Laser heterodyne interference displacement measurement method

Abstract

The invention relates to the technical field of optical metrology, in particular to a laser heterodyne interference displacement measurement method, which comprises the following steps of: component selection: adopting a reading head, a measurement grating, an electronic signal processing component and a real-time checking module, and transmitting a measurement source: transmitting measurement light to the measurement grating through the reading head, the reading head gives out a heterodyne reference electric signal and a heterodyne measurement electric signal, the heterodyne reference electric signal and the heterodyne measurement electric signal are input into an electronic signal processing part for signal settlement, displacement output of two degrees of freedom is achieved, a conclusion is drawn, the resolution ratio and precision are improved, and the measurement precision is improved. And meanwhile, polarization aliasing is avoided. By adopting the measurement method, polarization aliasing in the measurement process is avoided, nanometer or even higher resolution and precision can be realized, two-degree-of-freedom large-stroke displacement is measured at the same time, and meanwhile, a working end is monitored and adjusted in real time in a monitoring implementation mode.

Description

Technical Field

[0001] The invention relates to the technical field of optical metrology, and in particular to a laser heterodyne interference displacement measurement method. Background Art

[0002] The scope of optical metrology test is quite wide. The country has established metrology standards and testing methods in many aspects, mainly including: photometry, spectral photometry, chromaticity, radiometry, laser parameters, optical material parameters, optical film parameters, imaging optics, low-light image intensifier and night vision instrument parameters, optical fiber and optical communication function, optoelectronic device parameters and other metrology tests. Photometry is limited to a part of the radiation that can be seen by the human eye. It is measured by the visual effect of the human eye. The visual effect of the human eye is different for various wavelengths. It is usually expressed by V (λ) and defined as the human eye visual function or spectral luminous efficiency. Therefore, photometry is not a pure physical quantity, but a physiological and psychophysical quantity related to human vision. The main parameters of photometric measurement test are luminous intensity, brightness, illumination and luminous flux. The unit of luminous intensity is candela (cd), which is one of the 7 basic units in the International System of Units. It is impossible to derive it directly from other units. With the definition of the candela basic unit, the units of brightness, luminous flux and illumination and chromaticity generated by the light source can be derived. When studying laser heterodyne interference displacement, a measurement method is needed.

[0003] The existing patent, with the announcement number CN107255451B, discloses an angle-compensated laser heterodyne interference displacement measurement device and method. The present invention uses a corner cube prism coated with a semi-transparent and semi-reflective film as a measuring mirror for displacement and angle measurement. The interference signal generated by the laser heterodyne interference optical path is detected by a photoelectric detector, and the initial displacement measurement value is obtained through data acquisition and processing; the laser spot detects the laser spot position signal generated by the angle measurement optical path, and the pitch angle error value and the roll angle error value of the measured object are obtained through data acquisition and processing, and then the angle value required for displacement compensation can be obtained; the initial displacement value is compensated by the angle value to obtain the final displacement measurement value. The present invention solves the technical problem that the angle error of the corner cube prism in the traditional laser interferometric displacement measurement technology affects the displacement measurement accuracy, realizes high-precision displacement measurement, and can realize simultaneous detection of the three degrees of freedom of the roll angle, pitch angle and linear displacement of the measured object.

[0004] Although the above invention realizes high-precision displacement measurement and can realize simultaneous detection of the three degrees of freedom of the yaw angle, pitch angle and linear displacement of the object under test, it is easy to cause polarization aliasing in actual application, has low resolution, and cannot perform real-time monitoring and adjustment, thereby affecting the measurement operation of the method.

[0005] In view of this, the present invention proposes a laser heterodyne interference displacement measurement method to solve the above problem. Summary of the invention

[0006] In view of the shortcomings of the prior art, the purpose of the present invention is to propose a laser heterodyne interferometry displacement measurement method, which has the advantages of avoiding polarization aliasing, achieving nanometer or even higher resolution and accuracy, and simultaneously measuring large-stroke displacements of two degrees of freedom. At the same time, through the implementation of monitoring, the working end can be monitored and adjusted in real time, etc., which solves the problems of polarization aliasing that is easy to cause in actual application, low resolution, and inability to perform real-time monitoring and adjustment.

[0007] To achieve the above object, the present invention provides the following technical solutions:

[0008] A laser heterodyne interferometry displacement measurement method comprises the following steps:

[0009] a1. Component selection: using reading head, measuring grating, electronic signal processing components and real-time verification module;

[0010] a2. Transmitting measurement source: Transmitting measurement light to the measurement grating through the reading head;

[0011] a3. Measurement source diffraction return: The two diffracted light beams generated by the measurement grating return to the reading head along the original path;

[0012] a4. Provide electrical signals and transmit: the reading head gives the heterodyne reference electrical signal and the heterodyne measurement electrical signal to the electronic signal processing component;

[0013] a5. Perform signal settlement: realize displacement output of two degrees of freedom;

[0014] a6. Conclusion: The resolution and accuracy are improved while polarization aliasing is avoided.

[0015] As a preferred technical solution, two beams of measuring light are provided by the reading head, and both beams of measuring light are incident on the measuring grating at the Littrow angle.

[0016] As a preferred technical solution, the reading head provides one heterodyne reference electrical signal and two heterodyne measurement electrical signals.

[0017] As a preferred technical solution, the reading head and the measuring grating are bidirectionally connected, the output end of the reading head is electrically connected to the input end of the electronic signal processing component, and the input end of the real-time verification module is electrically connected to the output end of the electronic signal processing component.

[0018] As a preferred technical solution, the input end of the central processing unit (i.e., computer) is electrically connected to the output end of the real-time verification module, the output end of the central processing unit is signal-connected to the input end of the data display screen, and the data storage module is bidirectionally connected to the central processing unit.

[0019] As a preferred technical solution, the real-time verification module adopted includes a data conversion module, a data collection module, a data comparison module and a data verification module. The input end of the data conversion module is signal-connected to the output end of the electronic signal processing component, the output end of the data conversion module is signal-connected to the input end of the data collection module, the output end of the data collection module is signal-connected to the input end of the data comparison module, and the output end of the data comparison module is signal-connected to the input end of the data verification module.

[0020] As a preferred technical solution, the reading head provides a heterodyne reference electrical signal and a heterodyne measurement electrical signal to input into the electronic signal processing component, and then the data is converted through the real-time verification module, and then the data is collected. The collected data is compared through the data comparison module to achieve real-time monitoring, and then the compared data is verified, and then monitored and processed by the central processing unit to obtain the results.

[0021] As a preferred technical solution, the measured results are stored in the data storage module through the operation of the central processing unit, and the central processing unit transmits the measured results to the data display screen for display operation.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] 1. The present invention avoids polarization aliasing during the measurement process by adopting this measurement method, can achieve nanometer or even higher resolution and accuracy, and simultaneously measure large-stroke displacement of two degrees of freedom. At the same time, by implementing monitoring, the working end can be monitored and adjusted in real time.

[0024] 2. The present invention uses a reading head, a measuring grating, an electronic signal processing component, a real-time verification module and other components for measurement, thereby achieving the effect of maintaining the stability of the measured data and avoiding data deviation during use. At the same time, by using a data display screen and a data storage module, the measured structure can be displayed and stored, avoiding data confusion and maintaining the stability of the measurement method. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a schematic diagram of the process structure of the method of the present invention;

[0026] Figure 2 It is a schematic diagram of the flow structure of the real-time verification module in the method of the present invention. DETAILED DESCRIPTION

[0027] The embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. In the description of the present invention, it should be understood that the orientation or position relationship indicated by the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", etc. is based on the orientation or position relationship shown in the accompanying drawings, which is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the present invention. In addition, the terms "first" and "second" are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "multiple" is two or more, and the meaning of "several" is one or more, unless otherwise clearly and specifically defined.

[0028] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or mutual communication; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0029] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0030] The disclosure below provides many different embodiments or examples to realize different structures of the present invention. In order to simplify the disclosure of the present invention, the parts and settings of specific examples are described below. Of course, they are only examples, and the purpose is not to limit the present invention. In addition, the present invention can repeat reference numbers and / or reference letters in different examples, and this repetition is for the purpose of simplicity and clarity, which itself does not indicate the relationship between the various embodiments and / or settings discussed. In addition, the present invention provides various specific examples of processes and materials, but those of ordinary skill in the art can appreciate the application of other processes and / or the use of other materials.

[0031] In order to better understand the above technical solution, the above technical solution will be described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0032] According to the attached Figure 1-2 As shown, an embodiment of the present invention provides a laser heterodyne interferometry displacement measurement method, comprising the following steps:

[0033] a1. Component selection: using reading head, measuring grating, electronic signal processing components and real-time verification module;

[0034] a2. Transmitting measurement source: Transmitting measurement light to the measurement grating through the reading head;

[0035] a3. Measurement source diffraction return: The two diffracted light beams generated by the measurement grating return to the reading head along the original path;

[0036] a4. Provide electrical signals and transmit: the reading head gives the heterodyne reference electrical signal and the heterodyne measurement electrical signal to the electronic signal processing component;

[0037] a5. Perform signal settlement: realize displacement output of two degrees of freedom;

[0038] a6. Conclusion: The resolution and accuracy are improved while polarization aliasing is avoided.

[0039] By adopting this measurement method, polarization aliasing is avoided during the measurement process, and nanometer or even higher resolution and accuracy can be achieved. At the same time, large-stroke displacements of two degrees of freedom can be measured. At the same time, the working end can be monitored and adjusted in real time by implementing monitoring.

[0040] As a preferred embodiment of this embodiment, two beams of measuring light are provided by the reading head, and both beams of measuring light are incident on the measuring grating at the Littrow angle.

[0041] It is worth noting that two beams of measuring light are used, which facilitates comparative measurement during the measurement process and maintains the accuracy of the measurement results.

[0042] As a preferred embodiment of this embodiment, the reading head provides one heterodyne reference electrical signal and two heterodyne measurement electrical signals.

[0043] It is worth noting that one heterodyne reference electrical signal and two heterodyne measurement electrical signals are provided. During the measurement process, by comparing the references, the subsequent measurement results can be made more accurate and the errors after the measurement can be reduced.

[0044] As a preferred embodiment of this invention, the reading head and the measuring grating are connected bidirectionally, the output end of the reading head is electrically connected to the input end of the electronic signal processing component, and the input end of the real-time verification module is electrically connected to the output end of the electronic signal processing component.

[0045] It is worth mentioning that the reading head used consists of a magnetic fence and a reading head. It accurately measures the length of the object by measuring and reading the scale on the magnetic scale. It uses the magnetic field interaction between the magnetic strip on the fence and the reading head. When the object moves on the magnetic scale, the reading head will sense the changes in the magnetic strip on the fence and output the corresponding digital readings. The reading head has the characteristics of high precision, good stability, and fast response speed. It can measure and record the measurement results in real time and display them intuitively through a digital display. At the same time, the reading head also has multiple functions, such as data storage, error correction, etc. With these functions, users can perform data analysis and processing more conveniently. In addition to its application in measuring the length of objects, the reading head can also be used for angle measurement. The grating reading head is a photoelectric measuring instrument based on Moire fringe technology. It consists of a grating pair, a photoelectric receiving element, a light source and a lighting system composed of a collimator. The grating reading head determines the position of the object by measuring the Moire fringe signal on the grating. The measuring grating is a special photoelectric sensor, which is mainly used to detect and measure whether the product meets the specified requirements. Like ordinary through-beam photoelectric sensors, it contains a transmitter and a light receiver that are separated and placed opposite to each other, but its outer dimensions are larger and are long tubular. The detection light generated by the detection and measurement grating transmitter is not just one beam like an ordinary photoelectric sensor, but a light array is generated at a fixed interval along the length direction to form a "light curtain". In a scanning manner, it cooperates with the controller and its software to realize the function of detecting and measuring the outer dimensions of the object.

[0046] As a preferred embodiment of this invention, the input end of the central processing unit (i.e., computer) is electrically connected to the output end of the real-time verification module, the output end of the central processing unit is signal-connected to the input end of the data display screen, and the data storage module is bidirectionally connected to the central processing unit.

[0047] As a preferred embodiment of this embodiment, the real-time verification module adopted includes a data conversion module, a data collection module, a data comparison module and a data verification module. The input end of the data conversion module is signal-connected to the output end of the electronic signal processing component, the output end of the data conversion module is signal-connected to the input end of the data collection module, the output end of the data collection module is signal-connected to the input end of the data comparison module, and the output end of the data comparison module is signal-connected to the input end of the data verification module.

[0048] It is worth mentioning that the real-time verification module is used to facilitate the conversion and collection of data, and also to facilitate the verification operation of the measured data, thereby improving the accuracy of the measured data.

[0049] As a preferred embodiment of this invention, the reading head provides a heterodyne reference electrical signal and a heterodyne measurement electrical signal to input into the electronic signal processing component, and then the data is converted through the real-time verification module, and then the data is collected. The collected data is compared through the data comparison module to achieve real-time monitoring, and then the compared data is verified and then monitored and processed by the central processing unit to obtain the result.

[0050] As a preferred embodiment of the present invention, the measured results are stored in the data storage module through the operation of the central processing unit, and the central processing unit transmits the measured results to the data display screen for display operation.

[0051] It is worth mentioning that the data storage module and the data display screen can display and store the measurement results, avoid confusion of the results, and maintain the accuracy of the measurement results. By using the reading head, measuring grating, electronic signal processing components and real-time verification module and other components for measurement, the effect of maintaining the stability of the measured data can be achieved, avoiding data deviation during use. At the same time, by using the data display screen and the data storage module, the effect of displaying and storing the measured results can be achieved, avoiding data confusion and maintaining the stability of the measurement method.

[0052] When a laser heterodyne interference displacement measurement method of the present invention is used, a reading head gives two beams of measurement light to be incident on a measurement grating at a Littrow angle, two beams of diffracted light are generated and return along the original path, and the reading head gives a heterodyne reference electrical signal and two heterodyne measurement electrical signals, which are input into an electronic signal processing component to perform signal settlement and realize displacement output of two degrees of freedom. After solution, displacement output of two degrees of freedom is realized, and it is concluded that the measurement method avoids polarization aliasing, can achieve nanometer or even higher resolution and accuracy, and can simultaneously measure large-stroke displacement of two degrees of freedom, and at the same time, the working end can be monitored and adjusted in real time by implementing monitoring.

[0053] In the description of this specification, the description with reference to the terms "embodiment", "one embodiment", "certain embodiments", "illustrative embodiment", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0054] The basic principles, main features and advantages of the present invention are described above in conjunction with specific embodiments. Those skilled in the art should understand that the present invention is not limited by the above embodiments. The above embodiments and descriptions are only preferred examples of the present invention and are not intended to limit the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention to be protected. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A laser heterodyne interferometry displacement measurement method, characterized in that: The steps include: a1. Component selection: using reading head, measuring grating, electronic signal processing components and real-time verification module; a2. Transmitting measurement source: Transmitting measurement light to the measurement grating through the reading head; a3. Measurement source diffraction return: The two diffracted light beams generated by the measurement grating return to the reading head along the original path; a4. Provide electrical signals and transmit: the reading head gives the heterodyne reference electrical signal and the heterodyne measurement electrical signal to the electronic signal processing component; a5. Perform signal settlement: realize displacement output of two degrees of freedom; a6. Conclusion: The resolution and accuracy are improved while polarization aliasing is avoided.

2. The laser heterodyne interferometry displacement measurement method according to claim 1, characterized in that: The measuring light provided by the reading head is two beams, and both beams of measuring light are incident on the measuring grating at the Littrow angle.

3. The laser heterodyne interferometry displacement measurement method according to claim 1, characterized in that: The reading head provides one heterodyne reference electrical signal and two heterodyne measurement electrical signals.

4. The laser heterodyne interferometry displacement measurement method according to claim 1, characterized in that: The reading head and the measuring grating are connected in a bidirectional manner, the output end of the reading head is electrically connected to the input end of the electronic signal processing component, and the input end of the real-time verification module is electrically connected to the output end of the electronic signal processing component.

5. The laser heterodyne interferometry displacement measurement method according to claim 1, characterized in that: The input end of the central processing unit (ie, computer) is electrically connected to the output end of the real-time verification module, the output end of the central processing unit is signal-connected to the input end of the data display screen, and the data storage module is bidirectionally connected to the central processing unit.

6. The laser heterodyne interferometry displacement measurement method according to claim 1, characterized in that: The real-time verification module adopted includes a data conversion module, a data collection module, a data comparison module and a data verification module. The input end of the data conversion module is signal-connected to the output end of the electronic signal processing component, the output end of the data conversion module is signal-connected to the input end of the data collection module, the output end of the data collection module is signal-connected to the input end of the data comparison module, and the output end of the data comparison module is signal-connected to the input end of the data verification module.

7. The laser heterodyne interferometry displacement measurement method according to claim 1, characterized in that: The reading head provides a heterodyne reference electrical signal and a heterodyne measurement electrical signal to input into the electronic signal processing component, and then the data is converted through the real-time verification module, and then the data is collected. The collected data is compared through the data comparison module to achieve real-time monitoring, and then the compared data is verified, and then monitored and processed by the central processing unit to obtain the results.

8. The laser heterodyne interferometry displacement measurement method according to claim 1, characterized in that: The measured results are stored in the data storage module through the operation of the central processing unit, and the central processing unit transmits the measured results to the data display screen for display operation.

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