阅读说明：本技术 基于位错二维光栅阵列的双光栅结构三维微位移传感器 (Dislocation two-dimensional grating array-based double-grating structure three-dimensional micro-displacement sensor ) 是由 辛晨光 李孟委 亓杰 金丽 李晋华 于 2021-09-23 设计创作，主要内容包括：本发明属于三维微位移传感器技术领域,具体涉及一种基于位错二维光栅阵列的双光栅结构三维微位移传感器,包括激光器、准直扩束镜、上层二维光栅、下层位错式光栅、四象限探测器,所述激光器的上方设置有准直扩束镜,所述准直扩束镜上设置有上层二维光栅,所述上层二维光栅上设置有下层位错式光栅,所述下层位错式光栅上设置有四象限探测器。本发明通过采用双层光栅结构,利用二维光栅在近场区域内的自成像效应,实现了透过光强随位移变化,并由四象限探测器实现光电转化,再通过整体结构输出的经细化后的电学信号进行精准三维位移测量,提高了整体结构的精度。同时,利用四象限结构实现了整体系统的高度集成化。(The invention belongs to the technical field of three-dimensional micro-displacement sensors, and particularly relates to a dislocation two-dimensional grating array-based two-grating structure three-dimensional micro-displacement sensor which comprises a laser, a collimation beam expander, an upper two-dimensional grating, a lower dislocation grating and a four-quadrant detector. According to the invention, by adopting a double-layer grating structure and utilizing the self-imaging effect of the two-dimensional grating in the near field region, the transmission light intensity is changed along with displacement, the photoelectric conversion is realized by the four-quadrant detector, and the accurate three-dimensional displacement measurement is carried out by the refined electrical signal output by the integral structure, so that the precision of the integral structure is improved. Meanwhile, the high integration of the whole system is realized by utilizing a four-quadrant structure.)

1. The three-dimensional micro-displacement sensor with the double grating structure based on the dislocation two-dimensional grating array is characterized in that: including laser instrument (1), collimation beam expander (2), upper two-dimensional grating (3), lower floor dislocation formula grating (4), four-quadrant detector (5), the top of laser instrument (1) is provided with collimation beam expander (2), be provided with upper two-dimensional grating (3) on collimation beam expander (2), be provided with lower floor dislocation formula grating (4) on upper two-dimensional grating (3), be provided with four-quadrant detector (5) on lower floor dislocation formula grating (4).

2. The dislocation two-dimensional grating array-based double grating structure three-dimensional micro-displacement sensor according to claim 1, wherein: the lower layer dislocation type grating (4) comprises a first lower layer dislocation type two-dimensional grating (401), a second lower layer dislocation type two-dimensional grating (402), a third lower layer dislocation type two-dimensional grating (403) and a fourth lower layer dislocation type two-dimensional grating (404), the first lower layer dislocation type two-dimensional grating (401) and the second lower layer dislocation type two-dimensional grating (402) are arranged in parallel, the third lower layer dislocation type two-dimensional grating (403) and the fourth lower layer dislocation type two-dimensional grating (404) are arranged in parallel, the direction of the first lower layer dislocation type two-dimensional grating (401) and the direction of the second lower layer dislocation type two-dimensional grating (402) are defined as an X axis, an XYZ space coordinate system is established by right-hand screw regulation, the first lower layer dislocation type two-dimensional grating (401) and the second lower layer dislocation type two-dimensional grating (402) are staggered by one quarter of grating periods in the X axis direction, and the first lower layer dislocation type two-dimensional grating (401) and the third lower layer dislocation type two-dimensional grating (403) are staggered by four times in the Y axis direction One fourth of the grating period, the first lower layer dislocation type two-dimensional grating (401) and the fourth lower layer dislocation type two-dimensional grating (404) are staggered by one fourth of the self-imaging period in the Z-axis direction.

3. The dislocation two-dimensional grating array-based double grating structure three-dimensional micro-displacement sensor according to claim 1, wherein: the grating period of the upper-layer two-dimensional grating (3) is the same as that of the lower-layer dislocation grating (4), the grating period of the upper-layer two-dimensional grating (3) is 100nm-1 mu m as that of the lower-layer dislocation grating (4), the thickness of the upper-layer two-dimensional grating (3) is 50nm-1 mu m as that of the lower-layer dislocation grating (4), and the duty ratio of the upper-layer two-dimensional grating (3) to the lower-layer dislocation grating (4) is 0.5.

4. The dislocation two-dimensional grating array-based double grating structure three-dimensional micro-displacement sensor according to claim 1, wherein: the upper two-dimensional grating (3) is provided with a material with good light blocking characteristics at the incident wavelength, the material with good light blocking characteristics adopts a semiconductor or metal with low transmittance, and the transmittance of the non-etching area of the upper two-dimensional grating (3) at the incident wavelength is not higher than 50%.

5. The dislocation two-dimensional grating array-based double grating structure three-dimensional micro-displacement sensor according to claim 2, wherein: four quadrants of the four-quadrant detector (5) correspond to the first lower-layer dislocation type two-dimensional grating (401), the second lower-layer dislocation type two-dimensional grating (402), the third lower-layer dislocation type two-dimensional grating (403) and the fourth lower-layer dislocation type two-dimensional grating (404) one by one.

6. The dislocation two-dimensional grating array-based double grating structure three-dimensional micro-displacement sensor according to claim 1, wherein: the distance between the upper surface of the lower dislocation grating (4) and the upper surface of the upper two-dimensional grating (3) is integral multiple of T, the T is the period of self-imaging in the off-plane direction, and the lower dislocation grating is arranged on the upper surface of the lower two-dimensional grating in the vertical directionD is the grating period, and lambda is the laser wavelength.

7. The control method of the dislocation two-dimensional grating array-based double grating structure three-dimensional micro-displacement sensor is characterized in that: comprises the following steps: the light emitted by the laser (1) is collimated and expanded by the collimating and expanding lens (2) and then vertically incident to the upper two-dimensional grating (3), self-imaging is generated after diffraction of the upper two-dimensional grating (3), the lower dislocation grating (4) is placed in a self-imaging area, light beams transmitted by the lower dislocation grating (4) are received by the four-quadrant detector (5), the first lower dislocation grating (401) and the second lower dislocation grating (402) are staggered by a quarter of a grating period in the X-axis direction, the first lower dislocation grating (401) and the third lower dislocation grating (403) are staggered by a quarter of a grating period in the Y-axis direction, and the first lower dislocation grating (401) and the fourth lower dislocation grating (404) are staggered by a quarter of a self-imaging period in the Z-axis direction, the light intensity received by the four-quadrant detector (5) is a four-way sine curve, finally, four quadrants of the four-quadrant detector (5) output four voltage signals respectively, wherein the output signal of the first quadrant is a reference signal, the output signals of the other three quadrants under the condition of displacement input in the corresponding direction are staggered by 90 degrees with the output signal of the first quadrant, and then corresponding voltage signals are output, so that A, B phase output of electrical signals of three-dimensional displacement measurement is realized.

Technical Field

The invention belongs to the technical field of three-dimensional micro-displacement sensors, and particularly relates to a double-grating-structure three-dimensional micro-displacement sensor based on a dislocation two-dimensional grating array.

Background

The ultra-precise positioning detection technology is an important technical field of modern precision manufacturing, and the nanoscale multi-dimensional displacement measurement technology is one of the key problems restricting the development of the ultra-precise positioning technology. Among them, the nano-grating detection method has been widely used due to its advantages of high resolution, small volume, anti-electromagnetic interference, etc. At present, a multi-dimensional micro-displacement detection method based on a grating displacement detection technology is mostly based on a doppler shift principle, and an integrated system is composed of a plurality of one-dimensional displacement detection unit structures or a multi-dimensional displacement measurement system is composed of a multi-light path interference structure so as to realize multi-dimensional displacement measurement. However, the above method has problems of complicated optical path, large volume, low integration, high cost, and the like. The problems limit the application of the method in the aspects of multi-dimensional displacement detection, positioning and the like of the tool bit of the integrated numerical control machine tool.

Disclosure of Invention

Aiming at the technical problems of complex light path, large volume, low integration and high cost of the method, the invention provides the dislocation two-dimensional grating array-based double-grating structure three-dimensional micro-displacement sensor with high integration, high measurement precision and small volume.

In order to solve the technical problems, the invention adopts the technical scheme that:

two grating structure three-dimensional micro displacement sensor based on dislocation two-dimensional grating array, including laser instrument, collimation beam expander, upper two-dimensional grating, lower floor's dislocation formula grating, four-quadrant detector, the top of laser instrument is provided with the collimation beam expander, be provided with upper two-dimensional grating on the collimation beam expander, be provided with lower floor's dislocation formula grating on the upper two-dimensional grating, be provided with the four-quadrant detector on the dislocation formula grating of lower floor.

The lower layer dislocation type grating comprises a first lower layer dislocation type two-dimensional grating, a second lower layer dislocation type two-dimensional grating, a third lower layer dislocation type two-dimensional grating and a fourth lower layer dislocation type two-dimensional grating, the first lower layer dislocation type two-dimensional grating and the second lower layer dislocation type two-dimensional grating are arranged in parallel, the third lower layer dislocation type two-dimensional grating and the fourth lower layer dislocation type two-dimensional grating are arranged in parallel, the direction of the first lower layer dislocation type two-dimensional grating and the direction of the second lower layer dislocation type two-dimensional grating are defined as an X axis, an XYZ space coordinate system is established by using a right-hand screw rule, the first lower layer dislocation type two-dimensional grating and the second lower layer dislocation type two-dimensional grating are staggered by a quarter of a grating period in the X axis direction, the first lower layer dislocation type two-dimensional grating and the third lower layer dislocation type two-dimensional grating are staggered by a quarter of a grating period in the Y axis direction, and the first lower layer dislocation type two-dimensional grating and the fourth lower layer dislocation type two-dimensional grating are staggered by a quarter of a grating in the Z axis direction One self-imaging period.

The grating period of the upper-layer two-dimensional grating is the same as that of the lower-layer dislocation grating, the grating period of the upper-layer two-dimensional grating is 100nm-1 mu m, the thickness of the upper-layer two-dimensional grating is 50nm-1 mu m, and the duty ratio of the upper-layer two-dimensional grating to the lower-layer dislocation grating is 0.5.

The upper two-dimensional grating is provided with a material with good light blocking characteristics at an incident wavelength, the material with good light blocking characteristics adopts a semiconductor or metal with low transmittance, and the transmittance of a non-etching area of the upper two-dimensional grating at the incident wavelength is not higher than 50%.

And four quadrants of the four-quadrant detector correspond to the first lower-layer dislocation type two-dimensional grating, the second lower-layer dislocation type two-dimensional grating, the third lower-layer dislocation type two-dimensional grating and the fourth lower-layer dislocation type two-dimensional grating one to one.

The distance between the upper surface of the lower layer dislocation grating and the upper surface of the upper layer two-dimensional grating is integral multiple of T, the T is the period of self-imaging in the out-of-plane direction, and the lower layer dislocation grating and the upper surface of the upper layer two-dimensional grating are arranged in parallel in the same plane, and the distance between the upper surface of the lower layer dislocation grating and the upper surface of the upper layer two-dimensional grating is integral multiple of the TD is the grating period, and lambda is the laser wavelength.

The light emitted by the laser is vertically incident to the upper two-dimensional grating after being collimated and expanded by the collimating and expanding lens, the light is diffracted by the upper two-dimensional grating to generate self-imaging, the lower dislocation type grating is placed in a self-imaging area, the light beam transmitted by the lower dislocation type grating is received by the four-quadrant detector, the first lower dislocation type two-dimensional grating and the second lower dislocation type two-dimensional grating are staggered by a quarter of a grating period in the X-axis direction, the first lower dislocation type two-dimensional grating and the third lower dislocation type two-dimensional grating are staggered by a quarter of a grating period in the Y-axis direction, the first lower dislocation type two-dimensional grating and the fourth lower dislocation type two-dimensional grating are staggered by a quarter of a self-imaging period in the Z-axis direction, the light intensity received by the four-quadrant detector is a four-way sine curve, and finally, four-quadrant detectors output four-way voltage signals respectively, the output signal of the first quadrant is a reference signal, the output signals of the other three quadrants under the condition of corresponding directional displacement input are staggered by 90 degrees with the output signal of the first quadrant, and then corresponding voltage signals are output, so that A, B-phase output of the electrical signals of three-dimensional displacement measurement is realized.

Compared with the prior art, the invention has the following beneficial effects:

according to the invention, by adopting a double-layer grating structure and utilizing the self-imaging effect of the two-dimensional grating in the near field region, the transmission light intensity is changed along with displacement, the photoelectric conversion is realized by the four-quadrant detector, and the accurate three-dimensional displacement measurement is carried out by the refined electrical signal output by the integral structure, so that the precision of the integral structure is improved. Meanwhile, the high integration of the whole system is realized by utilizing a four-quadrant structure.

Drawings

FIG. 1 is a schematic structural view of the present invention;

FIG. 2 is a schematic structural diagram of an upper two-dimensional grating according to the present invention;

FIG. 3 is a schematic diagram of the structure of the lower dislocation grating of the present invention;

FIG. 4 is a side view of an underlying dislocation grating of the present invention;

FIG. 5 is a diagram of X-Y plane self-imaging simulation results of the present invention;

FIG. 6 is a graph of the intensity distribution of the self-imaging light in the X direction according to the present invention;

FIG. 7 is a graph of the intensity distribution of the self-imaging light in the Y direction according to the present invention;

FIG. 8 is a graph showing the X-Z plane self-imaging simulation result and the light intensity distribution on the Z axis according to the present invention;

FIG. 9 is a diagram showing the variation of the transmitted light intensity with the displacement in the same grating region according to the present invention;

FIG. 10 is a diagram showing the variation of the transmitted light intensity phase difference between adjacent grating regions according to the present invention.

Wherein: the laser device comprises a laser 1, a collimation beam expander 2, an upper-layer two-dimensional grating 3, a lower-layer dislocation type grating 4, a four-quadrant detector 5, a first lower-layer dislocation type two-dimensional grating 401, a second lower-layer dislocation type two-dimensional grating 402, a third lower-layer dislocation type two-dimensional grating 403 and a fourth lower-layer dislocation type two-dimensional grating 404.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

In the description of the present invention, it is to be noted that, unless otherwise explicitly specified or limited, the terms "connected" and "connected" are to be interpreted broadly, e.g., as being fixed or detachable or integrally connected; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.

Two grating structure three-dimensional micro displacement sensor based on dislocation two-dimensional grating array, as shown in fig. 1, fig. 2, including laser 1, collimation beam expander 2, upper two-dimensional grating 3, lower floor dislocation formula grating 4, four-quadrant detector 5, the top of laser 1 is provided with collimation beam expander 2, is provided with upper two-dimensional grating 3 on the collimation beam expander 2, is provided with lower floor dislocation formula grating 4 on the upper two-dimensional grating 3, is provided with four-quadrant detector 5 on the dislocation formula grating 4 of lower floor.

Further, as shown in fig. 3 and 4, the lower layer dislocation grating 4 includes a first lower layer dislocation two-dimensional grating 401, a second lower layer dislocation two-dimensional grating 402, a third lower layer dislocation two-dimensional grating 403, and a fourth lower layer dislocation two-dimensional grating 404, the first lower layer dislocation two-dimensional grating 401 and the second lower layer dislocation two-dimensional grating 402 are arranged in parallel, the third lower layer dislocation two-dimensional grating 403 and the fourth lower layer dislocation two-dimensional grating 404 are arranged in parallel, the direction of the first lower layer dislocation two-dimensional grating 401 and the second lower layer dislocation two-dimensional grating 402 is defined as an X axis, a right-hand screw XYZ spatial coordinate system is established, the first lower layer dislocation two-dimensional grating 401 and the second lower layer dislocation two-dimensional grating 402 are staggered by a quarter of grating period in the X axis direction, the first lower layer dislocation two-dimensional grating 401 and the third lower layer dislocation two-dimensional grating 403 are staggered by a quarter of grating period in the Y axis direction, the first lower-layer dislocation two-dimensional grating 401 and the fourth lower-layer dislocation two-dimensional grating 404 are dislocated by a quarter of a self-imaging period in the Z-axis direction.

Further, in order to ensure good sinusoidal response of the output signal to displacement, the grating periods of the upper two-dimensional grating 3 and the lower dislocation grating 4 are the same, the grating periods of the upper two-dimensional grating 3 and the lower dislocation grating 4 are 100nm-1 μm, the thicknesses of the upper two-dimensional grating 3 and the lower dislocation grating 4 are 50nm-1 μm, and the duty ratio of the upper two-dimensional grating 3 and the lower dislocation grating 4 is 0.5.

Further, in order to achieve good self-imaging light intensity distribution, the upper two-dimensional grating 3 is provided with a material with good light blocking characteristics at an incident wavelength, the material with good light blocking characteristics is made of a semiconductor or metal with low transmittance, and the transmittance of a non-etched area of the upper two-dimensional grating 3 at the incident wavelength is not higher than 50%.

Further, to realize good four-quadrant signal output, four quadrants of the four-quadrant detector 5 correspond to the first lower layer dislocation type two-dimensional grating 401, the second lower layer dislocation type two-dimensional grating 402, the third lower layer dislocation type two-dimensional grating 403, and the fourth lower layer dislocation type two-dimensional grating 404 one to one.

Further, in order to ensure good sinusoidal response of the output signal to displacement, the distance between the upper surface of the lower layer dislocation grating 4 and the upper surface of the upper layer two-dimensional grating 3 is integral multiple of T, T is the period of self-imaging in the off-plane direction,d is the grating period and λ is the laser wavelength.

The working process of the invention is as follows: light emitted by a laser 1 is collimated and expanded by a collimating and expanding lens 2 and then vertically enters an upper two-dimensional grating 3, self-imaging is generated after diffraction of the upper two-dimensional grating 3, a lower dislocation grating 4 is placed in a self-imaging area, light beams transmitted by the lower dislocation grating 4 are received by a four-quadrant detector 5, a first lower dislocation two-dimensional grating 401 and a second lower dislocation two-dimensional grating 402 are staggered by a quarter of a grating period in the X-axis direction, a first lower dislocation two-dimensional grating 401 and a third lower dislocation two-dimensional grating 403 are staggered by a quarter of a grating period in the Y-axis direction, a first lower dislocation two-dimensional grating 401 and a fourth lower dislocation two-dimensional grating 404 are staggered by a quarter of a self-imaging period in the Z-axis direction, light intensity received by the four-quadrant detector 5 is a four-way sine curve, and finally four quadrants of the four-quadrant detector 5 output four-way voltage signals respectively, the output signal of the first quadrant is a reference signal, the output signals of the other three quadrants under the condition of corresponding directional displacement input are staggered by 90 degrees with the output signal of the first quadrant, and then corresponding voltage signals are output, so that A, B-phase output of the electrical signals of three-dimensional displacement measurement is realized.

The specific implementation parameters are as follows:

laser wavelength: λ ═ 0.635 μm;

laser power: 1.2 mW;

grating period: d is 1 μm;

the duty ratio of the grating is as follows: 0.5;

grating material: and Al.

The specific analysis is as follows:

when a black-and-white grating made of an Al material is adopted, the thickness of the grating is set to be 150nm, and an inverted-triangular self-imaging area exists in the light beam transmission direction of the grating. The grating image exists at each self-imaging period position in the off-plane direction, the light intensity distribution is the same as the structure of the grating, namely, the light intensity distribution corresponds to the grating slits and the grating lines of the grating, so that a self-imaging plane exists at the position which is an integral multiple of the self-imaging off-plane period from the grating plane, as shown in fig. 5. In the X direction and the Y direction of the plane, the light intensity is detected, and a sinusoidal light intensity signal can be obtained, as shown in fig. 6 and 7. In the in-plane direction, the self-imaging period is the same as the grating period. In the self-imaging space, the light intensity is detected along the Z-axis, and a sinusoidal light intensity signal can also be obtained, as shown in fig. 8. Therefore, the lower-layer dislocation type two-dimensional grating with the same parameters is placed in the self-imaging area of the upper-layer two-dimensional grating, and when the upper-layer two-dimensional grating has displacements in the X axis and the Y axis of the inner direction of the lower-layer dislocation type two-dimensional grating and the Z axis of the out-of-plane direction of the lower-layer dislocation type two-dimensional grating, the light intensity of the transmission light of each quadrant of the lower-layer dislocation type two-dimensional grating generates sinusoidal variation along with the displacement.

Wherein the period of the self-imaging in the out-of-plane direction is

Where d is the grating period, λ is the laser wavelength, T is the period of the self-image in the out-of-plane direction, and when the grating period is 1 μm and the laser wavelength is 0.635 μm, Z ═ 2.79 μm can be obtained from the above formula, i.e., the period of the self-image in the out-of-plane direction is 2.79 μm.

When the distance between the first quadrant grating area and the two adjacent grating areas is changed, the phase of the transmitted light intensity of the other grating area changing with the relative displacement is changed by taking the first quadrant grating area as a reference, as shown in fig. 9, and when and only when the distance between the two grating areas is nd + d/2, the phase difference of the transmitted light intensity of the two grating areas changing with the displacement is 90 °, as shown in fig. 10.

From the above, when the upper two-dimensional grating structure moves in the in-plane X, Y direction and the out-of-plane Z direction, the displacement in three directions can be obtained by four paths of output signals of the detector 5, and when the signals are connected to the subdivision circuit, the displacement detection resolution can be subdivided to nanometer, so that the measurement accuracy of the whole structure is improved.

Meanwhile, due to the adoption of a high-integration two-dimensional grating and a dislocation two-dimensional grating array, three-dimensional displacement detection is realized in a single optical axis direction through a small number of devices such as a light source, a double-layer grating and a detector, the measurement structure is obviously simplified, and the system integration level is improved.

Although only the preferred embodiments of the present invention have been described in detail, the present invention is not limited to the above embodiments, and various changes can be made without departing from the spirit of the present invention within the knowledge of those skilled in the art, and all changes are encompassed in the scope of the present invention.