TW201812707A - Anti-noise three dimensional scanning system - Google Patents

Abstract

A three dimensional scanning system includes a polarized linear light source, a telecentric image capturing device, and a first polarized element. The polarized linear light source provides a polarized linear light beam to a detecting surface. A diffusion angle of the polarized linear light beam is smaller than about 5 degrees. The telecentric image capturing device is configured to capture the polarized linear light beam on the detecting surface. The first polarized element is disposed between the telecentric image capturing device and the detecting surface. The polarization of the polarized linear light beam is substantially perpendicular to the polarization of the first polarized element.

Description

   Anti-Noise Stereo Scanning System   

This disclosure relates to a stereo scanning system.

With the advancement of technology, more and more electronic products have started to use metal materials as housings to increase the aesthetics of the products. The metal shell can be machined (such as a milling machine or a lathe) to obtain the required shapes and features. These shapes and features can be captured by optical instruments for inspection. However, after processing, the metal surface may become rough (such as the knife pattern produced by processing). As a result, the image captured by the optical instrument may contain information about the rough surface, making the measurement unstable and even impossible to measure. Get the features you want to detect.

One aspect of this disclosure provides a stereo scanning system including a polarized parallel line light source, a telecentric image capturing device, and a first polarizing element. A polarized parallel line light source provides a polarized line beam to the surface to be measured. The polarization angle of the polarized light beam is less than 10 degrees. The telecentric image capturing device is used to capture the polarized light beam on the surface to be measured. The first polarizing element is placed between the telecentric image capturing device and the surface to be measured. The polarization state of the polarized light beam and the polarization state of the first polarization element are substantially the same.

In the above embodiments, the stereo scanning system uses a combination of a polarized beam with a small diffusion angle, a first polarizing element, and a telecentric image capture device to eliminate measurement errors caused by irregularities in the surface structure of the object under test.

110‧‧‧polarized parallel line light source

112, 115‧‧‧ polarized beams

114, 116‧‧‧ Optical axis

122‧‧‧polarized light source

123‧‧‧polarized beam

124‧‧‧ cylindrical lens

152‧‧‧ Camera

154‧‧‧Telecentric lens

160‧‧‧first polarizing element

900‧‧‧ platform

905‧‧‧DUT

910‧‧‧Test surface

126, 136‧‧‧collimation element

132‧‧‧line light source

133‧‧‧line beam

138‧‧‧Second polarizing element

150‧‧‧ Telecentric image capture device

912‧‧‧normal

C‧‧‧Area

D‧‧‧ direction

θ, θ’‧‧‧ diffusion angle

FIG. 1 is a schematic diagram of a three-dimensional scanning system, a platform, and a test object according to an embodiment of the disclosure.

FIG. 2 is a schematic diagram of the polarized parallel line light source of FIG. 1 according to an embodiment.

FIG. 3 is a schematic diagram of the polarized parallel line light source of FIG. 1 according to another embodiment.

FIG. 4 is a schematic diagram of the polarization parallel line light source of FIG. 1 according to still another embodiment.

In the following, a plurality of implementations of the present disclosure will be disclosed graphically. For the sake of clear description, many practical details will be explained in the following description. However, it should be understood that these practical details should not be used to limit this disclosure. That is, in some embodiments of the present disclosure, these practical details are unnecessary. In addition, in order to simplify the drawings, some conventional structures and components will be shown in the drawings in a simple and schematic manner.

FIG. 1 is a schematic diagram of a three-dimensional scanning system, a platform 900, and a test object 905 according to an embodiment of the disclosure, and FIG. 2 is a schematic diagram of the polarized parallel line light source 110 of FIG. The stereo scanning system includes a polarized parallel line light source 110, a telecentric image capturing device 150, and a first polarizing element 160. The polarization parallel line light source 110 provides a polarization line light beam 112 to a surface to be measured 910. The diffusion angle θ (as shown in FIG. 2) of the polarized light beam 112 is less than 10 degrees. In a preferred embodiment, the diffusion angle θ is less than 5 degrees. The telecentric image capturing device 150 is configured to capture a polarized light beam 115 on the surface 910 to be measured. The first polarizing element 160 is disposed between the telecentric image capturing device 150 and the surface 910 to be measured. The polarization state of the polarized light beam 112 is substantially orthogonal to the polarization state of the first polarization element 160.

In this paper, the diffusion angle θ is the degree to which the light beam spreads as the propagation distance increases. The larger the degree of diffusion, the larger the diffusion angle θ, and vice versa. In FIG. 2, the polarized light beam 112 propagates along an optical axis 114, and the edge of the polarized light beam 112 and the optical axis 114 are sandwiched by a diffusion angle θ. If the diffusion angle θ is 0 degrees, the polarized light beam 112 is parallel light, that is, the parallel light beam does not diffuse as the propagation distance increases.

In some embodiments, the test surface 910 can be the surface of a platform 900. However, in this embodiment, a test object 905 can be placed on the platform 900, and a stereo scanning system is used to scan the three-dimensional appearance of the test object 905. If the three-dimensional scanning system scans the object to be measured 905, the surface to be measured 910 is the surface to which the object to be measured 905 and the platform 900 are illuminated by the polarization beam 112. If the stereo scanning system scans the surface of the platform 900, the surface to be measured 910 is the surface to which the platform 900 is irradiated by the polarized light beam 112. For the sake of clarity, the surface of the object to be measured 905 irradiated by the polarization beam 112 is taken as an example of the surface to be measured 910.

In this embodiment, the stereo scanning system uses a combination of the polarized light beam 112 with a small diffusion angle θ, the first polarizing element 160 and the telecentric image capturing device 150 to eliminate the amount of the object 905 caused by the irregular surface structure Test error. Specifically, the object to be measured 905 may be a metal case, for example, a metal case with a knife pattern on its surface after machining. For a test object 905 with a rough surface, measuring the surface topography can easily produce irregular scattered light due to the rough surface. These scattered light will form noise on the captured image, increasing the difficulty of subsequent analysis.

However, in this embodiment, the polarized parallel line light source 110 provides a polarized line light beam 112, that is, the polarized line light beam 112 has a specific polarization state. The polarized light beam 112 forms a line on the test surface 910 of the test object 905, and the fluctuation of the line can reflect the shape of the test surface 910. With the relative movement between the object to be measured 905 and the polarized light beam 112, the polarized light beam 112 scans the surface to be measured 910, so the complete shape of the surface to be measured 910 can be reflected. When the polarized light beam 112 is irradiated on the surface 910 to be measured, slight defects caused by the cutting pattern or other machining of the measured surface 910 may cause irregular scattering of the polarized light beam 112, and these irregular scattering will cause The polarization state of the polarization line light beam 112 changes irregularly. When the polarized light beam 112 with an irregular polarization state reaches the first polarizing element 160, it will be filtered by the first polarizing element 160, so only a part of the polarized light beam 115 having the stereo information of the surface 910 to be measured can pass through the first The polarizing element 160 reaches the telecentric image capturing device 150. On the other hand, since the telecentric image capturing device 150 has a characteristic of receiving substantially parallel light, it can receive a polarized light beam 115 with a small diffusion angle scattered from the surface to be measured 910, and will not receive irregular scattering due to the surface knife pattern. Large beam angle of other beams.

To sum up, even if part of the polarized light beam 112 is irradiated to the surface to be measured 910 due to the knife pattern, irregular scattering may occur. However, these irregularly scattered beams can be obtained by the first polarizing element 160 and the telecentric image capturing device 150 It is filtered, so the features of the test surface 910 can be enhanced, and at the same time, the image of the rough surface is suppressed, so that the features of the test object 905 can be highlighted to obtain a clear characteristic image of the test object 905. In this way, the test object 905 can be detected without surface treatment (such as sandblasting), which can greatly simplify the manufacturing process.

Please refer to Figure 2. In some embodiments, the polarized parallel line light source 110 includes a polarized light source 122, a lenticular lens 124, and a collimating element 126. The polarized light source 122 is used to provide a polarized light beam 123. The lenticular lens 124 is used to shape the polarized light beam 123 into a polarized light beam 112. The collimation element 126 is used to collimate the polarized light beam 112. Specifically, the polarization light source 122 may be, for example, a light source having a polarization state, such as a laser light source, or a combination of other light sources and a polarization element. The polarized light source 122 may be a point light source. Herein, the light point of the polarized light beam 123 provided by the point light source is substantially non-linear, such as a circle or a circle. The lens curved surface of the lenticular lens 124 is curved in a single axial direction. Therefore, the polarized light beam 123 can be deformed in a single axial direction (such as diffusion after convergence), so that the polarized light beam 123 becomes a polarized light beam 112. The collimating element 126 can collimate the polarization line beam 112 to converge the diffusion angle θ of the polarization line beam 112. In other words, the diffusion angle θ 'of the polarization line light beam 112 that has not passed through the collimation element 126 is larger than the diffusion angle θ of the polarization line light beam 112 that has passed through the collimation element 126. In some embodiments, the collimating element 126 may be a lens, but the disclosure is not limited thereto.

The structure of the polarization parallel line light source 110 is not limited to the structure of FIG. 2. Please refer to FIG. 3, which is a schematic diagram of the polarization parallel line light source 110 according to another embodiment of FIG. 1. In this embodiment, the collimated parallel line light source 110 may omit the collimation element 126 in FIG. 2, that is, the polarized parallel line light source 110 includes a polarized light source 122 and a lenticular lens 124. In this embodiment, the polarization line beam 112 in the region C (that is, a portion of the polarization line beam 112 near the optical axis 114) has a small diffusion angle θ. Therefore, only the polarization line beam 112 in the region C can be used. The baffle blocks the polarization beam 112 outside the area C, or the telecentric image capturing device 150 can only receive the polarization beam 112 in the area C. The other details of this embodiment are the same as those in FIG. 2 and therefore will not be described again.

FIG. 4 is a schematic diagram of the polarization parallel line light source 110 according to still another embodiment of FIG. 1. In this embodiment, the polarization parallel line light source 110 includes a line light source 132, a collimating element 136, and a second polarizing element 138. The linear light source 132 is used to provide a linear light beam 133. The collimating element 136 is used to collimate the light beam 133. The second polarizing element 138 is used to polarize the collimated linear beam 133 into a polarized linear beam 112. Specifically, the linear light source 132 may be a light bar including a plurality of point light sources 134 arranged along a direction D. The point light source 134 may be a light emitting diode or other suitable light sources. The collimating element 136 can collimate the linear beam 133 to converge the diffusion angle of the linear beam 133. Then, the linear light beam 133 is polarized by the second polarizing element 138 into a polarized light beam 112. The polarization state of the second polarization element 138 is substantially orthogonal to the first polarization element 160 (as shown in Fig. 1). Although in FIG. 4, the collimating element 136 is disposed between the linear light source 132 and the second polarizing element 138, in other embodiments, the second polarizing element 138 may be disposed between the linear light source 132 and the collimating element 136. In other words, the linear light beam 133 provided by the linear light source 132 can pass through the second polarizing element 138 and then pass through the collimating element 136. The other details of this embodiment are the same as those in FIG. 2 and therefore will not be described again.

Please return to Figure 1. In this embodiment, the polarized light beam 112 is incident on the surface to be measured 910 in a forward direction, and the telecentric image capturing device 150 captures the polarized light beam 115 on the surface to be measured 910 obliquely. Specifically, the test surface 910 has a normal 912. “Forward incidence” indicates that the optical axis 114 of the polarization line beam 112 provided from the polarization parallel line light source 110 is substantially parallel to the normal line 912, and “oblique capture” indicates the polarization line beam 115 received by the telecentric image capture device 150 The intersection angle between the optical axis 116 and the optical axis 114 is greater than 0 degrees. The larger the intersection angle, the better the effect of eliminating (or anti) noise. In a preferred embodiment, the intersection angle is greater than 20 degrees. Because the polarized light beam 112 enters the surface to be measured 910 in a forward direction, and the telecentric image capturing device 150 captures the polarized light beam 115 obliquely, the polarized light scattered by the telecentric image capturing device 150 is mainly scattered from the measured surface 910. Light beam 115.

In FIG. 1, the telecentric image capturing device 150 includes a camera 152 and a telecentric lens 154. A telecentric lens 154 is interposed between the camera 152 and the first polarizing element 160. The telecentric lens 154 may include a plurality of lenses (not shown). The telecentric lens 154 is designed to make substantially parallel light incident, so that the camera 152 is mainly imaged by the parallel light. Such a design can prevent the imaging magnification of the object from being changed by the distance of the object, and can exclude the imaging of the light beam with a large diffusion angle at the camera 152.

To sum up, the polarized parallel line light source provides a polarized light beam to form a line on the surface to be measured, and its undulation can reflect the shape of the surface to be measured. When the polarized light beam is irradiated onto the surface to be measured, the small defects caused by the knife pattern or other mechanical processing on the surface to be measured may cause irregular scattering of the polarized light beam. When the polarized light beam with irregular polarization reaches the first polarizing element, it will be filtered by the first polarizing element, so only a part of the polarizing light beam with stereo information of the surface to be measured can reach the telecentricity through the first polarizing element. Image capture device. The telecentric image capturing device can receive polarized light beams with a small diffusion angle scattered from the surface to be measured, and will not receive light beams with a large diffusion angle scattered irregularly due to the surface knife pattern. In this way, the stereo scanning system can eliminate measurement errors caused by irregular surface structures of the object to be measured.

Although this disclosure has been disclosed as above in the form of implementation, it is not intended to limit this disclosure. Any person skilled in this art can make various changes and decorations without departing from the spirit and scope of this disclosure. Therefore, the protection of this disclosure The scope shall be determined by the scope of the attached patent application.

Claims (10)

    A stereo scanning system includes: a polarized parallel line light source, providing a polarized line beam to a surface to be measured, wherein a diffusion angle of the polarized line beam is less than 10 degrees; a telecentric image capturing device for capturing the measured The polarization line beam on the surface; and a first polarization element placed between the telecentric image capturing device and the surface to be measured, wherein the polarization state of the polarization line beam and the polarization state of the first polarization element are substantially Orthogonal.         The stereo scanning system according to claim 1, wherein the polarized parallel line light source comprises: a polarized light source for providing a polarized light beam; and a lenticular lens for shaping the polarized light beam into the polarized light beam.         The stereo scanning system according to claim 2, wherein the polarization parallel line light source further comprises a collimating element for collimating the polarization line beam.         The stereo scanning system according to claim 2, wherein the polarized light source is a laser light source.         The stereo scanning system according to claim 1, wherein the polarized parallel line light source comprises: a line light source for providing a line beam; a collimating element for collimating the line beam; and a second polarization element for The collimated linear beam is polarized into the polarized beam.         The three-dimensional scanning system according to claim 5, wherein the line light source includes a plurality of point light sources arranged in a direction.         The three-dimensional scanning system according to claim 5, wherein the point light sources are light emitting diodes.         The three-dimensional scanning system according to claim 1, wherein the polarization beam enters the surface to be measured in a forward direction.         The three-dimensional scanning system according to claim 1, wherein the telecentric image capturing device captures the polarization beam on the surface to be measured obliquely.         The stereoscopic scanning system according to claim 1, wherein the telecentric image capturing device comprises: a camera; and a telecentric lens disposed between the camera and the first polarizing element.