# US 2019/0376784 A1 · Device, method and system for generating dynamic projection patterns in a confocal camera

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- Number: US 2019/0376784 A1
- Document ID: US20190376784A1
- Status: Published application
- Kind: A1
- Application number: 16/003,628
- Filed: 2018-06-08
- Published: 2019-12-12
- Earliest claimed: 2018-06-08
- Assignees: DENTSPLY SIRONA Inc.
- Applicants: DENTSPLY SIRONA Inc.
- Inventors: Michael TEWES; Markus BERNER
- Web page: https://patentgrep.com/patent/US20190376784A1

## CPC

- A61B 1/247: with means for viewing areas outside the direct line of sight, e.g. dentists' mirrors
- G01B 11/2513: {with several lines being projected in more than one direction, e.g. grids, patterns}
- A61B 1/00194: {adapted for three-dimensional imaging}
- A61C 9/0066: {Depth determination through adaptive focusing}
- G01B 11/24: for measuring contours or curvatures
- G01B 11/2518: {Projection by scanning of the object}
- A61B: DIAGNOSIS; SURGERY; IDENTIFICATION (usefulness limited to only animals A61D)
- G01B: MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- A61C: DENTISTRY; APPARATUS OR METHODS FOR ORAL OR DENTAL HYGIENE (non-driven toothbrushes A46B; {tongue scrapers A61B17/24;} preparations for dentistry A61K6/00; preparations for cleaning the teeth or mouth A61K8/00, A61Q11/00)

## Abstract

A device, method and system for utilizing an optical array generator, confocal measurement/depth of focus techniques to generate dynamic patterns in a camera for projection onto the surface of an object for three-dimensional (3D) measurement. Projected light patterns are used to generate optical features on the surface of an object to be measured and optical 3D measuring methods which operate according to triangulation, confocal and depth of focus principles are used to measure the object.

## Claims

### Claim 1

A camera, comprising:
an optical array generator for generating a plurality of dynamic patterns for projection, the optical array generator further comprising:
a light source including a plurality of discrete regions wherein a luminous intensity of each of the plurality of discrete regions is controlled independently,
a lens array comprising a plurality of lenses, each lens being constructed to image light from the light source onto an image plane to form the plurality of dynamic patterns and,
a collimator constructed to direct light of the light source onto the lens array;
an imaging sensor arranged within the camera to record a plurality of reflected images from a surface of an object to be measured;
a variable imaging optics arranged within the camera to focus the plurality of dynamic patterns onto the surface of the object and to image the plurality of reflected images onto the imaging sensor;
wherein the variable imaging optics is constructed such that a depth of focus of the variable imaging optics is controlled during projection and/or imaging so that features of the plurality of dynamic patterns are projected onto the object with maximum contrast at the depth of focus and/or features of the plurality of reflected images are imaged onto the sensor with maximum contrast at the depth of focus.

### Claim 2 (depends on 1)

The camera of claim 1, wherein the light source is selected from the group consisting of LED dies, laser diodes and an end of a plurality of optical fibers that have other light sources attached to the other end.

### Claim 3 (depends on 1)

The camera of claim 1, wherein the light source includes at least three discrete regions.

### Claim 4 (depends on 1)

The camera of claim 1, wherein the depth of focus of the variable imaging optics is substantially smaller than a thickness of the object.

### Claim 5 (depends on 1)

The camera of claim 1, wherein the imaging sensor is constructed to perform in-pixel demodulation.

### Claim 6 (depends on 1)

The camera of claim 1, wherein the dynamic patterns are complementary checkerboard patterns or complementary stripe patterns

### Claim 7 (depends on 1)

The camera of claim 1, wherein each of the plurality of lenses is cylindrical.

### Claim 8

A method for generating a plurality of dynamic patterns for measuring an object, the method comprising:
electronically controlling the luminous intensities of each of a plurality of discrete regions of a light source to generate structured light for a collimator;
directing the structured light from the light source onto a lens array using the collimator;
producing sub-images of the structured light using a plurality of lenses of the lens array wherein the sub-images are formed in an image plane of the lens array to form the plurality of dynamic patterns;
controlling a depth of focus of the variable imaging optics during projection and/or imaging so that features of the plurality of dynamic patterns are projected onto the object with maximum contrast at the depth of focus and/or features of a plurality of reflected images are imaged onto an imaging sensor with maximum contrast at the depth of focus.

### Claim 9 (depends on 8)

The method of claim 8, further comprising the step of recording the plurality of reflected images from the surface of the object with the imaging sensor to create an image stack.

### Claim 10 (depends on 9)

The method of claim 9, further comprising processing the plurality of reflected images to obtain a three-dimensional image of the object by determining for each sensor pixel, a maximum amplitude across the image stack.

### Claim 11 (depends on 9)

The method of claim 9, further comprising processing the plurality of reflected images to obtain a three-dimensional image of the object by determining a variable imaging optics position that produces the maximum contrast of the dynamic pattern for a region of the object.

### Claim 12 (depends on 8)

The method of claim 8, further comprising aligning the lens array with pixels of the imaging sensor by displacing the light source such that the dynamic patterns in the image plane of the lens array are also shifted.

### Claim 13 (depends on 8)

The method of claim 8, further comprising performing lateral fine adjustment by using a magnification of the optical array generator wherein a required alignment accuracy of the lens array is reduced to an alignment accuracy of the light source.

### Claim 14

A system for generating a plurality of dynamic patterns for measuring an object, the system comprising:
at least one processor operable to:
electronically control the luminous intensities of each of a plurality of discrete regions of a light source to generate structured light for a collimator;
direct the structured light from the light source onto a lens array using the collimator;
produce sub-images of the structured light using a plurality of lenses of the lens array wherein the sub-images are formed in an image plane of the lens array to form the plurality of dynamic patterns;
controlling a depth of focus of the variable imaging optics during projection and/or imaging so that features of the plurality of dynamic patterns are projected onto the object with maximum contrast at the depth of focus and/or features of a plurality of reflected images are imaged onto an imaging sensor with maximum contrast at the depth of focus.