Method for detecting three-dimensional geometric contours of an object

Abstract

To provide a detection method for detecting texture of a geometric element, a geometric shape, and a geometric center.SOLUTION: A method includes the steps of: projecting, onto an object, a first light beam which is magnified and collimated, acquiring a projection of light which is transmitted in an optical axis of the first light beam of the object by a first light sensor, and reconstructing a texture and a shape by calculation; projecting, onto the object, a second light beam, rotating the object and acquiring reflected light by a second light sensor to acquire a continuous contour locus of the object, and reconstructing an outline locus of the object by calculation; and calculating a geometric center by the outline locus, and reconstructing an object three-dimensional geometric contour by using the outline locus as well as the texture and the shape.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a method for detecting the three-dimensional geometrical contour of an object, and in particular to a method for detecting the texture and shape of an object using a light wavefront, and detecting the outer contour of an object using a light beam to construct the actual geometrical structure of the object.

[0002] In the quality inspection of industrial products or products, optical technology is an important technology. The quality requirements of optical components such as lenses are becoming increasingly strict in terms of component size and special applications, and in the quality inspection process, the method of inspecting the quality of optical components is important. Optical detection methods can be divided into contact detection methods and non-contact detection methods. Contact detection methods directly contact the product, which may damage the surface of the object being measured. Therefore, non-contact detection methods are mostly used in the optical field. Non-contact detection methods use the interference phenomenon between the detection light beam and the reference light beam to observe the change in the interference fringes, and then reconstruct the shape (contour) of the object through calculation. In this case, the interference fringes are affected by many factors such as vibration and temperature, so high accuracy and stability are required. Due to the complexity of the interference fringes or light spots, if the coherence or collimation of the light beam is poor, it will affect the accuracy of the judgment of the imaging results, and the consideration of factors and parameters when calculating the reconstruction may be too complicated, which may affect the analysis and reconstruction process.

[0003] Therefore, by developing a detection method that has less interference, a simple detection mechanism, and not too complicated calculation processing, it is possible to reduce detection costs and improve accuracy. Summary of the Invention

[0004] In order to solve the above-mentioned problems, the objective of the embodiment of the present invention is to provide a detection method that can reduce the interference of the external environment and improve the detection accuracy or precision. In order to achieve the above-mentioned objective, the present invention provides a detection method for detecting the texture and geometric feature of a geometric element and the geometric center, which is used to detect the three-dimensional geometric contour of an object, and includes the steps of: a first light beam projection means projects a first light beam onto the object along a first optical axis, the first light beam is expanded and collimated, and the expanded and collimated first light beam passes through the object to form a feature detection light beam, thereby forming an image on a first optical sensor; the first optical sensor obtains an image formed by the object projected in the direction of the first optical axis, and constructs the texture and feature through calculation; a second light beam projection means projects a second light beam onto the object along a second optical axis, and the second light beam is reflected to form a trajectory detection light beam; a step of rotating the object, the second light beam projecting means projecting the second light beam continuously or intermittently onto the surface of the object in the direction of the second optical axis, the second light sensor acquiring a continuous shape locus formed in the direction of the second optical axis of the object, and reconstructing an outer contour of the object by calculation; and a step of calculating a geometric center using the outer contour, and combining the outer contour, the texture and the shape to construct a three-dimensional geometric contour of the object.

[0005] Preferably, the rotation of the object in the detection method is performed by a five-axis stage, although the present invention is not limited thereto.

[0006] Preferably, rotation of the object is effected by a piezoelectric actuator.

[0007] Preferably, the first light beam projection means applied in the detection method is a laser device.

[0008] Preferably, the laser device is a helium-neon laser device, a carbon dioxide laser device, a hydrogen fluoride laser device, a YAG laser device or a YVO4 laser device, but the present invention is not limited thereto.

[0009] Preferably, the second light beam projecting means is capable of forming coherent light.

[0010] Preferably, the optical sensor applied in the detection method is a photodetector integrated chip such as a charge coupled device (CCD), a complementary metal-oxide-semiconductor (CMOS), or other photoelectron device capable of converting optical energy into electrical energy. Effect of the Invention

[0011] According to the detection method for detecting the texture, geometric feature, and geometric center of a geometric element of the present invention, the feature of an object is obtained by an optical wavefront, and at the same time, the outer contour of the object is obtained by scanning with a light beam in another direction, and the three-dimensional spatial relationship between the actual feature features of the object and the geometric contour is accurately reconstructed by a superposition operation. [Brief description of the drawings]

[0012] [Figure 1] FIG. 2 is a conceptual diagram showing a system embodiment of a detection method for detecting texture, geometric features, and geometric centers of geometric elements of the present invention. [Diagram 2] 1 is a conceptual diagram showing an object shape and an outline contour recorded in an embodiment of a detection method for detecting the texture, geometric shape, and geometric center of a geometric element of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The following embodiments and drawings are for explaining the present invention, and are not intended to limit the scope of the present invention.

[0014] (Definition of terms) The term "laser device" as used herein refers to a device capable of emitting laser light, and includes a conventional discharge mechanism, gain media, resonant cavity, or pump. The term "laser light" generally refers to a device in which energy is applied to cause electrons to transition from a low energy level to a high energy level to an excited state, and then spontaneous emission occurs when the electrons return to the low energy level, and the photons emitted by the spontaneous emission collide with other atoms in a similar excited state to induce similar transitions, and the light induced to be emitted is stimulated emission, and thus, after continuous excitation, high-intensity light is finally formed. The laser light is characterized by the fact that the photons have the same frequency, phase (coherence), and traveling direction. Therefore, any laser device having the above characteristics, or any other light-emitting unit equivalent to a laser device that can form a focused beam with a small divergence angle, may be the light projection means referred to in the present invention. Specific examples of laser devices include gas laser devices such as helium-neon lasers, carbon dioxide lasers, and hydrogen fluoride lasers, and solid-state laser devices such as YAG lasers (yttrium-aluminum doped garnet crystal lasers) and YVO4 lasers (neodymium doped vanadium lasers), but are not limited to these.

[0015] As used herein, the term "expander" refers to a lens that expands an input beam into a larger diameter output beam, and can be a concave lens or a convex lens with an internal focus, or a combination of lenses, such as a convex lens with an additional convex lens, or a convex-convex lens.

[0016] A "tube lens," as described herein, is a lens or combination of lenses for focusing and collimating a beam of light.

[0017] Please refer to FIG. 1. FIG. 1 is a schematic diagram of the structure of the present invention for detecting the texture, geometric shape, and geometric center of a geometric element. It should be noted that FIG. 1 is a schematic diagram, and the arrangement relationship and structure of each element are merely exemplary, and the actual arrangement is not limited to the drawing. The system of the present invention for detecting the texture, geometric shape, and geometric center of a geometric element includes a shape detection mechanism 10 and a trajectory detection mechanism 20. The shape detection mechanism 10 is used to obtain the shape information of the object W in the axial direction by irradiating the object W to be detected with a light wavefront. The trajectory detection mechanism 20 is used to obtain the outer contour of the object W in the other axial direction by continuously irradiating the object W to be detected with a light beam. The outer contour can calculate the geometric center of the object, and after a superposition operation with the shape information, the three-dimensional contour of the object W can be further reconstructed.

[0018] The appearance detection mechanism 10 is used to project a light wave, transmit the light wave through the object W to be detected, analyze the light spot change of the light wavefront, and obtain the appearance information projected by the object W by calculation. In this embodiment, the appearance detection mechanism 10 includes a first light beam projection means 11, a reflecting mirror 12, a beam expanding and collimating unit 13, a moving mechanism 14, a first optical sensor 15, and a first analysis unit 16. The first light beam projection means 11 can emit a light beam toward the reflecting mirror 12, and the first light beam L1 reflected by the reflecting mirror 12 is irradiated to the beam expanding and collimating unit 13 along the first optical axis A1 (Z axis), and the beam expanding and collimating unit 13 expands and collimates the first light beam L1 to form an expanded and collimated light beam L2 toward the object W to be detected, and the appearance detection light beam L3 after passing through the object W is projected (photographed) on the first optical sensor 15. The first optical sensor 15 is electrically connected to a first analysis unit 16 for processing and analyzing the image information captured by the first optical sensor 15 .

[0019] When the expanded and collimated light beam L2 is directed to an object W to be detected, if the surface or overall shape of the object W changes, for example, if it has a protrusion or a depression, the incident light beam will refract inside the object W, creating an optical path difference, which changes the phase and changes the image formation. This change can be shown as an image of a gradation change (see Figure 2).

[0020] The light beam projection means 11 is a light emitting element capable of emitting a focused beam, and in this embodiment, a helium neon laser device or a YAG laser device can be used to emit a single light beam that is focused, has a very small divergence angle, and is collimated to a nearly straight line. The closer the projected light beam is to a collimated straight line, the greater the reduction in interference and the greater the accuracy of calculation. The laser has the same photon frequency, phase (coherence) and direction of travel, and other light beam projection means having the characteristics of such a laser device may be used as the light beam projection means to be applied to the present invention, and is not limited to laser devices. Examples of laser devices include gas laser devices such as helium neon lasers, carbon dioxide lasers, and hydrogen fluoride lasers, and solid-state laser devices such as YAG lasers (yttrium-doped aluminum garnet crystal lasers) and YVO4 lasers (neodymium-doped yttrium vanadate lasers), but the present invention is not limited thereto.

[0021] Considering the volume design of the detection device, it is preferable that the light beam projection means 11 includes a reflecting mirror 12 for changing the direction of the light path and reflecting it to a desired position. If this space is not required, the light beam projection means 11 can directly emit the first light beam L1 without the need to install the reflecting mirror 12, but one or more reflecting mirrors 12 may be installed to provide a special light path. In this embodiment, the beam expansion / collimation unit 13 is used to correct and maintain the collimation of the expanded light beam by expanding and collimating the light beam diameter emitted from the light beam projection means 11. In this embodiment, the beam expansion / collimation unit 13 includes an expander 131 and a tube lens 132. In this embodiment, the expander 131 realizes the expansion of the light beam diameter in order to increase the range projected on the surface of the object W to be detected. The expander is usually a concave lens or a convex lens with an internal focus, or a lens combination of a concave-convex lens and a convex-convex lens formed by adding a convex lens separately. The tube lens 132 is a lens or a combination of lenses for collecting and collimating the light beam expanded by the expander 131. This allows the beam expanding and collimating unit 13 to expand and collimate the incident beam, so that the divergence angle of the light beam can be controlled within a relatively small range, interference caused by light divergence can be avoided, and detection accuracy can be improved.

[0022] The face detection mechanism 10 is provided with a moving mechanism 14, which can rotate the object W to provide different directions and angles of the object surface, so that the projected light beam can scan the entire contour. In this case, the automatic control operation can reduce or avoid major interference and errors caused by manual movements. The moving mechanism 14 is a multi-axis moving or rotating device, and in this embodiment, it is a five-axis platform that can move in three axes and rotate in two axes, so that more surfaces of the object W can be provided and the accuracy of the movement or rotation can be ensured. A piezoelectric element actuator (PZT actuator) can be used according to the characteristics and requirements of the object W to be detected. The moving mechanism 14 of the present invention is not particularly limited.

[0023] The trajectory detection mechanism 20 includes a second light beam projection means 21, a second optical sensor 22, and a second analysis unit 23. In this embodiment, the second light beam projection means 21 can generate coherent light and may be the laser device described above, but the present invention is not limited thereto. The coherent light may be a light beam of different wavelengths in addition to a light beam of the same wavelength. The light emitted from the second light beam projection means 21 is a light beam having a plurality of different wavelengths of light (e.g., a white light source). However, the phase change of the coherent light is easy to analyze, and the trajectory of the shape of the detected object can be clearly shown. The second light beam L4 generated by the second light beam projection means 21 is projected toward the object W along the optical axis A2 (X-axis), and after being reflected by the object W, is reflected toward the optical axis A3 (Y-axis) or in a direction that forms a certain angle with the optical axis A3 to form a trajectory detection light beam L5. The trajectory detection light beam L5 is projected onto the second optical sensor 22 to form an image (shadow). The second optical sensor 22 is electrically connected to the second analysis unit 23, which processes and analyzes the image information acquired by the second optical sensor 22. The second optical sensor 22 and the first optical sensor 15 are devices that can sense the intensity of the light spot and convert it into an electrical signal, and in this embodiment, the second optical sensor 22 and the first optical sensor 15 may be a charge-coupled device or a complementary metal oxide semiconductor, but the present invention is not limited thereto.

[0024] Please refer to Fig. 1 and Fig. 2. Fig. 2 is a diagram showing an object shape and an external contour shown in an embodiment detected by the method for detecting texture, geometric shape, and geometric center of a geometric element provided by the present invention. In the embodiment of the present invention, the shape detection mechanism 10 can calculate and restore the surface shape and texture of the object W from the shape projection (shape X, shape Y) of the object W projected from the direction of the first optical axis A1 (Z axis) of the object W by Newton's ring or descent method. In addition, the trajectory detection mechanism 20 can obtain the external contour (shape X, shape Y) of the side direction of the object W from each direction of the optical axis A2 (X axis) and A3 (Y axis) plane. Therefore, according to the present invention, the geometric center of the object W can be calculated from the external contour, and the shape information detected by the shape detection mechanism 10 and the trajectory detection mechanism 20 can be superimposed and calculated on the external contour to reconstruct the three-dimensional geometric structure of the surface of the object W. Since the present invention is detected by three-dimensional scanning, the surface shape of the detected object can be accurately reconstructed, and performing quality control inspection or geometric shape inspection to evaluate the surface roughness and flatness of manufactured products can be completed very quickly and easily, which is beneficial for industrial applicability. [Explanation of symbols]

[0025] 10. Face detection mechanism 11 First beam projection means 12 Reflective mirror 13 Beam expansion and collimation unit 131 Expander 132 Tube Lens 14 Moving mechanism 15 First light sensor 16 First Analysis Unit 20 Trajectory detection mechanism 21 Second beam projection means 22 Second optical sensor 23 Second Analysis Unit L1 First light beam L2 Expanded and collimated light beam L3 Face detection light beam L4 Second light beam L5 Trajectory detection light beam A1 1st optical axis A2 X-axis A3 Y axis W object

Claims

1. A method for detecting a three-dimensional geometric contour of an object, comprising: a first light beam projection means projects a first light beam along a first optical axis onto the object, the first light beam is expanded and collimated, the expanded and collimated first light beam passes through the object to form a feature detection light beam, and an image is formed on a first optical sensor, the first optical sensor obtains an image formed by the object projected in the direction of the first optical axis, and constructs texture and feature by calculation; a second light beam projecting means projects a second light beam along a second optical axis onto the object, the second light beam being reflected to form a trajectory detection light beam, so that an image is formed on a second optical sensor, and the second optical sensor acquires a shape trajectory formed in the direction of the second optical axis of the object; Rotating the object, the second light beam projecting means projects the second light beam continuously or intermittently on the surface of the object in the direction of the second optical axis, the second optical sensor acquires a continuous shape trajectory formed in the direction of the second optical axis of the object, and reconstructs the shape trajectory of the object by calculation; calculating a geometric center according to the shape trajectory; and constructing a three-dimensional geometric contour of the object by combining the shape trajectory, the texture and the appearance.

2. 2. The method for detecting a three-dimensional geometric contour of an object according to claim 1, wherein the object is rotated by a five-axis stage.

3. 2. The method for detecting a three-dimensional geometric contour of an object according to claim 1, wherein the object is rotated by a piezoelectric actuator.

4. 2. The method for detecting the three-dimensional geometric contour of an object according to claim 1, wherein said first light beam projecting means is a laser device.

5. The first light beam projection means is a helium-neon laser device, a carbon dioxide gas laser device, a hydrogen fluoride laser device, a YAG laser device, or a YVO ４ 5. The method for detecting the three-dimensional geometric contour of an object according to claim 4, characterized in that the object is a laser device.

6. 2. The method for detecting the three-dimensional geometric contour of an object according to claim 1, wherein the second light beam projecting means is a light beam projecting means capable of forming a coherent light.

7. 2. The method of claim 1, wherein the first and second optical sensors are charge coupled devices (CCDs) or complementary metal oxide semiconductors (CMOSs).

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