Three-dimensional profile measurement system

Abstract

The invention provides an object three-dimensional contour measurement system. The measuring system comprises a light source unit used for emitting light beams; the light source modulation unit is used for modulating the light beam into structured light with a preset frequency and projecting the structured light with the preset frequency to an object so as to form interference fringes on the surface of the object; wherein the structured light with the preset frequency is formed by overlapping the structured light with the first frequency and the structured light with the second frequency; the image acquisition unit is used for acquiring a stripe image of the object; the control device is used for processing the stripe image to obtain a frequency spectrum image, and the frequency spectrum image comprises a frequency spectrum area of the object surface contour; obtaining a first phase corresponding to the structured light of the first frequency, a second phase corresponding to the structured light of the second frequency and an equivalent phase corresponding to the structured light of the preset frequency according to the frequency spectrum region; and obtaining the contour height of the object according to the first phase, the second phase and the equivalent phase. And the precision of the obtained contour height of the object is higher.

Description

Technical Field

[0001] The present application relates to the field of measurement technology, and in particular to a three-dimensional profile measurement system. Background Art

[0002] The measurement system or instrument for measuring the three-dimensional data of an object is easily affected by external factors such as the environment, which in turn affects the measurement effect. For example, when the light intensity of the ambient light is too strong, it will interfere with the formation of diffraction fringes, and the diffraction fringes image carrying the phase information of the object obtained by the camera device is not complete, and the accuracy of the obtained measurement data is reduced. For another example, when a detector with a small handheld light source power scans an object, the scanning light is unstable due to the movement of the hand, which will reduce the repeatability of the accuracy. That is, after repeatedly scanning the object and analyzing all the scanned data, the data obtained by repeated scanning cannot compensate for each other's errors, and the accuracy of the obtained measurement data is reduced. Summary of the invention

[0003] In view of this, the present application provides a three-dimensional profile measurement system to improve the measurement accuracy of the three-dimensional profile of an object.

[0004] A first aspect of an embodiment of the present application provides a three-dimensional profile measurement system, comprising:

[0005] A light source unit, used for emitting a light beam;

[0006] A light source modulation unit, used for modulating a light beam into a structured light of a preset frequency, and projecting the structured light of the preset frequency onto an object to form interference fringes on the surface of the object; wherein the structured light of the preset frequency is formed by superimposing the structured light of the first frequency and the structured light of the second frequency;

[0007] An image acquisition unit, used for acquiring a fringe image of an object;

[0008] A control device, used for processing the fringe image to obtain a spectrum image, wherein the spectrum image includes a spectrum region of the surface contour of the object;

[0009] Obtaining, according to the spectrum region, a first phase corresponding to the structured light of the first frequency, a second phase corresponding to the structured light of the second frequency, and an equivalent phase corresponding to the structured light of a preset frequency;

[0010] The profile height of the object is obtained according to the first phase, the second phase and the equivalent phase.

[0011] In the above technical solution, the light source modulation unit can modulate the light beam into structured light of the first frequency and the second frequency and superimpose the structured light of the first frequency and the second frequency into structured light of a preset frequency. After the structured light of the preset frequency is projected onto the object, interference fringes are generated. The interference fringes of the preset frequency make the phase information of the surface of the object richer and the precision of the measured object higher. That is, the control device obtains the first phase, the second phase and the equivalent phase corresponding to the structured light of the first frequency, the second frequency and the preset frequency according to the fringe image of the preset frequency, and the precision of the contour height of the object obtained according to the first phase, the second phase and the equivalent phase is higher.

[0012] In some embodiments of the first aspect, the light beam emitted by the light source unit is laser.

[0013] In some embodiments of the first aspect, the light source modulation unit includes a light source collimation unit, a light source frequency modulation unit and a light source projection unit; the light source collimation unit is used to collimate the multiple light beams emitted by the light source unit into multiple light beams parallel to each other; the light source frequency modulation unit is used to adjust the multiple light beams parallel to each other into structured light of a preset frequency; and the light source projection unit is used to project the structured light of the preset frequency onto an object.

[0014] In some embodiments of the first aspect, the light source frequency modulation unit includes a first diffractive optical element and a second diffractive optical element; the first diffractive optical element is used to adjust a plurality of mutually parallel light beams into structured light with a first frequency; the second diffractive optical element is used to adjust the structured light of the first frequency into structured light with a preset frequency; wherein the second diffractive optical element can adjust the plurality of mutually parallel light beams into structured light with a second frequency, and the structured light of the preset frequency is formed by superposition of the structured light of the first frequency and the structured light of the second frequency.

[0015] In some embodiments of the first aspect, both the exit surface of the first diffractive optical element and the exit surface of the second diffractive optical element are provided with protrusions and / or recesses.

[0016] In some embodiments of the first aspect, the control device is also used to: compare the periods of the first phase and the second phase; determine the height of the first phase or the second phase with the larger period as the reference height; and obtain the contour height of the object based on the equivalent height of the equivalent phase and the reference height.

[0017] In some embodiments of the first aspect, the control device is also used to: compare a reference height and a preset height; if the preset height is greater than the reference height, determine the equivalent height as the contour height of the object; if the preset height is less than or equal to the reference height, determine the reference height as the contour height of the object.

[0018] In some embodiments of the first aspect, the control device is also used to: obtain a reference height based on the second phase, the first distance between the light source unit and the image acquisition unit, the second distance between the image acquisition unit and the reference plane, and the period corresponding to the second phase; and obtain an equivalent height based on the equivalent phase, the first distance, the second distance, and the equivalent period.

[0019] In some embodiments of the first aspect, the control device is also used to: obtain spectrum information in a spectrum region using a filter; and obtain a first phase corresponding to the structured light of a first frequency, a second phase corresponding to the structured light of a second frequency, and an equivalent phase corresponding to the structured light of a preset frequency based on the spectrum information.

[0020] In some embodiments of the first aspect, the filter is a diamond filter, wherein the center of the diamond filter is the point with the largest grayscale value in the first spectrum region, and the short axis of the diamond filter is smaller than the third distance and smaller than the fourth distance; wherein the third distance is the distance from the vertex to the center of the second spectrum region, the fourth distance is the distance from the bottom point to the center of the third spectrum region, the second spectrum region is located above the vertex of the first spectrum region, and the third spectrum region is located below the bottom point of the first spectrum region. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 A schematic diagram of the structure of a three-dimensional profile measurement system according to an embodiment of the present application.

[0022] Figure 2 A schematic diagram of the structure of an object according to an embodiment of the present application.

[0023] Figure 3 This is a stripe image acquired by the image acquisition unit of the embodiment of the present application.

[0024] Figure 4 for Figure 3 The spectral image obtained by transforming the fringe image shown.

[0025] Figure 5 To read with a diamond filter Figure 4 An application scenario diagram of the spectrum information of the spectrum image shown.

[0026] Figure 6 for Figure 5 A local enlarged view of the spectrum information shown.

[0027] Figure 7 To read with a diamond filter Figure 4 Another application scenario diagram of the spectrum information of the spectrum image shown.

[0028] Figure 8 To read with a diamond filter and an elliptical filter Figure 4 An application scenario diagram of the spectrum information of the spectrum image shown.

[0029] Fig. 9 for Figure 3 The phase package diagram obtained by transforming the fringe image shown.

[0030] Fig.10 for Fig. 9 The phase packaging diagram shown is one of the schematic diagrams for restoring the three-dimensional outline of the object.

[0031] Fig.11 for Fig. 9 The phase packaging diagram shown is a second schematic diagram of restoring the three-dimensional outline of the object. DETAILED DESCRIPTION

[0032] In the present application, the term "plurality" refers to two or more. In addition, it should be understood that in the description of the present application, the terms "first", "second", etc. are only used for the purpose of distinguishing descriptions, and cannot be understood as controlling or implying relative importance, nor can they be understood as controlling or implying an order.

[0033] In the embodiments of the present application, words such as "exemplary" or "for example" are used to indicate examples, illustrations or descriptions. Any embodiment or design described as "exemplary" or "for example" in the embodiments of the present application should not be interpreted as being more preferred or more advantageous than other embodiments or designs. Specifically, the use of words such as "exemplary" or "for example" is intended to present related concepts in a specific way.

[0034] The following is a brief description of the relevant technology.

[0035] The measurement system or instrument for measuring the three-dimensional data of an object is easily affected by external factors such as the environment, which in turn affects the measurement effect. For example, when the light intensity of the ambient light is too strong, it will interfere with the formation of diffraction fringes, and the diffraction fringes image carrying the phase information of the object obtained by the camera device is not complete, and the accuracy of the obtained measurement data is reduced. For another example, when a detector with a small handheld light source power scans an object, the scanning light is unstable due to the movement of the hand, which will reduce the repeatability of the accuracy. That is, after repeatedly scanning the object and analyzing all the scanned data, the data obtained by repeated scanning cannot compensate for each other's errors, and the accuracy of the obtained measurement data is reduced.

[0036] In view of this, the present application provides a three-dimensional profile measurement system to improve the accuracy of measuring the three-dimensional profile of an object.

[0037] See also Figure 1 , Figure 1 This is a schematic structural diagram of a three-dimensional profile measurement system according to an embodiment of the present application. The three-dimensional profile measurement system 100 includes a light source unit 10 , a light source modulation unit 20 , an image acquisition unit 30 and a control device 40 .

[0038] The light source unit 10 is used to emit a light beam. In some embodiments, the light source unit 10 may be a laser unit 10, the laser unit 10 includes a laser, and the light beam emitted by the light source unit 10 is a laser. It can be understood that compared with the light beam emitted by a digital light source (digital light processing, DLP) or a liquid crystal chip (liquid crystal on silicon, LCOS) as LED light, the light power of the laser emitted by the laser unit 10 is stronger. A light beam with stronger light power is less susceptible to external factors, such as being less affected by ambient light and the movement of the laser unit 10. When scanning a large object, due to the large size of the object, each part of the object needs to be scanned in turn, so the light source unit 10 needs to move to change the projection direction. At this time, the laser with stronger light power is not affected by the movement of the laser unit 10, and can emit a more stable laser. At the same time, when repeatedly scanning the same part of the object, the data obtained by repeated scanning with a more stable laser can compensate for errors with each other, and the obtained measurement data has higher accuracy.

[0039] When scanning objects with lower tones (such as black) or high reflectivity, the laser with stronger optical power can scan more 3D contour information of the object without the need for prior powder spraying on the surface of the object, even if it is absorbed by the object with lower tones or reflected by the object with high reflectivity. Since more 3D contour information is obtained per unit space scan, the measurement accuracy is higher and the resolution of the reconstructed 3D object is higher.

[0040] The light source modulation unit 20 is used to modulate the light beam emitted by the light source unit 10 into a structured light of a preset frequency, and project the structured light onto an object to form a plurality of interference fringes on the surface of the object. The light source modulation unit 20 includes a light source collimation unit 21, a light source frequency modulation unit 22, and a light source projection unit 23. The light source modulation unit 20 takes the light source unit 10 as a starting point, and arranges the light source collimation unit 21, the light source frequency modulation unit 22, and the light source projection unit 23 in sequence according to the emission path of the light source unit 10.

[0041] The light source collimating unit 21 is used to collimate multiple light beams into mutually parallel light beams. In some embodiments, the light source collimating unit 21 is a collimator. It can be understood that the light beams are emitted from the light source unit 10 to the light source collimating unit 21, and the multiple light beams emitted from the exit surface of the light source collimating unit 21 are parallel to each other to form a light field composed of parallel light beams.

[0042] The light source frequency modulation unit 22 is used to adjust multiple parallel light beams into structured light of a preset frequency. In some embodiments, the light source frequency modulation unit 22 includes a plurality of diffractive optical elements (DOE) arranged in sequence. The exit surface of each diffractive optical element is provided with a microstructure, and the microstructure is composed of a convex portion and / or a concave portion whose size is less than a preset value. The microstructure of each diffractive optical element is different, so that each diffractive optical element can adjust the light beam to a different frequency, that is, each diffractive optical element has a different adjustment frequency. In one embodiment, the light source frequency modulation unit 22 includes two diffractive optical elements arranged in sequence, a first diffractive optical element 221 and a second diffractive optical element 222, and the exit surface of the first diffractive optical element 221 is opposite to the incident surface of the second optical element 222. When the light beam is emitted from the exit surface of the first diffractive optical element 221, the frequency of the light beam is adjusted to the first frequency, and the light beam is adjusted to the structured light, and then, when the structured light is emitted from the exit surface of the second diffractive optical element 222, it is adjusted to the preset frequency. It can be understood that the first diffractive optical element 221 can adjust the frequency of the light beam to a first frequency, and the second diffractive optical element 222 can adjust the frequency of the light beam to a structured light of a second frequency. When the structured light of the first frequency is emitted from the exit surface of the second diffractive optical element 222, the structured light of the first frequency and the second frequency are superimposed to form a structured light of a preset frequency. It can be understood that the structured light of the preset frequency is modulated by the first diffractive optical element 221 and the second diffractive optical element 222. The control device 40 can analyze the relevant information (such as phase information and period, etc.) of the structured light of the first frequency, the second frequency and the preset frequency according to the fringe image of the structured light of the preset frequency. The present application can obtain structured light of multiple frequencies by setting a plurality of diffractive optical elements with different microstructures. The structured light of multiple frequencies is superimposed to form a structured light of a preset frequency. After the structured light is projected onto the object 1, interference fringes of equivalent period (interference fringes are moiré fringes) are generated, that is, the corresponding period of the first frequency and the corresponding period of the second frequency are superimposed to generate interference fringes of equivalent period, and the interference fringes will be deformed on the surface of the object 1. By analyzing these deformed fringes, the phase information of the three-dimensional contour of the object 1 can be obtained. Compared with the single-frequency structured light emitted by a digital light source, the interference fringes of equivalent period make the phase information of the three-dimensional profile of the object 1 richer and the measurement accuracy higher.

[0043] The light source projection unit 23 is used to project structured light onto the object 1. In some embodiments, the light source projection unit 23 is a lens. The image acquisition unit 30 is used to acquire a stripe image of the object 1. The stripe image carries phase information of the three-dimensional surface profile of the object 1. In some embodiments, the image acquisition unit 30 is a CCD (charge coupled device) camera.

[0044] The control device 40 is used to obtain the phase information of the three-dimensional profile of the object 1 according to the fringe image, and obtain the profile height of the object 1 according to the phase information. The control device 40 can be a personal computer (PC), a cloud server, a desktop, a network server, a service cluster, a personal digital assistant (PDA), a mobile phone, a wireless terminal device, an embedded device or other devices with data processing functions.

[0045] In one embodiment, starting from the laser unit 10, the light source collimating unit 21, the first diffractive optical element 221, the first diffractive optical element 222 and the light source projection unit 23 are arranged in sequence according to the emission path of the laser. After the laser emitted by the laser unit 10 enters the light source collimating unit 21, the first diffractive optical element 221, the second diffractive optical element 222 and the light source projection unit 23 in sequence, the light source projection unit 23 projects the structured light of the preset frequency adjusted by the laser onto the object 1 (the shape of the object 1 is as shown in FIG. 1 ). Figure 2 A plurality of interference fringes are formed on the object 1, and the image acquisition unit 30 acquires the fringed image of the object 1. The fringed image is as shown in FIG. Figure 3 shown.

[0046] The control device 40 is used for processing the fringe image to obtain a spectrum image, wherein the spectrum image has a spectrum region related to the surface contour of the object 1 .

[0047] Specifically, the control device 40 generates the following formula (1) according to the deformed fringes in the fringes image:

[0048]

[0049] Where (x, y) represents the fringe image coordinates, x and y are the values ​​of the column and row of the image coordinates respectively; I(x, y) represents the light intensity; a(x, y) is the average light intensity of the image background: b n (x, y) is the amplitude of the fringe light intensity variation; is the carrier phase. When n=1, it indicates the phase information formed by the structured light of the first frequency, when n=2, it indicates the phase information formed by the structured light of the second frequency, and when n=3, it indicates the phase information formed by the structured light of the preset frequency.

[0050] Next, expand formula (1) into the following formula (2).

[0051]

[0052] Formula (2) is transformed by Fourier transform to obtain the spectrum image, which is as follows: Figure 4 As shown, the spectrum image includes a spectrum region, and the spectrum region is Figure 4 In the bright area, the spectrum area carries spectrum information, and the spectrum information in the spectrum area is expressed as formula (3)

[0053]

[0054] The control device 40 is further configured to obtain spectrum information in the spectrum region using a filter.

[0055] Specifically, Figure 5 As shown, a diamond filter is used to read the spectrum information in the spectrum image. Figure 6 for Figure 5 The enlarged view of the spectrum information. The following formula (4) is the formula of the diamond filter. Figure 7 As shown, the emission period of the structured light can be calculated by adjusting the frequency of the first diffractive optical element 221 and the frequency of the first diffractive optical element 222. According to the emission period of the structured light, the coordinate point with the maximum gray value in the spectrum region, that is, the peak value f 0 , P 1 (h 1 ,k 1 ) and P 2 (h 2 ,k 2 ). Each peak value represents the place with the largest gray value in a spectrum area, that is, Figure 6 The brightest place. Figure 7 Three spectrum regions 01, 02 and 03 are shown. It can be understood that region 01 is located below the bottom point 021 of region 02, and region 01 is located above the vertex 022 of region 02. The peak value is taken as the center of the diamond filter, and the peak value P is taken as the peak value P. 1 (h 1 ,k 1 ) as an example (area 02 as an example), the center of the diamond filter is the peak value P 1 (h 1 ,k 1 ), find the vertex f of region 03 0c and the bottom point f of area 01 2c Based on the first direction (f x direction), the long axis f of the diamond filter a From the center of the diamond filter to f 0 Based on the second direction (f y direction), the short axis f of the diamond filter b Less than peak value P 1 to f 0c A vertical distance, and less than the peak value P 1 The end point 2cAccording to the above principle, the diamond filter equation has the following conditions as shown in formula (4):

[0056]

[0057] forf b <P 1 f 0c And f b <P 1 f 2c ——(4)

[0058] Among them, h, K are the coordinates of the peak value, x, y are the coordinates of the spectrum information in the spectrum image, and f b is the short axis of the diamond filter, f a is the major axis of the diamond filter.

[0059] It is understandable that Figure 8 As shown, the diamond filter reads less unnecessary information than the elliptical filter. The unnecessary information includes non-spectral information.

[0060] The control device 40 is further configured to obtain a first phase of the structured light of the first frequency, a second phase of the structured light of the second frequency, and an equivalent phase of the structured light of the preset frequency according to the spectrum information.

[0061] Specifically, the spectrum information read by the diamond filter is subjected to inverse Fourier transform, and the spectrum information of the first frequency, the second frequency and the preset frequency is converted into phase information, that is, the first phase, the second phase and the equivalent phase of the three-dimensional surface profile of the object 1 are obtained respectively, and the expression formulas are shown in (5), (6) and (7) respectively. The spectrum image obtained by inverse Fourier transform is shown in Fig. 9 shown.

[0062]

[0063]

[0064]

[0065] The control device 40 is further configured to obtain a profile height of the object 1 according to the first phase, the second phase and the equivalent phase.

[0066] Specifically, in some embodiments, the periods of the first phase and the second phase are compared first.

[0067] The period can be obtained by analyzing the phase information, or the period of the first phase or the period of the second phase can be directly calculated from the adjustment frequency of the diffractive optical element.

[0068] Then determine the height of the first phase or the second phase with a larger period as the reference height. For example, in this embodiment, the period of the second phase is greater than the first phase, so the height corresponding to the second phase is determined as the reference height.

[0069] The calculation of the reference height and the equivalent height of the equivalent phase is shown in (8):

[0070]

[0071] Among them, h c2 Indicates the reference altitude, h ceq represents the equivalent height. d is the distance between the laser unit 10 and the image acquisition unit 30, l 0 is the distance between the image acquisition unit 30 and the reference plane, which is a plane used to calculate the positional relationship between the components of the measurement system 100. 2 is the period corresponding to the second phase, p eq is the equivalent period corresponding to the equivalent phase information, For the second phase, is the equivalent phase information.

[0072] After obtaining the reference height and the equivalent height, the control device 20 is further used to compare the reference height with the preset height. If the preset height is greater than the reference height, the equivalent height is determined to be the profile height. If the preset height is less than the reference height, the reference height is determined to be the profile height. The preset height refers to the true profile height of the three-dimensional profile of the object 1 (e.g. Figure 1 The H) in the figure can be measured in advance and stored in the control device.

[0073] It can be understood that when measuring the three-dimensional profile of object 1 using the principle of interference imaging, if the height of the three-dimensional profile of object 1 is too large and exceeds the fringe period, the system cannot measure the height of the position where the height is too large, and the object 1 reconstructed using the measurement data will have a breakpoint at this position. Therefore, when the preset break height is greater than the reference height, the equivalent height is determined to be the profile height. In this way, selecting an equivalent height with a larger period can improve the measurement limit of the surface height of the measurement system 100. When the preset break height is less than or equal to the reference height, it means that the surface height of object 1 will not exceed the measurement limit of the system, and determining the reference height as the profile height can improve the resolution.

[0074] Finally, the control device 40 is also used to reconstruct the three-dimensional contour of the object 1 according to the Euler formula, phase restoration technology and contour height.

[0075] It can be understood that, because the tangent function (tan-1) is a discontinuous function, the restored phase value is a discontinuous state. In order to combine the restored discontinuous state to obtain a continuous phase distribution, the Euler transformation and phase unwrapping technology must be used to restore the continuous phase, and then reconstruct the three-dimensional contour of the object 1. The reconstructed three-dimensional contour of the object 1 is as follows Fig.10 and Fig.11 shown.

[0076] In this embodiment, the light source modulation unit 20 can modulate the light beam into structured light of the first frequency and the second frequency and superimpose the structured light of the first frequency and the second frequency into structured light of a preset frequency. After the structured light of the preset frequency is projected onto the object, interference fringes are generated. The interference fringes of the preset frequency make the phase information of the surface of the object richer and the precision of the measured object higher. That is, the control device obtains the first phase, the second phase and the equivalent phase corresponding to the structured light of the first frequency, the second frequency and the preset frequency according to the fringe image of the preset frequency, and the precision of the contour height of the object obtained according to the first phase, the second phase and the equivalent phase is higher.

[0077] The present embodiment, comparative example 1 and comparative example 2 are compared according to the following comparison conditions, and the comparison results are summarized as shown in Table 1 below. The comparison conditions include the number of images to be acquired, the average error percentage, low segment difference reconstruction and high segment difference reconstruction. Among them, the number of images to be acquired refers to the number of images required to measure the object 1 when constructing the three-dimensional contour of the object, the average error percentage refers to the average error in the contour height between the three-dimensional contour of the measured object 1 and the three-dimensional contour of the real object 1, the low segment difference reconstruction refers to the reconstruction result of the upper and lower surfaces of the height of the object 1 when the height is lower than a preset height, and the high segment difference reconstruction refers to the reconstruction result of the upper and lower surfaces of the height of the object 1 when the height is higher than a preset height.

[0078] Comparative Example 1 refers to a method for obtaining the three-dimensional contour of the object to be measured by using DLP as the light source unit 10 and combining it with the optical phase shift method.

[0079] The difference between Comparative Example 2 and the present embodiment is that the light source unit 10 of Comparative Example 2 is a DLP, the light source modulation unit 20 is different, and the filter used is an elliptical filter.

[0080] Table 1

[0081]

[0082] It can be seen from Table 1 above that the error percentage of the three-dimensional contour of object 1 measured according to this embodiment is lower, and both the low step difference and the high step difference can be reconstructed, indicating that, compared with Comparative Examples 1 and 2, the measurement method of this embodiment has higher measurement accuracy. Specifically, Comparative Example 1 must read at least 4 images to reconstruct, so it is more susceptible to environmental interference and has a larger average error. At the same time, since the phase shift method uses a single-frequency Fourier transform algorithm, the structured light projected onto the object has only one frequency, and it is impossible to reconstruct the height of the contour of an object whose height is higher than a preset height. Comparative Example 2 uses an elliptical filter, reads unnecessary information, and has a larger average error. Moreover, Comparative Examples 1 and 2 use DLP as the light source unit, and the light intensity of the emitted light beam is less than that of the laser unit 10 of this embodiment, which also makes the average error greater than that of this embodiment.

[0083] Those skilled in the art will understand that the present application is not limited to the specific embodiments herein, and that various obvious changes, readjustments and substitutions can be made by those skilled in the art without departing from the protection scope of the present application. Therefore, although the present application is described in more detail through the above embodiments, the present application is not limited to the above embodiments, and may include more other equivalent embodiments without departing from the concept of the present application, all of which belong to the protection scope of the present application.

Claims

1. A three-dimensional profile measurement system, It is characterized in that include: A light source unit, used for emitting a light beam; A light source modulation unit, used for modulating the light beam into a structured light of a preset frequency, and projecting the structured light of the preset frequency onto an object to form interference fringes on the surface of the object; wherein the structured light of the preset frequency is formed by superimposing the structured light of the first frequency and the structured light of the second frequency; An image acquisition unit, used for acquiring a fringe image of the object; A control device, used for processing the fringe image to obtain a spectrum image, wherein the spectrum image includes a spectrum region of the surface contour of the object; Obtaining, according to the spectrum region, a first phase corresponding to the structured light of the first frequency, a second phase corresponding to the structured light of the second frequency, and an equivalent phase corresponding to the structured light of the preset frequency; A profile height of the object is obtained according to the first phase, the second phase and the equivalent phase.

2. The measuring system according to claim 1, It is characterized in that The light beam emitted by the light source unit is laser.

3. The measuring system according to claim 1, It is characterized in that The light source modulation unit includes a light source collimation unit, a light source frequency modulation unit and a light source projection unit; The light source collimating unit is used to collimate the multiple light beams emitted by the light source unit into multiple light beams parallel to each other; The light source frequency modulation unit is used to adjust the multiple mutually parallel light beams into structured light of the preset frequency; The light source projection unit is used to project the structured light of the preset frequency onto the object.

4. The measuring system according to claim 3, It is characterized in that The light source frequency modulation unit includes a first diffractive optical element and a second diffractive optical element; The first diffractive optical element is used to adjust the multiple mutually parallel light beams into structured light with the first frequency; The second diffractive optical element is used to adjust the structured light of the first frequency into structured light with the preset frequency; The second diffractive optical element can adjust the multiple mutually parallel light beams into structured light with the second frequency, and the structured light of the preset frequency is formed by superimposing the structured light of the first frequency and the structured light of the second frequency.

5. The measuring system according to claim 4, It is characterized in that The exit surface of the first diffractive optical element and the exit surface of the second diffractive optical element are both provided with protrusions and / or recesses.

6. The measuring system according to claim 1, It is characterized in that The control device is also used for: comparing periods of the first phase and the second phase; Determine the height of the first phase or the second phase having a larger period as a reference height; The profile height of the object is obtained according to the equivalent height of the equivalent phase and the reference height.

7. The measuring system according to claim 6, It is characterized in that The control device is also used for: Comparing the reference height with a preset height; If the preset height is greater than the reference height, determining the equivalent height as the outline height of the object; If the preset height is less than or equal to the reference height, the reference height is determined to be the contour height of the object.

8. The measuring system according to claim 6, It is characterized in that The control device is also used for: Obtaining the reference height according to the second phase, a first distance between the light source unit and the image acquisition unit, a second distance between the image acquisition unit and a reference plane, and a period corresponding to the second phase; The equivalent height is obtained according to the equivalent phase, the first distance, the second distance and the equivalent period.

9. The measuring system according to claim 1, It is characterized in that The control unit is also used to: Acquire spectrum information in the spectrum region by using a filter; The first phase corresponding to the structured light of the first frequency, the second phase corresponding to the structured light of the second frequency, and the equivalent phase corresponding to the structured light of the preset frequency are obtained according to the spectrum information.

10. The measuring system according to claim 9, It is characterized in that The filter is a diamond filter, wherein the center of the diamond filter is the point with the largest grayscale value in the first spectrum area, and the short axis of the diamond filter is smaller than the third distance and smaller than the fourth distance; wherein the third distance is the distance from the vertex of the second spectrum area to the center, the fourth distance is the distance from the bottom point of the third spectrum area to the center, the second spectrum area is located above the vertex of the first spectrum area, and the third spectrum area is located below the bottom point of the first spectrum area.

Images