A precision angle measurement device based on transmission grating and its measurement method

Abstract

The present invention discloses a precision angle measurement device based on a transmission grating and a measurement method thereof. A grating combination sensing unit consisting of a transmission grating and a reflector is provided. Incident light from a laser light source collimated by a convex lens is transmitted through the transmission grating to form a diffracted beam. The diffracted beam is reflected by the reflector and then transmitted through the transmission grating for a second diffraction, thereby forming an outgoing light parallel to the incident light. This light is then projected onto a planar array photoelectric position detector as measurement light. When the yaw or pitch angle of the grating combination sensing unit changes, the distance between the parallel incident light and the measurement light changes accordingly. Based on the distance between the incident light and the measurement light detected, the angular change occurring on the grating combination sensing unit is calculated, thereby achieving angle measurement of the target being measured. The present invention converts the angular change of the target being measured into a displacement change, achieving a balance between a long working measurement distance, a large measurement range, and high-resolution precision angle measurement.

Description

Technical Field

[0001] The present invention belongs to the technical field of precision angle measurement, and in particular relates to a precision angle measurement device based on a transmission grating and a measurement method thereof. Background Art

[0002] With the rapid development of ultra-precision machining and intelligent manufacturing, the demand for angle measurement in precision measurement technology and high-end precision equipment manufacturing is increasing. These devices and equipment not only require high-resolution angle measurement over a large measurement range, but also urgently need to be able to measure over long working distances. To meet these demands, the development of precision angle measurement technology with long working distances and a wide range is of great significance. Advances in these technologies can promote the development of large-scale, high-end ultra-precision equipment manufacturing and large scientific facilities.

[0003] Optical autocollimation angle measurement technology is currently one of the most commonly used measurement technologies in the field of precision angle measurement in the world. Due to its advantages such as non-contact measurement, high accuracy, and ease of use, it occupies an important position in the field of precision small-angle measurement. However, during the angle measurement process, due to the presence of the optical arm, the working measurement range of optical autocollimation angle measurement technology will be greatly reduced as the working distance increases. When performing angle measurement, the commonly used autocollimators and interferometers today will encounter the problem that the measuring light cannot return to the sensing end due to the long measurement distance, resulting in a significant reduction in the measurement range. If some indirect measurement methods are used, the cost is often very high and requires a lot of manpower and material resources. Therefore, while pursuing a long working measurement distance, ensuring the measurement range and resolution is one of the key concerns of the domestic and international testing industry. Summary of the Invention

[0004] In order to overcome the shortcomings of the above-mentioned prior art, the present invention provides a precision angle measurement device based on a transmission grating and a measurement method thereof, so as to eliminate the problem of a significant reduction in the measurement range caused by an increase in the measurement working distance, and achieve a balance between a long working measurement distance, a large measurement range and high-resolution precision angle measurement.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] The present invention is characterized by a precision angle measurement device based on a transmission grating. A grating combination sensing unit consisting of a transmission grating and a reflector is provided. Incident light formed by a laser light source being collimated by a convex lens is transmitted through the transmission grating to form a diffracted beam. The diffracted beam is reflected by the reflector and then transmitted through the transmission grating to undergo a second diffraction. The second diffraction forms outgoing light parallel to the incident light and projects it onto an array photoelectric position detector as measurement light. When the yaw or pitch angle of the grating combination sensing unit changes, the distance between the parallel incident light and the measurement light changes accordingly. Based on the detected distance between the incident light and the measurement light, the angle change occurring on the grating combination sensing unit is calculated to achieve angle measurement of the target being measured.

[0007] The characteristics of the precision angle measurement device based on the transmission grating of the present invention are also that: the device includes a one-dimensional angle measurement unit and a signal processing unit, and the grating combination sensing unit is a non-decoupled grating combination sensing unit;

[0008] The one-dimensional angle measurement unit is mounted on the front end of the measured target using a two-dimensional displacement adjustment base, on which a laser light source, a convex lens, and a first array photoelectric position detector are respectively arranged; the non-decoupled grating combination sensing unit is fixed to the measured target using an angle adjustment base, on which a first transmission grating and a plane reflector are respectively arranged, and the first transmission grating and the plane reflector are parallel to each other; the signal processing unit is a signal acquisition and processor including a host computer acquisition system, and is used to realize data interaction, display, and storage;

[0009] A laser beam emitted by the laser light source is collimated by a convex lens to form incident light, which is then incident on a first transmission grating. After being transmitted through the first transmission grating, the incident light is diffracted into multiple-order diffraction beams. A first-order diffraction beam in the multiple-order diffraction beam is reflected by a plane mirror to form reflected light. The reflected light is again transmitted through the first transmission grating and undergoes secondary diffraction. The secondary diffraction forms output light that is parallel to the incident light. The output light is projected onto the first array photoelectric position detector as measurement light. When the yaw angle or pitch angle of the non-decoupled grating combination sensing unit changes, the distance between the parallel incident light and the measurement light changes accordingly.

[0010] The signal processing unit calculates the one-dimensional angle change occurring on the non-decoupled grating combination sensing unit based on the distance between the incident light and the measurement light obtained by detection, thereby realizing one-dimensional angle measurement of the measured target.

[0011] The precision angle measurement device based on the transmission grating of the present invention is also characterized in that: the scribed lines of the first transmission grating are set in a vertical direction to achieve one-dimensional angle measurement of the roll angle; the scribed lines of the first transmission grating are set in a horizontal direction to achieve one-dimensional angle measurement of the pitch angle.

[0012] The precision angle measurement device based on the transmission grating of the present invention is also characterized in that the distance between the first transmission grating and the plane reflector is adjusted according to the set angle measurement resolution, and the larger the distance, the smaller the resolution.

[0013] The characteristic of the precision angle measurement method based on a transmission grating of the present invention is that the precision angle measurement device based on a transmission grating of the present invention is used for measurement, and the deflection angle change value Δθ occurring on the non-decoupled grating combination sensing unit is calculated by formula (1), and the deflection angle change value Δθ is the deflection angle change value of the measured target;

[0014]

[0015] in:

[0016] P is the grating constant of the first transmission grating;

[0017] λ is the wavelength of the laser light source;

[0018] d is the distance between the first transmission grating and the plane reflector;

[0019] F() represents the setting function of P, λ and d;

[0020] m is the diffraction order, and m is selected as +1;

[0021] θ m is the diffraction angle of the m-order beam;

[0022] Δθ is the angle between the incident light and the normal to the first transmission grating;

[0023] Δl1 is the displacement change value of the measurement light in the horizontal direction detected by the first array photoelectric position detector.

[0024] The precision angle measurement device based on the transmission grating of the present invention is also characterized in that the device comprises: a two-dimensional angle measurement unit, a decoupled grating combination sensing unit and a signal processing unit;

[0025] The two-dimensional angle measurement unit is mounted on the front end of the measured target using a two-dimensional displacement adjustment base, on which a laser light source, a convex lens, a beam splitter prism, a right-angle prism, a first array photoelectric position detector, and a second array photoelectric position detector are respectively arranged; the decoupled grating combination sensing unit is fixed to the measured target using an angle adjustment base, on which a yaw angle sensing optical path consisting of a first transmission grating and a first double-sided reflection right-angle prism, and a pitch angle sensing optical path consisting of a second transmission grating and a second double-sided reflection right-angle prism are respectively arranged; the signal processing unit is a signal acquisition and processor including a host computer acquisition system, used to realize data interaction, display, and storage;

[0026] The laser beam emitted by the laser light source is passed through a convex lens to generate a collimated beam, and the collimated beam is passed through a beam splitter prism and a right-angle prism to generate two parallel incident light beams, namely a first incident light transmitted by the beam splitter prism and a second incident light split by the beam splitter prism and deflected by the right-angle prism;

[0027] The first incident light is incident on the first transmission grating and, after being transmitted through the first transmission grating, is diffracted into a first multi-order diffracted light beam. A first-order diffracted light beam in the first multi-order diffracted light beam is reflected by a first double-sided reflecting right-angle prism and then transmitted through the first transmission grating to undergo a second diffraction. The second diffraction forms a first output light beam that is parallel to the first incident light beam. The first output light beam is projected onto the first area array photoelectric position detector as a first measurement light beam. When the deflection angle of the decoupled grating combination sensing unit changes, the distance between the first incident light beam and the first measurement light beam changes accordingly.

[0028] The second incident light is incident on the second transmission grating and, after being transmitted through the second transmission grating, is diffracted into a second multi-order diffracted light beam. A first-order diffracted light beam in the second multi-order diffracted light beam is reflected by a second double-sided reflection right-angle prism and then transmitted through the second transmission grating to undergo a second diffraction. The second diffraction forms a second output light beam that is parallel to the second incident light beam. The second output light beam is projected onto the second area array photoelectric position detector as a second measurement light beam. When the pitch angle of the decoupled grating combination sensing unit changes, the distance between the second incident light beam and the second measurement light beam changes accordingly.

[0029] The signal processing unit calculates the angular changes of the yaw angle and the pitch angle occurring on the decoupled grating combination sensing unit based on the distance between the first incident light and the first measuring light, and the distance between the second incident light and the second measuring light, thereby realizing two-dimensional angle measurement of the target being measured.

[0030] The precision angle measurement device based on the transmission grating of the present invention is also characterized by:

[0031] The structure of the deflection angle sensing optical path is set as follows: the scribed lines of the first transmission grating are set to be vertical, the plane of the first transmission grating is parallel to the inclined surface of the first double-sided reflection right-angle prism, and is horizontal to the inclined edge of the right-angle surface of the first double-sided reflection right-angle prism;

[0032] The structure of the pitch angle sensing optical path is set as follows: the scribed line direction of the second transmission grating is set horizontally, the plane of the second transmission grating is parallel to the inclined surface of the second double-sided reflection right-angle prism, and is horizontal to the hypotenuse of the right-angle surface of the second double-sided reflection right-angle prism.

[0033] The precision angle measurement device based on the transmission grating of the present invention is also characterized in that: the first double-sided reflection right-angle prism and the second double-sided reflection right-angle prism are both double-sided reflection right-angle prisms with double right-angle edges coated; when the angle of the decoupled grating combination sensing unit changes, the laser reflected by the first double-sided reflection right-angle prism only senses the angle information of the yaw angle change, and the laser reflected by the second double-sided reflection right-angle prism only senses the angle information of the pitch angle change.

[0034] Compared with the existing technology, the beneficial effects of the present invention are embodied in:

[0035] 1. The present invention combines a transmission grating with a plane mirror to convert angle information into displacement change information between parallel light and measure the displacement change, thereby effectively reducing the influence of the optical arm on the measurement range during long-stroke measurement.

[0036] 2. The present invention utilizes the characteristic of a double-sided reflecting right-angle prism that is insensitive to angular changes in a single direction and combines it with a transmission grating for measurement, thereby solving the problem of a significant attenuation of the measurement range due to an increase in the measurement working distance, while retaining the advantage of converting angle information under a plane mirror structure.

[0037] 3. The present invention uses a grating combination sensing unit as the angle sensing unit of the device. The resolution of the device is determined by the distance between the transmission grating and the plane reflector (double-sided reflective right-angle prism). During the initial design process, the resolution of the device can be improved by simply increasing the distance between the two devices. The adjustment is easy, the operation is convenient, and the size of the device is not required to be high.

[0038] 5. This invention is an integrated transmitter-receiver device. Its grating-combined sensing unit is compact and lightweight, and the measuring instrument itself consists solely of a transmitter and a photoelectric position detection component. Compared to the complex optical systems found in autocollimators and interferometers, the overall structure is more compact and simple, offering a wider range of applications, simpler operation, and easy installation on a variety of motion guides and angular motion mechanisms. While meeting the demands of high-precision measurement, it offers significant cost advantages. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 Schematic diagram of the structure of a one-dimensional precision angle measurement device based on a transmission grating in the present invention;

[0040] Figure 2 Schematic diagram of the measurement principle of the grating combination sensing unit in the present invention;

[0041] Figure 3 Schematic diagram of the structure of a two-dimensional precision angle measurement device based on a transmission grating in the present invention;

[0042] Figure 4a and Figure 4b Schematic diagram of the structure of the decoupled grating combination sensing unit in the present invention;

[0043] Numbers in the figure: 1a one-dimensional angle measurement unit, 1b two-dimensional angle measurement unit, 101 laser light source, 102 convex lens, 103 beam splitter prism, 104 right-angle prism, 105 first array photoelectric position detector, 106 second array photoelectric position detector, 107 two-dimensional displacement adjustment seat, 2a non-decoupled grating combination sensing unit, 2b decoupled grating combination sensing unit, 201 first transmission grating, 202 first double-sided reflection right-angle prism, 203 second transmission grating, 204 second double-sided reflection right-angle prism, 205 angle adjustment base, 206 plane reflector, 3 signal processing unit, 301 host computer acquisition system. DETAILED DESCRIPTION

[0044] The present invention discloses a precision angle measurement device based on a transmission grating, which is provided with a grating combination sensing unit consisting of a transmission grating and a reflector. Incident light formed by a laser light source being collimated by a convex lens is transmitted through the transmission grating to form a diffracted beam. The diffracted beam is reflected by the reflector and then transmitted through the transmission grating to undergo a second diffraction. The second diffraction forms outgoing light parallel to the incident light, which is projected onto a planar array photoelectric position detector as measurement light. When the yaw angle or pitch angle of the grating combination sensing unit changes, the distance between the parallel incident light and the measurement light changes accordingly. Based on the detected distance between the incident light and the measurement light, the angle change occurring on the grating combination sensing unit is calculated to achieve angle measurement of the target being measured.

[0045] Example 1:

[0046] See also Figure 1In this embodiment, the precision angle measurement device based on the transmission grating includes a one-dimensional angle measurement unit 1a and a signal processing unit 3, and the grating combination sensing unit is a non-decoupled grating combination sensing unit 2a; wherein, the one-dimensional angle measurement unit 1a is installed at the front end of the measured target using a two-dimensional displacement adjustment base 107, and a laser light source 101, a convex lens 102 and a first array photoelectric position detector 105 are respectively arranged on the two-dimensional displacement adjustment base 107; the non-decoupled grating combination sensing unit 2a is fixed to the measured target using an angle adjustment base 205, and a first transmission grating 201 and a plane reflector 206 are respectively arranged on the angle adjustment base 205, and the first transmission grating 201 and the plane reflector 206 are parallel to each other; the signal processing unit 3 is a signal acquisition and processor including a host computer acquisition system 301, which is used to realize data interaction, display and storage. The laser beam emitted by the laser light source 101 is collimated by the convex lens 102 to form an incident light, and is incident on the first transmission grating 201. After passing through the first transmission grating 201, the incident light is diffracted into multiple-order diffraction beams. The multiple-order diffraction beams are divided into 0th order, ±1st order, ±2nd order, etc. Considering factors such as the energy intensity of the diffracted light itself, the first-order diffraction light is used as the measurement beam in this embodiment, wherein the initial diffraction angle of the first-order diffraction light is a constant value, which is determined by the properties of the transmission grating itself. The first-order diffraction beam in the multiple-order diffraction beam passes through the plane reflector 2 06 is reflected to form reflected light, which is then transmitted again through the first transmission grating 201 and diffracted twice. Due to geometric relationships and symmetry principles, the secondary diffraction forms outgoing light parallel to the incident light. The outgoing light is projected onto the first array photoelectric position detector 105 as measurement light. During the measurement process, the first transmission grating 201 and the plane reflector 206 remain parallel and the distance between them does not change. When the yaw or pitch angle of the non-decoupled grating combination sensing unit 2a changes, the distance between the parallel incident light and the measurement light changes accordingly. The signal processing unit 3 calculates the one-dimensional angle change occurring on the non-decoupled grating combination sensing unit 2a based on the distance between the incident light and the measurement light detected, thereby achieving one-dimensional angle measurement of the target being measured.

[0047] In specific implementation, the corresponding technical measures also include:

[0048] The scribed lines of the first transmission grating 201 are set to be vertical to achieve one-dimensional angle measurement of the yaw angle; the scribed lines of the first transmission grating 201 are set to be horizontal to achieve one-dimensional angle measurement of the pitch angle.

[0049] The distance between the first transmission grating 201 and the plane reflective mirror 206 is adjusted according to the set angular resolution. The larger the distance, the smaller the resolution.

[0050] By using the two-dimensional displacement adjustment seat 107 and the angle adjustment base 205 to cooperate with each other, the reflected measurement light beam is hit on the center of the first array photoelectric position detector 105 before the measurement begins, completing the adjustment of the initial state.

[0051] See also Figure 2 When the collimated laser is reflected by the non-decoupled grating combination sensing unit 2a, a beam of outgoing light parallel to the incident light is generated. At this time, the zero-position distance between the parallel lights is L1, which is determined by the parameter characteristics of the grating itself and the spacing between the grating and the plane reflector. Since the position between the two optical devices remains fixed, according to the grating diffraction principle and the plane mirror reflection principle, when the non-decoupled grating combination sensing unit 2a undergoes a pitch or yaw angle change, the distance between the parallel lights will change, and the distance becomes L,1. The displacement change of the outgoing light is Δl1. According to the geometric relationship, the relationship between the yaw angle change θ and the outgoing light displacement change Δl1 can be obtained.

[0052] The precision angle measurement device based on the transmission grating in this embodiment is used for measurement. The deflection angle change value Δθ occurring on the non-decoupled grating combination sensing unit 2a is calculated by formula (1). The deflection angle change value Δθ is the deflection angle change value of the measured target.

[0053]

[0054] in:

[0055] P is the grating constant of the first transmission grating 201;

[0056] λ is the wavelength of the laser light source 101;

[0057] d is the distance between the first transmission grating 201 and the plane reflective mirror 206;

[0058] F() represents the setting function of P, λ and d;

[0059] m is the diffraction order, and m is selected as +1;

[0060] θ m is the diffraction angle of the m-order beam;

[0061] Δθ is the angle between the incident light and the normal line of the first transmission grating 201;

[0062] Δl1 is the displacement change value of the measurement light in the horizontal direction detected by the first array photoelectric position detector 105.

[0063] Example 2:

[0064] See also Figure 3In this embodiment, the precision angle measurement device based on the transmission grating includes a two-dimensional angle measurement unit 1b, a decoupled grating combination sensing unit 2b and a signal processing unit 3; wherein the two-dimensional angle measurement unit 1b is installed at the front end of the measured target by using a two-dimensional displacement adjustment base 107, and a laser light source 101, a convex lens 102, a beam splitter prism 103, a right-angle prism 104, a first array photoelectric position detector 105 and a second array photoelectric position detector 106 are respectively arranged on the two-dimensional displacement adjustment base 107; the decoupled grating combination sensing unit 2b is fixed to the measured target by using an angle adjustment base 205, and a first transmission grating 201 and a first double-sided array photoelectric position detector are respectively arranged on the angle adjustment base 205. The yaw angle sensing optical path formed by the reflecting right-angle prism 202, and the pitch angle sensing optical path formed by the second transmission grating 203 and the second double-sided reflection right-angle prism 204; the signal processing unit 3, which is a signal acquisition and processor including the host computer acquisition system 301, is used to realize data interaction, display and storage; the laser beam emitted by the laser light source 101 is generated into a collimated beam through the convex lens 102, and the collimated beam is generated into two parallel incident light beams through the beam splitter prism 103 and the right-angle prism 104, respectively. The first incident light is incident on the first transmission grating 201 and passes through the second transmission grating 203. After transmission through a transmission grating 201, the light is diffracted into a first multi-order diffracted light beam. The first-order diffracted light beam in the first multi-order diffracted light beam is reflected by the first double-sided reflecting right-angle prism 202, and then transmitted through the first transmission grating 201 to undergo a second diffraction. The second diffraction forms a first outgoing light beam that is parallel to the first incident light beam. The first outgoing light beam is projected onto the first array photoelectric position detector 105 as the first measuring light beam. When the deflection angle of the decoupled grating combination sensing unit 2b changes, the horizontal distance between the first incident light beam and the first measuring light beam changes accordingly. The second incident light beam is incident on the second transmission grating 203, and after transmission through the second transmission grating 203, it is diffracted into a second multi-order diffracted light beam. The first-order diffracted light beam in the second multi-order diffracted light beam is After being reflected by the second double-sided reflection right-angle prism 204 and then transmitted through the second transmission grating 203, secondary diffraction occurs, forming second output light parallel to the second incident light. The second output light is projected onto the second array photoelectric position detector 106 as second measuring light. When the pitch angle of the decoupled grating combination sensing unit 2b changes, the vertical distance between the second incident light and the second measuring light changes accordingly. The signal processing unit 3 calculates the angular changes of the yaw and pitch angles occurring on the decoupled grating combination sensing unit 2b based on the detected distances between the first incident light and the first measuring light, and the distances between the second incident light and the second measuring light, thereby achieving two-dimensional angle measurement of the target.

[0065] In specific implementation, the corresponding technical measures also include:

[0066] See also Figure 4a and Figure 4b The structure of the yaw angle sensing optical path is set as follows: the scribed lines of the first transmission grating 201 are set to be vertical, the plane of the first transmission grating 201 is parallel to the oblique surface of the first double-sided reflection right-angle prism 202, and is horizontal with the oblique side of the right-angle surface of the first double-sided reflection right-angle prism 202; the structure of the pitch angle sensing optical path is set to be horizontal, the scribed lines of the second transmission grating 203 are set to be horizontal, the plane of the second transmission grating 203 is parallel to the oblique surface of the second double-sided reflection right-angle prism 204, and is horizontal with the oblique side of the right-angle surface of the second double-sided reflection right-angle prism 204; wherein, by rotating the first transmission grating 201 and the first double-sided reflection right-angle prism 202 simultaneously by 90 degrees, the posture of the plane of the second transmission grating 203 and the second double-sided reflection right-angle prism 204 can be converted; during the measurement process, the transmission grating and the double-sided reflection right-angle prism remain parallel and the distance between them does not change.

[0067] The first double-sided reflecting right-angle prism 202 and the second double-sided reflecting right-angle prism 204 are both double-sided reflecting right-angle prisms with double right-angle edges coated. When the angle of the decoupled grating combination sensing unit 2b changes, the laser reflected by the first double-sided reflecting right-angle prism 202 only senses the angle information of the yaw angle change, and the laser reflected by the second double-sided reflecting right-angle prism 204 only senses the angle information of the pitch angle change, thereby achieving physical decoupling of the angles and eliminating the influence of angle coupling.

[0068] When using the precision angle measurement device based on the transmission grating in this embodiment for measurement, the double-sided reflecting right-angle prism has the same reflection effect as a plane mirror when utilizing its reflection function. The measurement method is the same as that in Example 1, that is, the yaw angle change value Δθ and the pitch angle change value Δα occurring on the decoupled grating combination sensing unit 2b are calculated by formula (1) in Example 1. The yaw angle change value Δθ and the pitch angle change value Δα are the yaw angle change values ​​of the measured target.

[0069] The present invention utilizes a transmission grating and a plane reflector (a double-sided right-angle reflector) as the device's sensing elements, converting the measured angular motion changes into displacement changes between parallel beams. This eliminates the significant reduction in measurement range caused by increasing the working distance during angle measurement, achieving a balance between a long working distance, a large measurement range, and high-resolution, precision angle measurement. This addresses the problem of reduced measurement range during long-distance measurements in traditional angle measurement methods.

[0070] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them. The various features of the present invention can be equivalently replaced with reference to the above examples, and these replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A precision angle measurement device based on a transmission grating, characterized by: A grating combination sensing unit consisting of a transmission grating and a reflector is provided. Incident light formed by a laser light source being collimated by a convex lens is transmitted through the transmission grating to form a diffracted beam. The diffracted beam is reflected by the reflector and then transmitted through the transmission grating to undergo a second diffraction. The second diffraction forms an outgoing light parallel to the incident light, which is projected onto a planar array photoelectric position detector as measurement light. When the yaw or pitch angle of the grating combination sensing unit changes, the distance between the parallel incident light and the measurement light changes accordingly. Based on the detected distance between the incident light and the measurement light, the angle change occurring on the grating combination sensing unit is calculated to achieve angle measurement of the target being measured.

2. The precision angle measurement device based on a transmission grating according to claim 1, characterized in that: The device comprises a one-dimensional angle measurement unit (1a) and a signal processing unit (3), and the grating combination sensing unit is a non-decoupled grating combination sensing unit (2a); The one-dimensional angle measurement unit (1a) is mounted on the front end of the measured target using a two-dimensional displacement adjustment seat (107), and a laser light source (101), a convex lens (102), and a first array photoelectric position detector (105) are respectively arranged on the two-dimensional displacement adjustment seat (107); the non-decoupled grating combination sensing unit (2a) is fixed on the measured target using an angle adjustment seat (205), and a first transmission grating (201) and a plane reflector (206) are respectively arranged on the angle adjustment seat (205), and the first transmission grating (201) and the plane reflector (206) are parallel to each other; the signal processing unit (3) is a signal acquisition and processor including a host computer acquisition system (301), and is used to realize data interaction, display, and storage; A laser beam emitted by the laser light source (101) is collimated by a convex lens (102) to form incident light, which is then incident on a first transmission grating (201). The incident light is diffracted into multiple-order diffraction beams after being transmitted through the first transmission grating (201). A first-order diffraction beam in the multiple-order diffraction beam is reflected by a plane reflector (206) to form reflected light. The reflected light is transmitted through the first transmission grating (201) again and undergoes secondary diffraction. The secondary diffraction forms output light parallel to the incident light. The output light is projected onto the first array photoelectric position detector (105) as measurement light. When the yaw angle or pitch angle of the non-decoupled grating combination sensing unit (2a) changes, the distance between the parallel incident light and the measurement light changes accordingly. The signal processing unit (3) calculates the one-dimensional angle change occurring on the non-decoupled grating combination sensing unit (2a) based on the distance between the incident light and the measurement light obtained through detection, thereby achieving one-dimensional angle measurement of the measured target.

3. The precision angle measurement device based on a transmission grating according to claim 2, characterized in that: The scribed lines of the first transmission grating (201) are arranged to be vertical, thereby achieving one-dimensional angle measurement of the deflection angle; The scribed lines of the first transmission grating (201) are arranged to be horizontal, thereby achieving one-dimensional angle measurement of the pitch angle.

4. The precision angle measurement device based on a transmission grating according to claim 2, characterized in that: The distance between the first transmission grating (201) and the plane reflector (206) is adjusted according to the set angular resolution. The larger the distance, the smaller the resolution.

5. A method for measuring precise angles based on a transmission grating, characterized in that The precision angle measurement device based on the transmission grating according to claim 2 is used for measurement, and the deflection angle change value Δθ occurring on the non-decoupled grating combination sensing unit (2a) is calculated by formula (1), wherein the deflection angle change value Δθ is the deflection angle change value of the measured target; in: P is the grating constant of the first transmission grating (201); λ is the wavelength of the laser light source (101); d is the distance between the first transmission grating (201) and the plane reflector (206); F() represents the setting function of P, λ and d; m is the diffraction order, and m is selected as +1; θ m is the diffraction angle of the m-order beam; Δθ is the angle between the incident light and the normal line of the first transmission grating (201); Δl1 is the displacement change value of the measurement light in the horizontal direction detected by the first array photoelectric position detector (105).

6. The precision angle measuring device based on a transmission grating according to claim 1 is characterized in that The device comprises: a two-dimensional angle measurement unit (1b), a decoupled grating combination sensing unit (2b) and a signal processing unit (3); The two-dimensional angle measurement unit (1b) is mounted on the front end of the measured target using a two-dimensional displacement adjustment seat (107), and a laser light source (101), a convex lens (102), a beam splitter prism (103), a right-angle prism (104), a first array photoelectric position detector (105), and a second array photoelectric position detector (106) are respectively arranged on the two-dimensional displacement adjustment seat (107); the decoupled grating combination sensing unit (2b) is fixed on the measured target using an angle adjustment seat (205), and a yaw angle sensing optical path consisting of a first transmission grating (201) and a first double-sided reflection right-angle prism (202), and a pitch angle sensing optical path consisting of a second transmission grating (203) and a second double-sided reflection right-angle prism (204) are respectively arranged on the angle adjustment seat (205); the signal processing unit (3) is a signal acquisition and processor including a host computer acquisition system (301), and is used to realize data interaction, display, and storage; The laser beam emitted by the laser light source (101) passes through a convex lens (102) to generate a collimated beam, and the collimated beam passes through a beam splitter prism (103) and a right-angle prism (104) to generate two parallel incident lights, namely, a first incident light transmitted by the beam splitter prism (103) and a second incident light split by the beam splitter prism (103) and deflected by the right-angle prism (104); The first incident light is incident on the first transmission grating (201), and is diffracted into a first multi-order diffraction light beam after being transmitted through the first transmission grating (201); a first-order diffraction light beam in the first multi-order diffraction light beam is reflected by a first double-sided reflection right-angle prism (202), and then transmitted through the first transmission grating (201) to undergo secondary diffraction, and a first outgoing light parallel to the first incident light is formed by the secondary diffraction, and the first outgoing light is projected onto the first planar array photoelectric position detector (105) as a first measurement light; when the deflection angle of the decoupled grating combination sensing unit (2b) changes, the distance between the first incident light and the first measurement light changes accordingly; The second incident light is incident on the second transmission grating (203), and is diffracted into a second multi-order diffraction light beam after being transmitted through the second transmission grating (203); a first-order diffraction light beam in the second multi-order diffraction light beam is reflected by a second double-sided reflection right-angle prism (204), and is then transmitted through the second transmission grating (203) to undergo secondary diffraction, and a second outgoing light parallel to the second incident light is formed by the secondary diffraction, and the second outgoing light is projected onto the second array photoelectric position detector (106) as a second measurement light; when the pitch angle of the decoupled grating combination sensing unit (2b) changes, the distance between the second incident light and the second measurement light changes accordingly; The signal processing unit (3) calculates the angular changes of the yaw angle and the pitch angle occurring on the decoupled grating combination sensing unit (2b) based on the distance between the first incident light and the first measuring light, and the distance between the second incident light and the second measuring light, thereby achieving two-dimensional angle measurement of the measured target.

7. The precision angle measurement device based on a transmission grating according to claim 6, characterized in that: The structure of the deflection angle sensing optical path is set as follows: the scribed line direction of the first transmission grating (201) is set to be vertical, the plane of the first transmission grating (201) is parallel to the inclined surface of the first double-sided reflection right-angle prism (202), and is horizontal to the inclined edge of the right-angle surface of the first double-sided reflection right-angle prism (202); The structure of the pitch angle sensing optical path is set as follows: the scribed line direction of the second transmission grating (203) is set to be horizontal, the plane of the second transmission grating (203) is parallel to the inclined surface of the second double-sided reflection right-angle prism (204), and is horizontal to the inclined edge of the right-angle surface of the second double-sided reflection right-angle prism (204).

8. The precision angle measurement device based on a transmission grating according to claim 7, characterized in that: The first double-sided reflection right-angle prism (202) and the second double-sided reflection right-angle prism (204) are both double-sided reflection right-angle prisms with double right-angle edges coated; when the decoupled grating combination sensing unit (2b) undergoes an angle change, the laser reflected by the first double-sided reflection right-angle prism (202) only senses the angle information of the yaw angle change, and the laser reflected by the second double-sided reflection right-angle prism (204) only senses the angle information of the pitch angle change.

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