Abstract: To enable differentiation between a particle and a ghost particle, a detector system is presented. The detector system is configured to output at least two detector signals corresponding to an intensity of radiation being incident on the detector system. If radiation is received from a ghost particle, not all of the at least two detector signals has a level above a predetermined threshold level, whereas radiation received from a contaminating particle results in all signals having a level above a threshold level. Thus, it may be determined with a high accuracy whether a particle or a ghost particle is redirecting radiation towards the detector system.

Abstract: A method of inspecting a light-management film comprises reflecting light from an overhead light source off a first side of the light-management film and examining the light-management film for defects; directing transmission light from a backlight source through a second side of the light-management film to the first side and examining the light-management film for defects; reflecting light from the overhead light source off the second side of the light-management film and examining the light-management film for defects; directing transmission light from the backlight source through the first side of the light-management film to the second side and examining the light-management film for defects; and measuring a location of each of the examined defects in the light-management film.

Abstract: Disclosed are process and apparatus for inspecting internal inclusions in internally transmissive substrates. The process involves applying a black coating to one major surface of the substrate, submerging the substrate in a refractive index-matching fluid, and scanning the substrate with a collimated light beam. The scattered light signals produced by the inclusions can be detected by the human eye or by using a light detector. By the use of index-matching fluid and the black coating, the signal-to-noise ratio of the process and apparatus are enhanced. A preferred black coating is one cured from an electron beam or photo polymerizable coating composition applied to the major surface. The process and apparatus are particularly suitable for inspecting internal inclusions in an internally transmissive substrate having considerable amount of surface defects or contoured surface that prevent it from inspection in a gas medium.

Abstract: A method and apparatus measure properties of two layers of a damascene structure (e.g. a silicon wafer during fabrication), and use the two measurements to identify a location as having voids. The two measurements may be used in any manner, e.g. compared to one another, and voids are deemed to be present when the two measurements diverge from each other. In response to the detection of voids, a process parameter used in fabrication of the damascene structure may be changed, to reduce or eliminate voids in to-be-formed structures.

Abstract: The invention provides a device to inspect an illumination optical device and a method to inspect an illumination optical device that make it possible to efficiently inspect illumination optical devices and to control manufacturing cost. A lens array inspecting device is provided with a light source device to emit a parallel luminous flux, lens array holders to retain lens arrays, which are test objects that split the parallel luminous flux into a plurality of partial luminous fluxes, and a ground glass on which the optical images of the luminous fluxes emitted through the lens arrays are projected. On the ground glass, a parting frame appropriate to a design illumination region is formed. Therefore, whether the lens arrays are defective or non-defective can be determined by checking whether the optical images projected onto the ground glass include the area of the parting frame.

Abstract: A test piece for an optoelectronic image analysis systems is disclosed. One embodiment has a planar substrate, on which a plurality of geometrical patterns of differing shapes and/or sizes are arranged in a durable, predetermined surface coverage. The geometrical patterns contrast optically against the substrate. The surface coverage of geometrical patterns on the substrate is provided such that an overlapping of the geometrical patterns is avoided. In addition, a method of fabrication of a test piece is provided, in which a metal film is deposited on a glass/ceramic substrate, subsequently the metal film is exposed according to a predetermined pattern, and finally the film is etched to create the geometrical pattern on the glass/ceramic substrate.

Abstract: There is provided a particle detector system and to detect particles on target including reticle and pellicle. The system includes a light transmitting device adapted to transmit light beam to a target through an electrowetting microlens, a light receiving device adapted to receive the transmitted light beam reflected by a surface of the target, a light refraction angle adjusting controller adapted to apply a voltage to the electrowetting microlens in order to adjust an incident angle of the light irradiated, and a detector adapted to analyze the light received by the light receiving device to determine whether there are particles on a surface of the target.

Abstract: A method of detecting contaminants on a window surface of a viewing system comprises the steps of: reflecting light off of contaminants on the window surface; capturing the reflected light in an image; converting the image into image data; and processing the image data to detect the contaminants on the window surface. Also, apparatus for detecting contaminants on an external surface of a window of a viewing system comprises: at least one light source for reflecting light from contaminants on the external surface; an imager for capturing an image of the reflected light and converting the image into image data; and a processor for processing the image data to detect the contaminants on the external surface.

Abstract: The invention is directed to a method and apparatus for mapping defects on a light transmissive support surface of a document scanning or photocopying device. The method includes a step of cleaning the support surface between steps of operating the device so as to reflect light from defects associated with the support surface. At least a selected characteristic of the reflected light, such as its intensity, at predetermined pixel locations before the step of cleaning is compared with the same characteristic of the reflected light at the same pixel locations after the step of cleaning. A selected pixel location is mapped to a defect map if (1) the characteristic for reflected light is substantially equal for the selected pixel location at each step of operating the device, and (2) the characteristic for the reflected light at a step of operating the device substantially meets a predetermined standard.

Abstract: The present invention relates to a method for inspecting a crack in a metal surface or the like, and, particularly, to an inspection method and apparatus for nondestructive inspection such as liquid penetrant inspection and magnetic particle testing. The present invention provides a flaw inspection method that essentially comprises the steps of illuminating a surface of a sample to be inspected, obtaining an image of the surface, characterizing a potential flaw on the inspected surface by processing the obtained image, displaying an image of the potential flaw, verifying that the potential flaw is a true flaw, and storing an image of the verified flaw in memory.

Abstract: An apparatus for feature detection of a test object includes at least one light source module and at least one image capturing unit. The light source module provides light to illuminate a test region of the test object, and includes a substrate, a set of light-emitting components, and a light-focusing unit. The light-emitting components are mounted on the substrate for emitting light in parallel directions that are generally transverse to the substrate. The light-focusing unit is to be disposed between the light-emitting components and the test object, receives the light emitted by the light-emitting components, and focuses the light on the test region of the test object. The image capturing unit captures an image of the test object at the test region.

Abstract: A holographic sensor for recognizing moisture on a glass pane of a motor vehicle is provided, having a casing, a carrier layer, a diffractive element and an adhesive layer, the diffractive element being fixed, preferably glued, on the carrier layer. The diffractive element may be embodied as an embossed hologram.

Abstract: Inspection system and method for high-throughput inspection, the system and method is capable to generate and sense transmitted and/or reflected short duration beams. According to one embodiment of the invention the transmitted and reflected short duration beams are generated and sensed simultaneously thus provide a reflected image and a transmitted image simultaneously. The reflected and transmitted short duration radiation beams are manipulated either in the frequency domain or are distinctly polarized such that they are directed to the appropriate area sensors. According to another aspect of the invention the system changes the manipulation of a short duration beam of radiation to selectively direct the short duration beam to distinct area sensors.

Abstract: A lithographic apparatus transfers a pattern from a patterning device onto a substrate and includes a projection system to project a patterned radiation beam onto the substrate; a controllable actuator to adjust a distance between the projection system and the substrate; and a particle detector system to detect a particle on a surface of the substrate. The particle detector system has illumination optics directing the radiation to a detection area of the surface of the substrate, detection optics receiving radiation from the detection area of the surface of the substrate, and a detector coupled to the detection optics to produce a measurement signal. The apparatus further has a processing system to determine the height of a particle from the measurement signal, generate a height excess signal if the height exceeds a threshold value, and control the actuator in response to the height excess signal.

Abstract: A reticle inspection apparatus for detecting defects on a reticle 16 includes an image data generator 42 for generating image data of the reticle 16, a definition analyzer 44 for analyzing definition of image from the image data, a definition judge device 45 for judging whether or not the definition of image is within a predetermined reference range and a sensor position regulating stage 34 for correcting a position of a position sensor 33 when the definition of image is out of the reference range. The reticle inspection apparatus constructed as mentioned is reliable and capable of automatically diagnosing an error of an auto-focusing function of the reticle inspection apparatus due to deformation, etc., of the reticle inspection apparatus.

Abstract: A method and apparatus measure properties of two layers of a damascene structure (e.g. a silicon wafer during fabrication), and use the two measurements to identify a location as having voids. One of the two measurements is of resistance per unit length. The two measurements may be used in any manner, e.g. compared to one another, and voids are deemed to be present when the two measurements diverge from each other. In response to the detection of voids, a process parameter used in fabrication of the damascene structure may be changed, to reduce or eliminate voids in to-be-formed structures.

Abstract: The present invention provides an object-sensing device capable of estimating the presence of an object attached on a sensing surface, the kind of the object and the state of the object. An image is formed by a lens with light via the sensing surface, and the light is received by a light-receiving element portion in which a plurality of micro-light-receiving elements are arranged. In the object detection mode, totally reflected light from the sensing surface is received by the light-receiving element portion. The components are arranged at an angle that allows total reflection when there is no object, and does not allow the total reflection condition to be satisfied when there is an object. In the light scattering object detection mode, scattered light from the sensing surface is received by the light-receiving element portion. A signal pattern is obtained by joining detection signal levels of the micro-light-receiving elements in accordance with the arrangement of the micro-light-receiving elements.

Abstract: A deposit detector in which deposit on a detection surface has a surface shape effect, and generation of a flashing phenomenon caused by irregular reflection of the light incident on the deposit from the outside is estimated. In a deposit detection mode, light emitted from a light source (10) for total reflection and total-reflected from the detection surface is received by a light-receiving element unit (50). Each element is disposed at such an angle that the light undergoes total reflection when no deposit is present or the condition of total reflection is not satisfied when deposit is present. Further, in a light-scattering deposit detection mode, light emitted from a scattering light source (20) and scattered by the detection surface is received by the light-receiving element unit (50). In an extraneous light quantity increase detection mode, extraneous light is received by the light-receiving element unit (50).

Abstract: Using an image signal acquired by picking up a sample to be inspected by a color video camera, penetrant inspection and magnetic-particle inspection, which are non-destructive inspections, are carried out so that deficiency candidates, including a pseudo deficiency, are automatically detected and displayed on a screen. A real deficiency can be detected from the displayed deficiency candidates. As image data is stored in memory means, information of a deficiency can be repeatedly reproduced on the screen. In the penetrant inspection, the chromaticity at each position on an image is acquired, a deficiency candidate is extracted based on the chrominance, and the deficiency is distinguished from a pseudo deficiency based on the differential value of the chrominance. A polarization filter eliminates regular reflection originating from illumination in the penetrant inspection, and an ultraviolet-rays cutting filter prevents noise in the magnetic-particle inspection.

Abstract: A method and apparatus measure properties of two layers of a damascene structure (e.g. a silicon wafer during fabrication), and use the two measurements to identify a location as having voids. The two measurements may be used in any manner, e.g. compared to one another, and voids are deemed to be present when the two measurements diverge from each other. In response to the detection of voids, a process parameter used in fabrication of the damascene structure may be changed, to reduce or eliminate voids in to-be-formed structures.

Abstract: A support structure utilizes a combination of positive pressure openings and negative pressure openings to precisely position a workpiece, such as a sheet of float glass. The positive pressure openings are supply openings that direct a flow of fluid, such as air, onto the surface of the workpiece. The negative pressure openings are exhaust openings that are used to regulate the leakage of fluid from between the workpiece and the support structure. In the preferred embodiment, the surface of the support structure includes raised regions that surround the exhaust openings and that function as self-regulating pinch valves. This arrangement enables an equilibrium condition to be quickly established and maintained upon placement of the workpiece on the support structure.

Abstract: An imaging system for detecting defects on a substrate. Sensor module ports are disposed on an imaging platform. Sensor modules are removably connected to the sensor module ports, and are adapted to sense swaths on the surface of the substrate. Each of the sensor modules includes a time domain integration sensor, optics, an analog controller, and a digital controller. The time domain integration sensor optically senses the swath. The optics focus light from the swath on the time domain integration sensor. The analog controller receives signals from the time domain integration sensor and provides data signals. The digital controller receives the data signals, integrates the data signals into an image of the swath, and provides the image as digital signals to the sensor module port. A master controller receives the digital signals, composites them into a single image of a desired portion of the surface of the substrate, and detects defects within the image.

Abstract: A holographic sensor for recognizing moisture on a glass pane (14) of a motor vehicle, having a casing (22), a carrier layer (28), and a diffractive element (12) and an adhesive layer (30), the diffractive element (12) being fixed, preferably glued, on the carrier layer (28). Furthermore, a sensor is shown, whose diffractive element (12) is embodied as an embossed hologram.

Abstract: A machine vision system includes an apparatus for registering an input image of an object, such as an aircraft engine blade, to a reference image comprising ideal specifications for the object in order to detect flaws in the object. The system includes one or more imaging devices for obtaining the input image representing the object. The system further includes a processor for registering the input image to the reference image. The processor includes a patch determining device for identifying low curvature portions of the reference image off-line. A transformation estimator matches the low curvature portions of the reference image to corresponding low curvature portions of the object, and provides a transformation matrix which maps points on the reference image 11 to corresponding points on the input image for precise and fast registration.

Abstract: Detecting decay of equipment lens anti-reflective coating (ARC) by detecting undesired residue is disclosed. The undesired residue detected correlates with the decay of the ARC, where a greater amount of undesired residue detected indicates a greater level of the decay. The undesired residue is detected due to stray light reflected by the ARC because of its decay. In the context of semiconductor fabrication equipment, photoresist residue results from negative photoresist on a semiconductor wafer, and may be viewed on one or more scribe lines of a mask within a field of view of the lens of the semiconductor fabrication equipment.

Abstract: A system and method of visually inspecting a transparent body and a translucent body comprises applying light to a reverse surface of an object to be inspected by a transmission light source, and applying light, at a low angle, to at least one of an obverse surface and the reverse surface of the object to be inspected by a reflection light source. Concave defects and adherents of the object to be inspected are detected by use of transmitted light emitted from the transmission light source, and adherents of the object to be inspected are detected by use of reflected scattered light emitted from the reflection light source.

Abstract: A method for detecting an anomaly on a first surface of a transparent substrate starts with providing a transparent substrate that has a reflective second surface. The method then comprises directing a radiation beam at the first surface of the substrate so that at least a portion of the radiation penetrates the substrate and strikes the reflective second surface. This radiation is reflected back as a reflected radiation beam through the first surface of the substrate. The method then comprises detecting radiation from the reflected radiation beam. This method can further comprise causing relative motion between the radiation beam and the first surface of the substrate. This method can also further comprise documenting the presence of an anomaly if the detected radiation shows that the reflected radiation beam was scattered upon traversing the first surface.

Abstract: A soil analysis system for determining one or more categories of soil based upon the particle sizes in a soil sample. The soil analysis system includes an image sensor and an image analysis assembly. The image sensor produces an image to distinguish individual particles of a soil sample and calculates particle size. The image analysis assembly is coupled to the image sensor to determine a category for each particle based upon the size of the particles, percentage of each category of particles, and one or more categories of soil for the soil sample.

Abstract: The invention relates to a method and device for detecting objects (3) on a windshield (2). The method comprises the following steps: Placing an optical sensor array (4) on the inner side of a section of the windshield (2), said array having a plurality of individual pixels and being focused on the outer side (7) of the windshield (2); determining the local frequency spectrum S(f) of the intensity fluctuations of pixels of the sensor array (4), said pixels being combined in one or more blocks, and afterwards; evaluating the local frequency spectrum, whereby the detected local frequency spectrum S(f) is compared to one or more reference frequency distributions, and whereby a control signal for triggering one or more actuators is generated when the determined local frequency spectrum S(f) sufficiently conforms to a reference frequency distribution. The device comprises a detecting unit (4) connected to a data processing unit (5).

Abstract: A contaminant inspecting device with multi-color light source comprises a support, a house mounted on the support, a transparent cover mounted on the house, a rotatable frame pivotally connected to the house, a plurality of varied color filters mounted on the frame, and a light source deposited within the house The light of the light source goes though the filter for transforming into a specific color light, and then the specific color light through the transparent cover is projected out of the house. The present invention further provides an inspecting method of the surface of the back light module using the multi-color light projected from the contaminant inspecting device with multi-color light source.

Abstract: There are described a semiconductor inspection system for inspecting recessed defects formed in a semiconductor wafer and a semiconductor device manufacturing method including an inspection step of inspecting recessed defects formed in a semiconductor wafer. The semiconductor inspection system and the semiconductor device manufacturing method enable the following operations: an operation of radiating a laser beam onto a semiconductor wafer; an operation of detecting light scattered from foreign particles, as a result of a laser beam being radiated onto the semiconductor wafer; an operation of converting the detected scattered light into an electric signal; and an operation of outputting information about the recessed defects formed in the semiconductor wafer by means of subtracting the data pertaining to only the foreign particles located on the semiconductor wafer from the data pertaining to both the foreign particles and recessed defects formed in the semiconductor wafer.

Abstract: A substrate treating method and apparatus which can perform in-situ monitoring of surface state of a semiconductor substrate. The substrate treating apparatus comprises substrate treating means for subjecting the substrate to a required treatment, means for condensing infrared radiation emitted by an infrared radiation source onto an outer peripheral part of the substrate and introducing the infrared radiation into the substrate, means for detecting the infrared radiation which has undergone multiple reflection inside the substrate and exited from the substrate, means for analyzing the detected infrared radiation, means for monitoring the surface state of the substrate, and control means for controlling the substrate treating means, based on the monitored surface state of the substrate.

Abstract: A method and an apparatus for detecting removable particulates initially on a test surface or surface to be inspected. The removable particles are transferred to a portion of a tacky surface on a carrier by adhering and then removing the portion of the tacky surface from the test surface. The carrier is received by a positioning means and passed through the field of view of a surface inspection means guided by a controller. Signals from the surface inspection means are combined with coordinates from the controller to produce particle coordinates, which indicate particulates initially on the test surface. Particle coordinates on the tacky surface measured before the tacky surface is adhered and removed from the test surface can be compared with particle coordinates measured after the tacky surface is adhered and removed from the test surface.

Abstract: There is described a method of processing an image recorded on a film, by which differences of gamma values between RGB image information and information on foreign substances or damages are corrected. The method comprises the steps of: irradiating a plurality of lights, whose wavelengths are different relative to each other, onto the film; reading the image by detecting the plurality of lights transmitted through the film or reflected from the film placed, so as to generate a plurality of color image data sets corresponding to a plurality of color images included in the image; and processing the plurality of color image data sets, so as to keep each of relative relationships or each of ratios, between gamma values of the plurality of color images, substantially constant.

Abstract: The invention concerns a method and device for automatic cleaning of opto-electronic measuring systems used in process-technology for the analysis of substances in liquids and gases by means of optical absorption and fluorescence. The method is characterized in that the soiling degree is detected by the opto-electronic sensor system itself and, with predetermined soiling degree, a cleaning liquid cleans the soiling-sensitive optical components and detects the residual soiling, which is then evaluated quantitatively and compensated for in the signal analysis.

Abstract: An assembly (10) for sensing moisture (20) on the exterior surface (22) of a windshield (14) from a position spaced from the interior surface (18) of the windshield (14). The assembly (10) includes a focal plane detector (12) comprising a plurality of pixels (24) adapted for disposition in spaced relationship to the interior surface (18) of the sheet of glass (14). An imaging lens (16) is adapted for disposition between the focal plane detector (12) and the interior surface (18) of the sheet of glass (14) for directing light waves from moisture (20) on the exterior surface (22) of the sheet of glass (14) through the imaging lens (16) to produce successive images of the moisture (20) on the focal plane detector (12).

Abstract: The invention relates to a method and device for detecting and localizing diffuse-reflecting coatings situated on a translucent pane. The aim of the invention is to make it possible to detect any diffuse-reflecting coatings in a non-contacting manner and to differentiate between coatings situated on the pane surface facing the sensor and those situated on the pane surface facing away from the sensor. To this end an image of an object is captured by a recording unit forming part of the device by positioning the pane in the optical path between the object and recording unit, after which the image information obtained is evaluated accordingly.

Abstract: In an inspection method for a transparent object, a transparent object is irradiated with light from a light source, and the surface or interior of the transparent object is inspected by observing transmitted light on the side of the transparent object that is opposite to the light source. An inspection apparatus for a transparent object includes a transparent-object-moving unit, an irradiation unit, and a detection unit. The transparent-object-moving unit moves a transparent object to an inspection position and fixes the transparent object in the inspection position. The irradiation unit emits light from a light source disposed on one side of the transparent object so as to irradiate light onto the transparent object fixed in the inspection position by the transparent-object-moving unit. The detection unit is located on the side of the transparent object opposite the light source and has a detector for detecting light that has been emitted from the light source and has passed through the transparent object.

Abstract: The invention relates to a method of determining the optical quality of and for detecting faults in flat glass, especially float glass, or other optically transparent materials, a video camera (1) being arranged to monitor an illuminating device (3) either through a glass (2) or by observing the reflection thereof on the glass or material, the focus being on the glass (2) and the material, respectively, and the video camera (1) generating signals in dependence on the quality of the glass (2), with these signals being evaluated, wherein an illuminating device (3) is used whose color and/or intensity is changed in a defined manner, the observation spot (6) of the video camera (1) in the faultless condition of the glass (2) is located substantially in the middle of the illuminating device (3), the illuminating device (3) has assigned thereto two video signals U1,U2, and a change of intensity of the video signals U1,U2 is used for evaluating the quality of the glass (2).

Abstract: Defect of an acrylic plate is detected such that a light beam, which dominantly includes non-parallel rays not parallel to a principal surface of the acrylic plate, is introduced through a side surface formed substantially perpendicularly to the principal surface of the acrylic plate. In this arrangement, transmitted light, which is obtained through the principal surface of the acrylic plate on the basis of the defect, is detected by using any one of or both of a light-receiving device with its light-receiving surface arranged and directed substantially in parallel to the principal surface of the acrylic plate and a light-receiving device with its light-receiving surface arranged and directed substantially perpendicularly to the principal surface of the acrylic plate. Thus, the defect of the acrylic plate is quantitatively detected by measuring the amount of light of the transmitted light.

Abstract: A process is provided for detecting small particles on wafer surfaces by irradiating the wafer surface with two light beams having a small difference in wavelength, collecting the light scattered by the wafer in at least one direction, separating the collected light into two component beams having the wavelengths of the irradiating beams, and comparing the intensities of the two component beams. The intensities of the component beams are transduced to digital signals which are fed to a comparator. An apparatus is also provided which comprises a stage for supporting a wafer, laser source and optics for generating two laser beams having different wavelengths, superimposing them and scanning the wafer with them, a sensor for sensing the light scattered by the wafer and separating it into two components having the said wavelengths, an A/D converter for generating digital signals corresponding to said components and a comparator for analyzing whether said signals indicate the presence of small particles.

Abstract: An apparatus for surface inspection according to the invention comprises an irradiating optical system for throwing an irradiating light beam from a light source onto the surface of an object of inspection, a light receiving optical system for receiving a scattered light beam reflected from the surface of the object of inspection irradiated by the irradiating optical system, a photosensing portion for forming a surface data signal from the scattered light beam received by the light receiving optical system, a displacement portion for displacing the surface of the object of inspection relative to the irradiating optical system, plus the light receiving optical system, continuously in the main scanning direction and intermittently in the sub-scanning direction, and a foreign matter detecting portion for detecting a foreign matter present on the surface of the object of inspection on the basis of the maximum value level of the surface data signal and obtaining the position, in the sub-scanning direction, of the

Abstract: Apparatus and method for measuring an aerial image whereby influences of various defects existing on patterns formed on a photomask as well as the surface of the photomask substrate can be inspected. The aerial image measuring apparatus includes an optical transmitting device, an optical reflecting device and an aerial image forming device. The optical reflecting device includes a beam splitter and a reflecting mirror. The reflecting mirror switches the path of light so that the light transmitted along the reflected light path is irradiated to the surface of the photomask on which the patterns are formed. According to an aerial image measuring method of the present invention, either transmitted light or reflected light is selected for analysis, the selected light is converted into an electrical signal to form an aerial image, and the aerial image is measured.

Abstract: A method and an apparatus for an optical inspection of an object, having upper and lower faces, so as to detect defects existing on the object. First and second beams of an incident radiation are produced and directed onto the object. A light component of the first incident beam, which is reflected from one face of the object, and a light component of the second incident beam, which is transmitted through the upper and lower faces of the object, are simultaneously sensed. First and second images, formed, respectively by reflected and transmitted light components are acquired and analyzed so as to provide data indicative of the defects.

Abstract: Particles are distinguished from pits, voids, scratches, and other subsurface defects in a surface of a substrate by impinging the defect with polarized light and integrating light scattered by the defect over a wide angular range to produce a total integrated response. Using a P-polarized incident light beam, particles are distinguished from subsurface defects by comparing the total integrated responses, which vary with changes in the incident angle. Alternatively, the defect is impinged with a P-polarized incident beam at a defined incident angle, and is then impinged with an S-polarized beam at the same incident angle. Total integrated responses are measured for both beams and a P-to-S ratio of the responses is calculated. Particles are distinguished from subsurface defects by comparing the P-to-S ratio to a predetermined threshold value which separates particles from subsurface defects.