Grating displacement measuring device

Abstract

The utility model relates to a grating displacement measuring device which comprises a reading head and a measuring grating, the reading head comprises a light source assembly, an indicating grating, a first detector and a plurality of second detectors, the indicating grating is used for receiving first emergent light and diffracting and transmitting the first emergent light to the measuring grating, and the measuring grating can generate relative displacement with the reading head in the first direction; the plane where the grid lines of the measuring grating are located is parallel to the plane where the grid lines of the indicating grating are located and parallel to the first direction. The measuring grating diffracts and reflects the received first emergent light to the indicating grating, and diffracts and reflects the received second emergent light to the first detector. The first emergent light diffracted and reflected by the measuring grating is diffracted and transmitted by the indicating grating and is propagated to form a plurality of beams of detection light, and the plurality of beams of detection light are propagated into the plurality of second detectors in a one-to-one correspondence manner. The detection precision of the grating displacement measuring device is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of grating displacement measurement, and particularly relates to a grating displacement measurement device. BACKGROUND

[0002] Grating displacement measurement is a high-precision measurement technology, which is based on the physical properties of light waves, and uses the diffraction principle and interference principle of a grating to light to realize detection of displacement. That is, when incident light passes through the stripes on the grating, diffraction occurs, and the displacement of an object relative to the grating can be determined by analyzing the interference or interference and diffraction light. That is, the detected signal is an interference signal after diffraction of the grating, and the displacement information is decoupled from the interference signal.

[0003] Grating displacement measurement technology plays an important role in the field of precision measurement due to its high precision and non-contact measurement characteristics. However, the measurement accuracy of the grating displacement measurement device in the related art still needs to be improved, and the installation accuracy and installation convenience are low. CONTENT OF THE INVENTION

[0004] Therefore, it is necessary to provide a grating displacement measurement device in view of the problem that the measurement accuracy of the grating displacement measurement device in the related art still needs to be improved, and the installation accuracy and installation convenience are low.

[0005] According to one aspect of the present application, a grating displacement measurement device is provided, which comprises:

[0006] a reading head, comprising a light source assembly, an indicating grating, a first detector and a plurality of second detectors, the light source assembly is configured to emit first and second exit light parallel to each other, the indicating grating is arranged on the light exit side of the light source assembly, and the indicating grating is configured to receive the first exit light and diffract and transmit the received first exit light; and

[0007] a measurement grating, which is arranged on the light exit side of the reading head and can produce relative displacement along a first direction with the reading head, the grating line plane of the measurement grating is parallel to the grating line plane of the indicating grating and parallel to the first direction; the measurement grating is configured to receive the first exit light and the second exit light through the indicating grating; and the measurement grating diffracts and reflects the received first exit light to the indicating grating, and diffracts and reflects the received second exit light to the first detector; the first exit light reflected by the measurement grating propagates to form a plurality of detection lights after being diffracted and transmitted by the indicating grating, and the plurality of detection lights propagate to the plurality of second detectors one by one.

[0008] The above grating displacement measurement device, the first exit light emitted by the light source assembly first passes through the indicating grating to occur the first diffraction and transmission, and propagates to the measurement grating. The light propagating to the measurement grating occurs diffraction and reflection again, and reflects and propagates to the indicating grating. The light propagating to the indicating grating occurs the second diffraction and transmission again. After the second diffraction and transmission, the light converges to form a plurality of light beams. A plurality of beams in the plurality of light beams are selected as detection light. The plurality of second detectors respectively and one by one correspondingly receive the plurality of detection light, so that the relative displacement light information of the measurement grating and the reading head along the first direction can be obtained. By detecting and analyzing the obtained plurality of detection light, the relative displacement of the measurement grating and the reading head can be obtained, so that the accurate detection of the relative displacement of the measurement grating and the reading head can be realized. At the same time, the measurement grating diffracts and reflects the second exit light and propagates to the first detector. The spot position of the light received by the first detector can determine the installation angle deviation between the reading head and the measurement grating in the three-dimensional space.

[0009] Therefore, the installation convenience and efficiency between the reading head and the measurement grating are improved, the installation accuracy is improved, and the detection accuracy is improved. It can be understood that during the detection process, the first detector can also detect whether the reading head and the measurement grating are slightly deviated or deflected, so that the relative position of the reading head and the measurement grating can be adjusted in time, the risk of measurement error caused by the deflection of the reading head and the measurement grating is reduced, and the detection accuracy is further improved.

[0010] In one embodiment, the light source assembly includes a light source, a beam splitter, and a mirror disposed on one side of the beam splitter. The beam splitter is disposed on the light exit side of the light source, and the beam splitter transmits part of the exit light of the light source to form the first exit light, and reflects part of the exit light of the light source to form the second exit light. The mirror is used to receive the second exit light reflected by the beam splitter, and reflects the second exit light, so that the propagation direction of the second exit light is parallel to the propagation direction of the first exit light.

[0011] In one embodiment, the reading head further includes a collimating lens. The collimating lens is located between the light source and the beam splitter, and between the indicating grating and the second detector. The collimating lens is used to collimate the exit light emitted by the light source, and to converge the light propagating from the indicating grating to the second detector.

[0012] In one of the embodiments, the read head further comprises a window member disposed on the light exit side of the light source assembly, the window member having a light transmission window for transmitting the second exit light; the indicator grating is disposed on the window member on a side opposite to the measurement grating, and the indicator grating is spaced apart from the light transmission window.

[0013] In one of the embodiments, the angle x between the grating line extension direction of the measurement grating and the grating line extension direction of the indicator grating satisfies: 0°≤x≤180° and x≠90°.

[0014] In one of the embodiments, along the first direction, the interval between two adjacent grating lines of the indicator grating is equal to the interval between two adjacent grating lines of the measurement grating.

[0015] In one of the embodiments, the measurement grating and the indicator grating are both one-dimensional diffraction gratings, and the grating line extension direction of the measurement grating is perpendicular to the first direction.

[0016] In one of the embodiments, a plurality of the second detectors are spaced apart from each other along the first direction.

[0017] In one of the embodiments, the grating displacement measurement device further comprises a signal processing member electrically connected to the plurality of second detectors respectively; the second detectors convert the received detection light into detection signals; and the signal processing member is used to calculate the plurality of detection signals to obtain the displacement of the read head relative to the measurement grating along the first direction. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 FIG. 1 is a structural schematic diagram of a grating displacement measurement device in one of the embodiments of the present application.

[0019] Figure 2 FIG. 3 is a structural schematic diagram of an indicator grating and a window member in one of the embodiments of the present application.

[0020] Figure 3 FIG. 4 is a simplified schematic diagram of the grating line interval of an indicator grating and the grating line interval of a measurement grating in one of the embodiments of the present application.

[0021] BRIEF DESCRIPTION OF DRAWINGS

[0022] 10, grating displacement measurement device;

[0023] 1, read head; 11, light source assembly; 111, light source; 112, beam splitter; 113, mirror; 12, indicator grating; 13, window member; 14, first detector; 15, second detector; 16, collimating lens; 17, diaphragm;

[0024] 2, measurement grating;

[0025] F1, first direction. DETAILED DESCRIPTION

[0026] In order to make the above objectives, features and advantages of the present application more clear and easily understood, the specific embodiments of the present application will be described in detail below with reference to the accompanying drawings. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present application. However, the present application can be practiced in a number of different ways without some of the specific details described herein, and it is understood that the present application is not limited to the specific embodiments described below.

[0027] In the description of the present application, it should be understood that, if there are terms such as "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. appear, these terms indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the purpose of facilitating the description of the present application and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application.

[0028] In addition, if the terms "first", "second" appear, these terms are only for the purpose of description, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features referred to. Therefore, the features limited by "first", "second" can explicitly or implicitly include at least one of the features. In the description of the present application, if the term "a plurality of" appears, the meaning of "a plurality of" is at least two, such as two, three, etc., unless otherwise specifically limited.

[0029] In the present application, unless otherwise specifically defined and limited, if the terms "mounting", "connecting", "connecting", "fixing" and the like appear, these terms should be broadly understood. For example, it can be fixedly connected, or it can be detachably connected, or it can be integrated; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the internal communication of two elements or the interaction relationship between two elements, unless otherwise specifically limited. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0030] In the present application, unless specifically defined and limited otherwise, if there is a description of a first feature on or above or below a second feature, it can mean that the first and second features are in direct contact, or the first and second features are indirectly in contact through an intermediate medium. Moreover, the first feature can be above or above and above the second feature, or it can only mean that the first feature is higher in horizontal height than the second feature. The first feature can be below or below and below the second feature, or it can only mean that the first feature is lower in horizontal height than the second feature.

[0031] It should be noted that if an element is referred to as being "fixed" or "set" on another element, it can be directly on the other element or there can be an intermediate element. If an element is considered to be "connected" to another element, it can be directly connected to the other element or there can be an intermediate element. If present, the terms "vertical", "horizontal", "up", "down", "left", "right" and similar expressions used in the present application are only for illustrative purposes and do not represent the only implementation.

[0032] Grating displacement measurement technology occupies an important position in the field of precision displacement measurement due to its small environmental requirements and high measurement resolution. This technology can provide nanometer-level or even sub-nanometer-level measurement accuracy. Compared with other displacement measurement technologies, such as laser displacement measurement technology, grating displacement measurement technology greatly reduces the requirements for humidity, temperature and air pressure of the use environment, which makes it maintain stable performance in various industrial environments.

[0033] However, the measurement accuracy of the grating displacement measurement device in the related art still needs to be improved, and its installation accuracy and installation convenience are low and also need to be improved.

[0034] Based on this, the present application provides a grating displacement measurement device for detecting the position of objects moving relative to each other in a measurement direction, and has more accurate measurement accuracy, and is more conducive to the improvement of installation convenience and accuracy.

[0035] Referring to Figure 1 As shown, Figure 1 is a structural schematic diagram of a grating displacement measurement device 10 in an embodiment of the present application.

[0036] The grating displacement measuring device 10 of the present application comprises a reading head 1 and a measuring grating 2, the reading head 1 can move along a first direction F1 relative to the measuring grating 2, when detecting the relative displacement between a first workpiece and a second workpiece, one of the first workpiece and the second workpiece is fixed relative to the position of the reading head 1, and the other is fixed relative to the position of the measuring grating 2, the displacement of the reading head 1 relative to the measuring grating 2 along the first direction F1 is the relative displacement between the first workpiece and the second workpiece.

[0037] The reading head 1 comprises a light source assembly 11, an indicating grating 12, a window piece 13, a first detector 14 and a plurality of second detectors 15. The light source assembly 11 is used to emit first and second exit lights parallel to each other. The indicating grating 12 and the window piece 13 are both arranged on the light emitting side of the light source assembly 11, the indicating grating 12 is used to receive the first exit light and diffract and transmit the received first exit light. The window piece 13 has a light transmission window for transmitting the second exit light.

[0038] The measuring grating 2 is arranged on the light emitting side of the reading head 1 and can produce relative displacement with the reading head 1 along the first direction F1, the plane of the grating lines of the measuring grating 2 is parallel to the plane of the grating lines of the indicating grating 12 and parallel to the first direction F1. The measuring grating 2 is used to receive the first exit light passing through the indicating grating 12 and the second exit light passing through the light transmission window. And the measuring grating 2 diffracts and reflects the received first exit light to the indicating grating 12 and diffracts and reflects the received second exit light to the first detector 14.

[0039] The first detector 14 can display the position of the light spot of the received light on the first detector 14, according to the center position of the light spot, the angular deviation between the reading head 1 and the measuring grating 2 can be judged, including the yaw, pitch and roll three angle deflections, so that the three-dimensional angular deviation detection can be realized. That is, the position display function of the first detector 14 is added, which can improve the installation efficiency and accuracy and simplify the installation process. It can also detect whether the reading head 1 and the measuring grating 2 have a slight shift or deflection in time, so as to adjust the relative position of the reading head 1 and the measuring grating 2 in time, improve the detection accuracy in the detection process. At the same time, it can also realize the three-dimensional displacement detection in space, not limited to the displacement along the first direction F1.

[0040] The first emergent light after diffraction and reflection of the measurement grating 2 is diffracted and transmitted by the indication grating 12, and propagates to form a plurality of beams of detection light, which are transmitted to the plurality of second detectors 15 one by one for resolving and detecting the corresponding displacement information.

[0041] It can be understood that the first emergent light emitted by the light source assembly 11 is first diffracted and transmitted by the indication grating 12, and propagates to the measurement grating 2. The light propagating to the measurement grating 2 is diffracted and reflected by the measurement grating 2, and propagates to the indication grating 12. The light propagating to the indication grating 12 is second diffracted and transmitted by the indication grating 12. After the second diffraction and transmission, the light converges to form a plurality of beams of light. A plurality of beams of light are selected as detection light, which are received by the plurality of second detectors 15 one by one, so that the relative displacement information of the measurement grating 2 and the reading head 1 along the first direction F1 can be obtained. By detecting and resolving the obtained plurality of beams of detection light, the relative displacement of the measurement grating 2 and the reading head 1 can be obtained, so that the relative displacement of the measurement grating 2 and the reading head 1 can be accurately detected.

[0042] Meanwhile, the measurement grating 2 diffracts and reflects the second emergent light and propagates to the first detector 14, so that the spot position of the light received by the first detector 14 can determine the installation angle deviation between the reading head 1 and the measurement grating 2 in the three-dimensional space. During installation, the installation accuracy between the reading head 1 and the measurement grating 2 can be determined by detecting the received light of the first detector 14, so as to reduce the risk of installation deviation, improve the installation efficiency and accuracy, and simplify the installation process. During detection, whether the reading head 1 and the measurement grating 2 are slightly deviated or deflected can also be detected by the first detector 14, so as to timely adjust the relative positions of the reading head 1 and the measurement grating 2, and improve the detection accuracy during detection.

[0043] The grating displacement measurement device 10 of the present application is beneficial to improve the installation convenience and efficiency between the reading head 1 and the measurement grating 2, improve the installation accuracy, and further improve the detection accuracy. During detection, whether the reading head 1 and the measurement grating 2 are slightly deviated or deflected can be detected by the first detector 14, so as to timely adjust the relative positions of the reading head 1 and the measurement grating 2, reduce the risk of measurement error caused by deflection of the reading head 1 and the measurement grating 2, and further improve the detection accuracy.

[0044] In some embodiments, reference can be made to Figure 1As shown, the light source assembly 11 comprises a light source 111, a beam splitter 112 and a mirror 113 arranged on one side of the beam splitter 112. The beam splitter 112 is arranged on the light emitting side of the light source 111, and the beam splitter 112 transmits part of the emitted light of the light source 111 to form the first emitted light, and reflects part of the emitted light of the light source 111 to form the second emitted light. The mirror 113 is used to receive the second emitted light reflected by the beam splitter 112, and reflects the second emitted light, so that the propagation direction of the second emitted light is parallel to the propagation direction of the first emitted light.

[0045] Thus, the light source assembly 11 finally emits the first emitted light and the second emitted light with parallel propagation directions. In this way, the second emitted light can also be used for auxiliary detection by the measurement grating 2, that is, whether a slight deviation or deflection occurs between the reading head 1 and the measurement grating 2 is detected by receiving the second emitted light by the first detector 14, without the need to additionally arrange other gratings and optical elements, which is conducive to the miniaturization design of the grating displacement measurement device 10.

[0046] In some embodiments, continuing to refer to Figure 1 As shown, the reading head 1 further comprises a collimating lens 16 located between the light source 111 and the beam splitter 112, and located between the indicating grating 12 and the second detector 15. The collimating lens 16 is used to collimate the emitted light of the light source 111, and to converge the light rays propagated from the indicating grating 12 to the second detector 15. The emitted light of the light source 111 is first collimated by the collimating lens 16, and then propagates into the beam splitter 112, which is conducive to improving the quality of the emitted light, and thus improving the detection accuracy. After being diffracted and transmitted by the indicating grating 12, the detection light propagates into the second detector 15 through the collimating lens 16. In this way, the detection light is converged in the second detector 15 to form a light spot, which is conducive to shortening the propagation path of the light rays, and is conducive to the miniaturization design of the grating displacement measurement device 10.

[0047] In some embodiments, continuing to refer to Figure 1 , in combination with referring to Figure 2 As shown, the indicating grating 12 is arranged on the window member 13 away from the measurement grating 2, and the indicating grating 12 is arranged in a spaced manner with the light transmission window. In this way, the risk of interference between the first emitted light passing through the indicating grating 12 and the second emitted light passing through the light transmission window is reduced, which is conducive to maintaining a certain interval between the first emitted light and the second emitted light, and the stability of the two is better, and thus the detection accuracy is improved.

[0048] In some embodiments, continuing to refer to Figure 1 and Figure 2As shown, the reading head 1 further comprises a diaphragm 17, which is arranged on the window member 13 and located at the light transmission window, so as to control the propagation direction and incidence range of the second emergent light and the light reflected by the measurement grating 2 to the first detector 14, so as to improve the light quality, optimize the spot quality, and further improve the detection accuracy.

[0049] In some embodiments, referring to Figure 1 , and referring to Figure 3 As shown, the angle x between the extension direction of the grating lines of the measurement grating 2 and the extension direction of the grating lines of the indicating grating 12 satisfies: 0°≤x≤180° and x≠90°. It can be understood that the grating lines of the measurement grating 2 and the grating lines of the indicating grating 12 can form multiple angles, which has a wide range of applications and is more conducive to improving the installation convenience of the reading head 1 and the measurement grating 2.

[0050] In some embodiments, as shown in Figure 3 Along the first direction F1, the pitch of the adjacent two grating lines of the indicating grating 12 is equal to the pitch of the adjacent two grating lines of the measurement grating 2, both of which are L. Thus, the first emergent light can be diffracted multiple times by the indicating grating 12 and the measurement grating 2 in turn and carry the movement information of the reading head 1 relative to the measurement grating 2 along the first direction F1. That is, when the reading head 1 moves relative to the measurement grating 2 along the first direction F1, the first emergent light can first be diffracted and transmitted by the indicating grating 12, then be diffracted and reflected by the measurement grating 2, and then be diffracted and transmitted by the indicating grating 12 again, and then propagate into the second detector 15, and then be analyzed by the signal processing member to obtain the displacement signal of the reading head 1 relative to the measurement grating 2. In this way, regarding the design of the grating lines of the indicating grating 12 and the measurement grating 2, only the pitch of the adjacent two grating lines of the indicating grating 12 and the measurement grating 2 along the first direction F1 needs to be equal, which has a wide range of applications.

[0051] In some embodiments, as shown in Figure 1 The measurement grating 2 and the indicating grating 12 are both one-dimensional diffraction gratings. That is, the measurement grating 2 and the indicating grating 12 both use one-dimensional diffraction gratings, which can very accurately predict the direction of each order light beam and provide a large degree of design freedom, so that excellent diffracted light can be obtained by calculating the grating line pitch, which is conducive to improving the detection accuracy and reducing the production cost. In some embodiments, the extension direction of the grating lines of the measurement grating 2 is perpendicular to the first direction F1, which is conducive to the convenience of production. As shown in Figure 3 The pitch of the adjacent two grating lines of the measurement grating 2 is L, and the pitch of the adjacent two grating lines of the indicating grating 12 is Lcosx, which is simple and convenient to design. Wherein, x is the angle between the grating lines of the measurement grating 2 and the grating lines of the indicating grating 12. For example, when x is 45°, the pitch of the adjacent two grating lines of the indicating grating 12 is 0.7071 times the pitch of the adjacent two grating lines of the measurement grating 2.

[0052] In some embodiments, continuing to refer to Figure 1 , the plurality of second detectors 15 are arranged along the first direction F1. In some embodiments, three second detectors 15 can be arranged to receive three detection lights respectively, as shown in Figure 1 , the second detector 15 has a plurality of light points distributed around it, and each intersection is a pattern of the light spots formed by the convergence of all light rays. Three of them can be selected as signal receiving points, or three detection lights can be selected.

[0053] It can be understood that the ±1 order and 0 order diffraction beams of the measurement grating 2 need to be used in the present application, and the (1, 0), (0, -1) or (-1, 0), (0, 1) order diffraction beams of the indicating grating 12 need to be indicated. Based on the Doppler measurement principle, when the measurement grating 2 and the reading head 1 move relative to each other, the second detector 15 can receive a detection light signal with a period of 1 / 2 of the interval between the adjacent two grating lines of the measurement grating 2, for example, if the interval between the adjacent two grating lines of the measurement grating 2 is 4 um, the second detector 15 will obtain a detection light signal with a period of 2 um. Three detectors output three phase signals with a certain phase difference, and the phase difference of the three phase signals is determined by the structure design of the indicating grating, specifically by the grating depth and the size between the adjacent two grating lines of the indicating grating. For example, the structure of the indicating grating can be designed to obtain phase signals with a phase difference of 120°. The Doppler measurement principle is a measurement technology based on the Doppler effect, which is a phenomenon that the frequency of the wave received by the observer is different from the frequency of the wave emitted by the wave source when there is relative motion between the wave source and the observer.

[0054] In some embodiments, the grating displacement measurement device 10 further comprises a signal processing part electrically connected to the plurality of second detectors 15, and the second detectors 15 convert the received detection light into detection signals. The signal processing part is used to calculate the plurality of detection signals to obtain the displacement of the reading head 1 relative to the measurement grating 2 along the first direction F1. Thus, the accurate detection of the movement information of the reading head 1 relative to the measurement grating 2 along the first direction F1 is realized.

[0055] In some embodiments, the first detector 14 can be a charge-coupled device (CCD), or a complementary metal-oxide semiconductor (CMOS), or other imaging photoelectric detectors or position detectors. It can be imaged, or it can only show the structure of the position change.

[0056] The grating displacement measuring device 10 of the present application, the first emergent light emitted by the light source assembly 11 first passes through the indicating grating 12 to occur the first diffraction and transmission, and propagates to the measuring grating 2. The light propagating to the measuring grating 2 again passes through the measuring grating 2 to occur the diffraction and reflection, and reflects to propagate to the indicating grating 12. The light after the second diffraction and transmission converges to form a plurality of light beams. A plurality of light beams in the plurality of light beams are selected as detection light. The plurality of detection light is received by the plurality of second detectors 15 respectively and one by one, so that the relative displacement light information of the measuring grating 2 and the reading head 1 along the first direction F1 can be obtained. The relative displacement of the measuring grating 2 and the reading head 1 is obtained by detecting and analyzing the obtained plurality of detection light, so that the accurate detection of the relative displacement of the measuring grating 2 and the reading head 1 can be realized. At the same time, the measuring grating 2 diffracts and reflects the second emergent light to propagate to the first detector 14. The spot position of the light received by the first detector 14 can determine the installation angle deviation between the reading head 1 and the measuring grating 2 in the three-dimensional space. In this way, the installation convenience and efficiency between the reading head 1 and the measuring grating 2 can be improved, the installation accuracy can be improved, and the detection accuracy can be improved. It can be understood that during the detection process, the first detector 14 can also detect whether the reading head 1 and the measuring grating 2 are slightly deviated or deflected, so as to timely adjust the relative position of the reading head 1 and the measuring grating 2, reduce the risk of measurement error caused by the deflection of the reading head 1 and the measuring grating 2, and further improve the detection accuracy. The three-dimensional displacement detection in space can also be realized, not limited to the displacement along the first direction F1.

[0057] The technical features of the above-described embodiments can be combined in any manner. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described, but as long as the combinations of the technical features do not contradict, they should be considered within the scope of the present disclosure.

[0058] The above-described embodiments only express several implementation manners of the present application, and the description is relatively specific and detailed, but it should not be understood as a limitation on the patent scope of the application. It should be pointed out that for ordinary skilled persons in the art, some modifications and improvements can be made without departing from the concept of the present application, and these belong to the protection scope of the present application. Therefore, the patent protection scope of the present application should be subject to the appended claims.

Claims

1. A grating displacement measurement apparatus, characterized by, The grating displacement measuring device comprises: a reading head, comprising a light source assembly, an indicating grating, a first detector and a plurality of second detectors, the light source assembly is configured to emit first and second exit lights parallel to each other, the indicating grating is arranged on the light exit side of the light source assembly, and is configured to receive the first exit light and diffract and transmit the received first exit light; and a measurement grating, arranged on the light exit side of the reading head, and capable of generating relative displacement with the reading head along a first direction, the grating line plane of the measurement grating is parallel to the grating line plane of the indicating grating and parallel to the first direction; the measurement grating is configured to receive the first exit light and the second exit light passing through the indicating grating, and diffract and reflect the received first exit light to the indicating grating and diffract and reflect the received second exit light to the first detector; the first exit light reflected by the measurement grating propagates to form a plurality of detection lights after being diffracted and transmitted by the indicating grating, and the detection lights propagate to the second detectors one by one.

2. The grating displacement measurement device of claim 1, wherein, The light source assembly comprises a light source, a beam splitter and a mirror arranged on one side of the beam splitter, the beam splitter is arranged on the light exit side of the light source, and the beam splitter transmits part of the exit light of the light source to form the first exit light and reflects part of the exit light of the light source to form the second exit light; The mirror is configured to receive the second exit light reflected by the beam splitter and reflect the second exit light, so that the propagation direction of the second exit light is parallel to the propagation direction of the first exit light.

3. The grating displacement measuring device of claim 2, wherein The reading head further comprises a collimating lens, which is located between the light source and the beam splitter and between the indicating grating and the second detectors, and is configured to collimate the exit light emitted by the light source and converge the light rays propagating from the indicating grating to the second detectors.

4. The grating displacement measurement device of claim 1, wherein, The reading head further comprises a window member, which is arranged on the light exit side of the light source assembly, has a light transmission window for transmitting the second exit light, and is arranged on the side of the window member away from the measurement grating.

5. The grating displacement measuring device of claim 4, wherein, The reading head further comprises a diaphragm, which is arranged on the window member and located at the light transmission window.

6. The grating displacement measurement device of claim 1, wherein, The included angle x between the grating line extension direction of the measurement grating and the grating line extension direction of the indicating grating satisfies 0°≤x≤180° and x≠90°.

7. The grating displacement measuring device of claim 6, wherein Along the first direction, the distance between two adjacent grating lines of the indicating grating is equal to the distance between two adjacent grating lines of the measurement grating.

8. The grating displacement measurement device of claim 1, wherein, The measurement grating and the indicating grating are both one-dimensional diffraction gratings, and the grating line extension direction of the measurement grating is perpendicular to the first direction.

9. The grating displacement measurement device of claim 1, wherein, The second detectors are arranged at intervals along the first direction.

10. The grating displacement measurement device of claim 1, wherein, The grating displacement measuring device further comprises signal processing units, which are electrically connected to the second detectors respectively; the second detectors convert the received detection light into detection signals; the signal processing units are used to calculate the detection signals to obtain the displacement of the read head relative to the measuring grating along the first direction.

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