Systems and methods for improved optical fringe generation and projection

Abstract

The problem of slow measurement of height properties using optical fringe projection is solved by systems that permit the measurement of height properties of surfaces in a single scan. For surfaces having a large range of scatter magnitudes in a single scan, the systems and methods alternately generate first and second sets of optical fringes having different peak optical intensities and alternately project the first and second sets of optical fringes to a surface for measurement. For surfaces having large height discontinuities, the systems and methods generate first and second sets of optical fringes having different pitches and orientations and project the first and second sets of optical fringes to a surface for measurement.

Description

SYSTEMS AND METHODS FOR IMPROVED OPTICAL FRINGE GENERATION AND PROJECTIONCROSS-REFERENCE

[0001] The present application claims priority to U.S. Provisional Patent Application No. 63 / 674,762, entitled “SYSTEMS AND METHODS FOR IMPROVED OPTICAL FRINGE GENERATION AND PROJECTION,” filed on July 23, 2024, which is incorporated herein by reference in its entirety for all purposes.BACKGROUND

[0002] Numerous applications in science and technology' may require rapid and accurate assessment of height properties of surfaces. For instance, the manufacture of optical components or of semiconductor devices may require rapid and accurate assessment for quality control purposes or to diagnose errors in manufacturing systems and methods. Such height properties may be measured by, for instance, projecting optical fringes at a surface and using positional changes of the fringes to measure the height of the surface at various locations. Current systems and methods for measuring height properties of surfaces may suffer from a variety of deficiencies, such as being too slow, too expensive, or too inaccurate. For instance, systems and methods that utilize fringe projection to measure height properties may require multiple scans of a surface when the surface displays a large range of scatter magnitudes, greatly slowing the surface measurement. As another example, systems and methods that utilize fringe projection to measure height properties may suffer from insufficient dynamic range, making it difficult to map height properties across surfaces having large height discontinuities. Accordingly, presented herein are systems and methods that utilize fringe patterns for improved measurement of surface height properties of surfaces.BRIEF DESCRIPTION OF THE DRAWINGS

[0003] Various embodiments of the inventions are disclosed in the following detailed description and the accompanying drawings.

[0004] FIG. 1 shows a schematic depicting an exemplary system for projecting fringes of different optical intensities to a surface.

[0005] FIG. 2 shows a flowchart depicting an exemplary’ method for projecting fringes of different optical intensities to a surface.

[0006] FIG. 3 shows a schematic depicting an exemplary system for projecting fringes of different pitches and orientations to a surface.

[0007] FIG. 4 shows a flowchart depicting an exemplary method for projecting fringes of different pitches and orientations to a surface.

[0008] FIG. 5 shows a schematic depicting an exemplary system for manufacturing structures and detecting and / or repairing defects in the manufactured structures by projecting fringes of different optical intensities, different pitches, and / or different orientations to the manufactured structures.

[0009] FIG. 6 is a flowchart for a method for operating the structure manufacturing system described herein with respect to FIG. 5.

[0010] FIG. 7 shows a block diagram of a computer system for implementing portions of the systems and methods described herein.

[0011] FIG. 8A depicts an example of a first set of optical fringes scattered from a surface.

[0012] FIG. 8B shows an example simulated second set of optical fringes having a fringe orientation opposite that of the first set of fringes scattered from a flat surface.

[0013] FIG. 8C shows the sum of the first and second sets of fringes.

[0014] FIG. 9A shows an example two-dimensional (2D) Fourier transform of the data depicted in FIG. 8A.

[0015] FIG. 9B shows an example phase map reconstructed from the 2D Fourier transform of FIG. 9 A.

[0016] FIG. 10A shows an example 2D Fourier transform of the data depicted in FIG. 8C.

[0017] FIG. 10B shows an example phase map reconstructed from the 2D Fourier transform of FIG. 10 A.DETAILED DESCRIPTION

[0018] The inventions can be implemented in numerous ways, including as a process; an apparatus; a system; a composition of matter; a computer program product embodied on a computer readable storage medium; and / or a processor, such as a processor configured to execute instructions stored on and / or provided by a memory coupled to the processor. In this specification, these implementations, or any other form that the inventions may take, may be referred to as techniques. In general, the order of the steps of disclosed processes may be altered within the scope of the inventions. Unless stated otherwise, a component such as a processoror a memory described as being configured to perform a task may be implemented as a general component that is temporarily configured to perform the task at a given time or a specific component that is manufactured to perform the task. As used herein, the term “processor” refers to one or more devices, circuits, and / or processing cores configured to process data, such as computer program instructions.

[0019] A detailed description of one or more embodiments of the inventions is provided below along with accompanying figures that illustrate the principles of the inventions. The inventions are described in connection with such embodiments, but the inventions are not limited to any embodiment. The scope of the inventions is limited only by the claims and the inventions encompass numerous alternatives, modifications and equivalents. Numerous specific details are set forth in the following description in order to provide a thorough understanding of the inventions. These details are provided for the purpose of example and the inventions may be practiced according to the claims without some or all of these specific details. For the purpose of clarity, technical material that is known in the technical fields related to the inventions has not been described in detail so that the inventions are not unnecessarily obscured.

[0020] As used herein, the term “or” shall convey both disjunctive and conjunctive meanings, unless otherwise indicated or impossible. For instance, the phrase “A or B” shall be interpreted to include element A alone, element B alone, and the combination of elements A and B. As another example, the phrase “A, B. or C” shall be interpreted to include element A alone, element B alone, element C alone, the combination of elements A and B but not C, the combination of elements A and C but not B, the combination of elements B and C but not A, and the combination of elements, A, B, and C.

[0021] As used herein, the phrases “interference pattern,” “optical fringe pattern,” “fringe pattern,” “optical fringes,” or “fringes” denote a series of alternating regions of high optical intensity and regions of low optical intensity resulting, respectively, from constructive and destructive interference of two or more beams of light.

[0022] As used herein, the phrases “pitch” or “fringe pitch” refer to the distance between subsequent maxima or minima in the optical intensity of interferometric fringe patterns. An interferometric fringe pattern displays alternating bright and dark bands, with the center of each bright band constituting a local maximum in optical intensity and the center of each dark band constituting a local minimum in optical intensity. The pitch or fringe pitch is thus the distance between the centers of two subsequent bright bands or two subsequent dark bands. For instance, an interferometric fringe pattern in which the centers of subsequent brightbands are separated by 10 micrometers (pm) may be referred to as having a fringe pitch of 10 pm.

[0023] As used herein, the phrases '‘orientation” or '‘fringe orientation” refer to the angle between the direction of a vector defined by a set of optical fringes and the direction in which the set of fringes are moved relative to a surface (e.g., by scanning the set of fringes across a fixed surface or by scanning the surface across a fixed set of fringes). The bright and dark bands of a set of fringes can be defined by a vector that proceeds from one bright band to a subsequent bright band or from one dark band to a subsequent dark band. This vector has a direction that is perpendicular to any given bright or dark band of the set of fringes. The orientation is thus the angle between this vector and the direction in which the set of fringes are moved relative to the surface (e.g., by scanning the set of fringes across a fixed surface or by scanning the surface across a fixed set of fringes).

[0024] Numerous applications in science and technology may require rapid and accurate assessment of height properties of surfaces. For instance, the manufacture of optical components or of semiconductor devices may require rapid and accurate assessment for quality control purposes or to diagnose errors in manufactunng systems and methods. Such height properties may be measured by, for instance, projecting optical fringes at a surface and using height measurement techniques. However, current systems and methods for measuring height properties of surfaces may suffer from a variety of deficiencies, such as being too slow, too expensive, or too inaccurate.

[0025] For instance, systems and methods that utilize fringe projection to measure height properties may require multiple scans of a surface when the surface displays a large range of scatter magnitudes. This may occur, for instance, when the surface contains polished and unpolished regions, smooth and rough regions, or different materials in different regions. The need for multiple scans of the surface may greatly slow the surface measurement, reducing throughput. Accordingly, presented herein are systems that permit the measurement of height properties of surfaces having a large range of scatter magnitudes in a single scan. Such systems and methods alternately generate first and second sets of optical fringes having different peak optical intensities and alternately project the first and second sets of optical fringes to a surface for measurement. Such alternating high and low intensity fringes may permit measurement both of regions that strongly scatter the fringes toward an optical detector and those that do so weakly. For instance, the high intensity fringes may produce a strong signal from regions that weakly scatter the fringes toward the optical detector, while the low intensity fringes may prevent saturation of the optical detector when the fringes are scattered by regions that stronglyscatter the fringes toward the optical detector.

[0026] As another example, systems and methods that utilize fringe projection to measure height properties may suffer from insufficient dynamic range, making it difficult to map height properties across surfaces having large height discontinuities. Such systems and methods may be unable to disambiguate between height discontinuities that are additively related by an integer number of the pitch period of the fringes. For instance, a fringe projection system that utilized a fringe pitch period of 20 pm may be unable to differentiate a 10 pm height discontinuity from a 30 pm or 50 pm height discontinuity. Such issues may be solved by projecting fringes having different fringe pitches at the surface. Unfortunately, such a solution generally requires multiple scans of the surface, slowing the surface measurement and reducing throughput. Accordingly, presented herein are systems that permit the measurement of height properties of surfaces displaying height discontinuities. Such systems and methods generate first and second sets of optical fringes having different pitches and orientations and project the first and second sets of optical fringes to a surface for measurement. The use of different fringe pitches may allow unambiguous determination of height discontinuities on the surface over a greatly enhanced dynamic range. The use of two different orientations may simplify the analysis of the data obtained from the two sets of fringes and permit the surface measurement to be conducted in a single scan.

[0027] The sy stems and methods may allow rapid characterization of the topographies of surfaces of optical components, semiconductor devices, or other manufactured items. Such rapid characterization may provide numerous benefits. For instance, rapid characterization may allow for higher throughput characterization of the topographies. Rapid characterization may also allow for an increase in accuracy of the characterization, as it may mitigate the error associated with thermal drift or vibrational noise within the measurement system (for instance, thermal drift or vibrational noise within an optical measurement system) or thermal drift or vibrational noise within a surface under study.Systems and methods for projecting fringes of different optical intensities to a surface

[0028] FIG. 1 shows a schematic depicting an exemplary system 100 for projecting fringes of different optical intensities to a surface. In the example shown, the system 100 comprises a fringe generation module 110. In some embodiments, the fringe generation module 110 is configured to generate sets of optical fringes 112. In some embodiments, the fringe generation module 110 is configured to alternately generate a first set of optical fringes having a first peak optical intensity and a second set of optical fringes having a second peak optical intensity. Since the first and second sets of optical fringes travel along substantially similaroptical paths, the first and second sets of optical fringes are generically depicted as a single element in FIG. 1. In some embodiments, the first and second peak optical intensities are different. In some embodiments, a ratio between the first peak optical intensity and the second peak optical intensity is at least about 2, 3, 4, 5, 6, 7, 8, 9, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 200, 300, 400, 500, 600, 700, 800, 900, 1,000, or more, at most about 1,000, 900, 800, 700, 600, 500, 400, 300. 200, 100, 90, 80, 70, 60, 50, 40, 30, 20, 10, 9, 8, 7, 6, 5, 4, 3, 2, or less, or within a range defined by any two of the preceding values.

[0029] In some embodiments, the fringe projection module 110 comprises a light source (not shown in FIG. 1) and an optical grating (not shown in FIG. 1). In some embodiments, the light source is configured to alternately generate first light having a first optical power (i.e., when used to generate the first set of optical fringes) and second light having a second optical power (i.e., when used to generate the second set of optical fringes). In some embodiments, the optical grating is configured to alternately: (a) receive the first light, generate first light beams having at least t o different diffraction orders from the first light, and project the first light beams (i.e., when used to generate the first set of optical fringes) and (b) receive the second light, generate second light beams having at least two different diffraction orders from the second light, and project the second light beams (i.e., when used to generate the second set of optical fringes). In some embodiments, the fringe generation module 110 further comprises at least one beam block (not shown in FIG. 1) configured to block one or more portions of the first or second light beams. For instance, in some embodiments, the optical grating is configured to generate first light beams (i.e., when used to generate the first set of optical fringes) having a -1 diffraction order, a 0 diffraction order, and a +1 diffraction order and the beam block is configured to block the -1 diffraction order (allowing the 0 diffraction order and +1 diffraction order portions of the first light beams to pass), to block the 0 diffraction order (allowing the -1 diffraction order and +1 diffraction order portions of the first light beams to pass), or to block the +1 diffraction order (allowing the -1 diffraction order and 0 diffraction order portions of the first light beams to pass). In some embodiments, the optical grating is configured to generate second light beams (i.e., when used to generate the second set of optical fringes) having a -1 diffraction order, a 0 diffraction order, and a +1 diffraction order and the beam block is configured to block the -1 diffraction order (allowing the 0 diffraction order and +1 diffraction order portions of the second light beams to pass), to block the 0 diffraction order (allowing the -1 diffraction order and +1 diffraction order portions of the second light beams to pass), or to block the +1 diffraction order (allowing the -1 diffraction order and 0 diffraction order portions of the second light beams to pass).

[0030] In the example shown, the system 100 comprises a fringe projection module 120. In some embodiments, the fringe projection module 120 is configured to alternately receive and project the first and second sets of optical fringes to a surface 130. In some embodiments, the fringe projection module 120 comprises at least one lens or objective (not shown in FIG. 1) configured to project the first and second sets of optical fringes to the surface 130.

[0031] In the example shown, the system 100 comprises a surface characterization module 140. In some embodiments, the surface characterization module 140 is configured to characterize the surface 130 based on at least a first scattering interaction between the first set of optical fringes and the surface 130 and a second scattering interaction between the second set of optical fringes and the surface 130. In some embodiments, the surface characterization module 140 comprises an optical detector (not shown in FIG. 1) configured to alternately receive a first set of scattered optical fringes resulting from the first scattering interaction and a second set of scattered optical fringes resulting from the second scattering interaction. In some embodiments, the optical detector has an aspect ratio of at least about 2;I, 3: 1, 4: 1, 5: 1, 6: 1, 7: 1, 8: 1. 9: 1, 10: 1, or higher, at most about 10:1, 9: 1. 8: 1. 7: 1, 6: 1. 5: 1, 4: 1, 3: 1. 2:1, or less, or an aspect ratio that is within a range defined by any two of the preceding values. In some embodiments, the optical detector has a frame rate of at least about 50 hertz (Hz), 60 Hz, 70 Hz, 80 Hz, 90 Hz, 100 Hz, 200 Hz. 300 Hz, 400 Hz, 500 Hz, 600 Hz, 700 Hz. 800 Hz, 900 Hz. 1 kilohertz (kHz), 2 kHz, 3 kHz, 4 kHz, 5 kHz, 6 kHz, 7 kHz. 8 kHz. 9 kHz, 10 kHz, or more, at most about 10 kHz, 9 kHz, 8 kHz, 7 kHz, 6 kHz, 5 kHz, 4 kHz, 3 kHz, 2 kHz, 1 kHz, 900 Hz, 800 Hz, 700 Hz, 600 Hz, 500 Hz, 400 Hz, 300 Hz, 200 Hz, 100 Hz, 90 Hz, 80 Hz, 70 Hz, 60 Hz, 50 Hz, or less, or a frame rate that is within a range defined by any two of the preceding values.

[0032] In some embodiments, the surface characterization module 140 comprises a computing system (such as computing system 700 described herein with respect to FIG. 7) configured to characterize the surface 130 based at least on the first set of scattered optical fringes and the second set of scattered optical fringes. In some embodiments, characterizing the surface 130 comprises determining a height map of the surface based at least on the first set of scattered optical fringes and the second set of scattered optical fringes. In some embodiments, the height map is determined by measuring the distance by which the first and / or second sets of scattered optical fringes have shifted on the optical detector for each location on the surface and calculating a corresponding surface height at each location. Such a measurement and calculation will be well known to a person having ordinary skill in the art.

[0033] In some embodiments, the first and second sets of optical fringes are alternated by generating and projecting the first and second sets of optical fringes on a frame-by-frame basis. That is, in some embodiments, the first set of optical fringes is generated and projected for a period of time corresponding to a first frame of an optical detector, the second set of optical fringes is then generated and projected for a period of time corresponding to a second frame of the optical detector, the first set of optical fringes is then generated and projected for a period of time corresponding to a third frame of the optical detector, and so forth. A person having skill in the art will recognize that other timing arrangements are possible. In some embodiments, the first and second set of optical fringes are alternately generated and projected over a period of at least about 50 microseconds (ps). 60 ps, 70 ps, 80 ps, 90 ps, 100 ps, 200 ps, 300 ps. 400 ps, 500 ps, 600 ps, 700 ps, 800 ps, 900 ps. 1 millisecond (ms), 2 ms, 3 ms, 4 ms, 5 ms, 6 ms, 7 ms, 8 ms, 9 ms, 10 ms, 20 ms, 30 ms, 40 ms, 50 ms, or more, at most about every 50 ms, 40 ms, 30 ms, 20 ms, 10 ms, 9 ms, 8 ms, 7 ms, 6 ms, 5 ms, 4 ms, 3 ms, 2 ms, 1 ms, 900 ps, 800 ps, 700 ps, 600 ps, 500 ps, 400 ps, 300 ps, 200 ps, 100 ps, 90 ps, 80 ps, 70 ps, 60 ps, 50 ps, or a period that is within a range defined by any two of the preceding values.

[0034] In some embodiments, the principles described herein with respect to FIG. 1 may be extended to utilize arbitrary numbers of sets of fringes. For instance, the system 100 may be used to alternately generate and project at least about 2, 3, 4, 5, 6, 7, 8, 9, 10, or more sets of fringes, at most about 10, 9, 8, 7, 6, 5, 4, 3, or 2 sets of fringes, or a number of sets of fringes that is within a range defined by any two of the preceding values. Each set of fringes may be associated with a different peak optical intensity.

[0035] FIG. 2 shows a flowchart depicting an exemplary method 200 for projecting fringes of different optical intensities to a surface. In the example shown, at least a first set of optical fringes having a first peak optical intensity and a second set of optical fringes having a second peak optical intensity are alternately generated at 210. In some embodiments, the first and second peak optical intensities are different. In some embodiments, the first or second peak optical intensity7is any first or second peak optical intensity7described herein with respect to FIG. 1.

[0036] In some embodiments, the first and second sets of optical fringes are generated using any fringe generation module described herein with respect to FIG. 1. For instance, in some embodiments, the first and second sets of optical fringes are generated using the light source and the optical grating described herein with respect to FIG. 1. In some embodiments, the light source is used to alternately generate first light having a first optical power and second light having a second optical power different from the first optical power, as described hereinwith respect to FIG. 1. In some embodiments, the optical grating is used to: alternately: (a) receive the first light, generate first light beams having at least two different diffraction orders from the first light, and project the first light beams and (b) receive the second light, generate second light beams having at least two different diffraction orders from the second light, and to project the second light beams, as described herein with respect to FIG. 1. In some embodiments, at least a portion of the first or second light beams is blocked (e.g., using the beam block described herein with respect to FIG. 1).

[0037] At 220, the first and second sets of optical fringes are alternately received and projected to a surface. In some embodiments, the first and second sets of optical fringes are received and projected to the surface using any fringe projection module described herein with respect to FIG. 1. For instance, in some embodiments, the first and second sets of optical fringes are projected to the surface using at least one lens or objective.

[0038] At 230, the surface is characterized based on at least a first scattering interaction between the first set of optical fringes and the surface and a second scattering interaction between the second set of optical fringes and the surface. In some embodiments, the surface is characterized using an optical detector described herein with respect to FIG. 1. In some embodiments, the optical detector is configured to alternately receive at least a first set of scattered optical fringes resulting from the first scattering interaction and a second set of scattered optical fringes resulting from the second scattering interaction, as described herein with respect to FIG. 1. In some embodiments, the surface is characterized using a computing system described herein with respect to FIG. 1 . In some embodiments, the computing system is used to characterize the surface based at least on the first set of scattered optical fringes and the second set of scattered optical fringes, as described herein with respect to FIG. 1. In some embodiments, the surface is characterized by determining a height map of the surface based at least on the first set of scattered optical fringes and the second set of scattered optical fringes, as described herein with respect to FIG. 1.Systems and methods for projecting fringes of different pitches and orientations to a surface

[0039] FIG. 3 shows a schematic depicting an exemplary system 300 for projecting fringes of different pitches and orientations to a surface. In the example shown, the system 300 comprises a fringe generation module 310. In some embodiments, the fringe generation module 310 is configured to generate a first set of optical fringes 312 and a second set of optical fringes 314. In the example shown, the first set of optical fringes 312 and the second set of optical fringes 314 are depicted as traveling along different optical paths that are separated in space.However, in some embodiments, the first set of optical fringes 312 and the second set of optical fringes 314 travel along substantially similar optical paths. That is, in some embodiments, the first set of optical fringes 312 and the second set of optical fringes 314 substantially overlap in space.

[0040] In some embodiments, the first set of optical fringes 312 have a first fringe pitch and the second set of optical fringes 314 have a second fringe pitch. In some embodiments, the first and second fringe pitches are different. In some embodiments, the first or second fringe pitch is at least about 10 pm, 15 pm, 20 pm, 25 pm, 30 pm, 35 pm, 40 pm, 45 pm, 50 pm, 55 pm, 60 pm, 65 pm, 70 pm, 75 pm, 80 pm, 85 pm, 90 pm, 95 pm, 100 pm, 105 pm, 110 pm, 115 pm, 120 pm, 125 pm, 130 pm, 135 pm, 140 pm, 145 pm, 150 pm, 155 pm, 160 pm, 165 pm, 170 pm. 175 pm, 180 pm, 185 pm. 190 pm, 195 pm, 200 pm, 205 pm, 210 pm. 215 pm,220 pm, 225 pm, 230 pm, 235 pm, 240 pm, 245 pm, 250 pm, 255 pm, 260 pm, 265 pm, 270 pm, 275 pm, 280 pm, 285 pm, 290 pm, 295 pm, 300 pm, or more, at most about 300 pm, 295 pm, 290 pm, 285 pm, 280 pm, 275 pm, 270 pm, 265 pm, 260 pm, 255 pm, 250 pm, 245 pm,240 pm, 235 pm, 230 pm, 225 pm, 220 pm, 215 pm, 210 pm, 205 pm, 200 pm, 195 pm, 190 pm, 185 pm. 180 pm, 175 pm, 170 pm. 165 pm, 160 pm, 155 pm. 150 pm, 145 pm. 140 pm.135 pm, 130 pm, 125 pm, 120 pm, 115 pm, 110 pm, 105 pm, 100 pm, 95 pm, 90 pm, 85 pm, 80 pm, 75 pm, 70 pm, 65 pm, 60 pm, 55 pm, 50 pm, 45 pm, 40 pm, 35 pm, 30 pm, 25 pm, 20 pm, 15 pm. 10 pm, or less, or within a range defined by any two of the preceding values. In some embodiments, the first fringe pitch is at least about 1%. 2%, 3%. 4%, 5%. 6%, 7%, 8%, 9%, 10%, 15%, 20%, 25%, or more larger than the second fringe pitch, at most about 25%, 20%, 15%, 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, 1%, or less larger than the second fringe pitch, or larger than the second fringe pitch by an amount that is within a range defined by any two of the preceding values.

[0041] In some embodiments, the first set of optical fringes 312 have a first fringe orientation and the second sets of optical fringes 314 have a second fringe orientation. In some embodiments, the first and second fringe orientations are different. In some embodiments, the first or second fringe orientation is at least about -85 degrees, -80 degrees, -75 degrees, -70 degrees, -65 degrees, -60 degrees, -55 degrees, -50 degrees, -45 degrees, -40 degrees, -35 degrees, -30 degrees, -25 degrees, -20 degrees, -15 degrees, -10 degrees, -5 degrees, 5 degrees, 10 degrees, 15 degrees, 20 degrees, 25 degrees, 35 degrees, 40 degrees, 45 degrees, 50 degrees, 55 degrees, 60 degrees, 65 degrees, 70 degrees. 75 degrees, 80 degrees, 85 degrees, or more, at most about 85 degrees, 80 degrees, 75 degrees, 70 degrees, 65 degrees, 60 degrees. 55 degrees, 50 degrees, 45 degrees, 40 degrees, 35 degrees, 30 degrees, 25 degrees, 20 degrees,15 degrees, 10 degrees, 5 degrees, -5 degrees, -10 degrees, -15 degrees, -20 degrees, -25 degrees, -30 degrees, -35 degrees, -40 degrees, -45 degrees, -50 degrees, -55 degrees, -60 degrees, -65 degrees, -70 degrees, -75 degrees, -80 degrees, -85 degrees, or less, or within a range defined by any two of the preceding values. In some embodiments, the first set of optical fringes 312 and the second set of optical fringes 314 are spectrally separated. That is, in some embodiments, the first set of optical fringes 312 is characterized by a first central wavelength and a first bandwidth, the second set of optical fringes 314 is characterized by a second central wavelength and a second bandwidth, the first and second central wavelengths are different, and the first and second bandwidths do not overlap. In some embodiments, the use of spectral separation between the first set of optical fringes 312 and the second set of optical fringes 314 substantially prevents interference between the first set of optical fringes 312 and the second set of optical fringes 314. In some embodiments, the use of spectral separation between the first set of optical fringes 312 and the second set of optical fringes 314 allows the first set of optical fringes 312 and the second set of optical fringes 314 to be combined using a spectral beamsplitter.

[0042] In some embodiments, the fringe projection module 310 comprises a light first light source (not shown in FIG. 3), a second light source (not shown in FIG. 3), a first optical grating (not shown in FIG. 3), and a second optical grating (not shown in FIG. 3). In some embodiment, the first light source is configured to generate first light and direct the first light to the first optical grating. In some embodiments, the first optical grating is configured to receive the first light, generate first light beams having at least a first -1 diffraction order and a first +1 diffraction order from the first light, and project the first light beams. In some embodiment, the second light source is configured to generate second light and direct the second light to the second optical grating. In some embodiments, the second optical grating is configured to receive the second light, generate second light beams having at least a second -1 diffraction order and a second +1 diffraction order from the second light, and project the second light beams. In some embodiments, the fringe generation module 310 further comprises at least one beam block (not shown in FIG. 3) configured to block light beams having a 0 diffraction order.

[0043] In the example shown, the system 300 comprises a fringe projection module 320. In some embodiments, the fringe projection module 320 is configured to receive and project the first set of optical fringes 312 and the second set of optical fringes 314 to a surface 330. In some embodiments, the fringe projection module 320 comprises at least one beam combiner, spectral beamsplitter, lens, or objective (not shown in FIG. 3) configured to projectthe first set of optical fringes 312 and the second set of optical fringes 314 to the surface 330. In some embodiments, the first set of optical fringes 312 and the second set of optical fringes 314 are projected to the surface 330 substantially simultaneously.

[0044] In the example shown, the system 300 comprises a surface characterization module 340. In some embodiments, the surface characterization module 340 is configured to characterize the surface 330 based on at least a first scattering interaction between the first set of optical fringes 312 and the surface 330 and a second scattering interaction between the second set of optical fringes 314 and the surface 130. In some embodiments, the surface characterization module 340 comprises an optical detector (not show n in FIG. 3) configured to alternately receive a first set of scattered optical fringes resulting from the first scattering interaction and a second set of scattered optical fringes resulting from the second scattering interaction. In some embodiments, the optical detector has an aspect ratio of at least about 2;1, 3: 1, 4: 1, 5: 1, 6: 1, 7: 1, 8: 1, 9: 1, 10:1, or higher, at most about 10: 1, 9: 1, 8: 1, 7: 1, 6: 1, 5: 1, 4: 1, 3: 1, 2: 1, or less, or an aspect ratio that is within a range defined by any tw o of the preceding values. In some embodiments, the optical detector has a frame rate of at least about 50 hertz (Hz). 60 Hz, 70 Hz, 80 Hz, 90 Hz. 100 Hz, 200 Hz. 300 Hz, 400 Hz, 500 Hz. 600 Hz, 700 Hz. 800 Hz, 900 Hz, 1 kilohertz (kHz), 2 kHz, 3 kHz, 4 kHz, 5 kHz, 6 kHz, 7 kHz, 8 kHz, 9 kHz, 10 kHz, or more, at most about 10 kHz, 9 kHz, 8 kHz, 7 kHz, 6 kHz, 5 kHz, 4 kHz, 3 kHz, 2 kHz, 1 kHz, 900 Hz. 800 Hz, 700 Hz. 600 Hz, 500 Hz. 400 Hz, 300 Hz. 200 Hz, 100 Hz. 90 Hz. 80 Hz. 70 Hz, 60 Hz, 50 Hz, or less, or a frame rate that is ithin a range defined by any two of the preceding values.

[0045] In some embodiments, the surface characterization module 340 comprises a computing system (such as computing system 700 described herein with respect to FIG. 7) configured to characterize the surface 330 based at least on the first set of scattered optical fringes and the second set of scattered optical fringes. In some embodiments, characterizing the surface 330 comprises determining a height map of the surface based at least on the first set of scattered optical fringes and the second set of scattered optical fringes. In some embodiments, the height map is determined by conducting multiple pitch fringe projection using the first and second fringe orientations.

[0046] In multiple pitch fringe projection, two sets of fringes having different fringe pitches are measured. The use of the two different fringe pitches enables unambiguous height measurements across a larger range of distances than w ould be possible using a single set of fringes having a single fringe pitch. Using a single set of fringes having a single fringe pitch 7 , any step height a + 7j / 2 will not be distinguishable from a step height of a + 3T1 / 2, a +57 / 2, and so forth. Thus, the unambiguous dynamic range using a single set of fringes is limited to 7j / 2. The use of two set of fringes having two different fringe pitches 1 and T2can greatly increase the unambiguous dynamic range. The use of two different fringe pitches emulates the use of a single equivalent fringe pitch Teq= T1T2 / \T1— T2\.

[0047] Unfortunately, current approaches to multiple pitch fringe projection generally require the two different sets of fringes with the different fringe pitches T and T2to be directed to the surface successively. That is, one measurement scan is taken using a set of fringes with fringe pitch 1 and a second measurement scan is then taken using a set of fringes with fringe pitch T2. This at least doubles the total measurement time required to construct a height map of the surface, decreasing throughput. The problem generally results from the fact that T and T2must be relatively close in value in order to obtain a Teqthat permits a sufficiently large unambiguous dynamic range and signal -to-noise ratio. Thus, projecting the two sets of fringes simultaneously will typically cause overlap even in the Fourier domain, making it difficult to separate the signals from the two sets of fringes and causing loss of information.

[0048] The use of two sets of optical fringes with different fringe pitches and different fringe orientations presented herein may solve the problems discussed above and allow simultaneous acquisition of signals from the first and second sets of optical fringes. This may allow the acquisition of both signals in a single measurement scan, increasing throughput. When the two sets of optical fringes are projected with different fringe pitches and different fringe orientations, the resultant optical signals captured by the optical detector may be subjected to a two-dimensional (2D) Fourier transform. Due to the different orientations, the Fourier transformed optical signals resulting from the first set of optical fringes will be contained within a different portion of the 2D Fourier domain from the Fourier transformed optical signals resulting from the second set of optical fringes. For instance, when the 2D Fourier transform is graphed, the Fourier transformed optical signals resulting from the first set of optical fringes may be contained with the upper left (i.e., -x. +y) and lower right (i.e., +x, -y) quadrants of the graph, while the Fourier transformed optical signals resulting from the second set of optical fringes may be contained with the lower left (i.e., -x, -y) and upper right (i.e., +x, +y) quadrants of the graph. The Fourier transform of the optical signal associated with the first set of optical fringes may thus be easily isolated and a 2D inverse Fourier transform may be performed to obtain the optical signal associated with the first set of optical fringes. Similarly, the Fourier transform of the optical signal associated with the second set of optical fringes may also be easily isolated and a 2D inverse Fourier transform may be performed toobtain the optical signal associated with the second set of optical fringes. An example is shown at FIGs. 7A-7B. In this manner, the benefits of multiple pitch fringe projection (i.e., a larger unambiguous dynamic range) may be obtained without needing to at least double the measurement scan time.

[0049] In some embodiments, the principles described herein with respect to FIG. 3 may be extended to utilize arbitrary numbers of sets of fringes. For instance, the system 300 may be used to generate and project at least about 2, 3. 4, 5, 6. 7, 8. 9, 10, or more sets of fringes, at most about 10, 9, 8, 7, 6, 5, 4, 3, or 2 sets of fringes, or a number of sets of fringes that is within a range defined by any two of the preceding values. Each set of fringes may be associated with a different pitch and / or orientation.

[0050] Although FIG. 3 depicts the fringe projection module 310 as projecting the first set of optical fringes 312 and the second set of optical fringes 314 as traveling along substantially parallel paths, the disclosure is not intended to be so limiting. In some embodiments, the first set of optical fringes 312 and the second set of optical fringes 314 maybe directed to the surface 130 along non-parallel paths. That is, in some embodiments, the first set of optical fringes 312 and the second set of optical fringes 314 may travel toward the surface 130 along paths that are at an angle relative to a plane defined by the surface 130. In some embodiments, the angle is at least about 5 degrees, 10 degrees, 15 degrees, 20 degrees, 25 degrees, 30 degrees, 35 degrees, 40 degrees, 45 degrees, 50 degrees. 55 degrees, 60 degrees, 65 degrees, 70 degrees. 75 degrees, 80 degrees, 85 degrees. 90 degrees, 95 degrees, 100 degrees, 105 degrees, 110 degrees, 1 15 degrees, 120 degrees, 125 degrees, 130 degrees, 135 degrees, 140 degrees, 145 degrees, 150 degrees, 155 degrees, 160 degrees, 165 degrees, 170 degrees, 175 degrees, or more, at most about 175 degrees, 170 degrees. 165 degrees, 160 degrees, 155 degrees, 150 degrees, 145 degrees, 140 degrees, 135 degrees, 130 degrees, 125 degrees, 120 degrees, 115 degrees, 1 10 degrees, 105 degrees, 100 degrees, 95 degrees, 90 degrees, 85 degrees, 80 degrees, 75 degrees, 70 degrees, 65 degrees, 60 degrees, 55 degrees, 50 degrees, 45 degrees, 40 degrees, 35 degrees, 30 degrees, 25 degrees, 20 degrees, 15 degrees, 10 degrees, 5 degrees, or less, or within a range defined by any two of the preceding values. Thus, in some embodiments, the first light source (not shown in FIG. 3) and the first optical grating (not shown in FIG. 3) are configured to direct the first set of fringes 312 along a first path that is at an angle to a second path along which the second light source (not shown in FIG. 3) and the second optical grating (not shown in FIG. 3) are configured to direct the second set of fringes 314. In some embodiments, the angle is any angle described herein.

[0051] FIG. 4 shows a flowchart depicting an exemplary method 400 for projectingfringes of different pitches and orientations to a surface. In the example shown, at least a first set of optical fringes having a first fringe pitch and a first fringe orientation and a second set of optical fringes having a second fringe pitch and a second fringe orientation are generated at 410. In some embodiments, the first and second fringe pitches are different. In some embodiments, the first or second fringe pitch is any first or second fringe pitch described herein with respect to FIG. 3. In some embodiments, the first and second fringe orientations are different. In some embodiments, the first or second fringe orientation is any first or second fringe orientation described herein with respect to FIG. 3.

[0052] In some embodiments, the first and second sets of optical fringes are generated using any fringe generation module described herein with respect to FIG. 3. For instance, in some embodiments, the first and second sets of optical fringes are generated using the first light source, second light source, first optical grating, and second optical grating described herein with respect to FIG. 3. In some embodiments, the first light source is used to generate first light and direct the first light to the first optical grating, as described herein with respect to FIG. 3. In some embodiments, the second light source is used to generate second light and direct the second light to the second optical grating, as described herein with respect to FIG. 3. In some embodiments, the first optical grating is used to receive the first light, generate first light beams having at least a first -1 diffraction order and a first +1 diffraction order from the first light, and project the first light beams, as described herein with respect to FIG. 3. In some embodiments, the second optical grating is used to receive the second light, generate second light beams having at least a second -1 diffraction order and a second +1 diffraction order from the second light, and project the second light beams, as described herein with respect to FIG. 3. In some embodiments, light beams having a 0 diffraction order are blocked (e g., using the beam block described herein with respect to FIG. 3).

[0053] At 420, the first and second sets of optical fringes are received and projected to a surface. In some embodiments, the first and second sets of optical fringes are received and projected to the surface using any fringe projection module described herein with respect to FIG. 3. For instance, in some embodiments, the first and second sets of optical fringes are projected to the surface using at least one beam combiner, lens, or objective.

[0054] At 430, the surface is characterized based on at least a first scattering interaction between the first set of optical fringes and the surface and a second scattering interaction between the second set of optical fringes and the surface. In some embodiments, the surface is characterized using an optical detector described herein with respect to FIG. 4. In some embodiments, the optical detector is configured to receive at least a first set of scattered opticalfringes resulting from the first scattering interaction and a second set of scattered optical fringes resulting from the second scattering interaction, as described herein with respect to FIG. 3. In some embodiments, the surface is characterized using a computing system described herein with respect to FIG. 3. In some embodiments, the computing system is used to characterize the surface based at least on the first set of scattered optical fringes and the second set of scattered optical fringes, as described herein with respect to FIG. 3. In some embodiments, the surface is characterized by determining a height map of the surface based at least on the first set of scattered optical fringes and the second set of scattered optical fringes, as described herein with respect to FIG. 3.

[0055] In some embodiments, the systems and methods described herein with respect to FIGs. 3 and 4 may be used to measure surface height properties with an enhanced unambiguous dynamic range compared with previous systems and methods. In some embodiments, the enhanced unambiguous dynamic range is at least about 10 pm, 15 pm, 20 pm, 25 pm, 30 pm, 35 pm, 40 pm, 45 pm, 50 pm, 55 pm, 60 pm, 65 pm, 70 pm, 75 pm, 80 pm, 85 pm, 90 pm, 95 pm, 100 pm, 105 pm, 110 pm. 115 pm, 120 pm, 125 pm, 130 pm, 135 pm, 140 pm. 145 pm, 150 pm, 155 pm. 160 pm, 165 pm, 170 pm. 175 pm, 180 pm. 185 pm.190 pm, 195 pm, 200 pm, 205 pm, 210 pm, 215 pm, 220 pm, 225 pm, 230 pm, 235 pm, 240 pm, 245 pm, 250 pm, 255 pm, 260 pm, 265 pm, 270 pm, 275 pm, 280 pm, 285 pm, 290 pm,295 pm, 300 pm, or more, at most about 300 pm, 295 pm, 290 pm, 285 pm, 280 pm, 275 pm,270 pm, 265 pm, 260 pm. 255 pm, 250 pm, 245 pm. 240 pm, 235 pm, 230 pm. 225 pm, 220 pm, 215 pm, 210 pm, 205 pm, 200 pm, 195 pm, 190 pm, 185 pm, 180 pm, 175 pm, 170 pm,165 pm, 160 pm, 155 pm, 150 pm, 145 pm, 140 pm, 135 pm, 130 pm, 125 pm, 120 pm, 115 pm, 110 pm, 105 pm, 100 pm, 95 pm, 90 pm, 85 pm, 80 pm, 75 pm, 70 pm, 65 pm, 60 pm, 55 pm, 50 pm, 45 pm, 40 pm, 35 pm, 30 pm, 25 pm, 20 pm, 15 pm, 10 pm, or less, or within a range defined by any two of the preceding values.Systems and methods for projecting fringes of different optical intensities, different pitches, and different orientations to a surface

[0056] The systems and methods for projecting fringes of different optical intensities described herein with respect to FIGs. 1-2 may be combined with the systems and methods for projecting fringes of different pitches and orientations described herein with FIGs. 3-4. Such combinations may simultaneously provide the advantages of different optical intensities (i.e., the ability to measure height properties of surfaces displaying a large range of scatter magnitudes) and of different pitches and orientations (i.e.. a large unambiguous dynamic range). Thus, two sets of optical fringes having different pitches and orientations (as describedherein with respect to FIGs. 3-4) may be projected to a surface at alternating first and second optical intensities (as described herein with respect to FIGs. 1-2).Systems and methods for manufacturing structures and detecting and / or repairing defects in the manufactured structures by projecting fringes of different optical intensities, different pitches, and / or different orientations to the manufactured structures.

[0057] FIG. 5 shows a schematic depicting an exemplary system 500 for manufacturing structures and detecting and / or repairing defects in the manufactured structures by projecting fringes of different optical intensities, different pitches, and / or different orientations to the manufactured structures. In the example shown, the system 500 includes detection apparatus (not shown in FIG. 5), a designing device 510, a forming device 520, a controller 530 (an inspection device), and a repairing device 540. In the example shown, the system 500 manufactures molded components such as automobile door parts, engine components, gear components, electronic components including circuit substrates, and the like.

[0058] A designing device 510 creates design information about the profile of a structure, and sends the created design information to the forming device 520. Further, the designing device 510 stores the created design information into an aforementioned coordinate storage portion 531 of the controller 530. The design information mentioned here indicates the coordinates of each position of the structure. The forming device 520 fabricates the structure based on the design information inputted from the designing device 510. The formation process of the forming device 520 includes at least one of casting, forging, and cutting.

[0059] In some embodiments, the detection apparatus comprises the system 100 described herein with respect to FIG. 1 or the system 300 described herein with respect to FIG. 3. The detection apparatus sends information indicating measured coordinates to the controller 530. The controller 530 includes the coordinate storage section 531 and an inspection section 532. The coordinate storage section 531 stores the design information from the designing device 510. The inspection section 532 reads out the design information from the coordinate storage section 531. The inspection section 532 creates information (profile information) signifying the fabricated structure from the information indicating the coordinates received from the detection apparatus. The inspection section 532 compares the information (the profile information) indicating the coordinates received from a profile measuring device 570 with the design information read out from the coordinate storage section 531. In some embodiments, the profile measuring device 570 comprises the system 100 described herein with respect toFIG. 1 or the system 300 described herein with respect to FIG. 3. Based on the comparison result, the inspection section 532 determines whether or not the structure is formed in accordance with the design information. In other words, the inspection section 532 determines whether or not the fabricated structure non-defective. When the structure is not formed in accordance with the design information, then the inspection section 532 determines whether or not it is repairable. When it is repairable, then the inspection section 532 determines the defective portions and repairing amount based on the comparison result, and sends information to the repairing device 540 to indicate the defective portions and repairing amount.

[0060] Based on the information indicating the defective portions and repairing amount received from the controller 530, the repairing device 540 processes the defective portions of the structure.

[0061] FIG. 6 is a flowchart for a method 600 for operating the structure manufacturing system 500 described herein with respect to FIG. 5. First, the design device 510 creates design information about the profile of a structure (step 601). Next, the forming device 520 fabricates the structure based on the designing information (step 602). Then, the detection apparatus measures the coordinates with respect to the profile of the structure (step 603). Then, the inspection section 532 of the controller 530 inspects whether or not the structure is fabricated in accordance with the design information by comparing the created profile information of the structure from the detection apparatus with the above design information (step 604).

[0062] Next, the inspection section 532 of the controller 530 determines whether or not the fabricated structure is non-defective (step 605). When the fabricated structure is nondefective (step 605: Yes), then the structure manufacturing system 500 ends the process. On the other hand, when the fabricated structure is defective (step 605; No), then the inspection section 532 of the controller 530 determines whether or not the fabricated structure is repairable (step 606).

[0063] When the fabricated structure is repairable (step 606; Yes), then the repairing device 540 reprocesses the structure (step 607) and then the process returns to step 603. On the other hand, when the fabricated structure is not repairable (step 606: No) then the structure manufacturing system 500 ends the process. With that, the process of the flowchart is ended.

[0064] In the above manner, because the detection apparatus in the above embodiments can correctly measure the coordinates of the structure, the structure manufacturing system 500 is able to determine whether or not the fabricated structure is non-defective. Further, when the structure is defective, the structure manufacturing system 500 is able to reprocess the structure to repair the same.Computer systems

[0065] Additionally, systems are disclosed that can be used to perform portions of the method 200 of FIG. 2 (such as operation 230 of method 200 described herein with respect to FIG. 2), the method 400 of FIG. 4 (such as operation 430 of method 400 described herein with respect to FIG. 4), or the method 600 of FIG. 6 (such as operation 604 or 605 of method 600 described herein with respect to FIG. 6). In some embodiments, the systems comprise one or more processors and memory coupled to the one or more processors. In some embodiments, the one or more processors are configured to implement the operation 230 of method 200, the operation 430 of method 400, or the operation 604 or 605 of method 600. In some embodiments, the memory is configured to provide the one or more processors with instructions corresponding to the operation 230 of method 200, the operation 430 of method 400, or the operation 604 or 605 of method 600. In some embodiments, the instructions are embodied in a tangible computer readable storage medium.

[0066] FIG. 7 is a block diagram of a computer sy stem 700 used in some embodiments to perform portions of methods described herein (such as operation 230 of method 200 as described herein with respect to FIG. 2, operation 430 of method 400 described herein with respect to FIG. 4, or operation 604 or 605 of method 600 described herein with respect to FIG. 6). In some embodiments, the computer system may be utilized as a component in the systems described herein (such as the surface characterization module 140 described herein with respect to FIG. 1, the surface characterization module 340 described herein with respect to FIG. 3, or the controller 530 described herein with respect to FIG. 3). FIG. 7 illustrates one embodiment of a general purpose computer system. Other computer system architectures and configurations can be used for carrying out the processing of the present inventions. Computer system 700, made up of various subsystems described below, includes at least one microprocessor subsystem 701. In some embodiments, the microprocessor subsystem comprises at least one central processing unit (CPU) or graphical processing unit (GPU). The microprocessor subsy stem can be implemented by a single-chip processor or by multiple processors. In some embodiments, the microprocessor subsystem is a general purpose digital processor which controls the operation of the computer system 700. Using instructions retrieved from memory 704, the microprocessor subsystem controls the reception and manipulation of input data, and the output and display of data on output devices.

[0067] The microprocessor subsystem 701 is coupled bi-directionally with memory 704, which can include a first primary storage, typically a random access memory (RAM), and a second primary storage area, typically a read-only memory (ROM). As is well known in theart, primary storage can be used as a general storage area and as scratch-pad memory, and can also be used to store input data and processed data. It can also store programming instructions and data, in the form of data objects and text objects, in addition to other data and instructions for processes operating on microprocessor subsystem. Also as well known in the art, primary storage typically includes basic operating instructions, program code, data and objects used by the microprocessor subsystem to perform its functions. Primary storage devices 704 may include any suitable computer-readable storage media, described below, depending on whether, for example, data access needs to be bi-directional or uni-directional. The microprocessor subsystem 701 can also directly and very rapidly retrieve and store frequently needed data in a cache memory (not shown).

[0068] A removable mass storage device 705 provides additional data storage capacity for the computer system 700, and is coupled either bi-directionally (read / write) or unidirectionally (read only) to microprocessor subsystem 701. Storage 705 may also include computer-readable media such as magnetic tape, flash memory, signals embodied on a carrier wave, PC-CARDS, portable mass storage devices, holographic storage devices, and other storage devices. A fixed mass storage 709 can also provide additional data storage capacity. The most common example of mass storage 709 is ahard disk drive. Mass storage 705 and 709 generally store additional programming instructions, data, and the like that typically are not in active use by the processing subsystem. It will be appreciated that the information retained within mass storage 705 and 709 may be incorporated, if needed, in standard fashion as part of primary storage 704 (e.g., RAM) as virtual memory.

[0069] In addition to providing processing subsystem 701 access to storage subsystems, bus 706 can be used to provide access other subsystems and devices as well. In the described embodiment, these can include a display monitor 708, a network interface 707, a keyboard 702, and a pointing device 703, as well as an auxiliary input / output device interface, a sound card, speakers, and other subsystems as needed. The pointing device 703 may be a mouse, stylus, track ball, or tablet, and is useful for interacting with a graphical user interface.

[0070] The network interface 707 allows the processing subsystem 701 to be coupled to another computer, computer network, or telecommunications network using a network connection as shown. Through the network interface 707, it is contemplated that the processing subsystem 701 might receive information, e.g., data objects or program instructions, from another network, or might output information to another network in the course of performing the above-described method steps. Information, often represented as a sequence of instructions to be executed on a processing subsystem, may be received from and outputted to anothernetwork, for example, in the form of a computer data signal embodied in a carrier wave. An interface card or similar device and appropriate software implemented by processing subsystem 701 can be used to connect the computer system 700 to an external network and transfer data according to standard protocols. That is, method embodiments of the present inventions may execute solely upon processing subsystem 701, or may be performed across a network such as the Internet, intranet networks, or local area networks, in conjunction with a remote processing subsystem that shares a portion of the processing. Additional mass storage devices (not shown) may also be connected to processing subsystem 701 through network interface 707.

[0071] An auxiliary I / O device interface (not shown) can be used in conjunction with computer system 700. The auxiliary I / O device interface can include general and customized interfaces that allow the processing subsystem 701 to send and, more typically, receive data from other devices such as microphones, touch-sensitive displays, transducer card readers, tape readers, voice or handwriting recognizers, biometrics readers, cameras, portable mass storage devices, and other computers.

[0072] In addition, embodiments of the present inventions further relate to computer storage products with a computer readable medium that contains program code for performing various computer-implemented operations. The computer-readable medium is any data storage device that can store data which can thereafter be read by a computer system. The media and program code may be those specially designed and constructed for the purposes of the present inventions, or they may be of the kind well known to those of ordinary skill in the computer software arts. Examples of computer-readable media include, but are not limited to, all the media mentioned above: magnetic media such as hard disks, floppy disks, and magnetic tape; optical media such as CD-ROM disks; magneto-optical media such as floptical disks; and specially configured hardware devices such as application-specific integrated circuits (ASICs), programmable logic devices (PLDs), and ROM and RAM devices. The computer-readable medium can also be distributed as a data signal embodied in a carrier wave over a network of coupled computer systems so that the computer-readable code is stored and executed in a distributed fashion. Examples of program code include both machine code, as produced, for example, by a compiler, or files containing higher level code that may be executed using an interpreter. The computer system shown in FIG. 7 is but an example of a computer system suitable for use with the inventions. Other computer systems suitable for use with the inventions may include additional or fewer subsystems. In addition, bus 706 is illustrative of any interconnection scheme serving to link the subsystems. Other computer architectures having different configurations of subsystems may also be utilized.Riblet applications

[0073] The systems and methods described herein may be applied to measuring a height property of a surface, such as a wing of an aircraft, a blade of a wind turbine, or the like. The systems and methods may be utilized to measure a height property such as a pattern of aerodynamic riblets on the wing, blade, or the like. For example, in some embodiments, a surface comprising a plurality of riblets may be moved in a linear direction of motion relative to the optical components described herein. In some embodiments, the optical components are moved in a linear direction of motion relative to the surface comprising the plurality of riblets. Examples of riblets are disclosed, for example, in U.S. Patent Nos. 4,706,910, 4,863,121, 4,907,765, 4,930,729, 5,133,519, 5,386,955, 5,542.630, 6,345,791, 6.729,846, 8,220,754, 8,413,928, 8,444,092. 8,460,779. 8,684.310, 9,272.791, 9.297,394, 9.751,618, 9,844,906, 10,422,363, 10,450,867, 10,569,365, and 10,882,605, and in U.S. Patent Application Publication Nos. 2021 / 0054859, 2018 / 0079492, and 2018 / 0283180, each of which is incorporated herein by reference in its entirety for all purposes.EXAMPLESExample 1; Simulated projection of fringes of different pitches and orientations to a flat surface

[0074] A first set of optical fringes with a fringe pitch of approximately 170 pm was projected to a surface. The first sets of optical fringes was projected at a fringe orientation of approximately 5 degrees. FIG. 8A depicts an example of a first set of optical fringes scattered from the surface. The phase of the first set of optical fringes scattered from the surface is proportional to the local topography of the surface. FIG. 8B shows an example simulated second set of optical fringes having a fringe orientation opposite that of the first set of fringes scattered from a flat surface. Since the simulated data was constructed using a flat surface, the phase of the second set of optical fringes was not changed upon scattering from the flat surface. FIG. 6C shows the sum of the first and second sets of fringes.

[0075] FIG. 9A shows an example 2D Fourier transform of the data depicted in FIG. 6A. As shown in FIG. 9 A, two peaks in the upper left (-x, +y) and lower right (+x, -y) quadrants are visible. FIG. 9B shows an example phase map reconstructed from the 2D Fourier transform of FIG. 9A.

[0076] FIG. 10A shows an example 2D Fourier transform of the data depicted in FIG. 8C. As shown in FIG. 10A, two peaks in the upper left (-x. +y) and lower right (+x, -y) quadrants correspond to the scattered first set of fringes, as in FIG. 9A. Additionally, two peaksin the lower left (-x, -y) and upper right (+x, +y) quadrants correspond to the scattered second set of fringes. FIG. 10B shows an example phase map reconstructed from the 2D Fourier transform of FIG. 10 A.

[0077] The results shown in FIGs. 9A-9B and 10A-10B demonstrate that the signals from the first and second sets of fringes (having different pitches and orientations) are fully separated in the Fourier domain. Thus, the signals can be separately processed to obtain the benefits of multiple pitch fringe projection even when the first and second sets of fringes are simultaneously directed to the surface. That is, surface information from the first set of fringes can be extracted by masking off unwanted information in the Fourier domain (i.e., Fourier peaks associated with the second set of fringes). An inverse Fourier transform may then by performed to obtain the surface information from the first set of fringes. Similarly, surface information from the second set of fringes can be extracted by masking off the Fourier peaks associated with the first set of fringes. An inverse Fourier transform may then be performed to obtain the surface information from the second set of fringes.RECITATION OF EMBODIMENTS

[0078] Embodiment 1. A system comprising: a fringe generation module configured to alternately generate at least a first set of optical fringes having a first peak optical intensity and a second set of optical fringes having a second peak optical intensity different from the first peak optical intensity; and a fringe projection module configured to alternately receive and project at least the first set of optical fringes and the second set of optical fringes to a surface.

[0079] Embodiment 2. The system of Embodiment 1, wherein the fringe generation module comprises a light source and an optical grating.

[0080] Embodiment 3. The system of Embodiment 2, wherein the light source is configured to alternately generate first light having a first optical pow er and second light having a second optical power different from the first optical power.

[0081] Embodiment 4. The system of Embodiment 3, wherein the optical grating is configured to alternately: (a) receive the first light, generate first light beams having at least tw o different diffraction orders from the first light, and project the first light beams to the fringe projecting system and (b) receive the second light, generate second light beams having at least two different diffraction orders from the second light, and to project the second light beams to the fringe projecting system.

[0082] Embodiment 5. The system of Embodiment 4, wherein the fringe generation module further comprises at least one beam block configured to block one or more portions of the first or second light beams.

[0083] Embodiment 6. The system of any one of Embodiments 1-5, wherein the fringe projection module comprises at least one lens or objective configured to project the first set of optical fringes and the second set of optical fringes to the surface.

[0084] Embodiment 7. The system of any one of Embodiments 1 -6. further comprising a surface characterization module configured to characterize the surface based on at least a first scattering interaction between the first set of optical fringes and the surface and a second scattering interaction between the second set of optical fringes and the surface.

[0085] Embodiment 8. The system of Embodiment 7, wherein the surface characterization module comprises an optical detector configured to alternately receive at least a first set of scattered optical fringes resulting from the first scattering interaction and a second set of scattered optical fringes resulting from the second scattering interaction.

[0086] Embodiment 9. The system of Embodiment 8, wherein the surface characterization module further comprises a computing system configured to characterize the surface based at least on the first set of scattered optical fringes and the second set of scattered optical fringes.

[0087] Embodiment 10. The system of Embodiment 9, wherein the characterizing the surface based at least on the first set of scattered optical fringes and the second set of scattered optical fringes comprises determining a height map of the surface based at least on the first set of scattered optical fringes and the second set of scattered optical fringes.

[0088] Embodiment 11. A method comprising: alternately generating at least a first set of optical fringes having a first peak optical intensity and a second set of optical fringes having a second peak optical intensity different from the first peak optical intensity; and alternately receiving and projecting at least the first set of optical fringes and the second set of optical fringes to a surface.

[0089] Embodiment 12. The method of Embodiment 11, wherein the first and second sets of optical fringes are generated using a light source and an optical grating.

[0090] Embodiment 13. The method of Embodiment 12, further comprising using the light source to alternately generate first light having a first optical power and second light having a second optical power different from the first optical power.

[0091] Embodiment 14. The method of Embodiment 13, further comprising using theoptical grating to alternately: (a) receive the first light, generate first light beams having at least two different diffraction orders from the first light, and project the first light beams and (b) receive the second light, generate second light beams having at least two different diffraction orders from the second light, and to project the second light beams.

[0092] Embodiment 15. The method of Embodiment 14, further comprising blocking one or more portions of the first or second light beams.

[0093] Embodiment 16. The method of any one of Embodiments 11-15, wherein the first set of optical fringes and the second set of optical fringes are projected to the surface using at least one lens or objective.

[0094] Embodiment 17. The method of any one of Embodiments 11-16, further comprising characterizing the surface based on at least a first scattering interaction between the first set of optical fringes and the surface and a second scattering interaction between the second set of optical fringes and the surface.

[0095] Embodiment 18. The method of Embodiment 17, wherein the characterizing the surface comprises using an optical detector configured to alternately receive at least a first set of scattered optical fringes resulting from the first scattering interaction and a second set of scattered optical fringes resulting from the second scattering interaction.

[0096] Embodiment 19. The method of Embodiment 18, wherein the characterizing the surface comprises using a computing system to characterize the surface based at least on the first set of scattered optical fringes and the second set of scattered optical fringes.

[0097] Embodiment 20. The method of Embodiment 19, wherein the characterizing the surface based at least on the first set of scattered optical fringes and the second set of scattered optical fringes comprises determining a height map of the surface based at least on the first set of scattered optical fringes and the second set of scattered optical fringes.

[0098] Embodiment 21. A system comprising: a fringe generation module configured to generate at least a first set of optical fringes having a first fringe pitch and a first fringe orientation and a second set of optical fringes having a second fringe pitch different from the first fringe pitch and a second fringe orientation different from the first fringe orientation; and a fringe projecting module configured to receive and project at least the first set of optical fringes and the second set of optical fringes to a surface.

[0099] Embodiment 22. The system of Embodiment 21, wherein the fringe generation module comprises a first light source, a second light source, a first optical grating, and a second optical grating.

[0100] Embodiment 23. The system of Embodiment 22, wherein the first light source is configured to generate first light and direct the first light to the first optical grating, and wherein the second light source is configured to generate second light and direct the second light to the second optical grating.

[0101] Embodiment 24. The system of Embodiment 23, wherein the first optical grating is configured to receive the first light, generate first light beams having at least a first - 1 diffraction order and a first +1 diffraction order from the first light, and project the first light beams to the fringe projecting system; and wherein the second optical grating is configured to receive the second light, generate second light beams having at least a second -1 diffraction order and a second +1 diffraction order from the second light, and to project the second light beams to the fringe projecting system.

[0102] Embodiment 25. The system of Embodiment 24, wherein the fringe generation module further comprises at least one beam block configured to block light beams having a 0 diffraction order.

[0103] Embodiment 26. The system of any one of Embodiments 21-25, wherein the fringe projection module comprises at least one beam combiner, lens, or objective configured to project the first set of optical fringes and the second set of optical fringes to the surface.

[0104] Embodiment 27. The system of any one of Embodiments 21-26, further comprising a surface characterization module configured to characterize the surface based on at least a first scattering interaction between the first set of optical fringes and the surface and a second scattering interaction between the second set of optical fringes and the surface.

[0105] Embodiment 28. The system of Embodiment 27, wherein the surface characterization module comprises an optical detector configured to receive at least a first set of scattered optical fringes resulting from the first scattering interaction and a second set of scattered optical fringes resulting from the second scattering interaction.

[0106] Embodiment 29. The system of Embodiment 28, wherein the surface characterization module further comprises a computing system configured to characterize the surface based at least on the first set of scattered optical fringes and the second set of scattered optical fringes.

[0107] Embodiment 30. The system of Embodiment 29, wherein the characterizing the surface based at least on the first set of scattered optical fringes and the second set of scattered optical fringes comprises determining a height map of the surface based at least on the first set of scattered optical fringes and the second set of scattered optical fringes.

[0108] Embodiment 31. A method comprising:generating at least a first set of optical fringes having a first fringe pitch and a first fringe orientation and a second set of optical fringes having a second fringe pitch different from the first fringe pitch and a second fringe orientation different from the first fringe orientation; and projecting at least the first set of optical fringes and the second set of optical fringes to a surface.

[0109] Embodiment 32. The method of Embodiment 31, wherein the first and second sets of optical fringes are generated using a first light source, a second light source, a first optical grating, and a second optical grating.

[0110] Embodiment 33. The method of Embodiment 32, further comprising using the first light source to generate first light and direct the first light to the first optical grating and using the second light source to generate second light and direct the second light to the second optical grating.

[0111] Embodiment 34. The method of Embodiment 33, further comprising using the first optical grating to receive the first light, generate first light beams having at least a first -1 diffraction order and a first +1 diffraction order from the first light, and project the first light beams; and using the second optical grating to receive the second light, generate second light beams having at least a second -1 diffraction order and a second +1 diffraction order from the second light, and to project the second light beams.

[0112] Embodiment 35. The method of Embodiment 34, further comprising blocking light beams having a 0 diffraction order.

[0113] Embodiment 36. The method of any one of Embodiments 31-35, wherein the first set of optical fringes and the second set of optical fringes are projected to the surface using at least one beam combiner, lens, or objective.

[0114] Embodiment 37. The method of any one of Embodiments 31-36, further comprising characterizing the surface based on at least a first scattering interaction between the first set of optical fringes and the surface and a second scattering interaction between the second set of optical fringes and the surface.

[0115] Embodiment 38. The method of Embodiment 37. wherein the characterizing the surface comprises using an optical detector to receive at least a first set of scattered optical fringes resulting from the first scattering interaction and a second set of scattered optical fringes resulting from the second scattering interaction.

[0116] Embodiment 39. The method of Embodiment 38, wherein the characterization the surface comprises using a computing system to characterize the surface based at least onthe first set of scattered optical fringes and the second set of scattered optical fringes.

[0117] Embodiment 40. The method of Embodiment 39. wherein the characterizing the surface based at least on the first set of scattered optical fringes and the second set of scattered optical fringes comprises determining a height map of the surface based at least on the first set of scattered optical fringes and the second set of scattered optical fringes.

[0118] Embodiment 41. A structure manufacturing method comprising: creating design information with respect to a profile of a structure; forming the structure based on the design information; measuring the profile of the formed structure by using the method of any one of Embodiments 11-20 or any one of Embodiments 31-40; and comparing the profile information obtained in the measuring with the design information.

[0119] Embodiment 42. The structure manufacturing method of Embodiment 41, further comprising repairing the structure, carried out based on a comparison result of the comparing.

[0120] Embodiment 43. The structure manufacturing method of Embodiment 42. wherein in the repairing, forming the structure is carried out again.

Claims

CLAIMS1 . A system comprising: a fringe generation module configured to generate at least a first set of optical fringes having a first fringe pitch and a first fringe orientation and a second set of optical fringes having a second fringe pitch different from the first fringe pitch and a second fringe orientation different from the first fringe orientation; and a fringe projecting module configured to receive and project at least the first set of optical fringes and the second set of optical fringes to a surface.

2. The system of claim 1, wherein the fringe generation module comprises a first light source, a second light source, a first optical grating, and a second optical grating.

3. The system of claim 2, wherein the first light source is configured to generate first light and direct the first light to the first optical grating, and wherein the second light source is configured to generate second light and direct the second light to the second optical grating.

4. The system of claim 3, wherein the first optical grating is configured to receive the first light, generate first light beams having at least a first -1 diffraction order and a first +1 diffraction order from the first light, and project the first light beams to the fringe projecting system; and wherein the second optical grating is configured to receive the second light, generate second light beams having at least a second -1 diffraction order and a second +1 diffraction order from the second light, and to project the second light beams to the fringe projecting system.

5. The system of claim 4, wherein the fringe generation module further comprises at least one beam block configured to block light beams having a 0 diffraction order.

6. The system of any one of claims 1-5, wherein the fringe projection module comprises at least one beam combiner, lens, or objective configured to project the first set of optical fringes and the second set of optical fringes to the surface.

7. The system of any one of claims 1-6, further comprising a surface characterization module configured to characterize the surface based on at least a first scattering interaction between the first set of optical fringes and the surface and a second scattering interaction between the second set of optical fringes and the surface.

8. The system of claim 7, wherein the surface characterization module comprises an optical detector configured to receive at least a first set of scattered optical fringes resulting from the first scattering interaction and a second set of scattered optical fringesresulting from the second scattering interaction.

9. The system of claim 8. wherein the surface characterization module further comprises a computing system configured to characterize the surface based at least on the first set of scattered optical fringes and the second set of scattered optical fringes.

10. The system of claim 9, wherein the characterizing the surface based at least on the first set of scattered optical fringes and the second set of scattered optical fringes comprises determining a height map of the surface based at least on the first set of scattered optical fringes and the second set of scattered optical fringes.

11. A method comprising: generating at least a first set of optical fringes having a first fringe pitch and a first fringe orientation and a second set of optical fringes having a second fringe pitch different from the first fringe pitch and a second fringe orientation different from the first fringe orientation; and projecting at least the first set of optical fringes and the second set of optical fringes to a surface.

12. The method of claim 11. wherein the first and second sets of optical fringes are generated using a first light source, a second light source, a first optical grating, and a second optical grating.

13. The method of claim 12, further comprising using the first light source to generate first light and direct the first light to the first optical grating and using the second light source to generate second light and direct the second light to the second optical grating.

14. The method of claim 13, further comprising using the first optical grating to receive the first light, generate first light beams having at least a first -1 diffraction order and a first +1 diffraction order from the first light, and project the first light beams; and using the second optical grating to receive the second light, generate second light beams having at least a second -1 diffraction order and a second +1 diffraction order from the second light, and to project the second light beams.

15. The method of claim 14, further comprising blocking light beams having a 0 diffraction order.

16. The method of any one of claims 11-15, wherein the first set of optical fringes and the second set of optical fringes are projected to the surface using at least one beam combiner, lens, or objective.

17. The method of any one of claims 11-16. further comprising characterizing the surface based on at least a first scattering interaction between the first set of optical fringes andthe surface and a second scattering interaction between the second set of optical fringes and the surface.

18. The method of claim 17, wherein the characterizing the surface comprises using an optical detector to receive at least a first set of scattered optical fringes resulting from the first scattering interaction and a second set of scattered optical fringes resulting from the second scattering interaction.

19. The method of claim 18, wherein the characterization the surface comprises using a computing system to characterize the surface based at least on the first set of scattered optical fringes and the second set of scattered optical fringes.

20. The method of claim 19, wherein the characterizing the surface based at least on the first set of scattered optical fringes and the second set of scattered optical fringes comprises determining a height map of the surface based at least on the first set of scattered optical fringes and the second set of scattered optical fringes.

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