A planar waveguide autocoupling alignment method based on a depth-of-field lens camera

Abstract

The application discloses a kind of plane waveguide automatic coupling alignment methods based on depth-of-field lens camera, including steps S1: fiber array FA is placed on the precision platform with the function of adjusting six-dimensional direction, plane waveguide chip is placed in the middle fixed, and the vertical and horizontal two directions of image information of plane waveguide chip and fiber array FA are respectively obtained by mutually perpendicular depth-of-field lens camera;Step S2: the image information obtained is handled, and the feature area of plane waveguide chip and fiber array FA is segmented.The plane waveguide automatic coupling alignment method based on depth-of-field lens camera disclosed in the application adjusts parallel by determining the parallelism of the specified surface of plane waveguide chip and fiber array FA, then takes the picture after parallel, calculates the distance of light channel of plane waveguide chip and fiber array FA, and realizes high-precision, high-efficiency automatic coupling alignment.

Description

Technical Field

[0001] This invention belongs to the field of communication technology, and specifically relates to an automatic coupling and alignment method for planar waveguides based on a depth-of-field lens camera. Background Technology

[0002] With the rapid development of optical communication technology, the demand for high-speed, high-capacity optical signal transmission is increasing. Planar waveguides, as an important optical communication component, have advantages such as low loss and high integration, and are widely used in optical communication systems. However, the coupling alignment between the planar waveguide and the fiber array (FA) is one of the key factors limiting its performance.

[0003] Traditional coupling alignment methods rely mainly on manual operation, which is not only inefficient but also difficult to guarantee accuracy. Therefore, developing an automatic and efficient coupling alignment method for planar waveguides and fiber arrays is of great significance.

[0004] In existing technologies, the coupling alignment between planar waveguide chips and fiber arrays mainly relies on mechanical alignment systems, which involve manually observing images and are cumbersome. Moreover, this method has limitations in terms of accuracy and efficiency, and the alignment system needs to be redesigned and adjusted for different chips and fiber arrays.

[0005] Therefore, further improvements will be made to address the aforementioned issues. Summary of the Invention

[0006] The main objective of this invention is to provide an automatic coupling alignment method for planar waveguides based on a depth-of-field lens camera. By determining the parallelism of a planar waveguide chip and a specified surface of an optical fiber array (FA), adjusting the parallelism, and then taking a picture after parallelization, the distance between the optical channels of the planar waveguide chip and the optical fiber array (FA) is calculated, thereby achieving high-precision and high-efficiency automatic coupling alignment.

[0007] To achieve the above objectives, this invention provides an automatic coupling alignment method for planar waveguides based on a depth-of-field lens camera, comprising the following steps: Step S1: Place the fiber array FA on a precision platform with six-dimensional orientation adjustment function, fix the planar waveguide chip in the middle, and acquire image information of the planar waveguide chip and the fiber array FA in the vertical and horizontal directions through mutually perpendicular depth-of-field lens cameras. Step S2: Process the acquired image information, segment the feature regions of the planar waveguide chip and the fiber array FA, ​​and obtain the sharpness value of each feature region and the sharpness difference between the fiber array FA region and the planar waveguide chip region. Step S3: Using the sharpness value of the planar waveguide chip area as a reference, use a six-dimensional adjustment platform to adjust the fiber array FA to rotate around the X-axis, Y-axis and Z-axis so that the sharpness difference is minimized and the array is parallel. Step S4: Obtain an image of the planar waveguide chip and the fiber array FA after they are parallel. Identify the feature points of the image through image processing technology. Accurately calculate the distances between the optical channels of the planar waveguide chip and the optical channels of the fiber array FA in the three directions of X-axis, Y-axis and Z-axis, respectively. Adjust the alignment using a six-dimensional adjustment platform. Step S5: After completing the position adjustment, the optical signal emitted by the light source is transmitted to the planar waveguide chip through the fiber array FA, ​​and the optical signal parameters (including optical power value) transmitted back from the planar waveguide chip are measured.

[0008] As a further preferred technical solution of the above technical solution, the image information obtained in step S1 includes the first, second and third surfaces of the planar waveguide chip and the fiber array FA in the vertical direction, and the fourth, fifth and sixth surfaces of the planar waveguide chip and the fiber array FA in the horizontal direction.

[0009] As a further preferred technical solution of the above technical solution, in step S2, the image obtained by the planar waveguide chip and the fiber array FA in the vertical direction of the segmented feature region is used to segment the first surface, the second surface and the third surface respectively and obtain the sharpness value, and the image obtained by the planar waveguide chip and the fiber array FA in the horizontal direction is used to segment the fourth surface, the fifth surface and the sixth surface respectively and obtain the sharpness value.

[0010] As a further preferred technical solution to the above technical solution, step S3 is specifically implemented as follows: Step S3.1: Adjust the parallelism of the first, second, and third surfaces. Using the clarity value of the second surface as a reference, control the six-dimensional adjustment platform to adjust the fiber array FA to rotate around the Y-axis until the clarity difference is at its minimum value, so that they are parallel. Step S3.2: Adjust the parallelism of the fourth, fifth and sixth surfaces. Using the clarity value of the fifth surface as a reference, control the six-dimensional adjustment platform to adjust the fiber array FA to rotate around the Y-axis. When the clarity difference is at its minimum, they are parallel.

[0011] As a further preferred technical solution to the above technical solution, in step S5, if the relevant parameters do not meet the standard, the position and angle parameters are adjusted again until the best transmission effect is achieved.

[0012] The beneficial effects of this invention are as follows: 1. High-precision automatic alignment: Utilizing the high-precision imaging capabilities of depth-sensing lens cameras, images of planar waveguides and fiber optic arrays can be accurately captured. Image processing techniques are then used to identify their feature points, thereby precisely calculating their relative positional relationships. This method significantly improves alignment accuracy and efficiency.

[0013] 2. Automated operation: The automatic coupling alignment method of the present invention can realize automated operation, thereby reducing manual intervention and operational difficulty, and improving production efficiency and quality.

[0014] 3. Applicable to various types of planar waveguide chips and fiber arrays: The automatic coupling alignment method of the present invention can be widely applied to the coupling alignment between various types of planar waveguide chips and fiber arrays, and has broad application prospects.

[0015] 4. Adjusting parallelism by comparing the sharpness of the planar waveguide and the fiber array: The parallelism between them is adjusted by comparing their sharpness. This method can effectively ensure the accuracy and stability of the coupling alignment.

[0016] 5. Strong applicability: The automatic coupling alignment method of the present invention is not only applicable to the coupling alignment between planar waveguides and fiber arrays, but can also be applied to other scenarios that require high-precision alignment, such as the alignment between optical devices.

[0017] 6. Good repeatability: Since the automatic coupling alignment method of the present invention is based on a depth-of-field lens camera, it has good repeatability and can be widely applied to various production environments and production lines. Attached Figure Description

[0018] Figure 1 This is a flowchart of an automatic coupling alignment method for planar waveguides based on a depth-of-field lens camera according to the present invention.

[0019] Figure 2 This is a schematic diagram of an automatic coupling alignment method for planar waveguides based on a depth-of-field lens camera according to the present invention.

[0020] Figure 3 This is a schematic diagram of an misaligned planar waveguide automatic coupling alignment method based on a depth-of-field lens camera according to the present invention.

[0021] The reference numerals in the attached drawings include: 1, first side; 2, second side; 3, third side; 4, fourth side; 5, fifth side; 6, sixth side. Detailed Implementation

[0022] The following description is intended to disclose the present invention and enable those skilled in the art to implement it. The preferred embodiments described below are merely examples, and other obvious variations will occur to those skilled in the art. The basic principles of the invention defined in the following description can be applied to other embodiments, modifications, improvements, equivalents, and other technical solutions that do not depart from the spirit and scope of the invention.

[0023] In the preferred embodiments of the present invention, those skilled in the art should note that the fiber optic array (FA) and the like involved in the present invention can be considered as prior art.

[0024] Preferred embodiment.

[0025] This invention discloses an automatic coupling alignment method for planar waveguides based on a depth-of-field lens camera, comprising the following steps: Step S1: Place the fiber array FA on a precision platform with six-dimensional orientation adjustment function, fix the planar waveguide chip in the middle, and acquire image information of the planar waveguide chip and the fiber array FA in the vertical and horizontal directions through mutually perpendicular depth-of-field lens cameras. Step S2: Process the acquired image information, segment the feature regions of the planar waveguide chip and the fiber array FA, ​​and obtain the sharpness value of each feature region and the sharpness difference between the fiber array FA region and the planar waveguide chip region respectively. Step S2 is implemented as follows: Step S2.1: Image preprocessing, wherein: First, the acquired images are preprocessed to improve the accuracy and stability of subsequent processing. Preprocessing steps include noise reduction and smoothing. Denoising: Use methods such as median filtering or Gaussian filtering to remove noise from the image; Smoothing: The image is further smoothed using methods such as mean filtering or bilateral filtering to reduce loss of detail and edge blurring; Step S2.2: Feature region segmentation, where: In the preprocessed image, the feature regions of the planar waveguide chip and the fiber array FA are segmented using methods such as threshold segmentation and edge detection. Thresholding segmentation: Based on the gray-level histogram or an adaptive thresholding method, a suitable threshold is determined to divide the pixels in the image into two or more classes, thereby achieving region segmentation; Edge detection: The Canny edge detection algorithm is used to detect edges in the image, further refining the segmentation of feature regions; Canny edge detection algorithm formula: ; Where Gx and Gy are the gradients in the horizontal and vertical directions, respectively, and G(x, y) is the gradient magnitude. Edge detection and connection are performed by setting high and low thresholds; Step S2.3: Calculation of sharpness value and calculation of sharpness difference, wherein: Within the segmented feature regions, the sharpness value of each region and the sharpness difference between the fiber array (FA) region and the planar waveguide chip region are calculated. The sharpness value can be obtained by calculating the gradient or variance of the pixels within the region.

[0026] Sharpness value calculation: The gradient mean is used as the sharpness index to calculate the sharpness value of each feature region. The larger the gradient or the larger the variance, the sharper the region.

[0027] Gradient mean formula: GM = (1 / N) ∑|G(x, y)|; Where GM is the gradient mean, N is the total number of pixels in the feature region, and G(x, y) is the gradient magnitude.

[0028] Sharpness difference calculation: The sharpness difference between the fiber array FA region and the planar waveguide chip region is calculated to evaluate the degree of matching between the two regions. The smaller the sharpness difference, the higher the degree of matching between the two regions. The absolute difference is used as the sharpness difference index.

[0029] The formula for absolute difference is: ΔC = |C_FA - C_WG|; Where ΔC is the absolute difference, and C_FA and C_WG are the sharpness values ​​of the FA region of the fiber array and the planar waveguide chip region, respectively.

[0030] Step S3: Using the sharpness value of the planar waveguide chip area as a reference, use a six-dimensional adjustment platform to adjust the fiber array FA to rotate around the X-axis, Y-axis and Z-axis so that the sharpness difference is minimized and the array is parallel. When the sharpness difference is at its minimum, the parallel implementation is as follows: The sharpness difference between the fiber optic array (FA) and the planar waveguide chip is minimized when their positional relationship is optimally parallel. In this state, the FA and the planar waveguide chip can be considered parallel. In other words, by adjusting the rotation of the FA around the X, Y, and Z axes, an attempt is made to find a position that minimizes the sharpness difference, thereby ensuring optimal parallelism between the FA and the planar waveguide chip.

[0031] In practice, the six-dimensional adjustment platform can provide fine-tuning of the position and orientation of the fiber optic array (FA) in space. By rotating it around the X, Y, and Z axes, the relative angle and position between the FA and the planar waveguide chip can be changed to find the minimum sharpness difference. When the sharpness difference is minimized, the two can be considered parallel.

[0032] Step S4: Obtain an image of the planar waveguide chip and the fiber array FA after they are parallel. Identify the feature points of the image through image processing technology. Accurately calculate the distances between the optical channels of the planar waveguide chip and the optical channels of the fiber array FA in the three directions of X-axis, Y-axis and Z-axis, respectively. Adjust the alignment using a six-dimensional adjustment platform. Step S4 is implemented as follows: Step S4.1: Image preprocessing: To enhance image quality and contrast, image preprocessing is performed first. This can include operations such as noise reduction, contrast enhancement, and edge sharpening.

[0033] Step S4.2: Feature point detection: The SIFT algorithm is used for feature point detection, identifying feature points in the optical channels of the planar waveguide chip and the fiber array (FA), including the entrance and exit center points of the planar waveguide chip's optical channel, and the center point of the optical channel to be aligned between the FA and the planar waveguide chip. This algorithm can detect scale- and rotation-invariant feature points. For each feature point, its descriptor is: (D(x,y,\sigma) = L(x,y,\sigma) - \frac{1}{2} \left[ L(x-1,y,\sigma) +L(x+1,y,\sigma) \right]); Where (L(x,y,\sigma)) is the Gaussian difference pyramid at scale (\sigma).

[0034] Step S4.3: Depth Information Acquisition: Using the depth information provided by the depth-sensing lens camera, obtain the coordinates of the center point of each optical channel on the Z-axis, i.e., the depth z. This is usually obtained through the depth map provided by the camera or directly from the camera's 3D point cloud data.

[0035] Step S4.4: 3D coordinate calculation: By combining the 2D coordinates (x, y) of the center point of the optical channel and the depth z, the 3D coordinates (X, Y, Z) of the center point of each optical channel can be calculated.

[0036] X = x - cx; Y = y - cy; Z = z; where (cx, cy) are the coordinates of the camera's optical center, usually set to the center of the image.

[0037] Step S4.5: Distance Calculation: After obtaining the three-dimensional coordinates of the optical channel center points of the planar waveguide chip and the fiber array FA, ​​the distance differences between them on the X-axis, Y-axis and Z-axis can be calculated.

[0038] ΔX = X_waveguide - X_fiber_array ΔY = Y_waveguide - Y_fiber_array ΔZ = Z_waveguide - Z_fiber_array, where (X_waveguide, Y_waveguide, Z_waveguide) represents the three-dimensional coordinates of the center point of the optical channel of the planar waveguide chip, and (X_fiber_array, Y_fiber_array, Z_fiber_array) represents the three-dimensional coordinates of the center point of the optical channel of the fiber array FA.

[0039] Step S4.6: Alignment Adjustment: Based on the calculated distance differences ΔX, ΔY and ΔZ, a six-dimensional adjustment platform is used for fine-tuning to minimize the distance difference between the optical channels of the planar waveguide chip and the optical channels of the fiber array FA in the three directions, thereby achieving automatic coupling alignment.

[0040] Step S5: After completing the position adjustment, the optical signal emitted by the light source is transmitted to the planar waveguide chip through the fiber array FA, ​​and the optical signal parameters (including optical power value) transmitted back from the planar waveguide chip are measured.

[0041] Specifically, the image information acquired in step S1 includes images obtained vertically from the planar waveguide chip and the fiber array FA. Figure 3 The images of the first surface 1, the second surface 2, and the third surface 3 shown, acquired horizontally by the planar waveguide chip and the fiber array FA, ​​include... Figure 3 The fourth side (4), the fifth side (5), and the sixth side (6) are shown.

[0042] Specifically, in step S2, the image obtained vertically from the planar waveguide chip and the fiber array FA divides the first surface 1, the second surface 2, and the third surface 3 and obtains the sharpness value, respectively. The image obtained horizontally from the planar waveguide chip and the fiber array FA divides the fourth surface 4, the fifth surface 5, and the sixth surface 6 and obtains the sharpness value, respectively.

[0043] Furthermore, step S3 is specifically implemented as follows: Step S3.1: Adjust the parallelism of the first surface 1, the second surface 2 and the third surface 3. Using the clarity value of the second surface 2 as a reference, control the six-dimensional adjustment platform to adjust the fiber array FA to rotate around the Y-axis. When the clarity difference is at its minimum, they are parallel. Step S3.2: Adjust the parallelism of the fourth surface 4, the fifth surface 5, and the sixth surface 6. Using the clarity value of the fifth surface 5 as a reference, control the six-dimensional adjustment platform to adjust the fiber array FA to rotate around the Y-axis. When the clarity difference is at its minimum, they are parallel.

[0044] Furthermore, in step S5, if the relevant parameters do not meet the standard, the position and angle parameters are adjusted again until the optimal transmission effect is achieved.

[0045] The present invention utilizes the high-precision imaging capability of a depth-sensing lens camera to achieve an automatic alignment method.

[0046] In this invention, the parallelism between the planar waveguide and the fiber array FA is adjusted by comparing their sharpness to achieve better results.

[0047] It is worth mentioning that the technical features such as fiber optic arrays (FA) involved in this patent application should be regarded as prior art. The specific structure, working principle, and possible control methods and spatial arrangement of these technical features can be adopted using conventional choices in the field, and should not be regarded as the inventive point of this patent. This patent will not be further elaborated in detail.

[0048] For those skilled in the art, modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this invention should be included within the protection scope of this invention.

Claims

1. A planar waveguide automatic coupling alignment method based on a depth-of-field lens camera, characterized in that, Includes the following steps: Step S1: Place the fiber optic array FA on a precision platform with adjustable six-dimensional orientation, fix the planar waveguide chip in the middle, and acquire image information of the planar waveguide chip and the fiber optic array FA in both vertical and horizontal directions using mutually perpendicular depth-of-field lens cameras; the image information acquired in step S1 includes the first, second, and third surfaces of the planar waveguide chip and the fiber optic array FA in the vertical direction, and the fourth, fifth, and sixth surfaces of the planar waveguide chip and the fiber optic array FA in the horizontal direction. Step S2: Process the acquired image information, segment the feature regions of the planar waveguide chip and the fiber array FA, ​​and obtain the sharpness value of each feature region and the sharpness difference between the fiber array FA region and the planar waveguide chip region; in step S2, for the segmented feature regions, the images acquired vertically from the planar waveguide chip and the fiber array FA will segment the first, second, and third surfaces and obtain sharpness values, and the images acquired horizontally from the planar waveguide chip and the fiber array FA will segment the fourth, fifth, and sixth surfaces and obtain sharpness values. Step S3: Using the sharpness value of the planar waveguide chip region as a reference, use a six-dimensional adjustment platform to adjust the fiber array FA around the X, Y, and Z axes so that it is parallel when the sharpness difference is minimized; Step S3 is specifically implemented as follows: Step S3.1: Adjust the parallelism of the first, second, and third surfaces. Using the clarity value of the second surface as a reference, control the six-dimensional adjustment platform to adjust the fiber array FA to rotate around the Y-axis until the clarity difference is at its minimum value, so that they are parallel. Step S3.2: Adjust the parallelism of the fourth, fifth and sixth surfaces. Using the clarity value of the fifth surface as a reference, control the six-dimensional adjustment platform to adjust the fiber array FA to rotate around the Y-axis. When the clarity difference is at its minimum, they are parallel. Step S4: Obtain an image of the planar waveguide chip and the fiber array FA after they are parallel. Identify the feature points of the image through image processing technology. Accurately calculate the distances between the optical channels of the planar waveguide chip and the optical channels of the fiber array FA in the three directions of X-axis, Y-axis and Z-axis, respectively. Adjust the alignment using a six-dimensional adjustment platform. Step S5: After completing the position adjustment, the optical signal emitted by the light source is transmitted to the planar waveguide chip through the fiber array FA, ​​and the optical signal parameters transmitted back from the planar waveguide chip are measured.

2. The planar waveguide automatic coupling alignment method based on a depth-of-field lens camera according to claim 1, characterized in that, In step S5, if the relevant parameters do not meet the standard, the position and angle parameters are adjusted again until the optimal transmission effect is achieved.

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