CN-122018086-A - Optical waveguide alignment method based on glass substrate

CN122018086ACN 122018086 ACN122018086 ACN 122018086ACN-122018086-A

Abstract

The invention relates to the technical field of photoelectric precision alignment, in particular to a glass substrate-based optical waveguide alignment method, which comprises the steps of collecting a global optical image of a target glass substrate through a high-resolution area array image sensor, identifying and extracting a waveguide structure pattern to generate a contour point cloud, and analyzing geometric characteristics to obtain a theoretical central axis coordinate expression of a waveguide; and separating a high-contrast partial image of the waveguide port, extracting a port edge sub-pixel coordinate set through edge sharpening and sub-pixel positioning, solving a position deviation vector by spatial matching with a theoretical central axis, generating a driving control quantity by combining with a bearing table calibration motion parameter, and driving the plane displacement of the bearing table to finish alignment correction. The method relies on a global structure to construct a reference, and realizes accurate deviation calculation through sub-pixel positioning and space matching, thereby completing the fine alignment of the glass substrate optical waveguide.

Inventors

CHEN QU
FANG FULIN
Bi Pengjun
ZENG HAI
Liu Songchen
FAN BAOHONG

Assignees

深圳市比洋光通信科技股份有限公司

Dates

Publication Date: 20260512
Application Date: 20260320

Claims (10)

1. A glass substrate-based optical waveguide alignment method, the method comprising: acquiring a global optical image of a target glass substrate on a bearing table through a high-resolution area array image sensor, wherein the global optical image comprises a waveguide structure pattern; Performing waveguide structure pattern region identification and boundary extraction on the global optical image to generate a waveguide structure contour point cloud; based on the contour point cloud of the waveguide structure, calculating a coordinate expression of a theoretical central axis of the waveguide structure under a sensor coordinate system through geometric feature analysis; separating a high-contrast local image of the target waveguide port under a specific illumination condition from an imaging result of the high-resolution area array image sensor; Performing edge sharpening and sub-pixel positioning processing on the high-contrast local image, and extracting a sub-pixel precision coordinate set of the actual edge of the target waveguide port; Carrying out space matching on the sub-pixel precision coordinate set of the actual edge of the target waveguide port and the theoretical central axis of the waveguide structure, and solving a position deviation vector of the actual port center and the theoretical axis; Generating a driving control quantity of compensating motion in a bearing table plane according to the position deviation vector and combining with a pre-calibrated bearing table motion parameter; and transmitting the driving control quantity to a motion controller of the bearing platform to drive the bearing platform to execute planar displacement, so as to finish one-time alignment correction.
2. The glass substrate-based optical waveguide alignment method of claim 1, wherein performing waveguide structure pattern region identification and boundary extraction on the global optical image to generate a waveguide structure profile point cloud comprises: Processing the global optical image by adopting a self-adaptive threshold segmentation algorithm, and separating a waveguide structure pattern area from a glass substrate background area to obtain a waveguide structure binarization image; Performing morphological opening operation on the binarized image of the waveguide structure, removing noise points and smoothing the edge of the waveguide structure; Performing an edge tracking algorithm on the smoothed waveguide structure binarized image to obtain a pixel-level coordinate sequence of the waveguide structure edge; and smoothing and resampling the pixel-level coordinate sequence by adopting a cubic spline interpolation method to obtain a continuous edge curve discrete point set, so as to form the waveguide structure contour point cloud.
3. The glass substrate-based optical waveguide alignment method according to claim 2, wherein calculating a coordinate expression of a theoretical central axis of the waveguide structure in a sensor coordinate system based on the waveguide structure contour point cloud through geometrical feature analysis comprises: screening out profile point subsets positioned on the long sides of the waveguide structure from the profile point cloud of the waveguide structure; Respectively carrying out least square straight line fitting on the profile point subsets of the long sides of the two sides to obtain two straight line equations representing the edges of the two sides of the waveguide; Calculating the midlines of the two straight lines based on two straight line equations representing the edges of the two sides of the waveguide, wherein the midlines are theoretical central axes of the waveguide structure; And recording a mathematical expression of the theoretical central axis under a sensor coordinate system in a point inclined mode or a parameter equation mode to obtain the coordinate expression.
4. A glass substrate-based optical waveguide alignment method according to claim 3, wherein performing edge sharpening and subpixel positioning processing on the high-contrast partial image to extract a subpixel accuracy coordinate set of an actual edge of a target waveguide port comprises: Applying a Sobel operator to the high-contrast partial image to perform gradient calculation, and enhancing the gradient response of the edge of the waveguide port; Carrying out gray value profile scanning on the gradient image along the normal direction perpendicular to the expected edge direction to obtain a gray value distribution curve; on the gray value distribution curve, locating a section with steepest gray value change, and performing Gaussian fitting on data points in the section; and traversing all to-be-measured points at the edge of the waveguide port by taking the center point of the Gaussian fitting curve as the sub-pixel precision position of the edge to obtain a series of sub-pixel precision position coordinates to form the sub-pixel precision coordinate set.
5. The glass substrate-based optical waveguide alignment method according to claim 4, wherein spatially matching the subpixel precision coordinate set of the actual edge of the target waveguide port with the theoretical central axis of the waveguide structure, and solving a position deviation vector of the actual port center and the theoretical axis, comprises: Calculating the actual geometric center coordinate of the target waveguide port through an ellipse fitting algorithm or a least square circle fitting algorithm based on the sub-pixel precision coordinate set of the actual edge of the target waveguide port; Calculating the axis point coordinate closest to the actual geometric center coordinate from a coordinate expression of the theoretical central axis of the waveguide structure under a sensor coordinate system; calculating a difference between the actual geometric center coordinate and the nearest axis point coordinate, wherein the difference is decomposed into a longitudinal deviation component along the axis direction and a transverse deviation component perpendicular to the axis direction in a sensor coordinate system XY plane; The longitudinal and transverse offset components together form the position offset vector.
6. The method of claim 5, wherein generating a driving control amount of compensation motion in a stage plane according to the position deviation vector and a pre-calibrated stage motion parameter, comprises: acquiring motion parameters of a bearing table, wherein the motion parameters comprise calibration conversion coefficients of the pixel size of an image sensor and the actual moving distance of the bearing table; multiplying the transverse deviation component and the longitudinal deviation component of the position deviation vector by the calibration conversion coefficient respectively, and converting the transverse deviation component and the longitudinal deviation component into a transverse displacement amount and a longitudinal displacement amount of the bearing platform which need to be compensated in an actual physical space; calculating the number of transverse motor driving pulses and the number of longitudinal motor driving pulses required for moving the bearing table to the target position by combining the current position feedback value of the bearing table in the motor driver; The number of horizontal motor drive pulses and the number of vertical motor drive pulses are used as the drive control amount.
7. The method for aligning an optical waveguide based on a glass substrate according to claim 6, wherein the step of obtaining the motion parameters of the stage comprises: fixing a calibration plate with standard scales on the bearing table; controlling the high-resolution area array image sensor to image the calibration plate, and acquiring a calibration plate image; Identifying at least two non-collinear characteristic points in the calibration plate image, and recording pixel coordinates of the characteristic points under an image sensor pixel coordinate system; Calculating the actual physical size corresponding to a single pixel of the image sensor according to the actual physical distance between the known feature points on the calibration plate to obtain a pixel equivalent calibration value; The bearing table is controlled to move a known physical displacement quantity along two mutually orthogonal axial directions in a plane respectively, images are acquired before and after the movement by the high-resolution area array image sensor, and coordinate changes of the same feature point under a pixel coordinate system are identified; And calculating the proportional relation between the actual physical displacement of the bearing table and the pixel movement amount of the image sensor under the drive of the unit pulse when the bearing table moves in each axial direction according to the physical displacement and the corresponding pixel coordinate variation, and obtaining the calibration conversion coefficient.
8. The glass substrate-based optical waveguide alignment method of claim 7, further comprising, after issuing the drive control amount to a motion controller of a stage: after the bearing table finishes the plane displacement, acquiring the aligned global optical image of the target glass substrate in the same area again through the high-resolution area array image sensor; Repeatedly executing the steps of generating a waveguide structure contour point cloud, calculating a theoretical central axis of a waveguide structure, extracting a sub-pixel precision coordinate set of an actual edge of a target waveguide port and solving a position deviation vector in the aligned global optical image; Judging whether the modular length of the newly solved position deviation vector is smaller than a preset alignment precision threshold value.
9. The method of claim 8, wherein determining whether the mode length of the newly solved positional deviation vector is less than a predetermined alignment accuracy threshold comprises: calculating the sum of the square of the transverse deviation component and the square of the longitudinal deviation component of the newly solved position deviation vector; performing squaring operation on the sum of the square of the transverse deviation component and the square of the longitudinal deviation component to obtain the modular length of the position deviation vector; and comparing the modular length of the position deviation vector with the alignment precision threshold value stored in the system in advance.
10. The glass substrate-based optical waveguide alignment method according to claim 9, further comprising, when the mode length of the positional deviation vector is not less than the alignment accuracy threshold: Repeatedly executing the step of generating the driving control quantity of the compensating motion in the bearing platform plane by taking the newly solved position deviation vector as input; And transmitting the newly generated driving control quantity to a motion controller of the bearing platform, and driving the bearing platform to execute a new round of plane displacement correction.

Description

Optical waveguide alignment method based on glass substrate Technical Field The invention relates to the technical field of photoelectric precise alignment, in particular to an optical waveguide alignment method based on a glass substrate. Background The existing glass substrate optical waveguide alignment technology mostly adopts a local image acquisition mode, completes reference positioning by depending on the local characteristics of a waveguide port, acquires port position information by a conventional pixel-level edge extraction mode, and performs alignment operation by means of single displacement of a bearing table after simply aligning and matching the port position with a preset reference. The local image acquisition mode cannot acquire the information of the whole structure of the waveguide, the reference deviation is easy to generate only depending on local features, the conventional edge extraction can only realize pixel-level positioning precision, the extraction precision of the edge coordinates of the port of the waveguide is limited, the space matching precision of the position of the local port and the whole axis of the waveguide is insufficient, the position deviation vector resolving result has errors, and the matching degree of the driving control quantity of the motion compensation of the bearing platform and the actual deviation is lower. The theoretical central axis reference is needed to be constructed by depending on the overall structure outline of the waveguide, the sub-pixel precision edge coordinates of the waveguide port are needed to be obtained and the precise space matching is completed with the theoretical central axis, and the adaptive bearing platform plane compensation motion driving control quantity is needed to be generated according to the precise position deviation vector. Disclosure of Invention The invention aims to solve the defects in the prior art, and provides an optical waveguide alignment method based on a glass substrate. In order to achieve the above purpose, the invention adopts the following technical scheme that the optical waveguide alignment method based on the glass substrate comprises the following steps: acquiring a global optical image of a target glass substrate on a bearing table through a high-resolution area array image sensor, wherein the global optical image comprises a waveguide structure pattern; Performing waveguide structure pattern region identification and boundary extraction on the global optical image to generate a waveguide structure contour point cloud; based on the contour point cloud of the waveguide structure, calculating a coordinate expression of a theoretical central axis of the waveguide structure under a sensor coordinate system through geometric feature analysis; separating a high-contrast local image of the target waveguide port under a specific illumination condition from an imaging result of the high-resolution area array image sensor; Performing edge sharpening and sub-pixel positioning processing on the high-contrast local image, and extracting a sub-pixel precision coordinate set of the actual edge of the target waveguide port; Carrying out space matching on the sub-pixel precision coordinate set of the actual edge of the target waveguide port and the theoretical central axis of the waveguide structure, and solving a position deviation vector of the actual port center and the theoretical axis; Generating a driving control quantity of compensating motion in a bearing table plane according to the position deviation vector and combining with a pre-calibrated bearing table motion parameter; and transmitting the driving control quantity to a motion controller of the bearing platform to drive the bearing platform to execute planar displacement, so as to finish one-time alignment correction. As a further aspect of the present invention, performing waveguide structure pattern region identification and boundary extraction on the global optical image to generate a waveguide structure contour point cloud, including: Processing the global optical image by adopting a self-adaptive threshold segmentation algorithm, and separating a waveguide structure pattern area from a glass substrate background area to obtain a waveguide structure binarization image; Performing morphological opening operation on the binarized image of the waveguide structure, removing noise points and smoothing the edge of the waveguide structure; Performing an edge tracking algorithm on the smoothed waveguide structure binarized image to obtain a pixel-level coordinate sequence of the waveguide structure edge; and smoothing and resampling the pixel-level coordinate sequence by adopting a cubic spline interpolation method to obtain a continuous edge curve discrete point set, so as to form the waveguide structure contour point cloud. As a further aspect of the present invention, based on the waveguide structure contour point cloud, a coordinate expression of a t