# US 12,474,266 B2 · Method and system for moiré profilimetry using simultaneous dual fringe projection

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- Number: US 12,474,266 B2
- Document ID: US12474266B2
- Status: Granted
- Kind: B2
- Application number: 17/932,551
- Filed: 2022-09-15
- Published: 2023-03-23
- Granted: 2025-11-18
- Earliest claimed: 2021-09-17
- Assignees: San Diego State University (SDSU) Foundation; Centro De Investigaciones En Optica A.C.
- Applicants: San Diego State University (Sdsu) Foundation; Centro De Investigaciones En Optica A.C.
- Inventors: Sungbum Kang; Sotero Ordoñes Nogales
- Web page: https://patentgrep.com/patent/US12474266B2

## CPC

- G01N 21/45: using interferometric methods; using Schlieren methods
- G01B 11/254: {Projection of a pattern, viewing through a pattern, e.g. moiré}
- G01N 2021/456: {Moire deflectometry}
- G01N: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES (measuring or testing apparatus or processes other than immunoassay, involving enzymes or microorganisms C12M, C12Q)
- G01B: MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS

## Abstract

In alternative embodiments, provided are moiré profilometry methods for analyzing a topography of an object comprising use of dual patterns that are simultaneously projected onto a surface of the object from two symmetric directions. In alternative embodiments, the projected dual patterns superimpose and generate a fringe pattern that contains a moiré pattern, the moiré pattern having a phase that is modulated according to the topography of the object. In alternative embodiments, the moiré pattern is extracted from the fringe pattern using a spatial or temporal method, and the phase is demodulated from the extracted moiré pattern using a spatial or temporal method.

## Claims

### Claim 1

A moiré profilometry method for analyzing a topography of an object, the method comprising:
simultaneously projecting dual patterns onto a surface of the object from two symmetric directions, the projected dual patterns superimposing and generating a fringe pattern that contains a moiré pattern, the moiré pattern having a phase that is modulated according to the topography of the object;
extracting the moiré pattern from the fringe pattern using a spatial or temporal method; and
demodulating the phase from the extracted moiré pattern using a spatial or temporal method;
wherein the extracting uses a spatial filtering method and the demodulating uses a temporal phase demodulation method.

### Claim 2

A moiré profilometry method for analyzing a topography of an object, the method comprising:
simultaneously projecting dual patterns onto a surface of the object from two symmetric directions, the projected dual patterns superimposing and generating a fringe pattern that contains a moiré pattern, the moiré pattern having a phase that is modulated according to the topography of the object;
extracting the moiré pattern from the fringe pattern using a spatial or temporal method; and
demodulating the phase from the extracted moiré pattern using a spatial or temporal method;
wherein the extracting uses a temporal extraction method and the demodulating uses a temporal phase demodulation method.

### Claim 3

A moiré profilometry method for analyzing a topography of an object, the method comprising:
simultaneously projecting dual patterns onto a surface of the object from two symmetric directions, the projected dual patterns superimposing and generating a fringe pattern that contains a moiré pattern, the moiré pattern having a phase that is modulated according to the topography of the object;
extracting the moiré pattern from the fringe pattern using a spatial or temporal method; and
demodulating the phase from the extracted moiré pattern using a spatial or temporal method;
wherein the extracting uses a spatial filtering method; and wherein the spatial filtering method further comprises determining a temporal sequence of the fringe pattern.

### Claim 4

A moiré profilometry method for analyzing a topography of an object, the method comprising:
simultaneously projecting dual patterns onto a surface of the object from two symmetric directions, the projected dual patterns superimposing and generating a fringe pattern that contains a moiré pattern, the moiré pattern having a phase that is modulated according to the topography of the object;
extracting the moiré pattern from the fringe pattern using a spatial or temporal method; and
demodulating the phase from the extracted moiré pattern using a spatial or temporal method;
wherein the demodulating uses a temporal phase demodulation method; and wherein the temporal extraction method uses a phase shifting algorithm (PSA).

### Claim 5

A moiré profilometry method for analyzing a topography of an object, the method comprising:
simultaneously projecting dual patterns onto a surface of the object from two symmetric directions, the projected dual patterns superimposing and generating a fringe pattern that contains a moiré pattern, the moiré pattern having a phase that is modulated according to the topography of the object;
extracting the moiré pattern from the fringe pattern using a spatial or temporal method; and
demodulating the phase from the extracted moiré pattern using a spatial or temporal method;
wherein the demodulating uses a temporal phase demodulation method that includes using a phase shifting algorithm (PSA).

### Claim 6

A system for moiré profilometry comprising:
first and second projectors having exit pupils disposed along a first plane that is separated by a distance from a reference plane, the first and second projectors being configured to simultaneously project dual patterns onto a surface of an object disposed between the reference plane and the first plane such that the projected dual patterns superimpose and generating a fringe pattern that contains a moiré pattern, the moiré pattern having a phase that is modulated according to the topography of the object;
an imaging apparatus having an entrance pupil coplanar with the exit pupils of the first and second projectors, the entrance pupil being configured to receive a reflection of the fringe pattern from the object;
a processor coupled to the imaging apparatus and configured to:
extract the moiré pattern from the fringe pattern using a spatial or temporal method; and
demodulate the phase from the extracted moiré pattern using a spatial or temporal method;
wherein the extracting uses a spatial filtering method and the demodulating uses a temporal phase demodulation method.

### Claim 7

A system for moiré profilometry comprising:
first and second projectors having exit pupils disposed along a first plane that is separated by a distance from a reference plane, the first and second projectors being configured to simultaneously project dual patterns onto a surface of an object disposed between the reference plane and the first plane such that the projected dual patterns superimpose and generating a fringe pattern that contains a moiré pattern, the moiré pattern having a phase that is modulated according to the topography of the object;
an imaging apparatus having an entrance pupil coplanar with the exit pupils of the first and second projectors, the entrance pupil being configured to receive a reflection of the fringe pattern from the object;
a processor coupled to the imaging apparatus and configured to:
extract the moiré pattern from the fringe pattern using a spatial or temporal method; and
demodulate the phase from the extracted moiré pattern using a spatial or temporal method;
wherein the extracting uses a temporal extraction method and the demodulating uses a temporal phase demodulation method.

### Claim 8

A system for moiré profilometry comprising:
first and second projectors having exit pupils disposed along a first plane that is separated by a distance from a reference plane, the first and second projectors being configured to simultaneously project dual patterns onto a surface of an object disposed between the reference plane and the first plane such that the projected dual patterns superimpose and generating a fringe pattern that contains a moiré pattern, the moiré pattern having a phase that is modulated according to the topography of the object;
an imaging apparatus having an entrance pupil coplanar with the exit pupils of the first and second projectors, the entrance pupil being configured to receive a reflection of the fringe pattern from the object;
a processor coupled to the imaging apparatus and configured to:
extract the moiré pattern from the fringe pattern using a spatial or temporal method; and
demodulate the phase from the extracted moiré pattern using a spatial or temporal method;
wherein the extracting uses a spatial filtering method; and wherein the spatial filtering method further comprises determining a temporal sequence of the fringe pattern.

### Claim 9

A system for moiré profilometry comprising:
first and second projectors having exit pupils disposed along a first plane that is separated by a distance from a reference plane, the first and second projectors being configured to simultaneously project dual patterns onto a surface of an object disposed between the reference plane and the first plane such that the projected dual patterns superimpose and generating a fringe pattern that contains a moiré pattern, the moiré pattern having a phase that is modulated according to the topography of the object;
an imaging apparatus having an entrance pupil coplanar with the exit pupils of the first and second projectors, the entrance pupil being configured to receive a reflection of the fringe pattern from the object;
a processor coupled to the imaging apparatus and configured to:
extract the moiré pattern from the fringe pattern using a spatial or temporal method; and
demodulate the phase from the extracted moiré pattern using a spatial or temporal method;
wherein the extraction uses a temporal extraction method; and wherein the temporal extraction method uses a phase shifting algorithm (PSA).

### Claim 10

A system for moiré profilometry comprising:
first and second projectors having exit pupils disposed along a first plane that is separated by a distance from a reference plane, the first and second projectors being configured to simultaneously project dual patterns onto a surface of an object disposed between the reference plane and the first plane such that the projected dual patterns superimpose and generating a fringe pattern that contains a moiré pattern, the moiré pattern having a phase that is modulated according to the topography of the object;
an imaging apparatus having an entrance pupil coplanar with the exit pupils of the first and second projectors, the entrance pupil being configured to receive a reflection of the fringe pattern from the object;
a processor coupled to the imaging apparatus and configured to:
extract the moiré pattern from the fringe pattern using a spatial or temporal method; and
demodulate the phase from the extracted moiré pattern using a spatial or temporal method;
wherein the demodulating uses a temporal phase demodulation method that includes using a phase shifting algorithm (PSA).