阅读说明：本技术 一种结构光干涉测速仪 (Structured light interference velocimeter ) 是由 王健 万镇宇 方良 汤子毅 于 2021-08-16 设计创作，主要内容包括：本发明公开了一种结构光干涉测速仪,包括发射设备、接收设备、反射式复合螺旋相位板；发射设备置于测量原地,用于发射、接收和处理光信号,接收设备置于远程待测物体处,用于探测和反向传输光信号,接收设备可采用迈克尔逊或马赫泽德干涉配置；发射设备和接收设备中采用扩束器和缩束器调节光束尺寸,保证光场在近远端间准直传输；反射式复合螺旋相位板粘贴在待测物体表面,将照射的探测光转换为结构光；参考高斯光和结构光合束为叠加光,在发射设备中利用双位置检测装置对叠加光检测并进行信号处理,可获取远程待测物体的平移、旋转或两者组合的多维度运动速度信息。本发明在光学测量和传感等方面具有广泛的应用前景,填补了相关技术领域的空白。(The invention discloses a structured light interference velocimeter, which comprises a transmitting device, a receiving device and a reflective composite spiral phase plate, wherein the transmitting device is connected with the receiving device through a transmission line; the transmitting device is arranged in a measurement original place and used for transmitting, receiving and processing optical signals, the receiving device is arranged at a remote object to be measured and used for detecting and reversely transmitting the optical signals, and the receiving device can adopt Michelson or Mach-Zehnder interference configuration; the beam expander and the beam reducer are adopted in the transmitting equipment and the receiving equipment to adjust the size of the light beam, so that the light field is ensured to be transmitted in a collimation manner between the near end and the far end; the reflective composite spiral phase plate is adhered to the surface of an object to be detected, and the irradiated detection light is converted into structured light; the reference Gaussian light and the structural light are combined into superimposed light, the superimposed light is detected by using a double-position detection device in the transmitting equipment, and signal processing is carried out, so that multi-dimensional motion speed information of translation, rotation or combination of the translation and the rotation of a remote object to be detected can be obtained. The invention has wide application prospect in the aspects of optical measurement, sensing and the like, and fills the blank of the related technical field.)

1. The structured light interference velocimeter is characterized by comprising a transmitting device (1), a receiving device (3) and a reflective composite spiral phase plate (4), wherein the transmitting device (1) is arranged on a measuring site and used for transmitting, receiving and processing optical signals, the receiving device (3) is arranged at a remote object to be measured and used for detecting and reversely transmitting the optical signals, and the reflective composite spiral phase plate (4) is arranged on the surface of the object to be measured;

the transmitting equipment (1) comprises a laser (11), a first beam expander (12), a first beam reducer (13) and a double-position detection device (14); the receiving device (3) comprises a second beam reducer (31), a first beam splitter (32), a first reflector (33), a second reflector (34) and a second beam expander (35); the laser (11) is used for outputting free-space Gaussian light, and the first beam expander (12) is used for expanding the beam size of the Gaussian light and sending the expanded beam size to the receiving device (3); the second beam reducer (31) is used for receiving Gaussian light emitted by the emitting device (1) and reducing the beam size, the first beam splitter (32) is used for splitting the Gaussian light into probe light and reference light, the first reflecting mirror (33) is used for reflecting the reference light back to the first beam splitter (32), the reflective composite spiral phase plate (4) is used for converting the vertically irradiated probe light into structured light and reflecting the structured light back to the first beam splitter (32), the first beam splitter (32) is also used for combining the Gaussian light and the structured light into superimposed light, the second reflecting mirror (34) is used for adjusting the propagation direction of the superimposed light, the second beam expander (35) is used for expanding and reversely transmitting the beam size of the superimposed light to the emitting device (1), and the first beam reducer (13) receives the light transmitted reversely by the receiving device and reduces the beam size, the double-position detection device (14) is used for detecting the superposed light and processing signals to acquire the speed information of the remote object to be detected.

2. A structured light interference velocimeter is characterized by comprising a transmitting device (1), a receiving device (3) and a reflective composite spiral phase plate (4); the transmitting equipment (1) is arranged on a measuring site and used for transmitting, receiving and processing optical signals, the receiving equipment (3) is arranged at a remote object to be measured and used for detecting and reversely transmitting the optical signals, and the reflective composite spiral phase plate (4) is arranged on the surface of the object to be measured;

the transmitting equipment (1) comprises a laser (11), a first beam expander (12), a first beam reducer (13) and a double-position detection device (14); the receiving device (3) comprises a second beam reducer (31), a first beam splitter (32), a second beam splitter (36), a third reflector (37), a third beam splitter (38) and a second beam expander (35); the laser (11) is used for outputting free-space Gaussian light, the first beam expander (12) is used for expanding and sending the beam size of the Gaussian light to the receiving device (3), the second beam reducer (31) is used for receiving the Gaussian light sent by the sending device and reducing the beam size, the first beam splitter (32) is used for dividing the Gaussian light into probe light and reference light, the reflective composite spiral phase plate (4) is used for converting the incident Gaussian light into structured light, the second beam splitter (36) is used for irradiating the probe light to the reflective composite spiral phase plate (4) and receiving the reflected structured light, the third reflector (37) is used for adjusting the propagation direction of the structured light, the third beam splitter (38) is used for combining the Gaussian light and the structured light into the superimposed light, and the second beam expander (35) is used for expanding and reversely transmitting the beam size of the Gaussian light to the sending device, the first beam reducer (13) is used for receiving the superposed light reversely transmitted by the receiving equipment (3) and reducing the size of the light beam, and the double-position detection device (14) is used for detecting the superposed light and processing signals to acquire the speed information of the remote object to be detected.

3. The structured light interference velocimeter is characterized by comprising a transmitting device (1), a receiving device (3) and a reflective composite spiral phase plate (4), wherein the transmitting device (1) and the receiving device (3) adopt bidirectional coaxial light beam transmission; the transmitting equipment (1) is arranged on a measuring site and used for transmitting, receiving and processing optical signals, the receiving equipment (3) is arranged at a remote object to be measured and used for detecting and reversely transmitting the optical signals, and the reflective composite spiral phase plate (4) is arranged on the surface of the object to be measured;

the transmitting equipment (1) comprises a laser (11), a first beam expander (12), a fourth beam splitter (15) and a double-position detection device (14), and the receiving equipment (3) comprises a second beam reducer (31), a first beam splitter (32) and a first reflector (33); the laser (11) is used for outputting free-space Gaussian light, the fourth beam splitter (15) is used for transmitting the Gaussian light output by the laser (11) to the first beam expander (12) and transmitting superimposed light received by the first beam expander (12) to the dual-position detection device (14), the first beam expander (12) is used for expanding and sending the beam size of the Gaussian light to the receiving equipment (3) and receiving superimposed light reversely transmitted by the receiving equipment (3) and reducing the beam size, the second beam splitter (31) is used for receiving the Gaussian light emitted by the emitting equipment (1) and reducing the beam size and is also used for expanding and reversely transmitting the beam size of the superimposed light to the emitting equipment (1), the first beam splitter (32) is used for splitting the Gaussian light into probe light and reference light, and the probe light and the reference light are converted into structured light for reflection after vertically irradiating the reflective composite spiral phase plate (4), the reference light is reflected by the first reflecting mirror (33), the first beam splitter (32) is further used for combining the structured light and the Gaussian light into the superposed light, and the double-position detection device (14) is used for detecting the superposed light and performing signal processing to obtain the speed information of the remote object to be detected.

4. A structured light interference velocimeter is characterized by comprising a transmitting device (1), a receiving device (3) and a reflective composite spiral phase plate (4); the transmitting equipment (1) and the receiving equipment (3) adopt bidirectional coaxial light beam transmission; the transmitting equipment (1) is arranged on a measuring site and used for transmitting, receiving and processing optical signals, the receiving equipment (3) is arranged at a remote object to be measured and used for detecting and reversely transmitting the optical signals, and the reflective composite spiral phase plate (4) is arranged on the surface of the object to be measured;

the transmitting equipment (1) comprises an optical fiber laser (16), a single-mode optical fiber (17), an optical fiber coupler (18), an optical fiber time delay device (110), a polarization controller (111), a first collimator (19), a second collimator (112), a fourth beam splitter (15), a first beam expander (12) and a double-position detection device (14), and the receiving equipment (3) comprises a second beam reducer (31); the optical fiber laser (16) is used for outputting a basic mode Gaussian light, the optical fiber coupler (18) is used for dividing the basic mode Gaussian light into a basic mode Gaussian probe light and a basic mode Gaussian reference light, the first collimator (112) is used for outputting the basic mode Gaussian probe light into a free space Gaussian light, the optical fiber time delay unit (110) is used for compensating an optical path difference between a reference light path and a probe light path, so that interference superposition of the structural light and the Gaussian light meets a coherence condition, the polarization controller (111) is used for eliminating polarization mismatch between the reference light path and the probe light path caused by long-distance transmission, the second collimator (112) is used for outputting the basic mode Gaussian reference light into the free space Gaussian light, the fourth beam splitter (15) is used for transmitting the probe light to the first beam expander (12) and combining the free space Gaussian light and the structural light received by the first beam expander (12) into a superposed light, the first beam expander (12) is used for expanding and sending the beam size of Gaussian light to the receiving equipment (3), and also receiving the structured light reversely transmitted by the receiving equipment (3) and reducing the beam size, the second beam expander (31) is used for receiving the Gaussian light transmitted by the transmitting equipment (1), vertically irradiating the reflective composite spiral phase plate (4) after reducing the beam size, reversely transmitting the structured light reflected by the reflective composite spiral phase plate (4) to the transmitting equipment (1) after reducing the beam size by the second beam expander (31), and the double-position detection device (14) is used for detecting the superimposed light and carrying out signal processing to obtain the speed information of a remote object to be detected.

5. A structured light interferometric velocimeter according to any one of claims 1-4, wherein the first beam expander (12) comprises a lens set and an encapsulating housing, the magnification of the first beam expander (12) being 5-20 times such that the beam size at the receiving device is smaller than the collecting aperture of the second beam reducer (31); the second beam expander (35), the first beam reducer (13), and the second beam reducer (31) have the same parameters as the first beam expander (12).

6. The structured light interferometer according to any of claims 1 to 4, wherein the reflective composite helical phase plate (4) converts free space Gaussian light into structured light comprising two different orbital angular momentum components, and wherein the beam size of the higher order orbital angular momentum component of the structured light is larger than the beam size of the lower order orbital angular momentum component; the center of the reflective composite spiral phase plate (4) is superposed with the rotation center of the object to be detected and is aligned with the optical axis of the detection light vertically irradiating the object to be detected; the reflective composite spiral phase plate (4) is a spiral phase plate or a metamaterial or super-surface structure light generating device.

7. A structured light interferometric velocimeter according to any one of claims 1-4, wherein the dual position detection means (14) comprises a beam splitter, a first detector, a second detector and a signal processing module; the beam splitter is used for dividing the superposed light into a first detection path and a second detection path, the first detector and the second detector are respectively arranged in a boundary annular area between the outer side and the inner side of the superposed light in the first detection path and the second detection path, and the signal processing module is respectively used for carrying out Fourier analysis on time domain signals collected by the first detector and the second detector to obtain the speed information of a remote object to be detected.

8. The structured light interferometric velocimeter of claim 7, wherein the signal processing module performs fourier analysis on the time domain signals collected by the first detector and the second detector, respectively, to obtain a first fourier magnitude spectrum, a second fourier magnitude spectrum, a first fourier phase spectrum, and a second fourier phase spectrum, subtracts the first fourier phase spectrum and the second fourier phase spectrum to obtain a fourier relative phase spectrum, uses a spectral peak with a lower relative amplitude as a first spectral peak and obtains a first peak frequency in the first fourier magnitude spectrum, uses a spectral peak with a higher relative amplitude as a second spectral peak and obtains a second peak frequency, and determines a first relative phase difference value and a second relative phase difference value in the fourier relative phase spectrum, respectively corresponding to the first peak frequency and the second peak frequency; and determining the signs of the first peak frequency and the second peak frequency by respectively using the signs of the first relative phase difference value and the second relative phase difference value, and calculating the speed information of the object to be detected by using the relation between the first peak frequency and the second peak frequency and the translational and rotational movement speeds of the object to be detected.

Technical Field

The invention belongs to the field of optical measurement, and particularly relates to a structured light interference velocimeter.

Background

The traditional laser interferometer constructed based on the classical doppler effect can measure the translational motion information of a target object by using a laser gaussian beam, for example, the horizontal displacement and the linear velocity of the target object are measured in a non-contact manner, but the traditional laser interferometer cannot measure the rotational motion information of the target object. At present, methods for acquiring the rotational motion information of the target object generally adopt contact type or mechanical type measurement, such as an angular velocity sensor based on a gyroscope design, and further such as an angular velocity measuring instrument based on a mechanical gear, and these methods cannot measure the translational motion information of the target object. For compound motion containing both translation motion information and rotation motion information, such as spiral motion, one-time non-contact simultaneous measurement of translation and rotation motion modes cannot be realized by the existing method. At present, an effective method for realizing real-time tracking of a motion track and a motion form of a target object with complex motion is lacked, and therefore, it is extremely necessary to design a device for real-time monitoring of compound motion.

In recent years, research has found that the structured light beam has spatially varying amplitude, polarization and phase distribution, wherein the phase-structured light beam can generate a rotating doppler effect, i.e. for rotating moving objects perpendicular to the propagation direction of the phase-structured light beam, a doppler shift of the light beam can be caused. The laser vortex beam is one of the phase-type structured beams, and has a characteristic that the phase is spatially distributed in a spiral shape. The coaxial interference light field of the Gaussian beam presents interference fringes distributed in concentric rings, namely Newton rings; the coaxial interference light field of the vortex light beam and the Gaussian light beam presents spiral interference fringes, and the number of the spiral fringes is consistent with the topological charge number of the vortex light beam; the coaxial interference optical field between the two vortex light beams with different topological charge numbers presents petal-shaped interference fringes, and the number of the petal fringes is consistent with the difference between the topological charge numbers of the two vortex light beams. For the coaxial interference light field of the vortex beam and the Gaussian beam, when the vortex beam rotates along the optical axis, a rotating Doppler effect is generated, and the rotating Doppler effect is visually expressed in the rotation of interference fringes; when the optical path difference between the vortex beam and the Gaussian beam changes along with time, a linear Doppler effect is generated, and the direct expression of the linear Doppler effect is that interference fringes rotate. Therefore, the rotation of the interference fringes of the vortex beam and the gaussian beam is determined by both the linear and the rotational doppler effects. For a coaxial interference light field between two vortex light beams with different topological charge numbers, when the two vortex light beams rotate along an optical axis simultaneously, a rotating Doppler effect is generated, and the rotating Doppler effect is visually expressed in the rotation of interference fringes; if the optical path difference between the two vortex lights is kept unchanged, the linear Doppler effect cannot occur. The most common method for generating a vortex beam in free space is to use a spiral phase plate, the thickness of which varies with the azimuth angle, so that the spiral phase plate can modulate an incident gaussian beam into a vortex beam with spiral phase distribution, wherein the topological charge number of orbital angular momentum contained in the vortex beam can be theoretically single or any combination of multiple. Linear and rotational doppler effects can exist between the gaussian light and the structured light at the same time, the two motions respectively correspond to a translational motion form and a rotational motion form, and in addition, rotational doppler effects can exist between vortex light beams with different topological charge numbers, which correspond to a rotational motion form.

Disclosure of Invention

Aiming at the defects of the prior art, the invention provides a structured light interference velocimeter, aiming at realizing one-time non-contact simultaneous measurement of full vector information of multi-dimensional complex motion of a remote object to be measured and filling the blank of the related technology.

To achieve the above object, according to an aspect of the present invention, there is provided a structured light interferometric velocimeter comprising: the device comprises a transmitting device, a receiving device and a reflective composite spiral phase plate; the transmitting equipment is arranged on a measuring site and used for transmitting, receiving and processing optical signals, the receiving equipment is arranged at a remote object to be measured and used for detecting and reversely transmitting the optical signals, and the reflective composite spiral phase plate is arranged on the surface of the object to be measured; the transmitting equipment comprises a laser, a first beam expander, a first beam reducer and a double-position detection device; the receiving device adopts a Michelson interference configuration and comprises a second beam reducer, a first beam splitter, a first reflecting mirror, a second reflecting mirror and a second beam expander; the laser outputs Gaussian light in a free space, the first beam expander expands the beam size of the Gaussian light and sends the expanded beam size to the receiving device, the second beam expander receives the Gaussian light emitted by the emitting device and reduces the beam size, the first beam splitter divides the Gaussian light into two paths of probe light and reference light, the first reflector reflects the reference light back to the first beam splitter, the reflective composite spiral phase plate is adhered to the surface of an object to be measured and converts the vertically irradiated probe light into structural light and reflects the structural light back to the first beam splitter, the first beam splitter also plays a role in beam combination and combines the Gaussian light and the structural light into superposed light, the second reflector adjusts the propagation direction of the superposed light, the second beam expander expands the beam size of the superposed light and reversely superposes the superposed light to the emitting device, the first beam expander receives the superposed light reversely transmitted by the receiving device and reduces the beam size, the double-position detection device detects the superposed light and processes signals, acquiring speed information of a remote object to be detected; the structured light interference velocimeter provided by the invention can be used for acquiring full vector motion information of the motion speed and direction of a block object with macroscopic size and any shape in a remote measurement scene aiming at a multi-dimensional motion form of translation, rotation or combination of the translation and the rotation.

According to another aspect of the present invention there is provided a structured light interferometric velocimeter, comprising: the device comprises a transmitting device, a receiving device and a reflective composite spiral phase plate; the transmitting equipment is arranged on a measuring site and used for transmitting, receiving and processing optical signals, the receiving equipment is arranged at a remote object to be measured and used for detecting and reversely transmitting the optical signals, and the reflective composite spiral phase plate is arranged on the surface of the object to be measured; the transmitting equipment comprises a laser, a first beam expander, a first beam reducer and a double-position detection device; the receiving equipment adopts a Mach Zehnder interference configuration and comprises a second beam reducer, a first beam splitter, a second beam splitter, a third reflector, a third beam splitter and a second beam expander; the laser outputs Gaussian light in a free space, the first beam expander expands the beam size of the Gaussian light and sends the expanded beam size to the receiving device, the second beam expander receives the Gaussian light emitted by the emitting device and reduces the beam size, the first beam splitter divides the Gaussian light into two paths of probe light and reference light, the reflective composite spiral phase plate is adhered to the surface of an object to be detected and can convert the incident Gaussian light into structured light, the second beam splitter irradiates the reflective composite spiral phase plate adhered to the surface of the object to be detected with the probe light and receives the reflected structured light, the third reflector adjusts the propagation direction of the structured light, the third beam splitter combines the Gaussian light and the structured light into superposed light, the second beam expander expands the beam size of the superposed light and reversely transmits the superposed light to the emitting device, the first beam expander receives the superposed light reversely transmitted by the receiving device and reduces the beam size, the double-position detection device detects the superposed light and processes signals, and acquiring the speed information of the remote object to be detected.

According to a further aspect of the present invention there is provided a structured light interferometric velocimeter, comprising: the device comprises a transmitting device, a receiving device and a reflective composite spiral phase plate; the transmitting equipment and the receiving equipment adopt bidirectional coaxial light beam transmission; the transmitting equipment is arranged on a measuring site and used for transmitting, receiving and processing optical signals, the receiving equipment is arranged at a remote object to be measured and used for detecting and reversely transmitting the optical signals, and the reflective composite spiral phase plate is arranged on the surface of the object to be measured; the transmitting equipment comprises a laser, a first beam expander, a fourth beam splitter and a double-position detection device, and the receiving equipment comprises a second beam reducer, a first beam splitter and a first reflector; the laser outputs Gaussian light in a free space, the fourth beam splitter transmits the Gaussian light output by the laser to the first beam expander and transmits superposed light received by the first beam expander to the double-position detection device, the first beam expander not only expands the beam size of the Gaussian light and transmits the expanded beam size to the receiving equipment, but also receives superposed light transmitted reversely by the receiving equipment and reduces the beam size, the second beam expander not only receives the Gaussian light transmitted by the transmitting equipment and reduces the beam size, but also expands the beam size of the superposed light and transmits the superposed light reversely to the transmitting equipment, the first beam splitter divides the Gaussian light into two paths of probe light and reference light, the probe light vertically irradiates a reflective composite spiral phase plate adhered to the surface of an object to be detected and is converted into structural light to be reflected, the reference light is reflected by the first reflecting mirror, the first beam splitter also combines the structural light and the Gaussian light into the superposed light, the double-position detection device detects the superposed light and processes signals, and acquiring the speed information of the remote object to be detected.

According to a further aspect of the present invention there is provided a structured light interferometric velocimeter, comprising: the device comprises a transmitting device, a receiving device and a reflective composite spiral phase plate; the transmitting equipment and the receiving equipment adopt bidirectional coaxial light beam transmission; the transmitting equipment is arranged on a measuring site and used for transmitting, receiving and processing optical signals, the receiving equipment is arranged at a remote object to be measured and used for detecting and reversely transmitting the optical signals, and the reflective composite spiral phase plate is arranged on the surface of the object to be measured; the transmitting equipment comprises a fiber laser, a single-mode fiber, a fiber coupler, a fiber delayer, a polarization controller, a first collimator, a second collimator, a fourth beam splitter, a first beam expander and a double-position detection device, and the receiving equipment only adopts a second beam reducer; the fiber laser outputs a basic mode Gaussian beam, the fiber coupler divides the basic mode Gaussian beam into two paths of a basic mode Gaussian probe beam and a basic mode Gaussian reference beam, the first collimator outputs the basic mode Gaussian probe beam as a free space Gaussian beam, the fiber delay is used for compensating the optical path difference between the reference optical path and the detection optical path, so that the interference superposition of the structural light and the Gaussian beam meets the coherence condition, the polarization controller eliminates the polarization mismatch between the reference optical path and the detection optical path caused by long-distance transmission, the second collimator outputs the basic mode Gaussian reference beam as the free space Gaussian beam, the fourth beam expander transmits the probe beam to the first beam expander and plays a role in beam combination, the free space Gaussian beam and the structure received by the first beam expander are combined into the superposed beam, the first beam expander not only expands the beam size of the Gaussian beam and transmits the superposed beam to the receiving equipment, but also receives the structural light reversely transmitted by the receiving equipment and reduces the beam size, the second beam reducer receives Gaussian light emitted by the emitting device, the Gaussian light vertically irradiates the reflective composite spiral phase plate adhered to the surface of the object to be detected after the size of the light beam is reduced, the structural light reflected by the reflective composite spiral phase plate is reversely transmitted to the emitting device after the size of the light beam is reduced by the second beam reducer, the double-position detection device detects the superposed light and performs signal processing, and the speed information of the remote object to be detected is obtained.

Preferably, the first beam expander is composed of a lens group and a packaging shell and plays a role in adjusting the size of the light beam, the magnification of the first beam expander is between 5 and 20 times, and the magnification is determined according to the distance between the transmitting device and the receiving device so as to ensure that the size of the light beam at the receiving device is smaller than the light-collecting aperture of the second beam expander; the first beam expander can be used in an inverted mode and used as a beam reducer with the same parameters; the second beam expander, the first beam reducer, and the second beam reducer may have the same parameters as the first beam expander.

Preferably, the reflective composite spiral phase plate converts the gaussian light in the free space into the structured light containing two different orbital angular momentum components, and in the structured light, the beam size of the orbital angular momentum component with the higher order is larger than that of the orbital angular momentum component with the lower order; the center of the reflective composite spiral phase plate is superposed with the rotation center of the object to be detected and is aligned with the optical axis of the detection light vertically irradiating the object to be detected.

Preferably, the dual position detection device includes a beam splitter, a first detector, a second detector and a signal processing module, the superimposed light has different intensity distributions on the outer side and the inner side; the beam splitter divides the superposed light into a first detection path and a second detection path, the first detector and the second detector are respectively arranged in a boundary annular area between the outer side and the inner side of the superposed light in the first detection path and the second detection path, and the signal processing module respectively carries out Fourier analysis on time domain signals collected by the first detector and the second detector to obtain the speed information of a remote object to be detected.

Preferably, the signal processing module performs fourier analysis on the time domain signals acquired by the first detector and the second detector respectively to obtain a first fourier magnitude spectrum, a second fourier magnitude spectrum, a first fourier phase spectrum and a second fourier phase spectrum, subtracts the first fourier phase spectrum and the second fourier phase spectrum to obtain a fourier relative phase spectrum, uses a spectral peak with lower relative amplitude as a first spectral peak and obtains a first peak frequency in the first fourier magnitude spectrum, uses a spectral peak with higher relative amplitude as a second spectral peak and obtains a second peak frequency, and determines a first relative phase difference value and a second relative phase difference value in the fourier relative phase spectrum respectively corresponding to the first peak frequency and the second peak frequency; and determining the signs of the first peak frequency and the second peak frequency by respectively using the signs of the first relative phase difference value and the second relative phase difference value, and calculating the speed information of the object to be detected by using the relation between the first peak frequency and the second peak frequency and the translational and rotational movement speeds of the object to be detected.

Through the technical scheme, the invention has the following beneficial effects:

1. the invention can realize one-time non-contact simultaneous measurement of the full vector information of the translational motion and the rotational motion of the moving object, and overcomes the limitation that the traditional laser single-frequency interferometer can only measure the translational velocity but can not measure the rotational velocity simultaneously.

2. The invention can measure the motion information, not only the motion speed, but also the motion direction, thereby realizing the real-time monitoring of the complex motion state of the moving object.

3. The velocimeter provided by the invention can realize remote measurement, greatly increases the distance range in a measurement application scene, and effectively overcomes the defect of the prior art in measuring the motion of a remote object.

4. The velocimeter provided by the invention belongs to an improved laser interference device, can be compatible with a laser velocimeter with mature technology at present, and is beneficial to production and manufacturing.

Drawings

FIG. 1 is a schematic structural diagram of a structured light interferometric velocimeter according to the present invention;

FIG. 2 is a schematic diagram of an improved structure of a structured light interferometer provided by the present invention;

FIG. 3 is a schematic diagram of another improved structure of a structured light interferometer provided by the present invention;

FIG. 4 is a schematic diagram of a further improved structure of a structured light interferometer provided by the present invention;

FIG. 5 is a schematic diagram of a beam expander and a beam reducer provided in an embodiment of the present invention;

FIG. 6 is a schematic diagram of a structure for generating a reflective composite helical phase plate according to an embodiment of the present invention;

FIG. 7 is a schematic diagram of a dual-position detection method and apparatus provided by an embodiment of the present invention;

fig. 8(a) is an experimental measurement result of simultaneous forward translation and counterclockwise rotation of a remote object to be measured according to an embodiment of the present invention;

fig. 8(b) is an experimental measurement result of simultaneous backward translation and counterclockwise rotation of the remote object to be measured according to the embodiment of the present invention;

fig. 8(c) is an experimental measurement result of simultaneous forward translation and clockwise rotation of the remote object to be measured according to the embodiment of the present invention;

fig. 8(d) is an experimental measurement result of simultaneous backward translation and clockwise rotation of the remote object to be measured according to the embodiment of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. In addition, the technical features involved in the embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.

The invention provides a structured light interference velocimeter, comprising: the device comprises a transmitting device, a receiving device and a reflective composite spiral phase plate; the transmitting equipment comprises a laser, a first beam expander, a first beam reducer and a double-position detection device; the receiving device adopts a Michelson interference configuration and comprises a second beam reducer, a first beam splitter, a first reflecting mirror, a second reflecting mirror and a second beam expander; the transmitting device is arranged in situ of a measuring field and used for transmitting, receiving and processing optical signals, the laser outputs Gaussian light in a free space, the first beam expander expands the beam size of the Gaussian light and transmits the expanded beam size to the receiving device, the receiving device is arranged at a remote object to be measured and used for detecting and reversely transmitting optical signals, the second beam reducer receives the Gaussian light transmitted by the transmitting device and reduces the beam size, the first beam splitter divides the Gaussian light into two paths of detection light and reference light, the first reflector reflects the reference light back to the first beam splitter, the reflective composite spiral phase plate is adhered to the surface of the object to be measured, the detection light irradiated vertically is converted into structured light and reflected back to the first beam splitter, the first beam splitter also plays a beam combining role to combine the Gaussian light and the structured light into superimposed light, the second reflector adjusts the propagation direction of the superimposed light, and the second beam expander expands the beam size of the superimposed light and reversely transmits the superimposed light to the transmitting device, the first beam reducer receives the superposed light reversely transmitted by the receiving equipment and reduces the size of the light beam, and the double-position detection device detects the superposed light and processes signals to acquire the speed information of the remote object to be detected; the structured light interference velocimeter provided by the invention can be used for acquiring full vector motion information of the motion speed and direction of a block object with macroscopic size and any shape in a remote measurement scene aiming at a multi-dimensional motion form of translation, rotation or combination of the translation and the rotation.

The invention also provides a structured light interference velocimeter, comprising: the device comprises a transmitting device, a receiving device and a reflective composite spiral phase plate; the transmitting equipment comprises a laser, a first beam expander, a first beam reducer and a double-position detection device; the receiving equipment adopts a Mach Zehnder interference configuration and comprises a second beam reducer, a first beam splitter, a second beam splitter, a third reflector, a third beam splitter and a second beam expander; the laser outputs Gaussian light in a free space, the first beam expander expands the beam size of the Gaussian light and sends the expanded beam size to the receiving device, the second beam expander receives the Gaussian light emitted by the emitting device and reduces the beam size, the first beam splitter divides the Gaussian light into two paths of probe light and reference light, the reflective composite spiral phase plate is adhered to the surface of an object to be detected and can convert the incident Gaussian light into structured light, the second beam splitter irradiates the reflective composite spiral phase plate adhered to the surface of the object to be detected with the probe light and receives the reflected structured light, the third reflector adjusts the propagation direction of the structured light, the third beam splitter combines the Gaussian light and the structured light into superposed light, the second beam expander expands the beam size of the superposed light and reversely transmits the superposed light to the emitting device, the first beam expander receives the superposed light reversely transmitted by the receiving device and reduces the beam size, the double-position detection device detects the superposed light and processes signals, and acquiring the speed information of the remote object to be detected.

The invention also provides a structured light interference velocimeter, comprising: the device comprises a transmitting device, a receiving device and a reflective composite spiral phase plate; the transmitting equipment comprises a laser, a first beam expander, a fourth beam splitter and a double-position detection device, and the receiving equipment comprises a second beam reducer, a first beam splitter and a first reflector; the laser outputs Gaussian light in a free space, the fourth beam splitter transmits the Gaussian light output by the laser to the first beam expander and transmits superposed light received by the first beam expander to the double-position detection device, the first beam expander not only expands the beam size of the Gaussian light and transmits the expanded beam size to the receiving equipment, but also receives superposed light transmitted reversely by the receiving equipment and reduces the beam size, the second beam expander not only receives the Gaussian light transmitted by the transmitting equipment and reduces the beam size, but also expands the beam size of the superposed light and transmits the superposed light reversely to the transmitting equipment, the first beam splitter divides the Gaussian light into two paths of probe light and reference light, the probe light vertically irradiates a reflective composite spiral phase plate adhered to the surface of an object to be detected and is converted into structural light to be reflected, the reference light is reflected by the first reflecting mirror, the first beam splitter also combines the structural light and the Gaussian light into the superposed light, the double-position detection device detects the superposed light and processes signals, and acquiring the speed information of the remote object to be detected.

The invention also provides a structured light interference velocimeter, comprising: the device comprises a transmitting device, a receiving device and a reflective composite spiral phase plate; the transmitting equipment comprises a fiber laser, a single-mode fiber, a fiber coupler, a fiber delayer, a polarization controller, a first collimator, a second collimator, a fourth beam splitter, a first beam expander and a double-position detection device, and the receiving equipment only adopts a second beam reducer; the fiber laser outputs a basic mode Gaussian beam, the fiber coupler divides the basic mode Gaussian beam into two paths of a basic mode Gaussian probe beam and a basic mode Gaussian reference beam, the first collimator outputs the basic mode Gaussian probe beam as a free space Gaussian beam, the fiber delay is used for compensating the optical path difference between the reference optical path and the detection optical path, so that the interference superposition of the structural light and the Gaussian beam meets the coherence condition, the polarization controller eliminates the polarization mismatch between the reference optical path and the detection optical path caused by long-distance transmission, the second collimator outputs the basic mode Gaussian reference beam as the free space Gaussian beam, the fourth beam expander transmits the probe beam to the first beam expander and plays a role in beam combination, the free space Gaussian beam and the structure received by the first beam expander are combined into the superposed beam, the first beam expander not only expands the beam size of the Gaussian beam and transmits the superposed beam to the receiving equipment, but also receives the structural light reversely transmitted by the receiving equipment and reduces the beam size, the second beam reducer receives Gaussian light emitted by the emitting device, the Gaussian light vertically irradiates the reflective composite spiral phase plate adhered to the surface of the object to be detected after the size of the light beam is reduced, the structural light reflected by the reflective composite spiral phase plate is reversely transmitted to the emitting device after the size of the light beam is reduced by the second beam reducer, the double-position detection device detects the superposed light and performs signal processing, and the speed information of the remote object to be detected is obtained.

Specifically, the first beam expander is composed of a lens group and a packaging shell and plays a role in adjusting the size of the light beam, the magnification factor of the first beam expander is between 5 and 20 times and is determined according to the distance between the transmitting device and the receiving device, so that the size of the light beam at the receiving device is smaller than the light receiving aperture of the second beam expander; the first beam expander can be used in an inverted mode and used as a beam reducer with the same parameters; the second beam expander, the first beam reducer, and the second beam reducer may have the same parameters as the first beam expander.

Specifically, the reflective composite spiral phase plate converts the gaussian light in the free space into structured light containing two different orbital angular momentum components, and in the structured light, the beam size of the orbital angular momentum component with a high order is larger than that of the orbital angular momentum component with a small order; the center of the reflective composite spiral phase plate is superposed with the rotation center of the object to be detected and is aligned with the optical axis of the detection light vertically irradiating the object to be detected.

Specifically, the double-position detection device comprises a beam splitter, a first detector, a second detector and a signal processing module, wherein the superposed light has different intensity distributions on the outer side and the inner side; the beam splitter divides the superposed light into a first detection path and a second detection path, the first detector and the second detector are respectively arranged in a boundary annular area between the outer side and the inner side of the superposed light in the first detection path and the second detection path, and the signal processing module respectively carries out Fourier analysis on time domain signals collected by the first detector and the second detector to obtain the speed information of a remote object to be detected.

Specifically, the signal processing module performs fourier analysis on time domain signals acquired by a first detector and a second detector respectively to obtain a first fourier magnitude spectrum, a second fourier magnitude spectrum, a first fourier phase spectrum and a second fourier phase spectrum, subtracts the first fourier phase spectrum and the second fourier phase spectrum to obtain a fourier relative phase spectrum, uses a spectral peak with lower relative amplitude as a first spectral peak and obtains a first peak frequency in the first fourier magnitude spectrum, uses a spectral peak with higher relative amplitude as a second spectral peak and obtains a second peak frequency, and determines a first relative phase difference value and a second relative phase difference value in the fourier relative phase spectrum respectively corresponding to the first peak frequency and the second peak frequency; and determining the signs of the first peak frequency and the second peak frequency by respectively using the signs of the first relative phase difference value and the second relative phase difference value, and calculating the speed information of the object to be detected by using the relation between the first peak frequency and the second peak frequency and the translational and rotational movement speeds of the object to be detected.

The following description is made with reference to the embodiments and the accompanying drawings.

As shown in fig. 1, the present invention provides a structured light interferometer, including: the device comprises a transmitting device 1, a receiving device 3, a reflective composite spiral phase plate 4; the transmitting device 1 comprises a laser 11, a first beam expander 12, a first beam reducer 13 and a double-position detection device 14; the receiving device 3 comprises a second beam reducer 31, a first beam splitter 32, a first mirror 33, a second mirror 34, a second beam expander 35. After the free space gaussian light output by the laser 11 is adjusted in beam size by the first beam expander 12, the free space gaussian light is sent to the receiving device 3 along the transmitting light path 2; the second beam reducer 31 receives the Gaussian light transmitted by the transmitting device 1 and reduces the beam size, the first beam splitter 32 divides the Gaussian light into two paths of detection light and reference light, the first reflector 33 reflects the reference light back to the first beam splitter 32, the reflective composite spiral phase plate 4 is adhered to the surface of the object to be detected 5, the detection light irradiated vertically is converted into structural light and reflected back to the first beam splitter 32, the first beam splitter 32 combines the Gaussian light and the structural light into superimposed light, the second reflector 34 adjusts the propagation direction of the superimposed light, and the second beam expander 35 enlarges the beam size of the superimposed light and reversely transmits the superimposed light to the transmitting device 1 along the receiving light path 6; the first beam reducer 13 receives the superposed light reversely transmitted by the receiving device 3 and reduces the size of the light beam, and the double-position detection device 14 detects the superposed light and performs signal processing to acquire the speed information of the remote object to be detected.

As shown in fig. 2, an improvement of a structured light interferometer provided by the present invention is as follows:

the device includes: the device comprises a transmitting device 1, a receiving device 3, a reflective composite spiral phase plate 4; the transmitting device 1 comprises a laser 11, a first beam expander 12, a first beam reducer 13 and a double-position detection device 14; the receiving device 3 comprises a second beam reducer 31, a first beam splitter 32, a second beam splitter 36, a third mirror 37, a third beam splitter 38, a second beam expander 35. After the free space gaussian light output by the laser 11 is adjusted in beam size by the first beam expander 12, the free space gaussian light is sent to the receiving device 3 along the transmitting light path 2; the second beam reducer 31 receives the gaussian light transmitted by the transmitting device 1 and reduces the size of the light beam, the first beam splitter 32 divides the gaussian light into two paths of detection light and reference light, the reflective composite spiral phase plate 4 is adhered to the surface of the object 5 to be detected and converts the incident gaussian light into structured light, the second beam splitter 36 vertically irradiates the detection light on the reflective composite spiral phase plate 4 and receives the reflected structured light, the third reflector 37 adjusts the propagation direction of the structured light, the third beam splitter 38 combines the gaussian light and the structured light into superimposed light, and the second beam splitter 35 enlarges the size of the superimposed light and reversely transmits the superimposed light to the transmitting device 1 along the receiving light path 6; the first beam reducer 13 receives the superposed light reversely transmitted by the receiving device 3 and reduces the size of the light beam, and the double-position detection device 14 detects the superposed light and performs signal processing to acquire the speed information of the remote object to be detected.

As shown in fig. 3, another improvement of a structured light interferometer provided by the present invention is as follows:

the device includes: the device comprises a transmitting device 1, a receiving device 3, a reflective composite spiral phase plate 4; the transmitting device 1 comprises a laser 11, a first beam expander 12, a double-position detection device 14 and a fourth beam splitter 15; the receiving device 3 comprises a second beam reducer 31, a first beam splitter 32, a first mirror 33. The laser 11 outputs free space gaussian light, the fourth beam splitter 15 transmits the gaussian light output by the laser 11 to the first beam expander 12, and transmits the superimposed light received by the first beam expander 12 to the two-position detection device 14, the first beam expander 12 not only expands the beam size of the gaussian light and transmits the expanded beam size to the receiving device 3 along the transmission light path 7, but also receives the superimposed light transmitted in the reverse direction by the receiving device 3 and reduces the beam size, the second beam splitter 31 not only receives the gaussian light transmitted by the transmitting device 1 along the transmission light path 7 and reduces the beam size, but also expands the beam size of the superimposed light and transmits the expanded beam size to the transmitting device 1 along the transmission light path 7, the first beam splitter 32 divides the gaussian light into two paths of probe light and reference light, the probe light vertically irradiates the reflective composite spiral phase plate 4 adhered to the surface of the object 5 to be detected and is converted into structural light for reflection, the reference light is reflected by the first reflector 33, the first beam splitter 32 also combines the structured light and the gaussian light into superimposed light, and the dual-position detection device 14 detects and processes the superimposed light to obtain the speed information of the remote object to be detected.

As shown in fig. 4, a further improvement of the structured light interferometer provided by the present invention is as follows:

the device includes: the device comprises a transmitting device 1, a receiving device 3, a reflective composite spiral phase plate 4; the transmitting device 1 comprises a fiber laser 16, a single-mode fiber 17, a fiber coupler 18, a fiber delay 110, a polarization controller 111, a first collimator 19, a second collimator 112, a fourth beam splitter 15, a first beam expander 12 and a double-position detection device 14; the receiving device 3 comprises a second beam reducer 31. The fiber laser 16 outputs a fundamental mode Gaussian beam, the fundamental mode Gaussian beam is transmitted through a single-mode fiber 17, the fiber coupler 18 divides the fundamental mode Gaussian beam into a fundamental mode Gaussian probe beam and a fundamental mode Gaussian reference beam, the first collimator 19 outputs the fundamental mode Gaussian probe beam as a free space Gaussian beam, the fiber delay 110 compensates an optical path difference between the reference optical path and the detection optical path, the polarization controller 111 eliminates polarization mismatch between the reference optical path and the detection optical path caused by long-distance transmission, the second collimator 112 outputs the fundamental mode Gaussian beam as a free space Gaussian beam, the fourth beam splitter 15 transmits the probe beam to the first beam expander 12 and synthesizes the free space Gaussian beam and a structure received by the first beam expander 12 into a superimposed beam, the first beam expander 12 not only expands the beam size of the Gaussian beam and transmits the superimposed beam to the receiving device 3 along the transmission optical path 7, but also receives the structure light reversely transmitted by the receiving device 3 along the transmission optical path 7 and reduces the beam size, the second beam reducer 31 receives the gaussian light emitted by the emitting device 1 along the transmission light path 7, vertically irradiates the reflective composite spiral phase plate 4 adhered to the surface of the object 5 to be detected after reducing the size of the light beam, the structured light reflected by the reflective composite spiral phase plate 4 is reversely transmitted to the emitting device 1 along the transmission light path 7 after the size of the light beam is reduced by the second beam reducer 31, and the double-position detection device 14 detects the superimposed light and performs signal processing to obtain the speed information of the remote object to be detected.

Fig. 5 illustrates a beam expander and a beam reducer according to an embodiment of the present invention, in which the beam expander 12 includes an incident mirror 121, a sleeve 122, and an exit mirror 123; the beam reducer 31 includes an incident mirror 311, a sleeve 312, and an exit mirror 313. The incident mirror 121 and the exit mirror 313 are short-focus lenses, the exit mirror 123 and the incident mirror 311 are long-focus lenses, and the sleeve 122 and the sleeve 312 play roles of fixing the lens spacing and protecting in the beam expander 12 and the beam reducer 31, respectively.

Fig. 6 shows intensity and phase distribution of the reflective composite spiral phase plate and the structured light provided by the embodiment of the present invention, wherein the reflective composite spiral phase plate 4 is adhered to the surface of the object 5 to be measured, and the center thereof coincides with the rotation center of the object; the Gaussian light is vertically irradiated to the center of the reflective composite spiral phase plate 4 to reflect structural light containing two different orbital angular momentum topological charge numbers; the intensity of the structured light is periodically distributed in a petal shape, and the phase is periodically distributed in a way that the outer side and the inner side are different.

FIG. 7 shows a method and an apparatus for dual position detection according to an embodiment of the present invention, wherein the apparatus includes a sub-systemThe superposed light is divided into two paths by the beam splitter 141, one path passes through the first lens 142 and the first aperture 143 in sequence and is received by the first photoelectric detector 144, and the other path passes through the reflector 145, the second lens 146 and the second aperture 147 in sequence and is received by the second photoelectric detector 148; the first photodetector 144 and the second photodetector 148 convert the optical signal into an electrical signal and transmit the electrical signal to the signal processing module 1410 through the transmission line 149; the superposed light of the structured light and the reference light is divided into an inner area 1 and an outer area 2, the light field of the inner area 1 is formed by interference superposition of the reference light and a small topological charge group in the structured light and is expressed as a spiral interference fringe, the light field of the outer area 2 is formed by mutual interference superposition of two different topological charge groups in the structured light and is expressed as a petal-shaped interference fringe, and in the measuring process, the spiral interference fringe of the inner area 1 and the petal-shaped interference fringe of the outer area 2 rotate at different speeds; the first aperture 143 and the second aperture 147 are respectively disposed in the light beam diverging region behind the focus of the first lens 142 and the second lens 146, and are respectively disposed in the boundary annular region between the inner side and the outer side of the superimposed light at different azimuth angles, so as to filter out the extra light field energy except the detection points, and thus are equivalent to two detection points; the first photodetector 144 and the second photodetector 148 collect the time domain intensity signals of two detection points respectively, and can sense the light intensity changes from the region 1 and the region 2 at different frequencies; the signal processing module 1410 performs fourier analysis on the time domain intensity signal to obtain a fourier magnitude spectrum and a fourier phase spectrum of the signal, and subtracts the fourier phase spectrums of the two detection signals to obtain a fourier relative phase spectrum; two frequency spectrum peaks exist in the Fourier magnitude spectrums of the two detection signals, and the theoretical peak value frequency is respectively f₁＝|2kv_z+l₁Ω|/2π，f₂＝|(l₁-l₂) Omega/2 pi, where k is the wave number of the beam, v_zIs the translation speed of the remote object to be measured, omega is the rotation speed of the remote object to be measured, l₁In the structured lightOrbital angular momentum component of small topological charge number, l₂An orbital angular momentum component with a large topological charge number; in addition, positive and negative signs of a relative phase difference value corresponding to the two peak frequencies are found in the relative phase spectrum, namely the positive and negative signs of the two frequency shift values can be judged, and the two peaks can be distinguished through the peak amplitude of the two frequency spectrum peaks; and finally, solving two linear equations to obtain the speed and direction of the translational motion and the rotational motion of the object, namely obtaining the full vector information of the motion of the remote object to be measured.

The following provides an experimental measurement result diagram of the structured light interferometric velocimeter provided by the present invention for a remote object to be measured with a complex motion form in this embodiment, and fig. 8(a) is a signal fourier magnitude spectrum and a relative phase spectrum of two detection points measured for simultaneous forward translation and counterclockwise rotation from top to bottom in sequence; FIG. 8(b) is a top down sequence of signal Fourier magnitude and relative phase spectra for two probe points measured for simultaneous backward translation and counterclockwise rotational motion; FIG. 8(c) is a top down sequence of signal Fourier magnitude and relative phase spectra for two probe points measured for simultaneous forward translation and clockwise rotational motion; FIG. 8(d) is a top down sequence of signal Fourier magnitude and relative phase spectra for two probe points measured for simultaneous backward translation and clockwise rotational motion; according to the peak value height of two peaks in the Fourier spectrum of the detection signal, the two spectrum peaks can be distinguished, the peak value is higher than the spectrum peak 2, the peak value is lower than the spectrum peak 1, the forward linear motion and the anticlockwise rotary motion of an object are defined as two simple forward motions, and structured light generated by a reflection type composite spiral phase plate in experimental measurement contains 2 and 5 orders of topological charge numbers; for FIG. 8(a), the linear velocity component of the compound motion of the object is 5mm/s forward, the rotational velocity component is 1666.6 π rad/s counterclockwise, and two peak frequencies f in the frequency spectrum₁、f₂The measured values of (A) are 14240Hz and 2500Hz respectively, and the measured values in the corresponding relative phase spectrum are 136.8 degrees and-96.82 degrees respectively; for FIG. 8(b), the linear velocity component of the compound motion of the object is 5mm/s backward, the rotational velocity component is 1666.6 π rad/s counterclockwise, and two peak frequencies f in the frequency spectrum₁、f₂The measured values of (a) are 16890Hz and 2500Hz respectively, and the measured values in the corresponding relative phase spectrum are-64.16 degrees and-74.2 degrees respectively; for FIG. 8(c), the linear velocity component of the compound motion of the object is 5mm/s forward and the rotational velocity component is 1666.6 π rad/s clockwise, with two peak frequencies f in the spectrum₁、f₂The measured values of (A) are 17560Hz and 2500Hz respectively, and the measured values in the corresponding relative phase spectrums are 111.7 degrees and 74.25 degrees respectively; for FIG. 8(d), the linear velocity component of the compound motion of the object is 5mm/s backward, the rotational velocity component is 1666.6 π rad/s clockwise, and two peak frequencies f in the frequency spectrum₁、f₂The measured values of (1) are 14130Hz and 2500Hz respectively, and the measured values in the corresponding relative phase spectrum are-56.51 degrees and 82.78 degrees respectively; comparing the relative phase spectrums of the four measurement conditions, the method can find that four different combinations of positive and negative signs of the relative phase difference value corresponding to two spectrum peaks appear under the state of a remote object to be measured in four motion directions, substitutes the measurement result into a theoretical formula, calculates the measured value of the translational motion component and the rotational motion component to be consistent with an actual value within an error allowable range, and verifies the working reliability of the structured light interference velocimeter.

The present invention is not limited to the above embodiments, and those skilled in the art can implement the present invention in other various embodiments according to the disclosure of the present invention, so that all designs and concepts of the present invention can be changed or modified without departing from the scope of the present invention.