Device for measuring appearance and spectrum of inner surface of hollow cylinder

Abstract

The utility model relates to a device for measuring the appearance and spectrum of the inner surface of a hollow cylinder. The projection module, the imaging detection module and the to-be-measured cylindrical object form a structured light triangulation structure, the projection module projects a fringe pattern, and the fringe pattern is uniformly distributed on the inner surface of the to-be-measured cylindrical object after being reflected by the prism; the imaging detection module collects and outputs a diffraction dispersion deformation fringe pattern containing the inner surface morphology and spectral information of the to-be-detected cylindrical object. According to the fringe reflection technology and the diffractive optical phase encoding technology, the single free-form surface conical reflector is adopted, projection of fringe patterns on the inner surface of a cylindrical object is achieved, light of deformed fringe patterns is reflected and collected to the imaging detection module, and the deformation controller rapidly projects a phase shift fringe pattern. The sine property and the frequency consistency of the projection stripe light field pattern are improved; a single diffraction optical element is used for modulating a reflection fringe light field, diffraction imaging is achieved, and detection of the spectrum dimension is expanded while three-dimensional information is measured.

Description

Technical Field

[0001] The utility model relates to a three-dimensional shape measurement technology, in particular to a device for measuring the shape and spectrum of the inner surface of a hollow cylinder, and belongs to the field of advanced optical detection technology. Background Art

[0002] With the continuous development of modern equipment and the rapid advancement of computer technology, the development of three-dimensional morphology measurement devices for mirror reflective surfaces has also matured. Among them, deflectometry measurement is widely used in the measurement of most mirror objects because of its simple device and small system limitations. However, although the traditional deflectometry measurement device can quickly and accurately collect the stripe data containing the surface information of the part to be measured, it cannot obtain all the three-dimensional morphology information of the inner surface of the hollow cylinder at one time. In addition, the current deflectometry measurement device is often limited to the collection of three-dimensional data of the object to be measured, while ignoring its spectral characteristics. Therefore, designing a deflectometry measurement device that can obtain all the three-dimensional morphology and spectral information of the inner surface of the hollow cylinder at one time has become a direction of modern industrial detection. Summary of the invention

[0003] In view of the deficiencies in the prior art, the utility model provides a device with a simple system structure and easy operation, which can measure the inner surface morphology and spectrum of a hollow cylinder without significantly increasing the system device and complexity.

[0004] In order to achieve the above-mentioned invention object, the technical solution of the utility model is to provide a device for measuring the inner surface morphology and spectrum of a hollow cylinder, which includes a projection module, an imaging detection module, a prism, a loading platform and a control module; the projection module includes a flexible screen display and a deformation controller, the input end of the deformation controller is connected to the control module through a deformation control transmission line, and the output end of the deformation controller is connected to the input end of the flexible screen display for modulating the surface shape of the flexible screen display; the other input end of the flexible screen display is connected to the control module through a fringe pattern input transmission line, and the flexible screen display controls the shape of the flexible screen display. The preset fringe pattern input by the block is projected, and after being reflected by the prism, it is evenly distributed on the inner surface of the cylindrical object to be measured; the imaging detection module includes a planar array camera, a diffractive optical element and a filter; the display in the projection module, the camera, the diffractive optical element and the filter in the imaging detection module and the cylindrical object to be measured placed on the object loading platform form a structured light triangulation measurement structure, and the projection module and the imaging detection module focus on the inner surface of the cylindrical object to be measured; the imaging detection module outputs the measurement result of the collected diffraction dispersion deformation fringe pattern containing the inner surface morphology and spectral information of the cylindrical object to be measured through the measurement data output transmission line.

[0005] The prism described in the utility model is a free-form conical reflector. The diffractive optical element described is a ring-shaped diffractive lens with a microstructure regularly and periodically distributed on the surface, with a working spectrum of 400nm to 780nm and a main wavelength of 550nm. The filter described is a filter with a wide spectrum of 400nm to 780nm.

[0006] The utility model aims to solve a series of problems existing in the devices of the existing deflection measurement method, and provides a device for measuring the morphology and spectrum of the inner surface of a hollow cylinder. Based on the principle of phase deflectometry and spectral imaging of diffraction elements, combined with a prism, a deformable flexible screen and a diffraction optical element, the utility model can realize one-time acquisition of mixed coded imaging data containing three-dimensional and spectral information of the inner surface of the hollow cylindrical object to be measured, thereby realizing four-dimensional measurement of the inner surface of the hollow cylindrical object.

[0007] Compared with the prior art, the significant advantages of the utility model are:

[0008] The measuring device provided by the utility model integrates a flexible screen and its deformation control device into a projection module, and combines with a reflecting prism to realize the projection of a stripe pattern on the inner surface of a hollow cylindrical object to be measured; the measuring device uses a combination of a diffractive optical element, a filter and a camera to replace a traditional imaging detection device, so that the measuring device is simpler and easier to integrate; the deformed stripe pattern light field is reflected and focused by combining with a reflecting prism, and then after being modulated by the diffractive optical element, hybrid coded imaging containing three-dimensional and spectral information of the inner surface of the hollow cylindrical object to be measured is realized, and while obtaining the three-dimensional morphology of the inner surface of the hollow cylindrical object to be measured, its spectral characteristics are obtained, so as to realize four-dimensional measurement of the inner surface of the hollow cylindrical object to be measured. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 It is a schematic diagram of the structure of a device for measuring the inner surface morphology and spectrum of a hollow cylinder provided by an embodiment of the utility model.

[0010] Wherein: 1. projection module; 2. imaging detection module; 3. prism; 4. loading platform; 6. control module; 7. hollow cylindrical object to be measured; 11. flexible screen display; 12. deformation control device; 21. area array camera; 22. diffraction optical element; 23. filter; 51. fringe pattern input transmission line; 52. measurement data output transmission line; 53. deformation control transmission line; 71. inner surface of the hollow cylinder to be measured. DETAILED DESCRIPTION

[0011] The following is a further detailed description of a device for measuring the inner surface morphology and spectrum of a hollow cylinder provided by the utility model in conjunction with the accompanying drawings and embodiments. Example

[0012] See attached Figure 1, which is a schematic diagram of the structure of a device for measuring the inner surface morphology and spectrum of a hollow cylinder provided in this embodiment. The measuring device is composed of a projection module 1, an imaging detection module 2, a prism 3, a loading platform 4 and a control module 6. The hollow cylindrical object 7 to be measured is placed on the loading platform 4; the control module 6 inputs the preset fringe pattern to the projection module 1 through the data transmission line 51, and then the projection module 1 projects the fringe pattern to the inner surface of the hollow cylindrical object 7 to be measured, and the deformed fringe pattern modulated by the inner surface of the hollow cylindrical object 7 to be measured is collected by the imaging detection module 2, and the imaging detection module 2 inputs the collected deformed fringe pattern to the control module 6 through the data transmission line 52; the imaging detection module 2 includes a planar array camera 21, a diffractive optical element 22 and a filter 23. The projection module 1, the imaging detection module 2 and the hollow cylindrical object 7 to be measured form a structured light triangulation measurement structure, and the projection module 1 and the imaging detection module 2 focus on the inner surface of the hollow cylindrical object to be measured.

[0013] In this embodiment, the prism 3 is a conical reflector, which is a free-form surface reflector. The pattern projected by the projection module 1 is evenly distributed on the inner surface of the hollow cylindrical object 7 to be measured after being reflected by the prism 3. The diffractive optical element 22 is a ring-shaped diffractive lens with a regular periodic distribution of microstructures on the surface. The working spectrum is 400nm to 780nm, and the main wavelength is 550nm. It has the characteristics of in-plane dispersion and the point spread function distribution presents a "M"-shaped distribution, which meets the characteristics of central zero-order diffraction focusing and first-order diffraction dispersion spreading to the surroundings as the wavelength increases, while suppressing other order diffraction. The filter 23 is a 400nm to 780nm wide-band filter. The projection module 1 is a flexible screen display 11 and a corresponding deformation control device 12. The flexible screen display 11 realizes interactive control and data transmission with the control module 6 through the fringe pattern input transmission line 51. The deformation control device 12 is controlled by the feedback information of the control module 6 through the deformation control transmission line 53 to modulate the surface shape of the flexible screen display 11. The area array camera 21 is a Daheng industrial camera.

[0014] When the measuring device provided in this embodiment starts working, the control module 6 generates a stripe pattern according to the stripe coding method, inputs it to the flexible screen display 11 of the projection module 1 through the stripe pattern input transmission line 51, and projects the encoded stripe pattern onto the inner surface of the hollow cylindrical object 7 to be measured. The imaging detection module 2 collects the deformed stripe pattern modulated by the inner surface of the hollow cylindrical object 7 to be measured, and then outputs the measurement result through the measurement data output transmission line 52.

[0015] The measuring device provided by the utility model can use an achromatic network and a phase recovery algorithm to pre-process the initially collected data, obtain the phase information of the inner surface of the hollow cylindrical object 7 to be measured, and then feed it back to the deformation control device 12 in the projection module 1 through the deformation control transmission line 53 to modulate the surface shape of the flexible screen display 11; the imaging detection module 2 re-collects the re-projected deformation fringe pattern after the surface shape modulation of the flexible screen display 11, obtains the diffraction dispersion deformation fringe diagram containing the inner surface morphology and spectral information of the cylindrical object 7 to be measured, and outputs the measurement result through the measurement data output transmission line 52.

[0016] The diffraction dispersion deformation fringe pattern measurement result containing the inner surface morphology and spectral information of the cylindrical object 7 to be measured obtained at the output end of the imaging detection module 2 of the measuring device is input into the computer, and is processed by the three-dimensional reconstruction and spectral reconstruction modules respectively, so as to obtain the morphology and spectral information of the inner surface of the hollow cylindrical object 7 to be measured.

[0017] (1) Three-dimensional reconstruction: Use an achromatic network to achromatize the in-plane dispersion information of the diffraction dispersion deformation fringe pattern, and then use a phase recovery algorithm to calculate the accurate absolute phase distribution of the inner surface of the hollow cylindrical object 7 to be measured. According to the light model parameters obtained by system calibration and the absolute phase correspondence between the imaging end and the projection end, use ray tracing technology to reconstruct the three-dimensional morphology of the inner surface of the hollow cylindrical object 7 to be measured.

[0018] (2) Spectral reconstruction: Use a multispectral network to perform multispectral reconstruction on the in-plane dispersion information in the diffraction dispersion deformation fringe pattern, and then use the principle of multi-step phase shift to accumulate the fringe images under each spectral segment to obtain the spectral data of the inner surface of the hollow cylindrical object 7 to be tested.

[0019] The measuring device provided by the utility model is used to perform a phase recovery algorithm on the deformed fringe pattern after achromatic processing. The error of the fringe pattern can be suppressed by using one of the advanced iteration and its improved algorithm, principal component analysis and its improved algorithm, Lissajous ellipse fitting and its improved algorithm, phase histogram equalization and its improved algorithm, and the wrapped phase is calculated and then the wrapped phase is expanded using a multi-frequency heterodyne algorithm to obtain the entire phase distribution. The achromatic network can adopt one of the convolutional neural network or the Transformer network. The multispectral network can adopt one of the convolutional neural network or the Transformer network. The system calibration can adopt the light model calibration technology.

Claims

1. A device for measuring the inner surface morphology and spectrum of a hollow cylinder, characterized in that: It comprises a projection module (1), an imaging detection module (2), a prism (3), an object loading platform (4) and a control module (6); the projection module comprises a flexible screen display (11) and a deformation controller (12); the input end of the deformation controller is connected to the control module (6) via a deformation control transmission line (53); the output end of the deformation controller (12) is connected to the input end of the flexible screen display (11) for modulating the surface shape of the flexible screen display (11); the other input end of the flexible screen display (11) is connected to the control module (6) via a fringe pattern input transmission line (51); the flexible screen display (11) projects a preset fringe pattern input by the control module (6), and after being reflected by the prism (3), the fringe pattern is projected onto the flexible screen display (11). The optical components of the embodiment of the present invention are uniformly distributed on the inner surface of the cylindrical object (7) to be measured; the imaging detection module comprises an array camera (21), a diffractive optical element (22) and a filter (23); the display (11) in the projection module, the camera (21), the diffractive optical element (22) and the filter (23) in the imaging detection module and the cylindrical object (7) to be measured placed on the object loading platform (4) form a structured light triangulation measurement structure, and the projection module (1) and the imaging detection module (2) focus on the inner surface of the cylindrical object (7) to be measured; the imaging detection module (2) outputs the measurement result of the collected diffraction dispersion deformation fringe pattern containing the inner surface morphology and spectral information of the cylindrical object (7) to be measured through the measurement data output transmission line (52).

2. The device for measuring the inner surface morphology and spectrum of a hollow cylinder according to claim 1, characterized in that: The prism (3) is a free-form conical reflector.

3. The device for measuring the inner surface morphology and spectrum of a hollow cylinder according to claim 1, characterized in that: The diffractive optical element (22) is a ring-shaped diffractive lens with a microstructure regularly and periodically distributed on its surface, with an operating spectrum of 400nm to 780nm and a main wavelength of 550nm.

4. The device for measuring the inner surface morphology and spectrum of a hollow cylinder according to claim 1, characterized in that: The optical filter (23) is an optical filter with a wide spectrum range of 400nm to 780nm.

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