image correlation method according to the four images; adjusting a size of the first lens according to the actual moving distance; and displaying the adjusted size of the first lens to a user.

Abstract: A lens module testing method includes the following steps: providing a lens module having a lens and a barrel; determining whether a modulation transfer function value of the lens is in a predetermined range; if not, separating the lens and the barrel, and forming a first coating layer and a second coating layer on the lens to obtain a coated lens having a number of dots; capturing a first image of the coated lens; placing the coated lens in the barrel to obtain the lens module, and capturing a second image of the coated lens; randomly choosing one dot from the dots, and determining an actual moving distance of the chosen dot using a 3D-Digital Image Correlation according to the first image and the second image; adjusting a size of the lens according to the actual moving distance; and displaying the adjusted size of the lens to a user.

Abstract: A sample observation device includes: an excitation light generation unit; an intermediate image forming unit projecting excitation light to a sample and forming an intermediate image of the sample at an intermediate image position with observing light; a confocal modulation unit modulating spatial intensity distributions of the excitation light and the intermediate image at the position; a modulation drive unit moving a pattern of the modulation unit; an image relay unit relaying on a image forming surface the intermediate image; an image pickup unit converting the distribution of relayed intermediate image into digital image data; and an image processing unit processing on the digital image data. Cutoff frequency of the relay unit and Nyquist frequency of the pickup unit exceed cutoff frequency of the forming unit, and the processing unit performs a high frequency enhancing process for enhancing the high frequency component exceeding the cutoff frequency of the forming unit.

Abstract: A sample observation device includes: an excitation light generation unit; an intermediate image forming unit projecting excitation light to a sample and forming an intermediate image of the sample at an intermediate image position with observing light; a confocal modulation unit modulating spatial intensity distributions of the excitation light and the intermediate image at the position; a modulation drive unit moving a pattern of the modulation unit; an image relay unit relaying on a image forming surface the intermediate image; an image pickup unit converting the distribution of relayed intermediate image into digital image data; and an image processing unit processing on the digital image data. Cutoff frequency of the relay unit and Nyquist frequency of the pickup unit exceed cutoff frequency of the forming unit, and the processing unit performs a high frequency enhancing process for enhancing the high frequency component exceeding the cutoff frequency of the forming unit.

Abstract: The invention comprises a process for pre-aligning a lens with an optical system, the process comprising: providing a lens and an optical system having an optical axis, wherein the lens is apt to be aligned with the optical system to form on an image plane an image of a source object, the image having top, bottom, left and right edges; coarsely positioning the lens with respect to the optical system; and in a plane normal to the optical axis of the optical system, correcting the position of the lens until the values of four Combination Modulation Transfer Functions (C-MTF) are in predetermined ranges, the C-MTF being calculated at four coarse measurement locations situated close to the edges of the image along two coarse positioning axes crossing the center of the image, each for a combination pattern comprising a combination of a Sagittal pattern and a Tangential pattern.

Abstract: A system and method for searching an incident light field for atypical regions (e.g., hot spots or cool spots or spectrally distinctive regions) within the incident light field using a light modulator and a spectral sensing device. Once the atypical regions are identified, the light modulator may be used to mask the incident light field so that the spectral sensing device can make spatially-concentrated measurements of the wavelength spectrum of the atypical regions (or alternatively, the exterior of the atypical regions). Furthermore, in a compressive imaging mode, a sequence of spatial patterns may be supplied to the light modulator, and a corresponding sequence of wavelength spectra may be collected from the spectral sensing device. The wavelength spectra comprise a compressed representation of the incident light field over space and wavelength. The wavelength spectra may be used to reconstruct a multispectral (or hyperspectral) data cube.

Abstract: In the field of optical checking of optical instruments of telescope type, an instrument comprises an optical objective, a photo-detection housing arranged at the focus of said optical objective and at least one light source arranged in the vicinity of said photo-detection housing, the optical pupil of the optical objective having a first diameter. The checking means comprise a plane mirror having a second diameter that is smaller than the first diameter and means to arrange the plane mirror such that the image of the light source given by the optical objective and reflected by said plane mirror is focused on the photo-detection housing, means for analyzing said image received making it possible to determine the optical quality of the telescope. The plane mirror may be associated with an autonomous checking bench. It may also form part of the telescope and be incorporated into the protection hood for the optic.

Abstract: A method for measuring lens quality includes receiving and transmitting an image's information to a location module through an image collecting module. A location module partitions the image's information into a plurality of measure areas. An image processing module computes the Modulation Transfer Function (MTF) of each measure area. A comparing module compares the MTF with a predetermined MTF to determine quality of the lenses.

Abstract: In a precision testing method of an optical lens using a computing device, the computing device is connected to an imaging system. The computing device controls the imaging system to generate an image of an object according to light rays reflected from the object and collected by the optical lens. A dimension of the object is measured from the image. A maximum value and a minimum value of the dimension of the object are determined. A difference between the maximum value and the minimum value is calculated. According to the difference, it is determined whether the optical lens agrees with a precision requirement.

Abstract: A wavefront aberration measuring apparatus comprising: an illumination optical system provided to an incident side of a test lens; and a measuring optical system provided to an exit side of the test lens, the illumination optical system including an aperture stop capable of being opened and closed, and the illumination optical system being movable along an optical axis of the illumination optical system so as to adjust positions of the aperture stop and an entrance pupil of the test lens to have an optically conjugate relation with each other. Accordingly, it becomes possible to provide a wavefront aberration measuring apparatus capable of suppressing errors in measured result.

Abstract: A lens testing device includes a light source assembly, a pattern plate, and an imaging sensor. The light source assembly includes a transparent base plate, a light guide plate, and a number of illuminants. The light source assembly uses the light guide plate to uniformize light coming from the illuminants and emit the light onto the pattern plate. The imaging sensor is placed beneath the transparent base plate to sense the light passing through the pattern plate and focused by a lens under test.

Abstract: A method of rating eyewear includes providing eyewear to be rated, measuring a physical property of the eyewear selected from a group that includes ultraviolet radiation absorption, blue light radiation absorption, infrared radiation absorption, and light blocking capability, transforming the physical property into a rating value, and informing a prospective consumer of the rating value.

Abstract: A device for measuring eccentricity of a lens includes a support portion, an eccentricity detector, a driving device, a vacuum absorption device, a clamping device, and a rotatable pole. The support portion includes a plurality of gear teeth and a first through hole. The eccentricity detector is positioned above the lens. The driving device includes a driving mechanism and a motor. The motor rotates the driving mechanism. The vacuum absorption device includes an air pipe and a vacuum generation element. The vacuum generation element is for removing air from the air pipe. The clamping device includes a first clamping element and a second clamping element. The first clamping element cooperates with the second clamping element to locate and fix the lens. The rotatable pole includes a second through hole. The rotatable pole is for supporting the support portion.

Abstract: A method and system are for measuring and correcting shifts in the boresight, effective focal length, and focus of an optical system that are caused by temperature variations. The method can be used for systems which can be expected to operate in situations where the temperature variations are large, e.g. a FLIR system of a fighter plane, and also where the temperature variations can be very small however high accuracy is needed. The invention is based on placing radiation emitting sources before and as close as possible to the first optical element of the optical system and measuring the thermally induced shifts of the locations of the images of the radiation emitting sources on the surface of the detector of the optical system.

Abstract: In the field of optical checking of optical instruments of telescope type, an instrument comprises an optical objective, a photo-detection housing arranged at the focus of said optical objective and at least one light source arranged in the vicinity of said photo-detection housing, the optical pupil of the optical objective having a first diameter. The checking means comprise a plane mirror having a second diameter that is smaller than the first diameter and means to arrange the plane mirror such that the image of the light source given by the optical objective and reflected by said plane mirror is focused on the photo-detection housing, means for analyzing said image received making it possible to determine the optical quality of the telescope. The plane mirror may be associated with an autonomous checking bench. It may also form part of the telescope and be incorporated into the protection hood for the optic.

Abstract: A measurement method and an evaluating apparatus are provided which are capable of easily and accurately evaluating the light amount of a spot beam, the diffraction efficiency, and the intensity distribution in the optical axis direction by detecting even a weak diffracted beam in an arbitrary wavelength range converged by a diffraction optical element as an imaging lens.

Abstract: An evaluation method of a progressive-addition lens is provided. First, powers of the progressive-addition lens at a plurality of measurement points are measured to obtain an actually measured power distribution. Next, a comparison power distribution created based on the actually measured power distribution and a defective power distribution prepared in advance are compared with each other to perform similarity search between the both. Thereafter, whether or not the comparison power distribution and the defective power distribution are similar to each other is determined based on the result of the similarity search step, and if it is determined that the comparison power distribution and the defective power distribution are similar to each other, then the progressive-addition lens is evaluated as defective.

Abstract: A method for measuring the spatial frequency response (SFR) of an imaging system (299) including a display device (280) and an image capture device (290) is disclosed. The method displays a sequence of displayable test pattern images on the display device, the sequence comprising a first test pattern image and at least two subsequent test pattern images, each of the displayable test pattern images including a test pattern having at least one sinusoidal pattern at one or more spatial frequencies such that a phase shift of the sinusoidal pattern has a plurality of pre-determined values. The displayed images are captured with the image capture device to generate a corresponding sequence of captured test pattern images. The captured test pattern images are then compared with the displayable test pattern images to calculate the SFR at a plurality of image locations in the imaging system at the one or more spatial frequencies.

Abstract: The invention relates to a method of estimating at least one deformation of the wave front of an observation system or of an object observed by said observation system, characterized in that: at least one diversity image is acquired, in the vicinity of the focal plane of the observation system, in at least one diversity plane, the diversity image comprising a known diversity deformation; and in that in each diversity plane, an image model is determined based on at least one decomposition of the physical pupil of the system into a plurality of subpupils; a decomposition over each subpupil of the sought-after deformation in the form of at least one known deformation weighted by coefficients to be determined; a determination of the transfer function of the system by autocorrelation of its pupil; the linearization of each of the terms of the autocorrelation as a function of the coefficients of the sought-after deformation, the linearization being performed in the vicinity of the known diversity deformation; the o

Abstract: Systems and their methods of use for testing intraocular lenses outside of the lens capsule. In some embodiments the systems measure an accommodative response based on a force applied to the intraocular lens.

Abstract: A measurement method and an evaluating apparatus are provided which accurately evaluate the light amount of a spot beam, the diffraction efficiency, and the intensity distribution in the optical axis direction by detecting even a weak diffracted beam in an arbitrary wavelength range converged by a diffraction optical element as an imaging lens. Light emitted from a white light source passes through a wavelength band-pass filter and is diaphragmed by a pinhole slit. The resultant light is paralleled by a collimator lens and enters a diffraction optical element as an imaging lens. The light getting out from the diffraction optical element is converged to be a spot beam, is magnified by a microscope 18, and is then projected on a CCD. A distance changing member changes the distance between the CCD and the diffraction optical element, and then, the intensity distribution in the optical axis direction is measured.