# US 10,768,435 B2 · System, method and computer program product to project light pattern

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- Number: US 10,768,435 B2
- Document ID: US10768435B2
- Status: Granted
- Kind: B2
- Application number: 15/915,104
- Filed: 2018-03-08
- Published: 2019-01-10
- Granted: 2020-09-08
- Earliest claimed: 2014-08-12
- Assignees: Mantisvision Ltd.
- Applicants: Mantisvision Ltd.
- Inventors: Eyal Gordon
- Web page: https://patentgrep.com/patent/US10768435B2

## CPC

- G01B 11/2513: {with several lines being projected in more than one direction, e.g. grids, patterns}
- G01B 11/167: {by projecting a pattern on the object}
- G01B 11/22: for measuring depth
- G01C 3/02: Details
- G02B 27/0037: {with diffracting elements (G02B27/0056 takes precedence; holographic optical elements G02B5/32; zone systems G02B5/1876)}
- G02B 27/09: Beam shaping, e.g. changing the cross-sectional area, not otherwise provided for {(adapting the beam shape of a laser diode G02B19/0052; adapting the beam shape of an LED G02B19/0061; coupling into light guides using intermediate optical elements G02B6/4204; beam shaping specially adapted for lasers H01S3/005)}
- G02B 27/4233: {having a diffractive element [DOE] contributing to a non-imaging application (diffusers having a diffractive element G02B5/0252; filters having a diffractive element G02B5/203; systems for controlling the direction of light having diffractive elements G02B26/0808; scanning systems having diffractive elements G02B26/106; beam shaping systems using diffractive optical elements G02B27/0944; beam splitting or combining systems operating by diffraction G02B27/1086)}
- G02B 27/425: {in illumination systems (mask illumination systems in photolithographic systems G03F7/70158)}
- G02B 27/4272: {having plural diffractive elements positioned sequentially along the optical path}
- G06V 10/145: Illumination specially adapted for pattern recognition, e.g. using gratings
- H04N 13/254: in combination with electromagnetic radiation sources for illuminating objects
- H04N 23/11: for generating image signals from visible and infrared light wavelengths
- G03B 21/10: Projectors with built-in or built-on screen
- G03B 21/606: for relief projection
- G01B: MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01C: MEASURING DISTANCES, LEVELS OR BEARINGS; SURVEYING; NAVIGATION; GYROSCOPIC INSTRUMENTS; PHOTOGRAMMETRY OR VIDEOGRAMMETRY (measuring liquid level G01F; radio navigation, determining distance or velocity by use of propagation effects, e.g. Doppler effects, propagation time, of radio waves, analogous arrangements using other waves G01S)
- G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G06V: IMAGE OR VIDEO RECOGNITION OR UNDERSTANDING
- H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION
- G03B: APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FOR PROJECTING OR VIEWING THEM; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ACCESSORIES THEREFOR (optical parts of such apparatus G02B; photosensitive materials or processes for photographic purposes G03C; apparatus for processing exposed photographic materials G03D)

## Abstract

Disclosed are methods, circuits, optical assemblies, devices, systems and associated computer executable code for estimating for three dimensional imaging. According to some embodiments, there may be provided a projector operable to project a bi-dimensionally coded pattern to provide a first projection of the bi-dimensionally coded pattern and a second projection of the bi-dimensionally coded pattern. The first projection and the second projection may be offset or rigidly shifted with respect to one another, such that a first reflection off an object which is associated with the first projection and a second reflection off the object which is associated with the second projection are provided. A signal corresponding to the first reflection and a signal corresponding to the second reflection may be co-processed.

## Claims

### Claim 1

A depth sensing system, comprising:
a light source;
a diffractive optical element (“DOE”) configured to receive light from the light source and produce a bi-dimensional structured light pattern comprising a plurality of feature types, wherein:
each feature type is formed by a unique formation of feature elements,
the plurality of features types comprise a plurality of feature type pairs comprising a first feature type and a second feature type, and
in each feature type pair of the plurality of feature type pairs:
a second feature type is arranged at a 180° rotational transformation around a certain point with respect to the first feature type, and
a coding value of a feature element of the second feature type is an inverse of a coding value of a corresponding feature element, under the 180° rotational transformation, of the first feature type;
a sensor configured to capture an image of a reflected portion of a projection of the bi-dimensional structured light pattern; and
at least one processor configured to process the image and to compute depth parameters based on appearance in the image of the bi-dimensional structured light pattern.

### Claim 2 (depends on 1)

The system according to claim 1, wherein in each feature type pair from the plurality of feature type pairs, a feature element that provides a bright area in the first feature type is associated, under the 180° rotational transformation, with a feature element that provides a respective dim area in the second feature type, and a feature element that provides a dim area in the first feature type is associated, under the 180° rotational transformation, with a feature element that provides a respective bright area in the second feature type.

### Claim 3 (depends on 1)

The system according to claim 1, wherein the at least one processor is configured to rigidly shift the DOE or the light source or both, thereby producing at least a first projection of the bi-dimensional structured light pattern and a second projection of the bi-dimensional structured light pattern.

### Claim 4 (depends on 3)

The system according to claim 3, wherein the processor is adapted to rigidly shift the DOE or the light source or both by a predefined amount.

### Claim 5 (depends on 3)

The system according to claim 3, wherein the sensor is configured to capture at least a first image of a reflected portion of the first projection and a second image of a reflected portion of the second projection, wherein the processor is configured to apply a predefined mathematical operation between the first image and the second image to compute a derived image, and wherein the at least one processor is configured to extract from the derived image a plurality of product values, wherein each one of the product values is a result of the application of the predefined mathematical operation over an area of the first and second images.

### Claim 6 (depends on 5)

The system according to claim 5, wherein the at least one processor is configured to extract depth information using the plurality of product values and the first image, the second image or both.

### Claim 7 (depends on 1)

The system according to claim 1, wherein the bi-dimensional structured light pattern is coded using discrete cording.

### Claim 8 (depends on 1)

The system according to claim 1, wherein the light source comprises an emitters array comprising a plurality of individual emitters, each one of the individual emitters is configured to generate a beam of light, and wherein the at least one processor is configured to control activation of at least a first subgroup of emitters from the emitters array and a second subgroup of emitters from the emitters array, and
the at least one processor is configured to activate the first subgroup of emitters to project a first projection of the bi-dimensional structured light pattern, and the at least one processor is configured to activate the second subgroup of emitters to project a second projection of the bi-dimensional structured light pattern.

### Claim 9 (depends on 8)

The system according to claim 8, wherein the first projection of the bi-dimensional structured light pattern and the second projection of the bi-dimensional structured light pattern are rigidly shifted with respect to one another.

### Claim 10 (depends on 8)

The system according to claim 8, wherein light from the first subgroup of emitters and light from the second subgroup of emitters impinge on the DOE surface at different angles relative to one another.

### Claim 11

A method of sensing depth, comprising:
projecting light from a light source onto a diffractive optical element to thereby produce a bi-dimensional structured light pattern comprising a plurality of feature types, wherein:
each feature type is formed by a unique formation of feature elements,
the plurality of features types comprise a plurality of feature type pairs comprising a first feature type and a second feature type,
in each feature type pair of the plurality of feature type pairs a second feature type is arranged at a 180° rotational transformation around a certain point with respect to the first feature type, and
a coding value of a feature element of the second feature type is an inverse of a coding value of a corresponding feature element, under the 180° rotational transformation, of the first feature type;
capturing an image of a reflected portion of a projection of the bi-dimensional structured light pattern; and
processing the image and computing depth parameters based on appearance m the image of the bi-dimensional structured light pattern.

### Claim 12 (depends on 11)

The method according to claim 11 wherein in each feature type pair from the plurality of feature type pairs, a feature element that provides a bright area in the first feature type is associated, under the 180° rotational transformation, with a feature element that provides a respective dim area in the second feature type, and a feature element that provides a dim area in the first feature type is associated, under the 180° rotational transformation, with a feature element that provides a respective bright area in the second feature type.

### Claim 13 (depends on 11)

The method according to claim 11, further comprising rigidly shifting the DOE or the light source or both, thereby producing at least a first projection of the bi-dimensional structured light pattern and a second projection of the bi-dimensional structured light pattern.

### Claim 14 (depends on 13)

The method according to claim 13, further comprising:
capturing at least a first image of a reflected portion of the first projection and a second image of a reflected portion of the second projection; and
applying a predefined mathematical operation between the first image and the second image to compute a derived image; and
extracting from the derived image a plurality of product values, wherein each one of the product values is a result of the application of the predefined mathematical operation over an area of the first and second images.

### Claim 15 (depends on 14)

The method according to claim 14, wherein computing depth parameters comprises extracting depth information using the plurality of product values and the first image, the second image or both.

### Claim 16 (depends on 11)

The method according to claim 11, wherein the bi-dimensional structured light pattern is coded using discrete cording.

### Claim 17 (depends on 11)

The method according to claim 11, wherein the light source comprises an emitters array comprising a plurality of individual emitters, each one of the individual emitters is configured to generate a beam of light, and further comprising:
controlling activation of at least a first subgroup of emitters from the emitters array and a second subgroup of emitters from the emitters array;
activating the first subgroup of emitters to project a first projection of the bi-dimensional structured light pattern; and
activating the second subgroup of emitters to project a second projection of the bi-dimensional structured light pattern.

### Claim 18 (depends on 17)

The method according to claim 17, wherein the first projection of the bi-dimensional structured light pattern and the second projection of the bi-dimensional structured light pattern are rigidly shifted with respect to one another.