CN108278977B - Measuring instrument and measuring method - Google Patents
Measuring instrument and measuring method Download PDFInfo
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- CN108278977B CN108278977B CN201710011277.8A CN201710011277A CN108278977B CN 108278977 B CN108278977 B CN 108278977B CN 201710011277 A CN201710011277 A CN 201710011277A CN 108278977 B CN108278977 B CN 108278977B
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- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B11/00—Measuring arrangements characterised by the use of optical techniques
- G01B11/24—Measuring arrangements characterised by the use of optical techniques for measuring contours or curvatures
- G01B11/2441—Measuring arrangements characterised by the use of optical techniques for measuring contours or curvatures using interferometry
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Abstract
The invention provides a measuring instrument and a measuring method, wherein the measuring instrument comprises a light generation module, a light signal receiving module, a light path system, a control module and a spatial light modulation module. The light generation module generates an incident light beam and transmits the incident light beam to the spatial light modulation module and the object to be measured through the optical path system. The spatial light modulator receives a first modulation signal and the incident light beam, generates a first modulation light beam, and emits the first modulation light beam into the optical path system. The optical path system receives the first modulated light beam and the reference light beam and transmits the first modulated light beam and the reference light beam to the optical signal receiving module. The optical signal receiving module generates measurement data and transmits the measurement data to the control module. The measuring instrument and the measuring method provided by the invention can completely determine the parameters of the object to be measured by adopting the spatial light modulator and the iterative algorithm. Therefore, the measuring instrument and the measuring method provided by the invention have the characteristics of capability of measuring any type of surface, high measuring speed and high accuracy.
Description
Technical Field
The present invention relates to a measuring instrument and a measuring method, and more particularly, to a measuring instrument and a measuring method using a spatial light modulator.
Background
With advances in technology and increased levels of processing, there is a trend toward the use of high precision components in manufacturing to provide high performance products. In particular, highly accurate components (e.g., optics, lenses, mirrors, etc.) designed for specialized functions, which are not versatile and have relatively complex structures, are used. Even though the production costs of such complex high precision parts are high, the need for such parts in the industry is still growing, since when such high precision parts can be provided, the designer of the product can be made less restrictive, thereby achieving stronger product performance and better product morphology. This presents new challenges to component manufacturers in the quality control area. High precision measurement of such components is important for quality control in the manufacturing process. The conventional high-precision measurement method is to measure the produced part by using an interferometer and a high-precision reference piece. However, the conventional measurement method has the following problems:
1. the conventional measurement method requires a reference member with high accuracy to be manufactured. This can have a number of adverse consequences including increased cost and increased production cycle due to the difficulty in making high precision references, accumulation of errors due to errors in the references themselves, wear of the references due to repeated installation and removal of the references, etc.
2. The conventional measurement method is slow. The measurement is carried out by adopting a traditional interferometer, and the measurement speed is slow. The reason for the slow speed is various, for example, the measurement by using the traditional interferometer often causes the problems of eccentricity, off-axis and the like, and the problems of the eccentricity, the off-axis and the like, are adjusted by a physical mode, are calibrated continuously and have low efficiency.
3. The traditional measurement method has large uncertainty. On the one hand, conventional interferometers are used for measurement, and the measurement result is interference data (usually an interference image). People need to judge what difference exists between the part to be measured and the reference piece by experience through observing the obtained image, and the uncertainty is large. On the other hand, even if it is determined what difference exists between the component to be measured and the reference member, it is difficult to accurately determine the position and size of the difference, resulting in a great difficulty in eliminating the difference in the subsequent process.
Therefore, a new measuring instrument and a new measuring method are needed to solve the problems in the prior art.
Disclosure of Invention
The invention provides a measuring instrument and a measuring method, which have the characteristics of capability of measuring any type of surface, high measuring speed and high accuracy.
The invention provides a measuring instrument and a measuring method, wherein the measuring instrument provided by the invention comprises a light generation module, a light signal receiving module and an optical path system, and is characterized by further comprising the following components: the device comprises a control module and a spatial light modulation module. The light generation module generates an incident light beam and inputs the incident light beam into the optical path system. The light path system transmits the incident beam to the spatial light modulation module and the object to be measured. The spatial light modulator receives a first modulation signal from the control module and the incident light beam, generates a first modulation light beam, and inputs the first modulation light beam into the optical path system. The optical path system receives the first modulated light beam and the reference light beam returned from the object to be detected, and transmits the reference light beam to the optical signal receiving module. The optical signal receiving module receives the first modulated light beam and the reference light beam, generates measurement data and transmits the measurement data to the control module.
According to at least one embodiment of the present invention, the optical path system includes an optical system including a first lens subsystem, a second lens subsystem, and a combining subsystem. The combiner subsystem transmits the incident beam to the spatial light modulation module and the object to be measured, and transmits the first modulation beam and the reference beam to the optical signal receiving module. The first lens subsystem matches the incident beam transmitted to the spatial light modulation module by the combining subsystem according to the size of the spatial light modulator. The second lens subsystem matches the first modulated beam and the reference beam according to a size of the optical signal receiving module.
According to at least one embodiment of the invention, the control module generates a second modulation signal based on the measurement data, and takes the second modulation signal as a new first modulation signal, and receives the measurement data again.
According to at least one embodiment of the present invention, the control module receives and processes the measurement data, and calculates correction information according to the processed measurement data. The control module generates a second modulation signal according to the correction information and the first modulation signal.
According to at least one embodiment of the invention, the control module pre-processes the data, the pre-processing comprising mathematically transforming the data. The mathematical transform includes filtering out certain frequency domain information in the data.
According to at least one embodiment of the present invention, the control module stores a plurality of preset data patterns, and the control module determines the preset data pattern corresponding to the processed measurement data. And generating parameters corresponding to the processed measurement data according to the preset data mode, and generating correction information according to the parameters.
According to at least one embodiment of the present invention, the control module further stores at least one coincidence signal, and the control module compares the measurement data with the coincidence signal. When the measurement result does not match the coincidence signal, a second modulated light beam is generated and used as a new first modulated signal, and the measurement data is received again. The control module does not generate a second modulation signal when the measurement result matches the match signal.
According to at least one embodiment of the invention, the control module further comprises an iteration number memory and an iteration upper limit, and the control module compares the iteration number with the iteration upper limit when receiving the measurement data. When the iteration number is smaller than the iteration upper limit, the control module generates a second modulation signal according to the measurement data, takes the second modulation signal as a new first modulation signal, receives the measurement data again, and accumulates the iteration number stored in the iteration number memory. The control module does not generate the second modulation signal when the number of iterations is equal to the upper iteration limit.
According to at least one embodiment of the invention, when measuring an object to be measured with known ideal parameters, the control module generates a first modulation signal according to the ideal parameters of the object to be measured. When an object to be measured with an unknown shape is measured, the control module receives external input information and generates a first modulation signal according to the input information.
According to at least one embodiment of the present invention, the optical path system further includes an adjusting system, and the adjusting system is connected to the control module and moves the object to be measured or moves the optical path system according to the movement signal sent by the control module.
According to at least one embodiment of the invention, the control module performs calculation according to the measurement data obtained once or more times to obtain the measurement result.
In order to solve at least a part of technical problems of the present invention, the present invention further provides a measurement method, specifically comprising the steps of:
step 1: the light generation module emits an incident light beam and inputs the incident light beam into the optical path system; the light path system transmits the incident beam to an object to be detected and receives a reference beam returned by the object to be detected;
step 2: the control module generates a first modulation signal according to the ideal parameters of the object to be detected or external input information;
and step 3: the spatial light modulator modulates the incident beam into a first modulated beam according to a first modulation signal from the control module and inputs the first modulated beam into the optical path system;
and 4, step 4: the optical signal receiving module receives the first modulated light beam and the reference light beam output in the optical path system, generates measurement data according to the modulated light beam and the reference light beam, and transmits the measurement data to the control module;
and 5: the control module determines whether the measurement is complete,
if not, the control module generates a second modulation signal according to the measurement data and the first modulation signal; taking the second modulation signal as a new first modulation signal, and returning to the step 3;
and if the measurement is finished, outputting the parameter corresponding to the first modulation signal.
According to at least one embodiment of the present invention, the control module receives and processes the measurement data, and calculates correction information according to the processed measurement data. The control module generates a second modulation signal according to the correction information and the first modulation signal.
According to at least one embodiment of the invention, the control module pre-processes the data, the pre-processing comprising mathematically transforming the data. The mathematical transform includes filtering out certain frequency domain information in the data.
According to at least one embodiment of the present invention, the method for the control module to calculate the correction information according to the processing result includes:
the control module is stored with a plurality of preset data modes,
generating a preset data mode corresponding to the processed measurement data;
and determining correction information corresponding to the processed measurement data according to the preset data mode.
According to at least one embodiment of the invention, the method for judging whether the measurement is completed by the control module comprises the following steps:
and judging whether the frequency of taking the second modulation signal as a new first modulation signal is greater than a threshold value and/or judging whether the difference between the parameter corresponding to the current first modulation signal and the parameter of the object to be detected is less than a preset value.
According to at least one embodiment of the present invention, a method for determining whether a difference between a parameter corresponding to a current first modulation signal and a parameter of an object to be measured is smaller than a preset value includes:
the control module is stored with at least one coincidence signal, and compares the measurement data with the coincidence signal;
when the measurement result is not matched with the coincidence signal, the difference between the parameter corresponding to the current first modulation signal and the parameter of the object to be measured is not considered to be smaller than a preset value;
and when the measurement result is matched with the coincidence signal, the difference between the parameter corresponding to the current first modulation signal and the parameter of the object to be measured is considered to be smaller than a preset value.
According to at least one embodiment of the invention, when measuring an object to be measured with known ideal parameters, the control module generates a first modulation signal according to the ideal parameters of the object to be measured. When an object to be measured with an unknown shape is measured, the control module receives external input information and generates a first modulation signal according to the input information.
In order to solve at least a part of technical problems of the present invention, the measuring method of the present invention further comprises the steps of:
the adjusting system moves the first part of the object to be measured to the area where the light path system transmits the incident beam, or moves the light path system to transmit the incident beam to the first part of the object to be measured, and then step 1 is started; when the measurement is judged to be completed in the step 5, the adjusting system moves the second part of the object to be measured to the area to which the incident beam is to be transmitted by the optical path system, or moves the optical path system to transmit the incident beam to the second part of the object to be measured, and then the step 1 is restarted until all the areas to be measured of the object to be measured are measured;
the control module calculates the surface information of the object to be measured according to the result of each measurement and the moving distance of the adjusting system.
According to at least one embodiment of the present invention, the determination is performed each time the measurement data is obtained, and if the determination is sufficient to obtain the measurement result, the calculation is performed to obtain the measurement result. If the result is judged that the measurement result can not be obtained, the next measurement is carried out, and the judgment is carried out again.
According to at least one embodiment of the present invention, the method for determining after obtaining the measurement data each time comprises:
judging whether the quantity of the currently obtained measurement data reaches a measurement frequency upper limit or not, and if the quantity of the currently obtained measurement data is equal to the measurement frequency upper limit, judging that the quantity of the currently obtained measurement data is enough to obtain a measurement result; if the number of the currently obtained measurement data is smaller than the upper limit of the measurement times, judging that the measurement result cannot be obtained;
and/or judging whether the error of the obtained measurement data is smaller than a preset value, if the error of the currently obtained measurement data is smaller than or equal to the preset value, judging that the measurement result is enough; and if the error of the currently obtained measurement data is larger than the preset value, judging that the measurement result cannot be obtained.
The measuring instrument and the measuring method provided by the invention can completely determine the parameters of the object to be measured by adopting the spatial light modulator and the iterative algorithm, and realize measurement according to the tolerance. Therefore, the measuring instrument and the measuring method provided by the invention have the characteristics of capability of measuring any type of surface, high measuring speed and high accuracy.
It is to be understood that both the foregoing general description and the following detailed description of the present invention are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.
Drawings
The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the invention and together with the description serve to explain the principle of the invention. In the drawings:
fig. 1 shows a schematic structural view of an embodiment of the measuring instrument of the present invention.
Fig. 2 shows a schematic flow chart of an embodiment of the measurement method of the present invention.
Detailed Description
Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts. Further, although the terms used in the present invention are selected from publicly known and used terms, some of the terms mentioned in the description of the present invention may be selected by the applicant at his or her discretion, the detailed meanings of which are described in relevant parts of the description herein. Furthermore, it is required that the present invention is understood, not simply by the actual terms used but by the meaning of each term lying within.
Reference is first made to fig. 1 to illustrate a non-limiting example of the present invention. In this example, the surveying instrument has a structure as shown in fig. 1, and includes a control module 1, a light generation module 2, a spatial light modulation module 3, an optical signal receiving module 4, and an optical path system 5. The specific function of the various components of the meter in the present non-limiting example is illustrated in light path order:
the control module 1 is electrically connected with the spatial light modulation module 3 and the optical signal receiving module 4. The first modulation signal 11 may be sent to the spatial light modulation module 3, and the measurement data 41 output by the optical signal receiving module 4 may be received. The control module 1 may be any system with sufficient processing power. For example, it may be a microcomputer or a tablet computer.
The light generating module 2 generates an incident light beam 21 and inputs it to the optical path system 5.
At least a part of the function of the optical path system 5 is to transmit the incident light beam 21 generated by the light generation module 2 to the spatial light modulation module 3 and the object 6 to be measured.
The spatial light modulator 3 is used for simulating the light wave front reflected by the surface of the object 6 to be measured. Specifically, the spatial light modulator 3 receives the first modulation signal 11 from the control module 1, generates analog phase modulation according to the first modulation signal 11, generates a reflected light wavefront, modulates the incident light 21 transmitted from the optical path system 5 into a first modulation light beam 31, and inputs the first modulation light beam 31 into the optical path system 5.
The optical path system 5 has at least a part of the other functions of irradiating the incident beam 21 onto the object 6 to be measured, and the reference beam 61 reflected by the object to be measured also enters the optical path system 5.
At least a part of other functions of the optical path system 5 are to receive the first modulated light beam 31 and the reference light beam 61, combine them and transmit them to the optical signal receiving module 4.
The optical signal receiving module 4 receives the combined light beam of the modulated light beam 31 and the reference light beam 61, and generates the measurement data 41. And transmits the measurement data 41 to the control module 1. Specifically, the optical signal receiving module 4 may be a camera device. Interference data (interference may be an image or other form of data) generated by the modulated beam 31 and the reference beam 61 is collected and transmitted as measurement data 41 to the control module 1.
It is noted that the position of the spatial light modulator 3 and/or the object 6 to be measured may be adjustable. The tunable method may be varied. For example, the optical path system 5 may optionally further include a regulating system (not shown). This regulating system is connectable to and controllable by the control module 1. Under such an arrangement, the adjustment system moves the object 6 to be measured or moves the optical path system 5 according to the movement signal sent by the control module 1.
The advantages of such an arrangement include that the spatial light modulator 3 can simulate only a part of the surface of the object 6 to be measured each time, measure different parts of the object 6 to be measured in a manner similar to scanning for a plurality of times, and after the measurement of the plurality of parts is completed, the surface condition of the complete device to be measured can be obtained in a data processing manner (for example, image splicing) so as to realize the measurement of a larger object 6 to be measured, or realize the measurement of the object to be measured with higher precision. The specific method may be that the optical path system 5 is configured to transmit the incident light beam 21 to a specific area. The adjustment system first moves the first part of the object 6 to be measured to this specific area and then starts the measurement. After the measurement is completed, the adjustment system moves a second portion of the object 6 to be measured, which is different from the first portion, by the specific area and then restarts the measurement until all the areas to be measured of the object 6 to be measured are measured. Alternatively, the specific method may be that after the object 6 is set, the optical path system 5 is moved to transmit the incident beam 21 to the first portion of the object 6, and then the measurement is started. After the measurement is completed, the adjustment system moves the optical path system 5 so as to transmit 21 the incident light beam to a second portion of the object 6 to be measured, which is different from the first portion, and starts the measurement again. Until all areas of the object 6 to be measured have been measured. When measuring a large object using the above method, after all the areas to be measured are measured, the control module 1 may calculate the surface information of the object to be measured 6 according to the result of each measurement and the distance moved by the adjustment system.
The above example is only a non-limiting example of the present invention, and many of the modules may be implemented in various ways, and each module is described below as an example.
First, the optical system 5 will be explained. Optionally, the optical system 5 includes a first lens subsystem 51, a second lens subsystem 52, and a combining subsystem 53. In addition, the optical system 5 may also include one or more light intensity adjusting subsystems. The details of each subsystem are as follows:
the first lens subsystem 51 may include a size matching system for optically matching the size of the spatial light modulator with the combining subsystem 53, the object 6 to be measured, and the like. The first lens subsystem 51 may be a set of fixed lenses; or a plurality of sets of fixed lenses, so that the first lens subsystem is suitable for different objects to be detected, light sources and the like.
The second lens subsystem 52 may also include a size matching system that adjusts the combined light beam to fit the size of the optical signal receiving module 4 when transmitting the combined light beam to the optical signal receiving module 4.
Combining subsystem 53 may include a splitting/combining prism. The combining subsystem 53 is configured to divide the incident light beam 21 (coherent light) emitted by the light generating module 2 into two paths, transmit the two paths to the object 6 to be measured and the first lens subsystem 51 (finally transmit the two paths to the spatial light modulator 3), and output the light beams output by the spatial light modulator 3 and the object 6 to be measured to the optical signal receiving module 4. Preferably, the combining system 5 can adjust the spatial position of the object 6 to be measured and/or the spatial light modulator 3 to approximately satisfy the conditions of the same optical path, concentricity and the like. It can be understood that, because the spatial light modulator is used, the object to be measured and the spatial light modulator do not need to strictly realize the same optical path, concentricity and the like, and the spatial position parameters are within the adjustable range of the spatial light modulator. Compared with the traditional mode, the measurement efficiency is greatly improved.
The optical system 5 may also include one or more light intensity adjusting subsystems (not shown). The light intensity adjusting subsystem can attenuate or increase the light intensity of the spatial light modulator 3 or the light beam irradiated onto the object 6 to be measured, so that the intensities of the modulated light beam 31 and the reference light beam 61 finally reaching the optical signal receiving module 4 are substantially consistent, so that the two can form easily recognized information (such as interference fringes).
Next, the light generation module 2 will be explained. The light generating module 2 may be various devices that generate parallel light. For example, as a non-limiting example, light generating module 2 includes a light source 22 and a collimated light path 23. Wherein the light source 22 may employ a semiconductor laser. Light source 22 and collimated light path 23 cooperate to output substantially parallel light beams. Optionally, the light generating module 2 may have a plurality of different light sources 22 for selection or replacement, so as to achieve the effect of being able to test the color difference at different wavelengths. Optionally, the collimated light path 23 may have a function of appropriately adjusting the size of the light beam, so that the light beam can meet the size of the object to be measured and/or the requirements of the spatial light modulator.
In order to achieve a better measurement effect, the control module 1 may generate a second modulation signal according to the received measurement data 41 after receiving the measurement data 41, and send the second modulation signal to the spatial light modulator 3 again as a new first modulation signal 11. This process is referred to as an iteration of the first modulated signal 11. Optionally, the iteration of the first modulation signal 11 may be repeated, that is, the second modulation signal may be generated again according to the measurement data 41 measured by the new iterated first modulation signal 11, and the second modulation signal is taken as the new first modulation signal 11 again, and so on, and the iteration is performed on the first modulation signal repeatedly.
The specific method for generating the second modulation signal according to the received measurement data 41 may be that the control module 1 performs data processing on data formed by the measurement data 41, calculates correction information according to a processing result, and generates the second modulation signal according to the correction information and the first modulation signal 11. The method of calculating the correction signal according to the data processing result may be various, and one optional method is that a plurality of preset data patterns are stored in the control module 1, and the control module 1 determines the preset data pattern corresponding to the processed measurement data 41. And generating specific parameters corresponding to the processed measurement data 41 according to the judged preset data mode, and then generating correction information according to the generated specific parameters.
In one non-limiting example, the measurement data 41 is an interference image. The control module 1 stores three image modes of ring, barrel and pillow. After the optical signal receiving module 4 acquires the interference image, the current interference image of the control module 1 belongs to which of three image modes, i.e., "barrel", "ring", and "pincushion".
The present non-limiting example is further described below with the present interference image being in "annular" mode. And when the current interference image is determined to belong to the annular mode, determining correction information corresponding to the processed measurement data according to the preset data mode.
It should be noted that, there may be various methods for determining the correction information corresponding to the processed measurement data according to the preset data pattern. For example, specific parameters in the interference image may be determined first. The specific parameters may include the position of the center of a circle, the radius, the number of concentric rings, the width of the annular stripe, the distance between two adjacent annular stripes, and the like. The control module 1 generates the correction information according to the specific parameter, and then determines how to generate the second modulation signal.
Or continuing to take the example that the current interference image belongs to the "ring" mode, another method for determining the correction information corresponding to the processed measurement data according to the preset data mode may be that a plurality of preset measurement results corresponding to specific correction information are stored in the data mode stored in the control module 1. And comparing the processed interference image with a plurality of preset measurement nodes in a ring mode, and taking specific correction information corresponding to the matched preset measurement result as correction information to generate a second modulation signal.
Specifically, the plurality of predetermined measurements stored in the "ring" mode includes a predetermined measurement a corresponding to a "z-micron recess" (X, Y). When the processed interference image corresponds to the predetermined measurement result a, the control module 1 generates the second modulation signal according to the z micrometer recess at "(X, Y).
Referring to fig. 2, a specific method of modification and iteration is described below as an alternative example.
Step 1 the light generating module 2 emits an incident light beam 21. The light emission may be manually activated by a user, or may be activated by a control module 1 electrically connected to the light generation module 2 issuing a command to the light generation module 2. The incident beam 21 is input into the optical path system 5; and arranging the object 6 to be measured at the position corresponding to the light beam emitted from the optical path system 5, and inputting the reference light beam 61 into the optical path system 5.
Step 2: the control module 1 generates a first modulation signal 11. And transmits it to the spatial light modulator 3.
And step 3: the spatial light modulator 3 receives the first modulation signal 11 from the control module 1 and forms therewith a wavefront modulation of the optical wave of the virtual object surface. The incident light 21 enters the spatial light modulator 3 which has simulated the surface of the virtual object, and reflects the first modulated light beam 31, and the first modulated light beam 31 enters the optical path system 5.
And 4, step 4: the optical signal receiving module 4 receives the light beam formed by combining the first modulated light beam 31 and the reference light beam 61 emitted from the optical path system 5, generates measurement data 41 according to the combined light beam of the modulated light beam 31 and the reference light beam 61, and transmits the measurement data 41 to the control module 1. In the present non-limiting example, the optical signal receiving module 4 is a camera system, and the data obtained after photographing is output to the control module 1 as the measurement data 41.
And 5, finishing measurement and outputting a parameter corresponding to the current first modulation signal 11.
It should be noted that the above steps 1-5 are arranged in the above manner for convenience of description only. Although the above steps 1 to 5 may be performed in a manner that the steps 1 to 5 are sequentially performed, it does not mean that the above steps are performed only in a manner that the steps 1 to 5 are sequentially performed. In fact, the above steps may be carried out in any reasonable combination as will occur to those of skill in the art. Such combinations should be meaningless within the scope of the present invention.
In the above examples, the specific implementation method in many steps may be various. The following description will explain the specific embodiments
First, in step 2, the way in which the control module 1 generates the first modulation signal 11 may be various. For example, when testing an object under test 6 with known ideal parameters (e.g., the object under test is manufactured according to certain design parameters, which are the ideal parameters of the object under test 6), the control module 1 generates the first modulation signal 11 according to the ideal parameters. In this case, the spatial light modulator 3 achieves the effect that the modulated light beam 31 input to the optical path system 5 corresponds to a light beam reflected after an object having the same parameter as the ideal parameter is set in a corresponding position.
For another example, the control module 1 generates the first modulation signal 11 according to external input information. The method of generating the first modulation signal 11 according to the external input information may be various. One alternative embodiment is to generate the first modulation signal 11 according to a basic shape (e.g., spherical, aspherical, cylindrical, free-form) and basic parameters (e.g., radius of curvature, etc.) selected by a user. Another alternative embodiment is to generate the first modulation signal 11 from the rough shape of the object 6 to be measured, which is measured by other, less precise measuring methods. Still alternatively, another alternative embodiment may be that the control module stores preset start information (e.g. a plane, or a standard sphere). According to the invention, the initial information is selected as the initial modulation signal output according to the input from the user, and the actual parameters of the object to be measured are finally measured through multiple iterations.
Next, in the above example, the specific method of iterating the first modulated signal may be various. For example, an alternative method is that the control module 1 performs data preprocessing on the data obtained by measuring the data 41. The data preprocessing may include performing a mathematical transformation (e.g., fourier transformation, inverse fourier transformation, etc.) on the data, and then optionally processing the data (e.g., filtering, low-pass filtering, band-pass filtering, edge detection, etc.), the mathematical transformation further including filtering out specific frequency domain information in the data. And then carrying out data inverse transformation on the data. The control module 1 calculates the correction information according to the result of the data, and generates a second modulation signal according to the obtained correction information and the current first modulation signal 11. The above processing may be performed after the data obtained from the measurement data 41 is imaged.
Third, alternatively, as a camera system of the optical signal receiving module 4, a plurality of sets of data (for example, taking images of a plurality of frames) may be obtained as a result of interference of the modulations generated with respect to the same modulation signal, i.e., a plurality of measurement data 41 are generated. The control module 1 implements a better measurement by means of data (image) processing techniques. For example, noise generated by the photosensitive components of the photographic system can be eliminated by superposition and averaging of data (images).
Fourth, optionally, a step of determining whether to complete the measurement may be further included in the above step, and this step may be implemented by the control module 1. The method of determining whether the measurement process is completed may be various. As a non-limiting example, one of the alternative judgment methods may be an error judgment method. That is, it is determined whether the error between the parameter corresponding to the current first modulation signal 11 and the parameter of the object to be measured is within a preset acceptable range.
An optional specific method of the error determination method is that at least one coincidence signal is further stored in the control module 1, and the control module 1 compares the measurement data 41 with the coincidence signal and determines whether to complete the measurement according to the comparison result. Specifically, according to the principle of light interference, when the surface of the object simulated by the spatial light modulator 3 is identical to the surface of the object to be measured, a specific interference fringe will be formed. The control module 1 further stores at least one measurement result information (e.g., an interference fringe pattern) as an coincidence signal, and when the received measurement result does not match the measurement result information as the coincidence signal, it indicates that the difference between the parameter corresponding to the current first modulation signal and the parameter of the object to be measured is greater than a preset value. That is, at this time, the surface of the object simulated by the spatial light modulator 3 is not completely the same as the surface of the object to be measured, and the measurement is not completed. On the contrary, when the received measurement result matches the measurement result information as the coincidence signal, it indicates that the object simulated by the spatial light modulator 3 is identical to the surface of the object to be measured or differs within an acceptable range (for example, a tolerance), and it is judged that the measurement is completed. This has the advantage that it is ensured that the resulting parameter differs from the object to be measured by less than a predetermined value.
As another non-limiting example, another alternative decision method is the iterative ceiling method. An alternative embodiment is to provide an iteration number memory in the control module 1, which stores the number of iterations. Wherein the initial value of the number of iterations is zero. The control module 1 also presets an upper iteration limit. Each time the control module 1 receives measurement data 41, the number of iterations is first compared with the iteration upper limit.
If the current iteration number is smaller than the preset upper iteration limit, the control module 1 generates a second modulation signal according to the current measurement data 41, and uses the second modulation signal as a new first modulation signal 11 (i.e., performs iteration on the first modulation signal). The measurement data 41 are received again and the iteration counts stored in the iteration count memory are accumulated. When the iteration number is equal to the iteration upper limit, the control module 1 outputs a result instead of generating the second modulation signal, and clears the iteration number in the iteration number memory so as to perform the next measurement. This has the advantage that the number of iterations is determined and the total time of the measurement is relatively stable.
It should be noted that the non-limiting examples described above are merely exemplary of the determination method. In fact, there may be other ways of determining whether to end the iteration, such as using a combination of an error determination method and an iteration ceiling method, as shown in fig. 2.
In addition, according to at least one embodiment of the present invention, the method of obtaining the final measurement result may adopt other methods instead of the method of gradually approximating the actual value of the surface of the object to be measured by repeating iteration. For example, the measurement data may be obtained each time and then determined, and if it is determined that the measurement result is sufficiently obtained, the measurement result may be obtained by performing calculation. If the result is judged that the measurement result can not be obtained, the next measurement is carried out, and the judgment is carried out again.
As a non-limiting example, N predetermined surface parameters (e.g., including a plane, a sphere, a paraboloid) are stored in the control module 1. When measuring parameters of an object to be measured with an unknown shape, the control module 1 generates first modulation signals 11 (for example, a first modulation signal corresponding to a plane, a first modulation signal corresponding to a spherical surface, and a first modulation signal corresponding to a paraboloid) one by one according to the N preset surface parameters, and records measurement data 41 corresponding to each first modulation signal 11. And after the measurement is finished, calculating a final measurement result according to the preset surface parameters and the corresponding measurement data (the difference from the plane is A, the difference from the spherical surface is B and the difference from the paraboloid is C). At this time, each first modulation signal 11 is generated according to the preset surface parameters stored in the control module 1, and may be independent of the previous measurement data 41. After each measurement is completed, a judgment is made to determine whether to calculate a final measurement result from all currently obtained measurement data.
In the present example, the specific method of making the judgment each time the measurement data is obtained may be various. For example, one of the alternative determination methods is to determine whether the number of currently acquired measurement data reaches an upper limit of the number of measurements. If N predetermined surface parameters are stored in the control module 1, an upper limit of the number of measurements can be set to N. With this arrangement, the final measurement is started after N measurements have been made (i.e. measurements have been made with all the preset surface parameters).
Another alternative method may be to determine whether the error of the obtained measurement data is smaller than a preset value. For example, assume that the object to be measured is in fact a combination of a spherical surface and a planar surface. Assume that the control module measures using the surface preset parameters representing the plane at the 1 st time and the surface preset parameters representing the sphere at the 2 nd time. After 2 measurements have been completed, the final measurement can already be calculated. And judging that the error of the obtained measurement data is less than or equal to a preset error preset value, and obtaining a measurement result. On the contrary, if the object to be measured is a paraboloid, after 2 times of measurement is completed, the error of the obtained measurement data is still larger than the preset error preset value, and the result of measurement cannot be obtained.
Further, when the present measuring instrument is not used for the first time or a lot of times, the measuring instrument can be corrected using a standard object to be measured (for example, a standard flat mirror or a spherical mirror whose parameters and tolerances are known) as the object to be measured, and an error generated in the optical system or the spatial light modulator itself is compensated by presetting compensation at the time of setting the parameters by the spatial light modulator. For example, a standard plane mirror with known parameters is used as an object to be measured, the spatial light modulator is set as parameters of an ideal plane mirror, a certain error is found after measurement, the parameters of the spatial light modulator are obtained after multiple compensation measurements, and because the object to be measured is the standard known plane mirror, the generated error must come from the light generation module, the light signal receiving module, the light path system, the spatial light modulation module, and the like, the obtained parameters can be used as compensation parameters to zero the whole system at this time, that is, the data required to be obtained during subsequent measurement is the result obtained after the calculation of the actual measurement parameters and the compensation parameters (for example, the final measurement result is the result obtained by subtracting the compensation parameters from the actual measurement parameters).
The measuring instrument and the measuring method provided by the invention completely change the traditional measurement that only single measurement is carried out. And the difference between the object to be measured and the standard component is identified by experience only through manual observation. But repeated iteration is carried out to finally obtain the detailed condition of the surface of the object to be measured, thereby greatly improving the measurement effect and having at least the following advantages:
1. no reference piece needs to be manufactured. The present invention provides a gauge and method of measurement that does not require a reference, thereby eliminating the cost and time consumption associated with manufacturing the reference. Errors introduced by the reference are also eliminated.
2. The measuring speed is high. The measuring instrument and the measuring method provided by the invention do not need repeated alignment, and the alignment problems of eccentricity, off-axis and the like are eliminated by means of an iterative correction process, so that the efficiency is high.
3. The measurement result has high certainty. The actual condition of the surface of the object to be measured is finally obtained by the measuring instrument and the measuring method. By using the measuring instrument and the measuring method provided by the invention, the difference of the position of the object to be measured and the ideal parameter is clear at a glance. This has a great advantage for improving the production process.
It will be apparent to those skilled in the art that various modifications and variations can be made to the above-described exemplary embodiments of the present invention without departing from the spirit and scope of the invention. Thus, it is intended that the present invention cover the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.
Claims (17)
1. A measuring instrument comprises a light generation module, a light signal receiving module and an optical path system, and is characterized by further comprising: the system comprises a control module and a spatial light modulation module;
the light generation module generates an incident light beam and inputs the incident light beam into the optical path system;
the light path system transmits the incident beam to the spatial light modulation module and an object to be measured;
the spatial light modulator receives a first modulation signal from the control module and the incident light beam, generates a first modulation light beam and inputs the first modulation light beam into the optical path system;
the optical path system receives the first modulation light beam and the reference light beam returned from the object to be detected, and transmits the reference light beam to the optical signal receiving module;
the optical signal receiving module receives the first modulation light beam and the reference light beam, generates measurement data and transmits the measurement data to the control module;
the control module generates a second modulation signal according to the measurement data, takes the second modulation signal as a new first modulation signal, and receives the measurement data again;
wherein the control module further stores at least one coincidence signal, and the control module compares the measurement data with the coincidence signal;
when the measurement data is not matched with the coincidence signal, generating a second modulation light beam, taking the second modulation signal as a new first modulation signal, and receiving the measurement data again;
the control module does not generate a second modulation signal when the measurement data matches the coincidence signal.
2. The surveying instrument according to claim 1, characterized in that: the optical path system comprises an optical system which comprises a first lens subsystem, a second lens subsystem and a combiner subsystem;
the combiner subsystem transmits the incident beam to the spatial light modulation module and the object to be detected, and transmits a first modulation beam and a reference beam to the optical signal receiving module;
the first lens subsystem matches an incident beam transmitted to the spatial light modulation module by the combining subsystem according to the size of the spatial light modulator;
the second lens subsystem matches the first modulated optical beam and the reference optical beam according to a size of the optical signal receiving module.
3. The surveying instrument according to claim 1, characterized in that: the control module receives and processes the measurement data, and calculates correction information according to the processed measurement data;
the control module generates a second modulation signal according to the correction information and the first modulation signal.
4. A meter as claimed in claim 3, wherein: the control module preprocesses the data, the preprocessing including mathematically transforming the data;
the mathematical transform includes filtering out certain frequency domain information in the data.
5. A meter as claimed in claim 3, wherein: a plurality of preset data modes are stored in the control module, and the control module judges the preset data mode corresponding to the processed measurement data;
and generating parameters corresponding to the processed measurement data according to the preset data mode, and generating correction information according to the parameters.
6. The surveying instrument according to claim 1, characterized in that: the control module also comprises an iteration number memory and an iteration upper limit, when the control module receives the measurement data, the iteration number is compared with the iteration upper limit,
when the iteration times are smaller than the iteration upper limit, the control module generates a second modulation signal according to the measurement data, takes the second modulation signal as a new first modulation signal, receives the measurement data again, and accumulates the iteration times stored in the iteration times memory;
the control module does not generate a second modulation signal when the number of iterations is equal to the iteration upper limit.
7. The surveying instrument according to claim 1, characterized in that:
when an object to be measured with known ideal parameters is measured, the control module generates a first modulation signal according to the ideal parameters of the object to be measured;
when an object to be measured with an unknown shape is measured, the control module receives external input information and generates a first modulation signal according to the input information.
8. The surveying instrument according to claim 1, characterized in that: the optical path system further comprises an adjusting system, wherein the adjusting system is connected with the control module and moves the object to be detected or the optical path system according to the moving signal sent by the control module.
9. The surveying instrument according to claim 1, characterized in that: and the control module calculates according to the measurement data obtained once or for multiple times to obtain a measurement result.
10. A method of measurement, characterized by: the method comprises the following steps:
step 1: the light generation module emits an incident light beam, and the incident light beam is input into the optical path system; the light path system transmits the incident beam to an object to be detected and receives a reference beam returned by the object to be detected;
step 2: the control module generates a first modulation signal according to the ideal parameters of the object to be detected or external input information;
and step 3: the spatial light modulator modulates an incident beam into a first modulated light beam according to a first modulation signal from the control module, and inputs the first modulated light beam into the optical path system;
and 4, step 4: the optical signal receiving module receives the first modulated light beam and the reference light beam output in the optical path system, generates measurement data according to the modulated light beam and the reference light beam, and transmits the measurement data to the control module;
and 5: the control module determines whether the measurement is complete,
if not, the control module generates a second modulation signal according to the measurement data and the first modulation signal; taking the second modulation signal as a new first modulation signal, and returning to the step 3;
if the measurement is finished, outputting a parameter corresponding to the first modulation signal;
the method for judging whether the measurement is finished by the control module comprises the following steps:
judging whether the number of times of taking the second modulation signal as a new first modulation signal is greater than a threshold value and judging whether the difference between the parameter corresponding to the current first modulation signal and the parameter of the object to be detected is smaller than a preset value; or
Judging whether the difference between the parameter corresponding to the current first modulation signal and the parameter of the object to be detected is smaller than a preset value;
the method for judging whether the difference between the parameter corresponding to the current first modulation signal and the parameter of the object to be detected is smaller than a preset value comprises the following steps:
the control module is stored with at least one coincidence signal, and compares the measurement data with the coincidence signal;
when the measurement data is not matched with the coincidence signal, the difference between the parameter corresponding to the current first modulation signal and the parameter of the object to be measured is not considered to be smaller than a preset value;
and when the measurement data are matched with the coincidence signals, the difference between the parameters corresponding to the current first modulation signal and the parameters of the object to be measured is considered to be smaller than a preset value.
11. The measurement method according to claim 10, characterized in that: the control module receives and processes the measurement data, and calculates correction information according to the processed measurement data;
the control module generates a second modulation signal according to the correction information and the first modulation signal.
12. The measurement method of claim 10, wherein: the control module also preprocesses the data, the preprocessing including mathematically transforming the data;
the mathematical transform includes filtering out certain frequency domain information in the data.
13. The measurement method according to claim 11, characterized in that: the method for the control module to calculate the correction information according to the processed measurement data comprises the following steps:
the control module is stored with a plurality of preset data modes,
generating a preset data mode corresponding to the processed measurement data;
and determining correction information corresponding to the processed measurement data according to the preset data mode.
14. The measurement method according to claim 10, characterized in that:
when an object to be measured with known ideal parameters is measured, the control module generates a first modulation signal according to the ideal parameters of the object to be measured;
when an object to be measured with an unknown shape is measured, the control module receives external input information and generates a first modulation signal according to the input information.
15. The measurement method of claim 10, wherein: the method also comprises the following steps of,
moving the first part of the object to be detected to the area where the incident light beam is transmitted by the light path system by the adjusting system, or moving the light path system to transmit the incident light beam to the first part of the object to be detected, and then starting the step 1; when the measurement is judged to be completed in the step 5, the adjusting system moves the second part of the object to be measured to the area to which the incident beam is to be transmitted by the optical path system, or moves the optical path system to transmit the incident beam to the second part of the object to be measured, and then the step 1 is restarted until all the areas to be measured of the object to be measured are measured;
and the control module calculates the surface information of the object to be measured according to the measurement result and the moving distance of the adjusting system.
16. The measurement method according to claim 10, characterized in that: judging after the measurement data are obtained every time, and if the judgment is that the measurement result is obtained enough, calculating to obtain a measurement result;
if the result is judged that the measurement result can not be obtained, the next measurement is carried out, and the judgment is carried out again.
17. The measurement method according to claim 16, characterized in that: the method for judging after obtaining the measurement data each time comprises the following steps:
judging whether the quantity of the currently obtained measurement data reaches a measurement frequency upper limit or not, and if the quantity of the currently obtained measurement data is equal to the measurement frequency upper limit, judging that the quantity of the currently obtained measurement data is enough to obtain a measurement result; if the number of the currently obtained measurement data is smaller than the upper limit of the measurement times, judging that a measurement result cannot be obtained;
and/or judging whether the error of the obtained measurement data is smaller than a preset value, if the error of the currently obtained measurement data is smaller than or equal to the preset value, judging that the measurement result is enough; and if the error of the currently obtained measurement data is larger than the preset value, judging that the measurement result cannot be obtained.
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