CN113776459A

CN113776459A - Confocal three-dimensional measurement system and coordinate and color measurement method

Info

Publication number: CN113776459A
Application number: CN202111020692.2A
Authority: CN
Inventors: 魏悦
Original assignee: Shanghai Mediworks Precision Instruments Co Ltd
Current assignee: Shanghai Mediworks Precision Instruments Co Ltd
Priority date: 2021-09-01
Filing date: 2021-09-01
Publication date: 2021-12-10

Abstract

The invention discloses a confocal three-dimensional measurement system which is characterized by comprising a laser light source, a digital micromirror array, a light splitting device, a depth scanning lens and an image sensor, wherein the laser light source is arranged on the front side of the digital micromirror array; the laser light source emits collimated laser with a certain diameter to be projected on the digital micro-mirror array, a group of point arrays with certain intervals are projected on the surface of a target object to be measured through the light splitting device by the aid of the reflector array of the digital micro-mirror array, light spot information projected on different depths on the target object is collected by the image sensor after passing through the depth scanning lens.

Description

Confocal three-dimensional measurement system and coordinate and color measurement method

Technical Field

The invention relates to a confocal three-dimensional measurement system and a coordinate and color measurement method, belonging to the technical field of three-dimensional object detection.

Background

For three-dimensional measurement, the resolution precision of the conventional structured light or multi-view vision technology and the like in many applications cannot meet the measurement requirement, and real-time true color three-dimensional imaging modeling cannot be usually carried out. The confocal technology can effectively eliminate various scattered lights generated by a detection sample during imaging, so that the resolution limit of a common wide-field imaging system is broken through, but the confocal technology needs point-by-point scanning and is slow in imaging speed, and the confocal technology cannot be well adapted to some applications needing rapid imaging.

Disclosure of Invention

In order to solve the problems in the background art, the technical scheme of the invention is to provide a confocal three-dimensional measurement system, which is characterized by comprising a laser light source, a digital micromirror array, a light splitting device (including but not limited to a light splitting prism, a dichroic mirror and the like), a depth scanning lens and an image sensor; the laser light source emits collimated laser with a certain diameter to be projected on the digital micro-mirror array, a group of point arrays with certain intervals are projected on the surface of a target object to be measured through the light splitting device by the aid of the reflector array of the digital micro-mirror array, light spot information projected on the target object at different depths is collected by the image sensor after passing through the depth scanning lens.

Preferably, the depth scanning lens is a liquid zoom lens or a lens performing scanning movement in the depth direction.

Preferably, the laser light source includes a red laser light source, a green laser light source and a blue laser light source.

The technical scheme of the invention also provides a confocal three-dimensional coordinate measuring method, which is characterized by comprising the following steps:

step one, a laser source emits laser;

step two, the laser is projected to the digital micro-mirror array through collimation;

step three, controlling a reflector array of the digital micromirror array, and projecting a group of point arrays with specific intervals to the surface of a target object;

fourthly, the light spot information projected to different depths on the target object is collected by the image sensor after passing through the depth scanning lens;

controlling a depth scanning lens to scan in the depth direction, and judging the depth position at which the image of each light spot is focused according to the size and brightness of the light spot on an image sensor so as to obtain the space coordinates of all the light spots;

and step six, controlling pixel points of the digital micromirror array, scanning the projected point array in the X direction and the Y direction in sequence, and repeating the step three to the step five to finally obtain the space coordinate positions of all the points to be measured on the whole target object.

Preferably, in the fifth step, the depth scanning lens is controlled to scan in the depth direction, for example, if the light spot is at the parfocal position, a minimum-size and highest-brightness diffuse spot is obtained on the image sensor, after each depth scanning, images of the image sensor at all scanning positions are obtained, and according to the brightness distribution on each picture, which depth position the image of each light spot is focused on is determined, so that the spatial coordinates of all light spots can be obtained.

The technical scheme of the invention also provides a confocal three-dimensional color measurement method, which is characterized by comprising the following steps:

the method comprises the following steps that firstly, a laser light source sequentially emits red laser, green laser and blue laser;

projecting the three primary colors laser to the digital micromirror array through collimation;

step three, controlling a reflector array of the digital micromirror array, and projecting a group of point arrays with certain intervals to the surface of a target object;

controlling a depth scanning lens to scan in the depth direction, and judging the depth position at which the image of each light spot is focused according to the size and brightness of the light spot on the image sensor;

and step six, calculating the color of the point according to the brightness components of the red, green and blue colors recorded by the image sensor when the light point is at the focusing position.

The invention has the advantages that the fast confocal full-color scanning at different depth levels can be realized through the improved array confocal and depth scanning technology, and the high-speed, high-resolution and full-color three-dimensional imaging is considered.

Drawings

FIG. 1 is a schematic structural diagram of a confocal three-dimensional measurement system;

FIG. 2 is a schematic diagram of a point array projected by a digital micromirror array;

FIG. 3 is a schematic diagram of controlling the digital micromirror array to scan the projected spot array in the X direction.

Detailed Description

In order to make the invention more comprehensible, preferred embodiments are described in detail below with reference to the accompanying drawings.

Examples

In this embodiment, as shown in fig. 1, a laser source 1 emits collimated laser with a certain diameter, and projects the collimated laser onto a digital micromirror array 3, so as to control a mirror array of the digital micromirror array 3, and project a group of dot arrays with a certain interval to the surface of a target object 5 to be measured through a light splitter 4, where the dot arrays are generally distributed as shown in fig. 2.

Light spots projected to different depths on the target object 5 form diffuse spots with different sizes and energy distributions on the image sensor 7 after passing through the depth scanning lens 6. The depth scanning lens 6 may be a liquid zoom lens, or a lens that is mechanically movable in the depth direction. Controlling the depth scanning lens 6 to scan in the depth direction, for example, the light spot is at the parfocal position, will result in the smallest size and highest brightness of the diffuse spot on the image sensor. After each depth scanning, the image sensor images at all scanning positions are obtained, and the focusing position of each light spot in the depth direction is found according to the brightness distribution on each picture, namely the depth coordinate position of each light spot, wherein the Z direction is defined as the depth direction of the depth scanning lens 6, and the light spot array direction is X, Y direction, so that the projection X, Y coordinate of the light spot is easily obtained according to the position of the light spot on the image sensor, and the space coordinate position of the light spot can be obtained.

Taking two points in the projected dot matrix as an example, when the depth scanning lens is at the initial position, the two points form two light spots with lower brightness and larger size on the sensor, after the depth scanning starts, the light spots formed by the two points gradually shrink, the central brightness gradually increases, and at the depth a, the brightness of the first point reaches the highest value, and the size of the light spot is the smallest. When the depth b is scanned, the brightness of the second point is highest, and the spot size is smallest, so that the depth direction position of the first point is a, and the depth direction position of the second point is b.

The pixel points of the digital micromirror array 3 are controlled to scan the projected dot array in the X and Y directions sequentially, as shown in fig. 3. And finally obtaining the space coordinate positions of all the points to be measured on the whole target object 5.

The laser light source 1 can be a laser synthesis of three colors of red, green and blue, and finally the point cloud space position coordinates of the surface of the measured object and the color information of each imaging point can be obtained simultaneously. The three primary colors of laser are respectively projected according to the time sequence, red, green and blue are sequentially changed, the image sensor 7 records and obtains the brightness components of the red, green and blue colors of each point of the target object 5 at the focusing position, and therefore the color of the point is calculated.

Claims

1. A confocal three-dimensional measurement system is characterized by comprising a laser light source, a digital micromirror array, a light splitter, a depth scanning lens and an image sensor; the laser light source projects a beam of laser with a certain size, the laser beam is projected on the digital micro-mirror array, a group of point arrays with specific intervals are projected on the surface of a target object to be measured through the light splitter by the reflector array of the digital micro-mirror array, light spot information on different depths projected on the target object is collected by the image sensor after passing through the depth scanning lens.

2. The confocal three-dimensional measurement system of claim 1, wherein the depth-scanning lens is a liquid zoom lens or a lens that performs scanning motion in the depth direction.

3. The confocal three-dimensional measurement system of claim 1, wherein the laser source comprises a red laser source, a green laser source, and a blue laser source.

4. A confocal three-dimensional coordinate measurement method is characterized in that the confocal three-dimensional coordinate measurement system of claim 1 or 2 is adopted, and the specific steps are as follows:

step one, a laser source emits laser;

step two, collimating laser light to project to the digital micromirror array;

5. The confocal three-dimensional coordinate measurement method according to claim 4, wherein in the fifth step, the depth scanning lens is controlled to scan in the depth direction, such as the light spot is at the parfocal position, which results in the smallest size and highest brightness of the diffuse spot on the image sensor, after each depth scanning, the image sensor images at all scanning positions are obtained, and according to the brightness distribution on each frame, it is determined at which depth position the image of each light spot is focused, so that the spatial coordinates of all light spots can be obtained.

6. A confocal three-dimensional color measurement method is characterized in that the confocal three-dimensional measurement system of claim 3 is adopted, and the specific steps are as follows:

projecting the three primary colors collimated laser to a digital micromirror array;