Abstract: A measurement device including a light source configured to emit a broad-band light beam, an interference section configured to split the broad-band light beam into a measurement light beam and a reference light beam, and to generate an interference light beam from the reference light beam and a measurement light beam reflected from an object after shining the measurement light beam onto the object, a sweeper section configured to perform wavelength sweeping of the interference light beam, and a detection section configured to detect an interference light beam output from the sweeper section.

Abstract: A lithographic apparatus has a substrate holder configured to hold a substrate and a projection system configured to project a radiation beam onto the substrate held by the substrate holder. There is also a fluid handling system configured to confine immersion liquid to a space between a part of the projection system and a surface of the substrate so that the radiation beam can irradiate the surface of the substrate by passing through the immersion liquid. An excitation device is provided to generate surface acoustic waves in the substrate and propagating toward the immersion liquid.

Abstract: The present disclosure relates to a processing tool that includes a first wafer-mounting frame and a second wafer-mounting frame. The first wafer-mounting frame is configured to retain a target wafer. The second wafer-mounting frame is configured to retain a masking wafer. The masking wafer includes a mask pattern made up of a number of openings passing through the masking wafer to correspond to a predetermined deposition pattern to be formed on the target wafer. A deposition chamber is configured to receive the first and second wafer-mounting frames, when the first and second wafer-mounting frames are clamped together to retain the target wafer and the masking wafer. The deposition chamber includes a material deposition source configured to deposit material from the material deposition source through the number of openings in the mask pattern to form the material in the predetermined deposition pattern on the target wafer.

Abstract: There is provided a cleaning robot including a light source module and an image sensor. The light source module projects a horizontal line pattern toward a moving direction. The image sensor captures, toward the moving direction, an image of the horizontal line pattern. The light source module is arranged below the image sensor so as to eliminate the interference from second reflection.

Abstract: The disclosure relates to a damping arrangement for vibration damping of an element in an optical system, for example in a microlithographic projection exposure apparatus. A damping arrangement according to the disclosure has an element, a fluid located in a cavity, and at least one channel connected to the cavity. A vibration of the element causes vibration energy of the element to be dissipated by partial displacement of the fluid from the cavity into the at least one channel.

Abstract: An exposure tool is configured to remove contaminants and/or prevent contamination of mirrors and/or other optical components included in the exposure tool. In some implementations, the exposure tool is configured to flush and/or otherwise remove contaminants from an illuminator, a projection optics box, and/or one or more other subsystems of the exposure tool using a heated gas such as ozone (O3) or extra clean dry air (XCDA), among other examples. In some implementations, the exposure tool is configured to provide a gas curtain (or gas wall) that includes hydrogen (H2) or another type of gas to reduce the likelihood of contaminants reaching the mirrors included in the exposure tool. In this way, the mirrors and one or more other components of the exposure tool are cleaned and maintained in a clean environment in which radiation absorbing contaminants are controlled to increase the performance of the exposure tool.

Abstract: An exposure apparatus arranged to project a radiation beam onto a target portion of a substrate, the exposure apparatus having: a first substrate holder configured to hold the substrate; a second substrate holder configured to hold the substrate; a sensor holder configured to hold a sensor and/or detector; a first measurement device having a first alignment system having an alignment sensor configured to measure positions of a substrate alignment mark on the substrate; a second measurement device having a second alignment system having a further alignment sensor configured to measure positions of the substrate alignment mark on the substrate; a first scale arranged on a lower surface of the first substrate holder; and a first encoder head arranged to cooperate with the first scale, the first encoder head located beneath the first alignment system and held by a stationary support.

Abstract: The invention relates to an apparatus (10) and a method for optically characterizing or processing an object (60), and to an object transport unit (55).

Abstract: A method of manufacturing a semiconductor device includes dividing a number of dies along an x axis in a die matrix in each exposure field in an exposure field matrix delineated on the semiconductor substrate, wherein the x axis is parallel to one edge of a smallest rectangle enclosing the exposure field matrix. A number of dies is divided along a y axis in the die matrix, wherein the y axis is perpendicular to the x axis. Sequences SNx0, SNx1, SNx, SNxr, SNy0, SNy1, SNy, and SNyr are formed. p*(Nbx+1)?2 stepping operations are performed in a third direction and first sequence exposure/stepping/exposure operations and second sequence exposure/stepping/exposure operations are performed alternately between any two adjacent stepping operations as well as before a first stepping operation and after a last stepping operation. A distance of each stepping operation in order follows the sequence SNx.

Abstract: Embodiments provide image display systems and methods for a camera calibration using a two-sided diffractive optical element (DOE). More specifically, embodiments are directed to determining intrinsic parameters of a camera using a single image obtained using a two-sided DOE. The two-sided DOE has a first pattern on a first surface and a second pattern on a second surface. Each of the first and second patterns may be formed by repeating sub-patterns that are lined when tiled on each surface. The patterns on the two-sided DOE are formed such that the brightness of the central intensity peak on the image of the image pattern formed by the DOE is reduced to a predetermined amount.

Abstract: A stop, such as a numerical aperture stop, obscuration stop or false-light stop, for a lithography apparatus, includes a light-transmissive aperture and a stop element, in which or at which the aperture is provided. The stop element is opaque and fluid-permeable outside the aperture.

Abstract: Systems, apparatuses, and methods are provided for determining the alignment of a substrate. An example method can include emitting a multi-wavelength radiation beam including a first wavelength and a second wavelength toward a region of a surface of a substrate. The example method can further include measuring a first diffracted radiation beam indicative of first order diffraction at the first wavelength in response to an irradiation of the region by the multi-wavelength radiation beam. The example method can further include measuring a second diffracted radiation beam indicative of first order diffraction at the second wavelength in response to the irradiation of the region by the multi-wavelength radiation beam. Subsequently, the example method can include generating, based on the measured first set of photons and the measured second set of photons, an electronic signal for use in determining an alignment position of the substrate.

Abstract: A reticle thermal expansion calibration method includes exposing a group of wafers and generating a sub-recipe, performing data mining and data parsing to generate a plurality of overlay parameters, extracting a plurality of predetermined parameters from the plurality of overlay parameters, performing a linear regression on each of the predetermined parameters, and generating a coefficient of determination for each of the predetermined parameters.

Abstract: Some implementations described herein provide a reticle cleaning device and a method of use. The reticle cleaning device includes a support member configured for extension toward a reticle within an extreme ultraviolet lithography tool. The reticle cleaning device also includes a contact surface disposed at an end of the support member and configured to bond to particles contacted by the contact surface. The reticle cleaning device further includes a stress sensor configured to measure an amount of stress applied to the support member at the contact surface. During a cleaning operation in which the contact surface is moving toward the reticle, the stress sensor may provide an indication that the amount of stress applied to the support member satisfies a threshold. Based on satisfying the threshold, movement of the contact surface and/or the support member toward the reticle ceases to avoid damaging the reticle.

Abstract: A method includes calculating a processing tool offset for a processing tool, wherein the processing tool offset is a first portion of a process offset time attributable to a processing tool. The method further includes calculating a product offset, wherein the product tool offset is a second portion of the process offset time attributable to a product. The method further includes determining whether the product offset is stable based on a pre-determined tolerance and a number of processed wafers. The method further includes calculating an offset time for processing the product using the processing tool based on the calculated processing tool offset, without considering the product offset in response to a determination that the product offset is stable.

Abstract: A system for oblique incidence nanopatterning a sample using a grating beam-splitter is disclosed. The system also includes a grating beam-splitter on a tip-tilt adjustable mount. The system also includes a photoresist coated sample mounted on a tip-tilt-z adjustable mount. The system also includes an alignment system to allow adjustment of the tip-tilt adjustable mounts so that a surface of the grating beam-splitter and a surface of the photoresist coated sample are substantially parallel. The system also includes a laser operating at a wavelength suitable for exposure of the photoresist. The system also includes an optical system to deliver a laser beam at oblique incidence to the grating beam-splitter to expose the photoresist coated sample. The system also includes means to control an exposure dose of the laser beam. A system using two grating beam-splitters to provide increased alignment tolerance is also disclosed.

Abstract: A method for evaluating images of a printed pattern. The method includes obtaining a first averaged image of the printed pattern, where the first averaged image is generated by averaging raw images of the printed pattern. The method also includes identifying one or more features of the first averaged image. The method further includes evaluating the first averaged image, using an image quality classification model and based at least on the one or more features. The evaluating includes determining, by the image quality classification model, whether the first averaged image satisfies a metric.

Abstract: A method for manufacturing a semiconductor device is provided. The method includes the following operations. A first layout including a plurality of first features is provided. A modified second layout is determined. The modified second layout includes a plurality of modified features separated from each other, and each of the plurality of modified features respectively overlaps each of the plurality of first features. The modified second layout is outputted to a photomask.

Abstract: Devices are described for high accuracy displacement of tools. In particular, embodiments provide a device for adjusting a position of a tool. The device includes a threaded shaft having a first end and a second end and a shaft axis extending from the first end to the second end, a motor that actuates the threaded shaft to move in a direction of the shaft axis. In some examples, the motor is operatively coupled to the threaded shaft. The device includes a carriage coupled to the camera, and a bearing assembly coupled to the threaded shaft and the carriage. In some examples, the bearing assembly permits a movement of the carriage with respect to the threaded shaft. The movement of the carriage allows the position of the camera to be adjusted.

Abstract: A method of using a dual stage lithographic apparatus, wherein the lithographic apparatus includes: two substrate supports each arranged to move and support a substrate, a measure field in which selectively one of the two substrate supports is positioned to measure a feature of the substrate supported by the respective one of the two substrate supports, and an expose field in which selectively one of the two substrate supports is positioned to expose the substrate supported by the respective one of the two substrate supports to a patterned beam of radiation, the method including thermal relaxation of a substrate loaded on one of the two substrate supports, wherein the thermal relaxation is at least partially performed at the expose field and/or in transfer between the measure field and the expose field.

Abstract: An image processing apparatus stores data including a transmission destination to which an image generated by the scanner is to be transmitted and a token that is used for storing the image in the transmission destination and attempt to transmit an image generated by the scanner to a transmission destination included in the data, using the token, in response to an instruction from a user. If the transmission fails, the image processing apparatus provides a notification about an error notification including information for causing authentication for reacquisition of a token to a client terminal, receive a token reacquired according to the authentication from the client terminal, and attempt to transmit an image generated by the scanner to the transmission destination included in the data by using the reacquired token.

Abstract: To provide a new temperature distribution evaluation method, a temperature distribution evaluation device, and a soaking range evaluation method, as the temperature distribution evaluation method which evaluates a temperature distribution of a heating area 40A provided in a heating device 40, the present invention is a temperature distribution evaluation method which, in the heating area 40A, heats a semiconductor substrate 10 and a transmitting and receiving body 20 for transporting a raw material to and from the semiconductor substrate 10, and evaluates a temperature distribution of the heating area 40A on the basis of a substrate thickness variation amount A of the semiconductor substrate 10. Accordingly, temperature distribution evaluation can be implemented for a high temperature area at 1600-2200° C. or the like at which it is hard to evaluate the temperature distribution due to the limit of a thermocouple material.

Abstract: A mask structure for a deposition device includes first segments and second segments. The first segments are arranged in a direction surrounding a central axis and separated from one another. The second segments are disposed above the first segments. Each of the second segments overlaps two of the first segments adjacent to each other in a vertical direction parallel to an extending direction of the central axis. A deposition device includes a process chamber, a stage, and the mask structure. The stage is at least partially disposed in the process chamber and includes a holding structure of a substrate. The mask structure is disposed in the process chamber, located over the stage, and covers a peripheral region of the substrate to be held on the stage. An operation method of the deposition device includes horizontally adjusting positions of the first segments and the second segments respectively between different deposition processes.

Abstract: A particle beam system and, such as a multi-beam particle microscope, can have a current intensity of individual particle beams that is flexibly set over large value ranges without structural modifications. The particle beam system can include a condenser lens system, a pre-multi-lens array with a specific pre-counter electrode and a pre-multi-aperture plate, and a multi-lens array. The system can includes a controller to supply adjustable excitations to the condenser lens system and the pre-counter electrode so that the charged particles are incident on the pre-multi-aperture plate in telecentric manner.

Abstract: An arrangement apparatus includes a stage, an arrangement part, and a control part. The stage supports a substrate. The arrangement part holds a die and arranges multiple dies on the substrate supported by the stage. The control part has a map data indicating arrangement positions of the dies and generated based on a positional relationship among patterns formed by an exposure apparatus, and controls, based on the map data, relative positions between the stage and the arrangement part when arranging the dies on the substrate.

Abstract: Provided is an imprint apparatus that forms a pattern on a shot region of a substrate by curing an imprint material on the shot region by light irradiation in a state in which the imprint material is in contact with a mold. The apparatus comprises a shutter plate, and an adjuster configured to adjust a state of the shutter plate to control the light irradiation to the imprint material on the shot region, wherein the shutter plate includes a first passing portion used to irradiate a portion of an entire portion of the imprint material on the shot region with light, and the adjuster adjusts a tilt of the shutter plate.

Abstract: A device and a method for determining a microvibration effect on a millisecond-level space optical sensor are provided. The device includes: a light source, a star simulator, an air flotation vibration isolation platform, a suspension system/air flotation system, a zero stiffness system, a supporting system, a six-degree-of-freedom microvibration simulator, a signal driving apparatus, and a data acquisition and processing system. In the device for determining a microvibration effect on a space pointing measurement apparatus, a free boundary condition and a zero gravity environment are simulated by using a suspension system and a zero stiffness system. A light source and a star simulator simulate a star at infinity. A six-degree-of-freedom microvibration simulator simulates an on-orbit microvibration mechanical environment which is used as an input of a test. Extremely high-precision sensors collect system response data.

Abstract: An anti-shake camera includes a camera body, and a circuit board and a coil fixing plate which are fixed to a back surface of the camera body; a back surface of the coil fixing plate is divided into four areas according to diagonal lines, fan-shaped coils are respectively fixed to two symmetric areas among the four areas, and a rotating shaft is arranged in a center of the diagonal lines; and a substrate is arranged behind the back surface of the coil fixing plate, a surface, opposite to the back surface of the coil fixing plate, of the substrate is provided with a matching mechanism of the rotating shaft, and one or more fan-shaped permanent magnets forming gaps with included angles with the fan-shaped coils are fixed to areas, corresponding to areas of the coil fixing plate where no fan-shaped coils are fixed, on the substrate.

Abstract: A fluid handling system for wetting a substrate irradiated by radiation. The fluid handling system include a first device to confine a first liquid to a first space between the first device and the substrate. The first device includes a first liquid supply member to provide the first liquid to the first space and an extraction member to remove liquid. The fluid handling system further includes a second device including a second liquid supply member to provide a second liquid to a second space between the second device and the substrate, wherein there is a gap on the surface of the substrate between the first and second liquids. The fluid handling system is configured to provide the second liquid to the second space without removing any liquid from the second space to form a liquid layer, and is configured to provide the first and second liquids on the substrate simultaneously.

Abstract: A method for controlling a lithographic apparatus, and associated apparatuses. The method is configured to provide product structures to a substrate in a lithographic process and includes determining optimization data. The optimization data includes measured and/or simulated data of at least one performance parameter associated with the product structures and/or their arrangement which are to be applied to the substrate in the lithographic process. Substrate specific metrology data as measured and/or modelled before the providing of product structures to the substrate is determined, the substrate specific metrology data including metrology data relating to a characteristic of the substrate to which the structures are being applied and/or the state of the lithographic apparatus at the time that the structures are applied to the substrate.

Abstract: According to one embodiment, an apparatus is disclosed for implementing a radio frequency quadrupole stark decelerator (RFQ-SD). The RFQ-SD includes two dielectric plates having substantially planar shapes. The first dielectric plate includes a first set of wires being attached onto a surface of the first dielectric plate and a second set of wires being attached onto the surface of the first dielectric plate. The second dielectric plate includes a third set of wires being attached onto a surface of the second dielectric plate and a fourth set of wires being attached onto the surface of the second dielectric plate. The first dielectric plate and the second dielectric plate are spaced apart such that every four wires, two wires from the first dielectric plate and two wires from the second dielectric plate, form a quadrupole electric field channel for guiding neutral polar molecules.

Abstract: A method for obtaining a compensation pattern for a workpiece patterning device comprises printing (S11) a calibration pattern with a plurality of simultaneously operating exposure beams being sweepable in a second direction according to calibration pattern print data having a multitude of edges. Positions of the edges are measured (S12). Deviations of the measured positions relative calibration pattern are calculated (S13). Each deviation is associated (S14) with a used exposure beam, with a sweep position and a grid fraction position. Edge compensating data is computed (S15) for adapting edge representations of pattern print data prior to printing to compensate for the calculated deviations. The edge compensating data is dependent on the used exposure beam, the sweep position, and the grid fraction position.

Abstract: A fluid handling system that includes a liquid confinement structure configured to confine immersion liquid to a space between at least a part of the liquid confinement structure and a surface of a substrate. The fluid handling system also includes a mechanism configured to vibrate a vibration component in contact with the immersion liquid.

Abstract: A laser processing apparatus includes a laser beam applying unit for applying a laser beam to a workpiece, and a control unit. The laser beam applying unit includes a laser oscillator for emitting a laser, a condensing lens, a concave mirror having a focal point at a focused spot of the condensing lens and having a spherical reflecting surface, a beam splitter for transmitting therethrough the laser beam emitted from the laser oscillator toward the condensing lens and branching off a reflected beam, and a wavefront measuring unit for receiving the reflected beam and acquiring wavefront data. The control unit changes a phase pattern to be displayed on a display portion of a spatial light modulator on the basis of the wavefront data.

Abstract: Exemplary methods of packaging a substrate may include rotationally aligning a substrate to a predetermined angular position. The methods may include transferring the substrate to a metrology station. The methods may include measuring a topology of the substrate at the metrology station. The methods may include applying a first chucking force to the substrate to flatten the substrate. The methods may include generating a mapping of a die pattern on an exposed surface of the substrate. The methods may include transferring the substrate to a printing station. The methods may include applying a second chucking force to the substrate to flatten the substrate against a surface of the printing station. The methods may include adjusting a printing pattern based on the mapping of the die pattern. The methods may include printing the printing pattern on the exposed surface of the substrate.

Abstract: Embodiments of the present disclosure include a lithography apparatus, patterning system, and method of patterning a layered structure. The patterning system includes an image formation device and a reactive layer. The patterning system allows for creating lithography patterns in a single operation. The lithography apparatus includes the patterning system and an optical system. The lithography apparatus uses a plurality of wavelengths of light, along with the image formation device, to create a plurality of color patterns on the reactive layer. The method of patterning includes exposing the reactive layer to a plurality of wavelengths of light. The light reacts differently with different regions of the reactive layer, depending on the wavelength of light emitted onto the different regions. The method and apparatuses disclosed herein require only one image formation device and one lithography operation.

Abstract: A method is described. The method includes obtaining a relationship between a thickness of a contamination layer formed on a mask and an amount of compensation energy to remove the contamination layer, obtaining a first thickness of a first contamination layer formed on the mask from a thickness measuring device, and applying first compensation energy calculated from the relationship to a light directed to the mask.

Abstract: Laser processing apparatus includes movable mirror for changing paths of laser light for processing and measurement light, and stage for changing an incident angle of measuring light. Furthermore, laser processing apparatus includes lens for condensing laser light for processing and measurement light on processing point, controller for controlling laser oscillator, movable mirror, and stage based on corrected data for processing, and measurement processor for measuring a depth of keyhole generated at processing point. The corrected data for processing is data corrected so as to a deviation of an arrival position of at least one of laser light for processing and measurement light caused by chromatic aberration of lens on the surface of workpiece. With this configuration, an accurate depth of keyhole can be measured.

Abstract: Systems and methods of dispersion compensation in an optical device are disclosed. A holographic optical element may include a set of different holograms in a grating medium. Each hologram in the set may have a corresponding grating vector with a grating frequency and direction. The directions of the grating vectors may vary as a function of the grating frequency. Different holograms in the set may diffract light in a particular direction so that the light emerges from a boundary of the grating medium in a single given direction regardless of wavelength. A prism may be used to couple light into the grating medium. The prism may be formed using materials having dispersion properties that are similar to the dispersion properties of the grating material. The prism may have an input face that receives perpendicular input light. The prism may include multiple portions having different refractive indices.

Abstract: An image of a portion of a semiconductor die is obtained that shows one or more structures in a first process layer and one or more structures in a second process layer. Using machine learning, a first region is defined on the image that at least partially includes the one or more structures in the first process layer. Also using machine learning, a second region is defined on the image that at least partially includes the one or more structures in the second process layer. An overlay offset between the one or more structures in the first process layer and the one or more structures in the second process layer is calculated using the first region and the second region.

Abstract: A measurement apparatus and method for determining a substrate grid describing a deformation of a substrate prior to exposure of the substrate in a lithographic apparatus configured to fabricate one or more features on the substrate. Position data for a plurality of first features and/or a plurality of second features on the substrate is obtained. Asymmetry data for at least a feature of the plurality of first features and/or the plurality of second features is obtained. The substrate grid based on the position data and the asymmetry data is determined. The substrate grid and asymmetry data are passed to the lithographic apparatus for controlling at least part of an exposure process to fabricate one or more features on the substrate.

Abstract: A method includes receiving a wafer, measuring a surface topography of the wafer; calculating a topographical variation based on the surface topography measurement performing a single-zone alignment compensation when the topographical variation is less than a predetermined value or performing a multi-zone alignment compensation when the topographical variation is greater than the predetermined value; and performing a wafer alignment according to the single-zone alignment compensation or the multi-zone alignment compensation.

Abstract: An object of the present disclosure is to propose a height measuring device which performs height measurement with high accuracy at each height with a relatively simple configuration even when the sample surface height changes greatly. A height measuring device which includes a projection optical system configured to project a light ray onto an object to be measured and a detection optical system including a detection element configured to detect a reflected light ray from the object to be measured, where the projection optical system includes a light splitting element (103) which splits a trajectory of the light ray with which the object to be measured is irradiated into a plurality of parts, and thus it is possible to project a light ray to a predetermined position even when the object to be measured is located at a plurality of heights, is proposed.

Abstract: A lithographic system for projecting an image onto a workpiece using radiation is provided. The lithographic system includes: a support structure for supporting a workpiece; a radiation source for providing radiation to project an image on the workpiece; a reticle positioned between the radiation source and the workpiece; and a mask positioned adjacent the reticle, the mask being configured to block radiation from the radiation source, the mask including a heat removal apparatus.

Abstract: A lithography method to pattern a first semiconductor wafer is disclosed. An optical mask is positioned over the first semiconductor wafer. A first region of the first semiconductor wafer is patterned by directing light from a light source through transparent regions of the optical mask. A second region of the first semiconductor wafer is patterned by directing energy from an energy source to the second region, wherein the patterning of the second region comprises direct-beam writing.

Abstract: A lithographic system for projecting an image onto a workpiece using radiation is provided. The lithographic system includes: a support structure for supporting a workpiece; a radiation source for providing radiation to project an image on the workpiece; a reticle positioned between the radiation source and the workpiece; and a mask positioned adjacent the reticle, the mask being configured to block radiation from the radiation source, the mask including a heat removal apparatus.

Abstract: The present application provides a temperature control method, an apparatus, an electronic device and a storage medium for an etching workbench. A real-time temperature of an etching workbench and a real-time temperature of a temperature control fluid are acquired firstly; then, a temperature control instruction is determined according to the real-time temperature of the etching workbench, the real-time temperature of the temperature control fluid and a limit temperature; and finally, in response to the temperature control instruction, a target operating temperature of the etching workbench is stabilized within a preset range by a circulating temperature control fluid loop.

Abstract: There is provided an electronic device including a light source module, an image sensor and a processor. The light source module projects a first pattern and a second pattern toward a moving direction. The image sensor captures an image of the first pattern and an image of the second pattern. The processor calculates one-dimensional depth information according to the image of the first pattern and calculates two-dimensional depth information according to the image of the second pattern.

Abstract: An optical element and a lithographic apparatus including the optical element. The optical element includes a first member having a curved optical surface and a heat transfer surface, and a second member that comprises at least one recess, the at least one recess sealed against the heat transfer surface to form at least one closed channel between the first member and the second member to allow fluid to flow therethrough for thermal conditioning of the curved optical surface. In an embodiment, one or more regions of the heat transfer surface exposed to the at least one closed channel are positioned along a curved profile similar to that of the curved optical surface.

Abstract: Embodiments provide image display systems and methods for one or more camera calibration using a two-sided diffractive optical element (DOE). More specifically, embodiments are directed to determining intrinsic parameters of one or more cameras using a single image obtained using a two-sided DOE. The two-sided DOE has a first pattern on a first surface and a second pattern on a second surface. Each of the first and second patterns may be formed by repeating sub-patterns that are lined when tiled on each surface. The patterns on the two-sided DOE are formed such that the brightness of the central intensity peak on the image of the image pattern formed by the DOE is reduced to a predetermined amount.