CN110388884A - Structured Light Illumination 3D Measuring Device - Google Patents

Abstract

The invention discloses a three-dimensional measuring device for structured light illumination, comprising: a light source for emitting light beams; a beam splitting optical chip connected to the light source through an optical fiber for splitting the light beams to form multiple output beams emit light; a shifter, arranged on one side of the beam-splitting optical chip, mechanically connected with the beam-splitting optical chip, used to control the movement of the beam-splitting optical chip, and indirectly control the exit position of multiple beams of light; a photodetector, It is used to detect the reflected light beams reflected by the object to be measured by multiple beams of outgoing light; a control module is electrically connected to the light source, the displacer and the photodetector respectively, and is used to control the movement of the displacer and the photodetector. The invention utilizes a beam-splitting light chip to realize light splitting, and generates surface-structured light projection through interference. Its operating wavelength range is wide, it can be used in different application scenarios, and there is no diffraction loss, and the utilization rate of light energy is high; at the same time, the device has a simple structure and low cost And small size, suitable for a variety of job scenarios.

Description

Structured Light Illumination 3D Measuring Device

technical field

The invention relates to a three-dimensional measuring device, in particular to a structured light illumination three-dimensional measuring device.

Background technique

As an important measurement technology, optical three-dimensional measurement is widely used in medical, industrial and other industries due to its non-contact, fast and high-resolution measurement advantages. With the development of modern technology, especially the rapid development of laser technology, image processing technology and optical imaging technology, 3D measurement has developed different forms for different application scenarios.

Optical three-dimensional measurement methods can be divided into passive and active. Passive methods include monocular, binocular and multi-eye stereo vision methods; The method has the advantages of fast speed, directness and high precision, and is widely used in the measurement of various target sizes including large buildings to tiny objects.

In the three-dimensional measurement technology of structured light illumination, an existing technology is usually to use liquid crystal display or digital projector to realize the projection of types of structured light such as point, line, grating, etc. A device (usually a camera) is used to record the image of the surface of the object, and then through the analysis of the deformation of its structured light pattern, the measurement of the three-dimensional topography of the object surface is realized. In addition, in this type of technology, high-precision measurement can also be achieved through structured light projection using different encoding methods, but it is difficult to achieve miniaturization due to the large size of the projection equipment.

Another existing technology is to use line lasers to realize the projection of line structured light, and to realize three-dimensional measurement of objects by hand-held or fixed-angle scanning. Although this technique can realize the miniaturization of the measuring device, it needs to move the object (or the measuring device) to realize the measurement of the overall three-dimensional shape of the object. Another existing technology is to use vertical cavity surface emitting lasers with DOE (Diffractive optical elements, diffractive optical elements), and use the principle of optical diffraction to realize the projection of structured light patterns, thereby realizing three-dimensional measurement, which is widely used in the front of current mobile phones. For face recognition, although this technology has the advantages of small size and high diffraction efficiency, it relies on complex DOE design and processing, and the working wavelength must be related to the DOE design.

Therefore, based on the above existing problems in the prior art, it is urgent to develop a three-dimensional measurement device with structured light illumination that is small in size, low in cost and simple in structure.

Contents of the invention

(1) Technical problems to be solved

The invention provides a three-dimensional measurement device with structured light illumination to at least partly solve the shortcomings of the existing methods, which are bulky or cannot be fixed for measurement, and involve and process complicatedly.

(2) Technical solution

According to one aspect of the present invention, a three-dimensional measuring device with structured light illumination is provided, including a light source for emitting light beams; a beam-splitting optical chip connected to the light source through an optical fiber for splitting the light beams forming multiple beams of outgoing light; a shifter, arranged on one side of the beam-splitting optical chip, mechanically connected to the beam-splitting optical chip, used to control the movement of the beam-splitting optical chip, and indirectly control the exit position of multiple beams of light; A photodetector is used to detect multiple beams of outgoing light reflected by the object to be measured; a control module is electrically connected to the light source, the displacement device and the photoelectric detector, and is used to control the movement of the displacement device and control the photoelectric detector.

In a further solution, the light source is a laser light source with a single wavelength, and its wavelength range is 400-1600nm.

In a further solution, the beam-splitting optical chip includes a quartz substrate and a light-splitting waveguide, the output end surface of which is a plane, and the outgoing light is output vertically at a set divergence angle.

In a further solution, the displacement device is an electromechanical displacement device or a piezoelectric displacement device.

In a further solution, the photodetector includes a CMOS camera with a fixed or zoom lens.

In a further solution, the control module can be configured as a single-chip microcomputer system or FPGA (Field-Programmable Gate Array, Field-Programmable Gate Array). In addition, the control module also includes a communication port, and the measurement data is transmitted through the communication port. It is transmitted to the back-end computing system, and the back-end computing system uses the corresponding three-dimensional reconstruction algorithm to reconstruct the surface three-dimensional topography of the object to be measured.

In a further solution, the device further includes a casing, and the casing includes a horizontal base for fixing the light source, the beam splitting optical chip, the displacer, the photodetector and the control module on the same horizontal plane.

(3) Beneficial effects

It can be seen from the above technical solutions that the three-dimensional measurement device for structured light illumination provided by the present invention uses a beam-splitting light chip to achieve light splitting, and produces surface structured light projection through interference. Its operating wavelength range is wide and can be used in different application scenarios. There is no diffraction loss similar to that of a spatial light modulator, and its light energy utilization rate is high; at the same time, the device has a simple structure, low cost and small volume, and is suitable for various operating scenarios.

Description of drawings

Fig. 1 is a top view of a three-dimensional measurement device with structured light illumination according to an embodiment of the present invention.

Figure 2 is a front view of the device shown in Figure 1 .

Fig. 3 is a schematic diagram of three-dimensional measurement of the device shown in Fig. 1

Fig. 4 is an interference fringe image collected by the photodetector of the device shown in Fig. 1 .

[Description of Reference Signs]

1-light source; 2-optical fiber; 3-beam splitting chip; 4-displacer; 5-photodetector;

6-control module; 7-housing; 8-object to be measured; 301-quartz substrate; 302-split waveguide.

Detailed ways

In order to make the object, technical solution and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with specific embodiments and with reference to the accompanying drawings.

In the present invention, "disposed on" or "attached to" is used to include a direct contact relationship with a single or multiple components. Moreover, the ordinal numbers used in the specification and claims, such as "first", "second", "number one" or "number two", are used to modify the components claimed for protection, which do not themselves contain and represent the Parts have any previous ordinal numbers, nor do they imply the order of one part with another or in terms of manufacturing methods, and these ordinal numbers are used only to enable a part with a certain designation to be related to another part with the same designation Can make a clear distinction.

The invention provides a three-dimensional measurement device for structured light illumination, which uses a beam-splitting light chip to divide a single beam of incident light output by a light source into two or more beams, and directly outputs the two or more beams of light from a flat end surface to In the way of the object to be measured, the interference forms the surface structured light projection, and then the phase modulation of the interference fringes is realized through the displacement function of the displacer. The three-dimensional topography of the surface.

Fig. 1 is a top view of a structured light illumination three-dimensional measurement device according to an embodiment of the present invention, as shown in Fig. 1 , including:

A light source 1, in this embodiment, the light source 1 is a laser light source with a single wavelength, and its wavelength range is 400-1600nm;

The beam-splitting optical chip 3 is used to divide the single incident light of the light source 1 into two or more beams. The beam-splitting optical chip 3 is connected to the light source 1 through the optical fiber 2, and the single incident light generated by the light source 1 passes through The optical fiber 2 is coupled into the beam-splitting optical chip;

The displacement device 4 is arranged at one end of the beam-splitting optical chip 3 and is mechanically connected to the beam-splitting optical chip 3. The displacement device 4 can be an electromechanical displacement device or a piezoelectric displacement device for moving in the direction of the outgoing light The beam-splitting optical chip 3, so as to realize phase modulation of interference fringes;

The photodetector 5, which can be configured as a CMOS camera with a fixed-focus or zoom lens, is used to collect light information of a wavelength consistent with the light source, record the image of the object surface, and analyze the deformation of its structured light pattern, Thereby, the measurement of the three-dimensional topography of the object surface is realized. In other embodiments of the present invention, if the specificity of detection needs to be further improved, a film can be coated on the surface of the camera lens of the photodetector 5 so that it only detects the light of the output wavelength of the light source. .

The control module 6 is electrically connected to the light source 1, the shifter 4 and the photodetector 5 respectively, and is used to set the wavelength of the light source 1, the working mode of the shifter 4 and collect the data collected by the photodetector 5. In this embodiment Among them, the control module 6 can be configured as a single-chip microcomputer system or FPGA. Preferably, the control module 6 also includes a communication port, and the measurement data is transmitted to the back-end computing system through the communication port, and the back-end computing system utilizes the corresponding three-dimensional reconstruction The algorithm reconstructs the surface three-dimensional topography of the object to be measured.

In addition, the beam-splitting optical chip 3 includes a quartz substrate 301 and a light-splitting waveguide 302 , and the output end surface of the emitted light is a plane, perpendicular to the light-splitting waveguide 302 .

The device also includes a casing 7, and the casing 7 includes a horizontal base for fixing the light source 1, beam-splitting optical chip 3, displacer 4, photodetector 5 and control module 6 on the same horizontal plane.

Fig. 2 is the front view of the device shown in Fig. 1, as shown in Fig. 2, the shifter 4 is arranged on one side of the beam-splitting optical chip 3, by displacing the beam-splitting optical chip 3 in the outgoing light direction, the fringe displacement is realized, thereby obtaining Meet the data required for 3D image reconstruction with striped structured light.

FIG. 3 is a schematic diagram of three-dimensional measurement of the device shown in FIG. 1 , and a specific embodiment of the present invention will be further described below in conjunction with FIG. 3 , please refer to FIG. 3 .

In this embodiment, the wavelength of the light output by the light source 1 is 635nm, and the beam-splitting optical chip 3 is a PLC (planar lightwave circuit, planar light waveguide) optical chip, which can evenly divide the light into two beams, and the distance between the two light-splitting waveguides 302 is 250 μm , the displacement device 4 is a piezoelectric ceramic displacement device, which can drive the movement of the beam-splitting optical chip 3 under the control of the electrical signal output by the control module 6, and its moving direction is parallel to the connection line of the output points of the two optical waveguides 302, and the photoelectric detection Device 5 is a CMOS camera that includes a lens.

As shown in FIG. 3 , the light output by the two light-splitting waveguides 302 is directly irradiated on the object 8 to be measured, while the photodetector 5 collects the light reflected from the object to be measured. FIG. 4 is an interference fringe image collected by the photodetector of the device shown in FIG. 1 . As shown in FIG. 4 , according to the interference principle, the light output by the splitting waveguide 302 interferes on the surface of the object 8 to be measured to form an interference fringe image.

The image collected by the photodetector 5 is an image I with interference fringes, and its mathematical expression is:

I(x,y)=I'(x,y)+I"(x,y)cos(φ(x,y)).

Among them, x and y represent the coordinates of the pixel points of the image, and the phase φ(x, y) represents the information of the three-dimensional topography of the object surface.

The displacement of the beam-splitting optical chip 3 is driven by the displacement device 4 to realize the displacement of the interference fringe phase step length of π/2. In this embodiment, the displacement is performed 3 times, and a total of 4 images are collected. The mathematical expressions are respectively:

I ₁ (x, y) = I'(x, y)+I"(x, y) cos(φ(x, y))

I ₂ (x, y)=I'(x, y)+I"(x, y) cos(φ(x, y)+π/2)

I ₃ (x, y)=I'(x, y)+I"(x, y)cos(φ(x, y)+π)

I ₄ (x, y) = I'(x, y)+I"(x, y)cos(φ(x, y)+3π/2)

The phase φ(x, y) can be calculated based on these four images:

Finally, the three-dimensional surface topography of the object 8 to be measured can be recovered through the corresponding phase unwrapping algorithm.

Through the above statement, in view of the problems and shortcomings in the prior art, the embodiment of the present invention provides a three-dimensional measurement device for structured light illumination, which uses a beam splitter chip to achieve light splitting, and generates surface structured light projection through interference. Its working wavelength range is Wide, can be used in different application scenarios, and has no diffraction loss similar to the spatial light modulator, and its light energy utilization rate is high; at the same time, the device has a simple structure, low cost and small size, and is suitable for various operating scenarios.

The specific embodiments described above have further described the purpose, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above descriptions are only specific embodiments of the present invention, and are not intended to limit the present invention. Within the spirit and principles of the present invention, any modifications, equivalent replacements, improvements, etc., shall be included in the protection scope of the present invention.

Claims (7)

1. a kind of Structured Illumination three-dimensional measuring apparatus, comprising:

One light source, for emitting light beam；

One beam splitting optical chip is connect with the light source by an optical fiber, forms multi beam outgoing for the light beam to be carried out light splitting Light；

One shifter is set to beam splitting optical chip side, is mechanically connected with the beam splitting optical chip, for controlling beam splitting light Chip is mobile, indirectly controls the Exit positions of multi-beam；

One photodetector, the reflected beams reflected for detecting multi beam emergent light through object under test；

One control module, is electrically connected in the light source, shifter and photodetector, for the movement of command displacement device, And control photodetector.

2. the apparatus according to claim 1, wherein the light source is the laser light source with single wavelength, wavelength model It encloses for 400-1600nm.

3. the apparatus according to claim 1, wherein the beam splitting optical chip includes a quartz base plate and a light splitting waveguide.

4. device according to claim 3, wherein the output end face of the beam splitting optical chip is plane, the multi beam goes out Light is penetrated to set angle of divergence vertical output.

5. the apparatus according to claim 1, wherein the shifter is motor machine shifter or displacement bimorph device.

6. the apparatus according to claim 1, wherein the photodetector includes with fixed-focus or zoom lens CMOS camera.

7. the apparatus according to claim 1 is used for transmission measurement wherein the control module further includes a communication port Data.