CN114111640B - Sinusoidal stripe structured light projection system and working method - Google Patents
Sinusoidal stripe structured light projection system and working method Download PDFInfo
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- CN114111640B CN114111640B CN202111474841.2A CN202111474841A CN114111640B CN 114111640 B CN114111640 B CN 114111640B CN 202111474841 A CN202111474841 A CN 202111474841A CN 114111640 B CN114111640 B CN 114111640B
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B11/00—Measuring arrangements characterised by the use of optical techniques
- G01B11/24—Measuring arrangements characterised by the use of optical techniques for measuring contours or curvatures
- G01B11/25—Measuring arrangements characterised by the use of optical techniques for measuring contours or curvatures by projecting a pattern, e.g. one or more lines, moiré fringes on the object
- G01B11/254—Projection of a pattern, viewing through a pattern, e.g. moiré
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Abstract
A sinusoidal stripe structured light projection system and a working method thereof solve the problems that the prior DMD technology adopts binary pulse width modulation to obtain sinusoidal stripes which are not suitable for high-speed measurement, and the contrast of the sinusoidal stripes projected by adopting binary stripe defocusing can be reduced along with the increase of defocusing amount, and simultaneously the manufacturing cost is greatly reduced. It comprises the following steps: an illumination light source (1), a lens system (2), a micro motor (3), a displacement detector (4) and a phase-shifting reflector (5); the illumination system provides illumination for the sinusoidal fringe structured light projection system; the lens system converts parallel light emitted by the illumination light source into divergent light, and the superlens converts divergent light with uniform distribution characteristics into divergent light with sine stripe characteristics; the phase-shifting reflector regulates and controls the projection and phase of the sinusoidal stripe structure light; the micro motor drives the phase-shifting reflector to rotate; the displacement detector collects displacement data of the phase-shifting mirror.
Description
Technical Field
The invention relates to the technical field of photoelectric detection, in particular to a sinusoidal stripe structure light projection system and a working method adopted by the sinusoidal stripe structure light projection system.
Background
With the rapid development of high-end manufacturing industry, urgent needs are put forward for automatic measurement of complex curved surfaces of large-scale components, such as full-size profile measurement of automobile bodies, profile measurement of key areas of airplanes and the like. As a typical structured light three-dimensional measurement technology, the fringe projection contour technology has the advantages of simple structure, large measurement dynamic range, high precision, high speed and the like, and is a main technical means for detecting the three-dimensional shape of a large-size dynamic target.
Currently, fringe projection systems are mainly galvanometer and digital projectors. The vibrating mirror has small volume, low brightness and poor contrast ratio, which results in low measurement precision, while the digital projector based on the digital micro mirror element (Digital micromirror device, DMD) technology has fast development by virtue of high speed and high resolution, and mainly adopts binary pulse width modulation and binary stripe defocusing projection to realize the projection of sine stripes. The former is to decompose one gray sine stripe of pre-projection into N bit images based on PWM principle, and form sine stripe by controlling the integration time; the latter is to form a sinusoidal fringe by defocusing the binarized fringe pattern through the lens. The binary pulse width modulation method reduces the time response speed of a projection system due to the time integration of 'projection-image', and is not beneficial to the three-dimensional shape detection of a high-speed target. The binarization stripe defocusing projection is limited by the limited depth of field of the projection imaging lens, and the sinusoidal stripe contrast can be reduced along with the increase of the defocusing amount, so that the high-precision acquisition of the axial three-dimensional morphology in a large range is affected. In addition, the current domestic digital projector system is complex, the volume is large, the core DMD chip mainly depends on import, the cost is high, new technical approaches are urgently required to realize high-speed, resolution and low-cost positive line stripe structure light projection, and the problem of three-dimensional morphology measurement of large-size and high-speed targets is solved.
Disclosure of Invention
In order to overcome the defects of the prior art, the technical problem to be solved by the invention is to provide a sinusoidal stripe structure light projection system, which solves the problems that the prior DMD technology adopts binary pulse width modulation to obtain sinusoidal stripes which are not suitable for high-speed measurement, and the contrast of the sinusoidal stripes projected by adopting binary stripe defocusing can be reduced along with the increase of defocusing amount, and simultaneously greatly reduces the manufacturing cost.
The technical scheme of the invention is as follows: such sinusoidal fringe structured light projection system comprising: an illumination light source (1), a lens system (2), a micro motor (3), a displacement detector (4) and a phase-shifting reflector (5);
the illumination system provides illumination for the sinusoidal fringe structured light projection system; the lens system converts parallel light emitted by the illumination light source into divergent light, and the superlens converts divergent light with uniform distribution characteristics into divergent light with sine stripe characteristics; the phase-shifting reflector regulates and controls the projection and phase of the sinusoidal stripe structure light; the micro motor drives the phase-shifting reflector to rotate; the displacement detector collects displacement data of the phase-shifting mirror.
The invention adopts the superlens to convert the uniformly distributed characteristic divergent light into the divergent light with sine stripe characteristic, has high response speed and large depth of field compared with the projection device based on the DMD, does not depend on complex control program, thereby ensuring measurement accuracy; the phase adjustment of the sinusoidal stripes is realized by adopting the micro motor to control the phase shifting reflector, the function which can be completed by a complex electronic system can be realized only by mechanical control, the volume and the complexity of the system are greatly simplified, the cost is reduced, and the localization of the structured light projection system is promoted; therefore, the problem that the prior DMD technology adopts binary pulse width modulation to obtain sinusoidal fringes is not suitable for high-speed measurement, and the contrast of the sinusoidal fringes projected by adopting binary fringe defocusing can be reduced along with the increase of defocusing amount, and meanwhile, the manufacturing cost is greatly reduced.
The working method of the sinusoidal fringe structure light projection system is also provided, and the working method comprises the following steps:
(1) The illumination light source emits light rays, the light rays are changed into divergent light after passing through the lens system, the super surface of the lens system simultaneously converts the light rays into stripes with sine characteristics and projects the stripes onto the phase shifting reflector, and the stripes are irradiated to the surface of a measured object through the phase shifting reflector;
(2) When the sinusoidal stripes are subjected to phase shifting treatment, the micro motor controls the phase shifting reflector to rotate for a certain displacement, and the displacement accuracy is fed back by the displacement detector, so that the phase of the sinusoidal stripes projected to the surface of the measured object is accurately changed within a certain range.
Drawings
Fig. 1 is a schematic diagram of a sinusoidal fringe structured light projection system in accordance with the present invention.
Fig. 2 is a schematic structural view of a lens system according to the present invention.
FIG. 3 is a flow chart of a method of operation of a sinusoidal fringe structured light projection system in accordance with the present invention.
Detailed Description
In order that those skilled in the art will better understand the present invention, a technical solution in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in which it is apparent that the described embodiments are only some embodiments of the present invention, not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the present invention without making any inventive effort, shall fall within the scope of the present invention.
It should be noted that the term "comprising" and any variations thereof in the description of the invention and the claims and in the above-described figures is intended to cover a non-exclusive inclusion, such that a process, method, apparatus, article, or device comprising a list of steps or elements is not necessarily limited to those steps or elements that are expressly listed or inherent to such process, method, article, or device, but may include other steps or elements not expressly listed.
As shown in fig. 1, this sinusoidal fringe structured light projection system comprises: an illumination light source 1, a lens system 2, a micro motor 3, a displacement detector 4 and a phase shift reflector 5;
the illumination system provides illumination for the sinusoidal fringe structured light projection system; the lens system converts parallel light emitted by the illumination light source into divergent light, and the superlens converts divergent light with uniform distribution characteristics into divergent light with sine stripe characteristics; the phase-shifting reflector regulates and controls the projection and phase of the sinusoidal stripe structure light; the micro motor drives the phase-shifting reflector to rotate; the displacement detector collects displacement data of the phase-shifting mirror.
The invention adopts the superlens to convert the uniformly distributed characteristic divergent light into the divergent light with sine stripe characteristic, has high response speed and large depth of field compared with the projection device based on the DMD, does not depend on complex control program, thereby ensuring measurement accuracy; the phase adjustment of the sinusoidal stripes is realized by adopting the micro motor to control the phase shifting reflector, the function which can be completed by a complex electronic system can be realized only by mechanical control, the volume and the complexity of the system are greatly simplified, the cost is reduced, and the localization of the structured light projection system is promoted; therefore, the problem that the prior DMD technology adopts binary pulse width modulation to obtain sinusoidal fringes is not suitable for high-speed measurement, and the contrast of the sinusoidal fringes projected by adopting binary fringe defocusing can be reduced along with the increase of defocusing amount, and meanwhile, the manufacturing cost is greatly reduced.
Preferably, the illumination system employs LED illumination sources.
Preferably, as shown in fig. 2, the lens system includes, in order along the light emitting direction of the light source, a first lens 21, a second lens 22, a third lens 23, and a super lens 24, where the first lens, the third lens, and the super lens have positive focal power, the second lens has negative focal power, and the super lens performs super surface design and processing on the lens surface.
Preferably, the miniature motor adopts a stepping belt reduction gearbox motor GM18168-01.
Preferably, the displacement detector employs an MTE-40 grating detector with a resolution of up to 0.5 um.
As shown in fig. 3, there is also provided a method of operating a sinusoidal fringe structured light projection system, comprising the steps of:
(1) The illumination light source emits light rays, the light rays are changed into divergent light after passing through the lens system, the super surface of the lens system simultaneously converts the light rays into stripes with sine characteristics and projects the stripes onto the phase shifting reflector, and the stripes are irradiated to the surface of a measured object through the phase shifting reflector;
(2) When the sinusoidal stripes are subjected to phase shifting treatment, the micro motor controls the phase shifting reflector to rotate for a certain displacement, and the displacement accuracy is fed back by the displacement detector, so that the phase of the sinusoidal stripes projected to the surface of the measured object is accurately changed within a certain range.
Preferably, in the step (2), the micro motor rotates for a certain step distance, the phase-shifting mirror rotates for a certain displacement X at the same time, the error of the displacement X is compensated by the displacement detector, and at the moment, the sinusoidal stripe projected by the projection system completes the phase shift, so as to be used for acquiring the target three-dimensional data by the structured light three-dimensional measurement system.
The present invention is not limited to the preferred embodiments, but can be modified in any way according to the technical principles of the present invention, and all such modifications, equivalent variations and modifications are included in the scope of the present invention.
Claims (5)
1. A sinusoidal fringe structured light projection system, characterized by: it comprises the following steps: an illumination light source (1), a lens system (2), a micro motor (3), a displacement detector (4) and a phase-shifting reflector (5); the illumination system provides illumination for the sinusoidal fringe structured light projection system; the lens system converts parallel light emitted by the illumination light source into divergent light, and the superlens converts divergent light with uniform distribution characteristics into divergent light with sine stripe characteristics; the phase-shifting reflector regulates and controls the projection and phase of the sinusoidal stripe structure light; the micro motor drives the phase-shifting reflector to rotate; the displacement detector acquires displacement data of the phase-shifting reflector;
the illumination system adopts an LED illumination light source;
the lens system sequentially comprises a first lens (21), a second lens (22), a third lens (23) and a super lens (24) along the light emitting direction of the light source, wherein the first lens, the third lens and the super lens have positive focal power, the second lens has negative focal power, and the super lens is used for super surface design and processing on the surface of the lens.
2. The sinusoidal fringe structured light projection system of claim 1, wherein: the miniature motor adopts a stepping motor GM18168-01 with a reduction gearbox.
3. The sinusoidal fringe structured light projection system of claim 2, wherein: the displacement detector employs an MTE-40 grating detector with resolution up to 0.5 um.
4. A method of operating a sinusoidal fringe structured light projection system as recited in any one of claims 1-3 wherein: which comprises the following steps:
(1) The illumination light source emits light rays, the light rays are changed into divergent light after passing through the lens system, the super surface of the lens system simultaneously converts the light rays into stripes with sine characteristics and projects the stripes onto the phase shifting reflector, and the stripes are irradiated to the surface of a measured object through the phase shifting reflector;
(2) When the sinusoidal stripes are subjected to phase shifting treatment, the micro motor controls the phase shifting reflector to rotate for a certain displacement, and the displacement accuracy is fed back by the displacement detector, so that the phase of the sinusoidal stripes projected to the surface of the measured object is accurately changed within a certain range.
5. The method of operating a sinusoidal fringe structured light projection system of claim 4, wherein: in the step (2), the micro motor rotates for a certain step distance, the phase-shifting reflector rotates for a certain displacement X at the same time, the error of the displacement X is compensated by the displacement detector, and the sinusoidal stripes projected by the projection system complete the phase shift at the moment so as to be used for acquiring the target three-dimensional data by the structured light three-dimensional measurement system.
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| CN205718875U (en) * | 2016-06-28 | 2016-11-23 | 西安励德微***科技有限公司 | A kind of scan-type structure light projection system |
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| 叶红.第1.2.2节 干涉光场调控技术.《中国优秀硕士学位论文全文数据库 工程科技Ⅱ辑》.2021,(第undefined期),第10-14页. * |
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