Reflective Fourier Typography Imaging of Large Surfaces

Abstract

Various embodiments include reflective-mode Fourier ptychographic microscope (RFPM) devices and methods for using the RFPM. In one example, the RFPM includes a plurality of component light sources configured to direct radiation toward a surface. The plurality of component light sources has a plurality of individual light sources each configured to be individually activated. The RFPM further includes a collection system for receiving radiation reflected, scattered, or otherwise redirected from the surface, and a sensor element for converting light energy received from the collection system into an electrical signal output. Other devices, designs, and methods are disclosed.

Description

Technology Field

[0001] The disclosed subject generally relates to the field of detecting defects on surfaces and in the vicinity of surfaces (sub-surface defects). More specifically, the disclosed subject relates to the automated detection of defects using a reflective Fourier tychography system. Background Technology

[0002] Simultaneous camera inspection techniques for surfaces utilize expensive cameras with a large field of view and low resolution, or systems with high magnification and high resolution but coupled with a small field of view. For example, current machine vision technologies cannot inspect the surface of an entire part (which, for instance, could be an area of ​​approximately 0.25 m²) in a timely manner with sufficient resolution.

[0003] Conventional systems utilizing transmission mode techniques allow for high magnification techniques while using collection optics and thus allowing sampling of a larger image area. Referring to FIG. 1, a simplified drawing of a conventional transmission-mode, Fourier ptychographic microscope (TFPM) device (100) having multiplexed illumination in the form of a programmable LED array (110) is shown. The TFPM device (100) uses a conventional brightfield microscope (120) having a programmable LED array (110) as a light source. The programmable LED array (110) allows for the intentional patterning of illumination (101) in the Fourier plane (109) of the sample (103). Light (105) from a sample (103) is directed through the first optical lens (107) and the second optical lens (111) of a brightfield microscope (120). Transmitted light (113) is received by an imaging device (115). The imaging device (115) may include a camera. Image data acquired from the imaging device (115) is electrically coupled to a computing device (117). The image data is transmitted from the imaging device (115) to the computing device (117) for processing and final display on a monitor (not shown).

[0004] The LED array (110) includes a programmable controller (not shown, but understandable to those skilled in the art) configured to illuminate one or more of the light-emitting diodes placed on the surface of the LED array (110) as a function of time in a predetermined pattern and temporal sequence. Thus, the diagram in FIG. 1 illustrates a prior art system using Fourier typography that enables the use of a low numerical-aperture (NA) objective lens having a large field of view (FOV). Even with the use of a low NA objective lens, the Fourier typography device can achieve a high level of resolution across the entire image due to various light sources and generated light patterns. In addition to the illustrated LED array (110), various prior art examples of Fourier typography microscope devices also use a light source (e.g., LED) that can be tilted and repositioned relative to the sample.

[0005] However, while the TFPM device (100) and similar conventional devices have many useful applications for transmission microscopy observation, the TFPM device (100) is useful only for objects to which light is transmitted (e.g., biological samples). Therefore, the TFPM device (100) is not adaptable to reflection microscopy and imaging techniques. Additionally, the TFPM device (100) is not easily adaptable to scanning large samples having surface areas as noted above.

[0006] The information described in this section is provided to suggest context to those skilled in the art regarding the subject matter disclosed below and should not be construed as recognized prior art.

[0007] Claim of priority

[0008] This application claims the benefit of priority to U.S. Patent Application No. 62 / 942,636, filed on December 2, 2019, titled “REFLECTIVE FOURIER PTYCHOGRAPHY IMAGING OF LARGE SURFACES,” the entirety of which is incorporated herein by reference. Brief explanation of the drawing

[0009] FIG. 1 illustrates a simplified drawing of a conventional transmissive-mode, Fourier ptychographic microscope device having multiplexed illumination in the form of a programmable LED array. FIG. 2 illustrates an exemplary embodiment of a drawing of a reflective-mode Fourier ptychographic microscope (RFPM) device according to various embodiments of the disclosed subject matter. FIG. 3a illustrates another exemplary embodiment of the drawing of an RFPM device according to various embodiments of the disclosed subject matter. FIGS. 3B and FIGS. 3C illustrate exemplary embodiments of arrays of light sources that may be used with the RFPM device of FIG. 3A. Specific details for implementing the invention

[0010] The following description includes exemplary examples, devices, and apparatuses that embody various aspects of the subject matter disclosed. In the following description, numerous specific details are provided for the purpose of explanation and to provide an understanding of various embodiments of the subject matter of the invention. However, it will be obvious to those skilled in the art that various embodiments of the subject matter disclosed may be practiced without these specific details. Furthermore, known structures, materials, and techniques are not depicted in detail so as not to obscure the various illustrated embodiments.

[0011] The various exemplary embodiments discussed below focus on reflective-mode Fourier ptychography microscopy (RFPM) devices. Upon reading and understanding the disclosures provided herein, those skilled in the art will readily understand that various techniques, designs, and examples may all be applied in various combinations. As an introduction to the subject, some embodiments will be described briefly and generally in the following paragraphs, followed by a more detailed description with reference to the drawings.

[0012] Current inspection systems and methods used by manufacturers to inspect parts rely on techniques that include both human inspection to detect large defects (e.g., having a "diameter" of approximately 500 µm or more) and machine inspection, where a small percentage of the part's surface is inspected to detect small defects (e.g., approximately 10 µm or more). These inspection systems and methods, used by various manufacturers (e.g., manufacturers of semiconductor processes and metrology tools), generally inspect only about 0.0003% to about 0.0007% of the part's surface and use this small sample to extrapolate and estimate the quality of the entire part. This small inspected percentage of the part provides a confidence of only about 2% to about 4% that the inspected surface represents the actual quality state of the part. The reason modern systems and methods inspect only a very small percentage of the part is based on the physics of optics, as briefly described below.

[0013] As understood by those skilled in the art, microscope-based inspection systems generally use microscope objective lenses to collect light transmitted or reflected from an object. A skilled technician [regarding] the Rayleigh limit-of-resolution, L R Recognize that (how small features a microscope can analyze) is based on the following equation:

[0014]

[0015] Here, λ is the wavelength of light used to illuminate the target, and NA is the numerical aperture of the microscope objective lens. NA It is related to the refractive index of the medium between the lens and the object and the angle of light entering the lens:

[0016]

[0017] Here n is the refractive index of the medium in which the lens operates (e.g., n is approximately 1.00 for air, approximately 1.33 for water, and approximately 1.52 for high refractive index immersion oils); θ is the maximum half-angle of the cone-of-light that can enter (or exit) the objective lens. Therefore, aperture number, NA As increases, resolution limit, L R This reduction allows for the inspection of smaller features, such as defects.

[0018] however, NA As increases, the depth of field (e.g., image depth) and the viewable area decrease significantly. For example, depth of field DOF The aperture number according to the following equation NA Decreases by the square of:

[0019]

[0020] Consequently, as the resolution limit decreases (allowing for interrogations of increasingly smaller feature sizes), the depth of field decreases much more rapidly. The visible area also decreases proportionally. Thus, the disclosed subject provides a system that allows for the interrogation of small features but has a large depth of field and a large inspection area.

[0021] For example, the devices and methods of the disclosed subject matter can inspect the entire surface of a part in less than about 30 minutes with a resolution similar to that of standard microscope-based systems of the prior art, giving an increase of more than 13,000 times the efficiency for the sampled about 0.0003% to about 0.0007% described above, and thus can provide a significant improvement in measurement reliability at a level of up to about 95% to about 99.9997% reliability.

[0022] Various embodiments of the disclosed subject matter operate in a reflection mode to inspect, for example, hard material surfaces (e.g., non-biological, e.g., inorganic or non-organic materials). Surfaces, for example, may include various metallic (e.g., aluminum or stainless steel), ceramic (e.g., alumina, Al2O3) surfaces, ceramic-coated surfaces, elemental and compound semiconductor substrate surfaces, various types of plastics, glass surfaces (of various types known in the art), anodic surfaces, and oxidized surfaces, although many different types of surfaces and materials may be inspected using embodiments of the disclosed subject matter. In one example, the part may have a diameter of approximately 559 mm (approximately 22 inches, having a surface area of ​​about 0.25 m² on one side) (or other characteristic area dimensions), and the part may be inspected for defects having characteristic dimensions of approximately 5 µm to about 10 µm or more. In other embodiments, the part may have characteristic dimensions of approximately 5 µm to approximately 10 µm and may be inspected for larger defects over an area of ​​up to several square meters.

[0023] Various embodiments of the disclosed subject matter may also be used to identify, for example, material-composition variations, crystal-structure variations, or grain boundaries within a material. Materials having different compositions or different crystal structures have different refractive indices as material properties. Refractive indices affect how light is reflected and refracted through a material. Consequently, different refractive indices generate light of different intensities striking a sensor, thereby allowing, for example, the detection of compositional or structural boundaries. In addition, if the particle size of a material such as a ceramic or metal is approximately micron, grain boundaries and other defects that would generally require much higher magnification to observe can be detected using various embodiments of the disclosed subject matter. Furthermore, light scattered from grain boundaries taken from multiple angles of light can generate images that identify grain boundary information in addition to larger defects on a larger scale than that traditional optical systems can detect or identify.

[0024] The disclosed subject utilizes a camera with a large field of view while still achieving high resolution. Embodiments of the described device use incident light of multiple spatially and temporally generated angles, which are then computationally combined to increase resolution while doing so over a large surface area of ​​the part to be inspected. Due to the large number of incident light beams striking the surface of the inspected part, artifacts from a conventional single, high-intensity light beam are also reduced or eliminated. The disclosed device may use statistics and machine learning to interrogate only a portion of the surface while maintaining high confidence in the quality of the entire surface. Additionally, various embodiments of the disclosed subject may be modified with various types of lenses (e.g., objective lenses) and wavelengths to meet specific application requirements. Furthermore, the various embodiments described herein may be automated to scan the entire surface. For example, in one embodiment, to increase the inspected surface area, the RFPM device may be raster scanned or otherwise moved to different parts of the surface to be inspected. In another embodiment, the surface may be translated for the RFPM device. Still in other embodiments, the RFPM device is raster scanned and the surface is translated for the RFPM device simultaneously. Additionally, various embodiments may have predetermined criteria for passable parts, thereby eliminating the need for interpretation of one or more defects detected by the operator.

[0025] In a specific exemplary embodiment, the disclosed subject includes a reflective-mode Fourier ptychography microscopy (RFPM) device. The RFPM device operates in a reflective mode utilizing a plurality of component light sources (e.g., an LED array or other radiation source), a lens comprising collection optics for receiving specular and scattered light (light reflected from the surface or otherwise redirected) from the object under inspection, and a specular light sensor. In various embodiments, the specular light sensor may be offset by a specific number of angles from the vertical (orthogonal to the surface). The system takes a plurality of images having different illumination conditions (e.g., half-circle illumination of a plurality of component light sources) in both brightfield-imaging and darkfield-imaging to sample the Fourier space of the image of the surface. These images are then computationally reconstructed and overlaid to increase resolution and reduce aberrations. After reconstruction, the images are interrogated for defects using machine learning algorithms, and part quality is determined based on predetermined criteria.

[0026] Now, referring to FIG. 2, an exemplary embodiment of a reflective-mode Fourier ptychographic microscope (RFPM) apparatus (200) according to various embodiments of the disclosed subject matter is illustrated. The RFPM apparatus (200) is illustrated as comprising a light source array (210), a condenser (230), and a sample surface (203). The light source array (210) comprises a plurality of individual light sources (210A, 210B, …, 210N). In various embodiments, the individual light sources (210A, 210B, …, 210N) may each comprise a plurality of substantially monochromatic light sources. The light source array (210) may comprise individual light sources having one or more wavelengths, one or more polarization states, or other features. In a specific exemplary embodiment, the individual light sources (210A, 210B, …, 210N) comprise individual LEDs or clusters of LEDs of a specific wavelength, each tunable for a range of wavelengths (e.g., ultraviolet or infrared) including a correlated color temperature (CCT) or invisible colors. In various embodiments, the individual light sources may include other types of invisible light sources having wavelengths that extend deep into the ultraviolet range. Regardless of the type of light utilized, each of the individual light sources (210A, 210B, …, 210N) is programmable and can be activated (turned on or turned off) independently.

[0027] The condenser (230) includes an imaging lens (207) and a sensor element (209). Although the imaging lens (207) is depicted as a biconvex lens, this limitation is not implied, as the imaging lens (207) may include one or more of various lenses or groups of lenses as known in the art. The imaging lens (207) is depicted as having the full angle of the light weight (205) entering the lens. In certain exemplary embodiments, the imaging lens (207) may be replaced or used with other optical elements, such as mirrors. In certain exemplary embodiments, the condenser (230) includes a microscope objective lens. The sensor element (209) may include various types of light-sensing elements known in the art that convert received light energy into an electrical signal output (e.g., a photodetector). In certain exemplary embodiments, the sensor element (209) includes a CCD array.

[0028] A light source array (210) may be positioned at an angle (211) relative to the sample surface (203). The angle (211) may be fixed or variable depending on a number of factors understood by those skilled in the art. In various embodiments, the angle (211) may be 0° to about 2°, 0° to about 3°, 0° to about 5°, or greater. Additionally, individual light sources (210A, 210B, …, 210N) may have varying amounts of beam diffusion (201). Beam diffusion may be at or near 0° (e.g., for a laser or LED source) or greater than 0° for other types of light sources.

[0029] The concentrator (230) may be positioned at an angle (213) relative to the sample surface (203). The angle (213) may be fixed or variable depending on a number of factors understood by those skilled in the art. In various embodiments, the angle (213) may be 0° to about 2°, 0° to about 3°, 0° to about 5°, or greater. In a specific exemplary embodiment, the angle (213) is approximately equal to the angle (211) of the light source array (210). The concentrator (230) of the RFPM device (200) collects reflections that are reflected back or scattered from the sample surface (203) toward the concentrator (230).

[0030] Accordingly, each of the series of images is captured as a result of illumination from, for example, a coherent light source. However, due to multiple light sources, there are multiple angles of incidence, and many of these are substantially available simultaneously. Temporal or spatial patterning of various types of light may be employed by the RFPM device (200) to collect a series of images.

[0031] Accordingly, various imaging aspects are achieved using the same optical setup of FIG. 2 by simply selecting appropriate light sources (210A, 210B, …, 210N) (e.g., LEDs) within a light source array (210) that are activated (turned on and turned off) according to predetermined temporal and spatial patterns in various embodiments without moving parts. Consequently, each of the individual light sources, or the patterns of multiple light sources among the individual light sources within the light source array (210), correspond to illumination of the sample surface (203) at a unique angle or a range of angles. Thus, the range of illumination angles that can be patterned is much larger than the range of angles that pass through the condensers (230) and are therefore not set by the number of apertures of the condensers (230). As a result, illumination of the sample surface (203) by individual light sources closer to the central region of the light source array (210) produces bright-field images, while illumination of the sample surface (203) by individual light sources closer to the outer periphery of the light source array (210) (outside the aperture number of the condenser (230)) produces dark-field images. Bright-field images and dark-field images are understood and known to those skilled in the art.

[0032] For example, a pair of images having LEDs on half of the light source array (210) (e.g., across a selected symmetry line) are taken sequentially, allowing the RFPM device (200) to obtain phase derivative measurements by differential-phase contrast (DPC) techniques. Using DPC techniques, quantitative phase differences are obtained from images captured from the light source array (210) with different source patterns. Thus, quantitative phase is recovered from, for example, two images taken using complementary asymmetric illumination patterns. The difference between the two images is related to the phase derivative of the sample surface (203) along the asymmetric axis. Thus, the DPC technique is partially a coherent imaging technique (only illumination from a single LED among the LEDs contains a coherent light source). Due to the various patterning techniques that can be implemented using the light source array (210), DPC measurements can be implemented within the RFPM device (200) in substantial real-time and along multiple asymmetric axes without using any movable parts. Thus, implementing DPC techniques is possible without any mechanical changes on the illumination side (light source array (210) side) or detection (back-reflected or scattered) side (concentrator (230) side) of the RFPM device. Thus, various illumination strategies of the light source array (210) can be developed to accommodate different types of samples and imaging needs.

[0033] In general techniques of optics and light scattering, height information can be extracted by taking the phase difference or phase difference of multiple images and using this information to extract height features (e.g., characteristic height dimensions of a defect). In reflection microscopy using brightfield images, for example, two crescent illuminations (e.g., left and right, or top and bottom) may be taken. In off-axis illumination situations, the phase will vary substantially linearly with the contrast. However, in a single image, both the phase information and the amplitude information are inseparably convolved within the resulting signal, and consequently, the phase cannot be extracted individually from the signal. Multiple images from different angles will have the same amplitude contrast but different phase contrasts. Therefore, when taking the difference between images, the phase contrast can be isolated.

[0034] The phase can be related to the height or depth of the reflection mode by an equation.

[0035]

[0036] Here is the phase of the received signal, and is the wave vector in the z-direction, and h is the height of the feature of interest. Wave vector, It can be determined as follows.

[0037]

[0038] Here, θ is the angle between the imaging axis and the illumination point (or the angle between the vertical and the location of the LED if aligned vertically), and λ is the wavelength of light. Thus, the phase can be determined by the image, and if the illumination angle and the wavelength of light are known, a relative height map can be determined. This will indicate whether the defects are located above or below the generally flat plane of the part.

[0039] The technique provided above is generally valid for single reflections (not transmitted signals), but a similar set of mathematics, though more complex, can be used to extract similar information from transmitted signals. In the case of transparent coatings on solid surfaces, various types of reflections may be encountered. However, those skilled in the art will recognize how these reflections may be included in the given equations.

[0040] Now, referring to FIG. 3a, another exemplary embodiment of the drawing of an RFPM device (300) according to various embodiments of the disclosed subject matter is illustrated. The RFPM device (300) is illustrated as comprising a left light source array (310L) and a right light source array (310R). Each of the light source arrays (310L, 310R) comprises a plurality of individual light sources (not illustrated, but may be identical or similar to the light source array (210) of FIG. 2). The left light source array (310L) and the right light source array (310R) may each be at one or more angles (301L and 301R). Each of the left light source array (310L) and the right light source array (310R) may be at one or more different angles (301L and 301R) with respect to the angle on the opposing side. The respective angles (301L and 301R) for the left light source array (310L) and the right light source array (310R), respectively, may be fixed or variable. Additionally, although not explicitly illustrated, the RFPM device (300) may include a beam splitter element so that at least one of the light source arrays (310L, 310R) may be positioned substantially orthogonal to the beam path of the concentrators (230). Such beam splitter designs are known in the art. In other embodiments, the light source array may be located within a device that surrounds the concentrator (230) and houses the concentrator (230). Furthermore, FIG. 3a implies that the left light source array (310L) and the right light source array (310R) are planar elements, and this limitation is not inferred as discussed below with reference to FIG. 3b and 3c.

[0041] FIGS. 3B and FIGS. 3C illustrate exemplary embodiments of arrays of light sources that may be used with the RFPM device (300) of FIG. 3A. FIG. 3B illustrates an array (320) of a light source array (330) having a plurality of individual light sources (330A, 330B, …, 330N). Consequently, the lowest portion (e.g., the bottom surface of the light source array (330) closest to the surface) is illustrated. The angle (331) between adjacent rows of individual light sources (330A, 330B, …, 330N) may be determined based on a plurality of individual light sources among the light sources required for a predetermined size and other features of the surface to be inspected. Although the angle (331) is depicted as having adjacent rows of individual light sources (330A, 330B, …, 330N) spaced approximately 45° apart from each other, this limitation on the angle (331) should not be inferred.

[0042] Additionally, the individual light sources (330A, 330B, …, 330N) may not be arranged in linear arrays. The individual light sources may be arranged in various spatially-periodic and non-spatially-periodic (including random) arrays. For example, in a specific exemplary embodiment, the individual light sources are arranged in a series of concentric circles, where each adjacent row has the same number of individual light sources as the previous or subsequent row. In another specific exemplary embodiment, the individual light sources are arranged in a series of concentric circles, where each adjacent row has more or fewer individual light sources than the previous or subsequent row. In yet another specific exemplary embodiment, the individual light sources are arranged in an Archimedean spiral or other geometric arrangement. Additionally, the light source array (330) may include a locally planar surface (e.g., from the inner side of the array to the outer periphery). In other embodiments, the light source array (330) may include a concave surface or a convex surface, or any geometric combinations listed or considered.

[0043] For example, FIG. 3b shows a three-dimensional side view (340) of an array of the RFPM device (300) of FIG. 3a. In this side view, the RFPM device (300) is shown to have a substantially frustoconical shape. The angle (341) may be 0° or approximately 0° to 45° or greater.

[0044] Based on reading and understanding the disclosed subject matter, those skilled in the art will recognize that each of the various embodiments of the RFPM device may be used to measure defects on surfaces of various sizes and materials, and over large surface areas (e.g., fractions of very small square meters to several square meters or more). For very large surfaces, the RFPM device may be mounted on various types of conversion stages known in the art (e.g., xy stage or R-θ stage). In other embodiments, the sample itself may be converted to the RFPM device. Still in other embodiments, the sample and the RFPM device may both be converted to each other. Each of the subsequently acquired images may then be processed and stitched together, for example, via software, to form a single image. The size range of the detected defects may be from about 50 nm to about 50 mm of the characteristic dimensions of the detected defects. The total number of detected defects per unit area (over a predetermined size, such as about 5 µm or about 10 µm) can be detected. Additionally, various embodiments may determine the overall roughness level of all or part of the surface (e.g., RMS roughness value, R). RMS It can be used to determine ).

[0045] In other embodiments not explicitly described but understood by those skilled in the art, based on reading and understanding of the disclosed subject matter, various embodiments of the disclosed subject matter may also be used in various process steps of semiconductor manufacturing. For example, the disclosed subject matter may be used in-situ, within or near a deposition-process chamber, to monitor defects, film thicknesses, and film roughness levels when films or films are deposited on a substrate (e.g., a silicon wafer). Subsequently, results from such in-situ process monitoring may be reported to the end user substantially in real time or may be acquired and reported as a series of temporal images.

[0046] One embodiment using various embodiments of RFPM by using one or more of the various embodiments disclosed in this specification is, for example,

[0047] ⑴ The RFPM operator manually loads the part to be inspected onto a fixture that fixes the orientation of the part;

[0048] ⑵ The operator selects and starts a program for executing and controlling at least some aspects of the RFPM described above, and the program may be executed using a human-machine interface or another graphical user interface;

[0049] (3) RFPM automatically captures images of the part over the entire surface of the part or over predetermined portions (e.g., a predetermined percentage of the part sampled at specified locations) (e.g., defects ranging from 1 µm to 500 µm can be detected substantially simultaneously);

[0050] ⑷ Once the requested data is collected, computational methods known in the relevant technical field are used to process the images using machine learning, for example, which is used to analyze and quantify defects; and

[0051] (5) Based on a predetermined set of inputs (e.g., the number of defects of a predetermined size or larger per unit area, the fraction of the scanned part or the level of roughness over the whole, and other inputs and parameters described herein), the program computer determines whether the part passes or fails the inspection based on the programmed and analyzed defects.

[0052] These methods as described above may be implemented on various types of devices as described in more detail below. Devices include, for example, a special-purpose processor such as a field programmable gate array (FPGA) or an application-specific integrated circuit (ASIC) that is programmed as a computer or microprocessor, software, firmware, or as an example of a hardware implementation, according to one or more aspects of the disclosed subject matter described above.

[0053] Throughout this specification, a plurality of examples may implement components, operations, or structures described as a single example. Although individual operations of one or more methods are illustrated and described as separate operations, one or more of the individual operations may be performed simultaneously and are not required to be performed in the illustrated order. Structures and functionalities presented as separate components in exemplary configurations may be implemented as a combined structure or component. Similarly, structures and functionalities presented as a single component may be implemented as separate components. These and other variations, modifications, additions, and improvements fall within the scope of this specification.

[0054] Specific embodiments are described herein as comprising logic or a number of components, modules, or mechanisms. Modules may consist of software modules (e.g., code implemented on a machine-readable medium or as a transmitted signal) or hardware modules. A “hardware module” is a type of (tangible) unit capable of performing specific operations and may be configured or arranged in a specific physical manner. In various embodiments, one or more computer systems (e.g., a standalone computer system, a client computer system, or a server computer system) or one or more hardware modules of a computer system (e.g., a processor or a group of processors) may be configured by software (e.g., an application or part of an application) as hardware modules that operate to perform specific operations as described herein.

[0055] In some embodiments, the hardware module may be implemented mechanically, electrically, or any combination thereof. For example, the hardware module may include a dedicated circuitry or logic permanently configured to perform specific operations. For example, the hardware module may be a special-purpose processor, such as a Field Programmable Gate Array (FPGA) or an ASIC.

[0056] A hardware module may also include programmable logic or a network that is temporarily configured by software to perform specific operations. For example, a hardware module may include software contained within a general-purpose processor or another programmable processor. It will be recognized that in dedicated and permanently configured networks, or in networks that are temporarily configured (e.g., configured by software), the decision to mechanically implement the hardware module may be driven by cost and time considerations.

[0057] Accordingly, the former "hardware module" should be understood to include an entity of type that is physically configured to operate in a specific manner or to perform the specific operations described herein, and is permanently configured (e.g., embedded in hardware) or temporarily configured (e.g., programmed). As used herein, "hardware-implemented module" refers to a hardware module. When considering embodiments in which hardware modules are temporarily configured (e.g., programmed), each hardware module does not need to be configured or exemplified at any given moment in time. For example, if a hardware module includes a general-purpose processor configured by software to become a special-purpose processor, the general-purpose processor may be configured into different special-purpose processors (e.g., including different hardware modules) at different times. Accordingly, the software may configure the processor to configure a specific hardware module at one instance in time and to configure a different hardware module at different times.

[0058] Hardware modules may provide information to other hardware modules and receive information from them. Accordingly, the described hardware modules may be considered to be communicably coupled. If multiple hardware modules exist simultaneously, communication may be achieved through signal transmission between two or more of the hardware modules (e.g., through appropriate circuits and buses). In embodiments where multiple hardware modules are configured at different times or are exemplified, communication between these hardware modules may be achieved, for example, through the storage and retrieval of information in memory structures accessed by the multiple hardware modules. For example, one hardware module may perform an operation and store the output of the operation in a communicably coupled memory device. Subsequently, additional hardware modules may access the memory device to retrieve and process the stored output later. Hardware modules may also initiate communication with input or output devices and operate on resources (e.g., a collection of information).

[0059] Various operations of the exemplary methods described herein may be performed, at least in part, by one or more processors that are temporarily or permanently configured (e.g., by software) to perform the relevant operations. Whether temporarily or permanently configured, these processors may constitute processor-implemented modules that operate to perform one or more operations or functions described herein. As used herein, "processor-implemented module" refers to a hardware module implemented using one or more processors.

[0060] Similarly, the methods described herein may be at least partially processor-implemented processors, and the processor may be an example of hardware. For example, at least some of the operations of the method may be performed by one or more processors or processor-implemented modules. Furthermore, one or more processors may also operate to support the performance of the relevant operations in a "cloud computing" environment or as "SaaS (Software as a Service)." For example, at least some of the operations may be performed by a group of computers (as examples of machines including processors) with these operations accessible via a network (e.g., the Internet) and via one or more appropriate interfaces (e.g., API (Application Program Interface)).

[0061] The performance of specific operations may not only exist within a single machine but may also be distributed among one or more processors deployed across multiple machines. In some embodiments, one or more processors or processor-implemented modules may be located in a single geographic location (e.g., a home environment, an office environment, or a server farm). In other embodiments, one or more processors or processor-implemented modules may be distributed across multiple geographic locations.

[0062] As used herein, the term "or" may be interpreted in an inclusive or exclusive sense. Additionally, other embodiments will be understood by those skilled in the art by reading and understanding the provided disclosure. Furthermore, by reading and understanding the provided disclosure, those skilled in the art will readily understand that various combinations of techniques and examples provided herein may all be applied in various combinations.

[0063] Although various embodiments have been discussed individually, these individual embodiments are not intended to be considered as independent techniques or designs. As indicated above, each of the various parts may be interrelated, and each may be used individually or in combination with other embodiments of the reflection Fourier typography system discussed herein. For example, although various embodiments of methods, operations, and processes have been described, these methods, operations, and processes may be used in various combinations or individually.

[0064] Consequently, as will be apparent to those skilled in the art from reading and understanding the disclosure provided herein, many modifications and variations may be made. In addition to those listed herein, functionally equivalent methods and devices within the scope of this disclosure will be apparent to those skilled in the art from the foregoing descriptions. Parts and features of some embodiments may be included in or substituted for parts and features of other embodiments. Such modifications and variations are intended to fall within the scope of the appended claims. Accordingly, this disclosure is limited only by the conditions of these claims, along with the full range of equivalents granted by the appended claims. It is also understood that the terms used herein are for the purpose of describing specific embodiments only and are not intended to be limiting.

[0065] The summary of the present disclosure is provided to enable the reader to quickly ascertain the essence of the technical disclosure. The summary is submitted with the understanding that it is not intended to be used to interpret or limit the claims. Additionally, it may be understood that in the specific details for carrying out the foregoing invention, various features may be grouped together in a single embodiment for the purpose of simplifying the present disclosure. This method of disclosure is not to be interpreted as limiting the claims. Accordingly, the following claims are incorporated into the specific details for carrying out the invention in this specification, and each claim is independent as an individual embodiment.

[0066] The following numbered examples are embodiments of the disclosed subject matter.

[0067] Example 1: An embodiment of the disclosed subject describes a method of operating a reflective-mode Fourier ptychographic microscope (RFPM) to detect defects on the surface of a part. The method comprises the steps of: loading the part onto a holding fixture of the RFPM; generating at least one lighting pattern from a plurality of component light sources configured to direct radiation onto the surface, wherein the plurality of component light sources each have a plurality of individual light sources configured to be individually activated, and the at least one lighting pattern is selected from a plurality of patterns including temporal patterns and spatial patterns; collecting the directed radiation from the surface at a sensor element; obtaining phase derivative measurements from the radiation collected by the sensor element using differential-phase contrast (DPC) techniques; determining an angle between the imaging axis from the surface to the sensor element; and determining at least one height feature of one or more defects on the surface.

[0068] Example 2: The method of Example 1 further includes the step of raster scanning at least one generated light pattern across an area of ​​the surface.

[0069] Example 3: The method of Example 1 or Example 2 further includes the step of performing a raster scan across an area of ​​the surface by moving the part under at least one generated light pattern.

[0070] Example 4: Any one of the above examples' methods further comprises the step of scanning at least one generated light pattern across an area of ​​a surface; and the step of performing a raster scan across an area of ​​a surface by moving a part under at least one generated light pattern.

[0071] Example 5: In any one of the preceding examples, the area is selected to be at least about 0.25 square meters over the surface.

[0072] Example 6: Any one of the above examples' methods further includes the step of determining at least one wavelength for selected light sources among a plurality of individual light sources.

[0073] Example 7: In any one of the preceding examples, at least one lighting pattern is selected to illuminate the surface at multiple angles of incidence.

[0074] Example 8: In any one of the preceding examples, the temporal patterns and spatial patterns are predetermined.

[0075] Example 9: In any one of the preceding examples, the step of selecting a temporal pattern further includes: selecting a light source to be activated among a plurality of individual light sources; and determining which of the selected plurality of individual light sources is activated in time with respect to the remaining light sources among the selected plurality of individual light sources.

[0076] Example 10: In any one of the preceding examples, the step of selecting a spatial pattern includes the step of selecting a plurality of individual light sources to be activated for a substantially uniform time period.

[0077] Example 11: Any one of the preceding examples' methods further includes the step of determining an angle at which at least one midpoint of a generated light pattern is offset from the normal by a predetermined number of angles from the vertical relative to the surface.

[0078] Example 12: Any one of the preceding examples' methods further comprises the step of computationally combining at least one of the collected radiation directed from a surface to increase the resolution of defects detected across the Rayleigh resolution limit for the wavelengths of light from a plurality of individual light sources and a predetermined number of apertures.

[0079] Example 13: Any one of the preceding examples' methods further includes the step of selecting a condenser to focus radiation collected on a sensor element from a predetermined number of apertures.

[0080] Example 14: In any one of the preceding examples, the plurality-component light source comprises an LED array.

[0081] Example 15: In any one of the preceding examples, the step of generating at least one lighting pattern includes the step of selecting one of a plurality of individual light sources to include a group of LEDs from an LED array.

[0082] Example 16: In any one of the preceding examples, each of the plurality of individual light sources includes an LED.

[0083] Example 17: An embodiment of the disclosed subject describes a method for operating a reflective-mode Fourier ptychographic microscope (RFPM). The method comprises the steps of: loading a non-biological part to be inspected onto a fixture; and selecting a program to run and control one or more embodiments of the RFPM, wherein the embodiments may be selected from embodiments comprising a spatial pattern of multiple-component light sources, a temporal pattern of multiple-component light sources, a range of defect sizes to be detected, an area of ​​the part to be inspected, at least one height feature for one or more detected defects, and a number of multiple images of the non-biological part to be recorded.

[0084] Example 18: The method of Example 17 further includes the step of determining the roughness level of at least a portion of the area of ​​a part based on recorded images.

[0085] Example 19: The method of Example 17 or Example 18 further includes the step of selecting a size range of defects to be detected.

[0086] Example 20: Any one of Examples 17 to 19 further includes the step of selecting a range of angles in which a plurality of component light sources direct radiation toward a component.

[0087] Example 21: In any one of the methods of Examples 17 to 20, the non-biological component comprises at least one material selected from materials including metal surfaces, ceramic surfaces, ceramic-coated surfaces, elemental semiconductor substrate surfaces, compound semiconductor substrate surfaces, glass surfaces, anodized surfaces, plastics, and oxidized surfaces.

[0088] Example 22: In any one of the methods of Examples 17 to 21, the size range of the defects to be detected includes a range of about 50 nm to about 50 mm of the characteristic dimensions of the detected defects.

[0089] Example 23: An embodiment of the disclosed subject describes a method of operating a reflective-mode Fourier ptychographic microscope (RFPM) to detect defects on the surface of a part. The method comprises: generating at least one light emission pattern from a plurality of component light sources configured to direct radiation onto a surface, wherein the plurality of component light sources have a plurality of individual light sources, each of the plurality of individual light sources is configured to be individually activated, and at least one light emission pattern is selected from temporal patterns and spatial patterns; using both bright-field imaging and dark-field imaging to sample the Fourier space of an image of the surface; collecting the directed radiation from the surface at a sensor; obtaining phase derivative measurements by differential-phase contrast (DPC) techniques in a region near the defect from the directed radiation collected by the sensor; determining an angle between the imaging axis from the surface to the sensor; and determining at least one height feature of one or more defects on the surface.

[0090] Example 24: In the method of Example 23, the characteristic dimensions of the detected defects are about 5 μm, and the size is larger over an area of ​​up to several square meters.

[0091] Example 25: In either method of Example 23 and Example 24, the part is a non-biological part.

[0092] Example 26: In the method of Example 25, the non-biological component comprises at least one material selected from materials including metal surfaces, ceramic surfaces, ceramic-coated surfaces, elemental semiconductor substrate surfaces, compound semiconductor substrate surfaces, glass surfaces, anodized surfaces, plastics, and oxidized surfaces.

[0093] Example 27: In any one of the methods of Examples 23 to 26, the spatial pattern is selected to irradiate the surface with a number of incident angles substantially simultaneously during a time period for the selected spatial pattern.

[0094] Example 28: In any one of the methods of Examples 23 to 27, the step of selecting a temporal pattern further comprises: a step of selecting a light source to be activated among a plurality of individual light sources; and a step of determining which of the selected plurality of individual light sources is activated in time with respect to the remaining light sources among the selected plurality of individual light sources.

[0095] Example 29: In any one of the methods of Examples 23 to 28, the step of selecting a spatial pattern includes the step of selecting a plurality of individual light sources to be activated for a substantially uniform time period.

Claims

Claim 1 A method for operating a reflective-mode Fourier ptychographic microscope (RFPM) to detect defects on the surface of a component, comprising: loading the component onto a holding fixture of the RFPM; generating at least one lighting pattern from a plurality of component light sources configured to direct radiation onto the surface, wherein the plurality of component light sources each comprises a plurality of individual light sources configured to be individually activated, and the at least one lighting pattern is selected from a plurality of patterns including temporal patterns and spatial patterns; collecting the directed radiation from the surface at a sensor element; obtaining phase derivative measurements from the radiation collected by the sensor element using differential-phase contrast (DPC) techniques; determining an angle between the imaging axes from the surface to the sensor element; and determining at least one height feature of one or more defects on the surface. Claim 2 An RFPM operation method according to claim 1, further comprising the step of raster scanning the at least one generated light pattern across the area of ​​the surface. Claim 3 An RFPM operation method according to claim 1, further comprising the step of performing a raster scan across an area of ​​the surface by moving the part under the at least one generated light pattern. Claim 4 An RFPM operation method according to claim 1, further comprising the step of scanning the at least one generated light pattern across the area of ​​the surface; and the step of performing a raster scan across the area of ​​the surface by moving the part under the at least one generated light pattern. Claim 5 An RFPM operation method according to claim 1, wherein the area above the area of ​​the surface to be inspected is selected to be at least 0.25 square meters across the surface. Claim 6 An RFPM operation method according to claim 1, further comprising the step of determining at least one wavelength for selected light sources among the plurality of individual light sources. Claim 7 A method of RFPM operation according to claim 1, wherein at least one illumination pattern is selected to illuminate the surface at a plurality of incident angles. Claim 8 An RFPM operation method according to claim 1, wherein the temporal patterns and the spatial patterns are predetermined. Claim 9 An RFPM operation method according to claim 1, wherein the step of selecting the temporal pattern comprises: a step of selecting a light source to be activated among the plurality of individual light sources; and a step of determining which of the selected plurality of individual light sources is activated in time with respect to the remaining light sources among the selected plurality of individual light sources. Claim 10 An RFPM operation method according to claim 1, wherein the step of selecting the spatial pattern includes the step of selecting a light source to be activated for a uniform time period among the plurality of individual light sources. Claim 11 An RFPM operation method according to claim 1, further comprising the step of determining an angle at which the midpoint of the at least one generated light pattern is offset from the normal by a predetermined number of angles from the vertical relative to the surface. Claim 12 A method of RFPM operation according to claim 1, further comprising the step of computationally combining at least one of the collected radiation redirected from the surface to increase the resolution of the detected defects over the Rayleigh limit-of-resolution for the wavelengths of the light of the plurality of individual light sources and a predetermined number of apertures (numerical aperture). Claim 13 An RFPM operation method according to claim 1, further comprising the step of selecting collection optics to focus the collected radiation onto the sensor element from a predetermined number of apertures. Claim 14 A method of RFPM operation according to claim 1, wherein the plurality of component light sources comprises an LED array. Claim 15 In claim 14, the step of generating at least one lighting pattern comprises selecting one of the plurality of individual light sources to include a group of LEDs from the LED array, in an RFPM operation method. Claim 16 An RFPM operation method according to claim 1, wherein each of the plurality of individual light sources comprises an LED. Claim 17 A method for operating a reflective-mode Fourier ptychographic microscope (RFPM), comprising: loading a non-biological part to be inspected onto a fixture; selecting a program to run and control one or more modes of the RFPM, wherein the modes are selectable from modes including a spatial pattern of a plurality of component light sources, a temporal pattern of a plurality of component light sources, a range of defect sizes to be detected, an area of ​​the part to be inspected, at least one height feature for one or more detected defects, and a number of multiple images of the non-biological part to be recorded; and acquiring phase derivative measurements from radiation collected by a sensor element using differential-phase contrast (DPC) techniques. Claim 18 An RFPM operation method according to claim 17, further comprising the step of determining the level of roughness of at least a portion of the area of ​​the part based on the recorded images. Claim 19 An RFPM operation method according to claim 17, further comprising the step of selecting a size range of defects to be detected. Claim 20 An RFPM operation method according to claim 17, further comprising the step of selecting a range of angles in which the plurality of component light sources direct radiation toward the component. Claim 21 In claim 17, the non-biological component comprises at least one material selected from materials including metal surfaces, ceramic surfaces, ceramic-coated surfaces, elemental semiconductor substrate surfaces, compound semiconductor substrate surfaces, glass surfaces, anodized surfaces, plastics, and oxidized surfaces, in a method of operating an RFPM. Claim 22 In claim 17, the RFPM operation method, wherein the size range of the defects to be detected comprises a range of 50 nm to 50 mm of the characteristic dimensions of the detected defects. Claim 23 A method for operating a reflective-mode Fourier ptychographic microscope (RFPM) to detect defects on the surface of a component, comprising the steps of: generating at least one light emission pattern from a plurality of component light sources configured to direct radiation onto a surface, wherein the plurality of component light sources have a plurality of individual light sources, each of the plurality of individual light sources is configured to be individually activated, and the at least one light emission pattern is selected from temporal patterns and spatial patterns; using both brightfield imaging and darkfield imaging to sample the Fourier space of an image of the surface; collecting the directed radiation from the surface at a sensor; obtaining phase derivative measurements by differential-phase contrast (DPC) techniques in a region close to a defect from the directed radiation collected by the sensor; and determining an angle between the imaging axes from the surface to the sensor. RFPM operation method comprising the step of determining at least one height characteristic of one or more defects on the surface. Claim 24 In claim 23, the RFPM operation method wherein the characteristic dimensions of the detected defects are 5 μm and the size is larger over an area of ​​up to several square meters. Claim 25 In claim 23, the RFPM operation method, wherein the above-mentioned part is a non-biological part. Claim 26 In claim 25, the non-biological component comprises at least one material selected from materials including metal surfaces, ceramic surfaces, ceramic-coated surfaces, elemental semiconductor substrate surfaces, compound semiconductor substrate surfaces, glass surfaces, anodized surfaces, plastics, and oxidized surfaces, in a method of operating RFPM. Claim 27 In claim 23, the RFPM operation method wherein the spatial pattern is selected to irradiate the surface with a plurality of incident angles simultaneously during a time period for the selected spatial pattern. Claim 28 In claim 23, the step of selecting the temporal pattern comprises: a step of selecting a light source to be activated among the plurality of individual light sources; and a step of determining which of the selected plurality of individual light sources is activated in time with respect to the remaining light sources among the selected plurality of individual light sources, RFPM operation method. Claim 29 In claim 23, the step of selecting the spatial pattern includes the step of selecting a light source to be activated for a uniform time period among the plurality of individual light sources, RFPM operation method.

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