A multi-sensor-based optical element assembly method, device and medium

Abstract

This invention discloses a method, apparatus, and medium for assembling optical elements based on multiple sensors. The assembly method includes: setting two optical elements, respectively located at conjugate positions between two calibrated image sensors and a beam splitter; illuminating a light source so that the beam emitted by the light source passes through the beam splitter and through the two optical elements respectively, obtaining through-hole images of the two optical elements; fixing one of the two optical elements as a reference, and during the adjustment of the other optical element, keeping the plane of the first optical element parallel to the photosensitive surface of the corresponding image sensor, until the intersection-exchange ratio (IoU) of the through-hole images of the two optical elements is within a preset threshold range. This invention fundamentally solves the problems of low precision and poor consistency in traditional manual assembly methods. Using one optical element as a reference, the spatial projection of the two optical elements is acquired in real time through an imaging system, and the position and orientation of the other optical element are adjusted accordingly, achieving strict conjugate alignment of the two optical elements.

Description

Technical Field

[0001] This invention belongs to the field of machine vision, and particularly relates to a method, apparatus and medium for assembling optical elements based on multiple sensors. Background Technology

[0002] In precision optical systems, it is often necessary to achieve a precise spatial conjugate configuration of two optical elements with through-hole structures (such as slits) relative to a beam splitter prism. This configuration is widely used in spectral imaging, confocal measurement, interferometry, and beam shaping. In a typical application, the first optical element is placed on one side of the first light-transmitting surface of the beam splitter prism, and the second optical element is placed on the other side, forming a conjugate relationship through the beam-splitting surface inside the prism. To ensure system imaging quality, energy efficiency, or signal contrast, the two optical elements need to be precisely aligned in the direction perpendicular to the optical axis. Their conjugate error typically needs to be controlled within the micrometer or even sub-micrometer range, especially when the through-hole size is small, which drastically increases the difficulty of assembly and adjustment.

[0003] Traditional assembly and adjustment processes often rely on a combination of manual visual observation and mechanical fine-tuning frames. Operators use a magnifying microscope or camera monitor to observe the projection or transmitted images of two through-holes on the prism's imaging surface. By repeatedly rotating and translating the fine-tuning frame manually, the images of the two through-holes are visually aligned to approximately coincide. Then, adhesive is applied for curing or locking to secure the alignment. Finally, system-level performance testing verifies the conjugation effect. However, this method has several inherent drawbacks: First, the human eye has limited resolution, making it difficult to accurately quantify minute offsets and angular deviations, and subjective judgment varies greatly, leading to uncontrollable assembly and adjustment accuracy. Second, when the through-hole shape is not limited to rectangular slits, it is difficult to standardize the manual alignment benchmark, making judgment even more challenging. Third, during curing or locking, adhesive shrinkage, stress release, or mechanical return errors can easily introduce secondary offsets, rendering the original alignment invalid. Fourth, in mass production, the process suffers from poor consistency and repeatability, severely restricting product yield and production efficiency, and rework operations are complex and costly.

[0004] Therefore, achieving high-precision, repeatable, and quantifiable automatic alignment of dual optical elements relative to a beam splitter during assembly has become a pressing technical challenge in the field of precision optical assembly. This invention addresses these issues by providing a multi-sensor-based optical element assembly method, apparatus, and medium, fundamentally improving the insufficient precision and poor consistency of traditional assembly methods. Summary of the Invention

[0005] The purpose of this invention is to overcome the above-mentioned problems in the prior art and provide an optical element assembly method, device and medium based on multiple sensors, which fundamentally improves the problems of insufficient accuracy and poor consistency of traditional assembly methods.

[0006] To achieve the above-mentioned technical objectives and effects, the present invention is implemented through the following technical solution: A method for assembling optical components based on multiple sensors, comprising: Two flat optical elements with arbitrary-shaped through holes of the same shape are set up and located at the conjugate positions between the two calibrated image sensors and the beam splitter, respectively. The planes of the two optical elements are adjusted to be parallel to the photosensitive surfaces of the two image sensors. Lighting up the light source causes it to emit a uniform beam of light, which is directed toward the beam splitter. The beam passes through the beam splitter and two optical elements, reaching two image sensors to obtain images of the through holes of the two optical elements. One of the two optical elements is fixed as a reference. During the adjustment of the other optical element, the plane of the optical element is kept parallel to the photosensitive surface of the corresponding image sensor until the cross-over ratio of the through-hole images of the two optical elements is within a preset threshold range. In this configuration, the photosensitive surfaces of the two calibrated image sensors are parallel to and directly opposite the first and second light-transmitting surfaces of the beam splitter, respectively, and the coordinate mapping relationship between the two image sensors is known; the first and second light-transmitting surfaces are adjacent to each other and are located on opposite sides of the beam splitter surface of the beam splitter; the optical axis of the light source is consistent with the optical axis of the beam splitter, and the uniform beam has consistent illuminance at any position on a plane perpendicular to the optical axis of the light source.

[0007] Furthermore, calibrating the two image sensors includes: Place a calibration object between the light source and the beam splitter, so that the plane of the calibration object is parallel to the first or second light-transmitting surface; The light source is turned on, so that the beam emitted by the light source passes through the calibration object and the beam splitter in sequence and then enters the two image sensors respectively, thus obtaining two images of the calibration object; Adjust the two image sensors respectively so that the difference in sharpness values ​​of all feature points in the calibration image corresponding to each image sensor is less than a preset threshold; The calibration object contains at least three non-collinear feature points.

[0008] Furthermore, the method for determining whether the cross-union ratio of the through-hole images of the two optical elements is within a preset threshold range is as follows: After calibration, extract all feature point data from each calibrated object image; Establish a mapping model between all feature point data in two calibration object images, and fit the corresponding mapping relationship; Based on the mapping relationship, the through-hole image of any optical element is corrected, and the corrected through-hole image of the optical element is compared with the through-hole image of another optical element until the cross-comparison ratio is within a preset threshold range.

[0009] Furthermore, the adjustment to make the planes containing the two optical elements parallel to the photosensitive surfaces of the two image sensors includes: A telecentric lens is used to face the non-light-transmitting surface of the beam splitter to photograph the two optical elements, resulting in side view images of the two optical elements; Adjust the two optical elements separately until the intersection of the non-light-transmitting surface of the beam splitter and the first light-transmitting surface and the second light-transmitting surface is parallel to the length direction of the side view image corresponding to the first optical element and the second optical element, and the width of the two side view images is equal to the imaging width under the theoretical posture. The non-light-transmitting surface is perpendicular to both the first light-transmitting surface and the second light-transmitting surface.

[0010] Furthermore, adjusting another optical element includes: The optical element being adjusted is moved along a direction perpendicular to the plane of the optical element being adjusted until the coordinate mapping relationship between the two image sensors is known, so that the width of the through-hole images of the two optical elements is consistent in the corrected unified coordinate system. Calculate the slope difference in the same feature direction in the through-hole images of two optical elements, and rotate the adjusted optical element according to the slope difference; Calculate the centroid offset of the through-hole images of the two optical elements, and translate the optical element being adjusted along the plane of the optical element being adjusted based on the centroid offset; The mapping relationship between the centroid offset and the corresponding translation is known.

[0011] Furthermore, after adjusting another optical element, the process also includes: Measure the distance between the optical element being adjusted and the beam splitter, and select a shim of the corresponding thickness and apply adhesive to the optical element being adjusted by deducting the reserved adhesive layer thickness. Adjust the optical elements during the dispensing and curing process to keep the cross-over ratio of the through-hole images of the two optical elements within a preset threshold range.

[0012] The present invention also provides a method for assembling optical components based on multiple sensors, comprising: Two flat optical elements with arbitrarily shaped through holes of the same shape are set up and located at the conjugate positions between the two calibrated image sensors and the flat beam splitter, respectively. The planes of the two optical elements are adjusted so that they are parallel to the photosensitive surfaces of the two image sensors. The light source is lit, causing it to emit a uniform beam of light that is directed toward the flat beam splitter. The beam passes through two optical elements and reaches two image sensors, resulting in through-hole images of the two optical elements. One of the two optical elements is fixed as a reference. During the adjustment of the other optical element, the plane of the optical element is kept parallel to the photosensitive surface of the corresponding image sensor until the cross-over ratio of the through-hole images of the two optical elements is within a preset threshold range. The photosensitive surfaces of the two calibrated image sensors are perpendicular to each other, aligned with the two sides of the flat beam splitter, and each forms a 45-degree angle with the plane of the flat beam splitter. The coordinate mapping relationship between the two image sensors is known. The optical axis of the light source is consistent with the optical axis of the flat beam splitter, and the illuminance of the uniform beam is consistent at any position on the plane perpendicular to the optical axis of the light source.

[0013] The present invention also provides a method for assembling optical components based on multiple sensors, comprising: At least three flat optical elements with through holes of arbitrary shapes and the same through hole shape are provided, respectively located at the conjugate positions between at least three calibrated image sensors and multi-beam splitters, and adjusted so that the planes of at least three optical elements are parallel to the photosensitive surfaces of the corresponding image sensors. Lighting up the light source causes it to emit a uniform beam of light, which is directed toward the incident surface of the multi-beam splitter. The beam passes through each optical element via the multi-beam splitter and reaches the corresponding image sensor, resulting in at least three through-hole images of the optical elements. Fix any one of the optical elements as a reference, and while adjusting the other optical elements, keep the plane of the adjusted optical element parallel to the photosensitive surface of the corresponding image sensor until the cross-over ratio of the through-hole images of all optical elements is within a preset threshold range. In this configuration, the photosensitive surfaces of at least three calibrated image sensors are parallel to and directly opposite the exit surfaces of the multi-beam splitter, and the coordinate mapping relationship between all image sensors is known. The multi-beam splitter is used to split the light beam entering the incident surface into at least three exit beams through the exit surfaces. The optical axis of the light source is consistent with the optical axis of the multi-beam splitter, and the uniform beam has consistent illuminance at any position on a plane perpendicular to the optical axis of the light source.

[0014] This invention also provides an optical element assembly device based on multiple sensors, which utilizes the above-described assembly method to achieve adjustment. It is used to respectively position two flat optical elements at the conjugate positions of the first and second light-transmitting surfaces of a beam splitter, wherein the first and second light-transmitting surfaces are adjacent and located on opposite sides of the beam splitter surface. The assembly device includes: Two calibrated image sensors are provided, with their photosensitive surfaces parallel and directly facing the first and second light-transmitting surfaces of a beam splitter, respectively. The coordinate mapping relationship between the two image sensors is also known. A light source, positioned on either the side of the first or second light-transmitting surface, is used to emit a uniform light beam and direct it toward a beam splitter. The light beam passes through two optical elements via the beam splitter and is captured by two image sensors to obtain images of the through-holes of the two optical elements. The optical axis of the light source is aligned with the optical axis of the beam splitter, and the uniform light beam has consistent illuminance at any position on a plane perpendicular to the optical axis of the light source. The adjustment mechanism includes a translation adjustment module and a rotation adjustment module. The translation adjustment module is used to translate the optical element in the direction perpendicular to the plane where the optical element is located. The rotation adjustment module is used to rotate the optical element in the plane where the optical element is located, while keeping the plane where the optical element is located parallel to the photosensitive surface of the corresponding image sensor, until the intersection ratio of the two optical element images is within a preset threshold range. Both optical elements have through holes of arbitrary shape and the through holes are identical. They are respectively set at the conjugate position between the two image sensors and the beam splitter, and the planes on which the two optical elements are located are parallel to the photosensitive surfaces of the two image sensors.

[0015] The present invention also provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the above-described assembly method.

[0016] The beneficial effects of this invention are: (1) This invention fundamentally solves the problems of low precision and poor consistency in traditional manual assembly and adjustment methods. Taking one of the optical elements as a reference, the spatial projection of the two optical elements is obtained in real time through the imaging system, and the position and orientation of the other optical element are adjusted accordingly. Strict conjugate alignment of the two optical elements can be achieved at the sub-pixel level, which significantly improves the spectral resolution and signal-to-noise ratio of the coaxial spectral confocal system.

[0017] (2) The present invention only requires adjustment of six degrees of freedom of the optical element. By fixing one of the optical elements in advance as a reference, only the six degrees of freedom of the other optical element need to be adjusted in the subsequent process, which simplifies the complexity of the adjustment model.

[0018] (3) By using two pre-calibrated image sensors, the present invention can compare the through-hole image of the first optical element and the through-hole image of the second optical element in the same image coordinate system, thereby adjusting the spatial pose of the second optical element. At the same time, it can monitor the displacement, rotation and optical axis movement of the plane where the second optical element is located in real time. Attached Figure Description

[0019] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this application, illustrate exemplary embodiments of the invention and, together with their description, serve to explain the invention and do not constitute an undue limitation thereof. In the drawings: Figure 1 This is a flowchart of the assembly method in this invention; Figure 2 This is a schematic diagram of the adjustment device in this invention.

[0020] In the figure: 1-beam splitter prism; 11-first light-transmitting surface; 12-second light-transmitting surface; 13-beam splitter surface; 2-first optical element; 3-second optical element; 4-first image sensor; 5-second image sensor; 6-light source. Detailed Implementation

[0021] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] For ease of understanding, let's take the dual-slit assembly and adjustment in a coaxial spectral confocal system as an example. Traditional slit bonding assembly and adjustment methods are no longer sufficient to meet the demands of mass production and high reliability. To further improve the reliability of slit adjustment, consider the following two methods: First, there is the bonding method based on mechanical limiting and shim control. The operator first fixes the beam splitter to the base, then inserts a metal or thin-film shim approximately 30μm thick between the slit and the beam splitter to control the adhesive layer gap. Optical adhesive is then applied to the side to fill the gap, and finally the shim is removed and cured. However, this method has drawbacks: the shim itself has manufacturing tolerances (±3-5μm) and is prone to deformation after repeated use, resulting in poor adhesive layer thickness consistency; changes in the air gap cannot be observed in real time during adjustment, making it difficult to compensate for beam splitter surface errors or slit substrate warping; the conjugate alignment between the two slits relies entirely on external references or operator visual inspection, with an accuracy typically only reaching ±5μm, which cannot meet submicron-level conjugate requirements.

[0023] Second, a visually assisted bonding method using a single-axis or three-axis displacement stage and a microscope is employed. The slit is mounted on a three-axis precision displacement stage, a beam splitter is fixed, and the intersection-to-exclusion ratio of the slit edge and the prism's marked line is observed under a microscope. The displacement stage is then adjusted gradually. The adhesive layer thickness is indirectly calculated using the stage's feed scale or a displacement sensor. After adhesive dispensing and curing, testing and verification are performed. However, this method has several drawbacks: the microscope's limited depth of field makes it difficult to clearly image and quantify the minute air gap (approximately 30 μm) between the prism and the slit; adhesive layer thickness control is an "open-loop" method, unable to be corrected in real-time after dispensing and before curing, making it prone to deviations from the target thickness due to adhesive shrinkage or surface tension; and when the two slits are assembled and adjusted independently, the lack of a fixed "reference slit" as a conjugate reference leads to accumulated relative positional errors between the two slits. Example 1

[0024] To solve similar problems mentioned above with optical components, such as Figure 1 As shown, this embodiment first provides a method for assembling optical components based on multiple sensors, including: Two flat optical elements with identical through-holes of arbitrary shapes are positioned at conjugate positions between two calibrated image sensors and a beam splitter prism. The planes of the two optical elements are adjusted so that they are parallel to the photosensitive surfaces of the two image sensors. The photosensitive surfaces of the two calibrated image sensors are parallel to and directly opposite the first and second light-transmitting surfaces of the beam splitter prism, respectively, and the coordinate mapping relationship between the two image sensors is known. The first and second light-transmitting surfaces are adjacent and located on opposite sides of the beam splitter prism's beam-splitting surface. The beam splitter prism is a cubic structure formed by cementing two right-angled triangular prisms together. The "conjugate position" is a predetermined position, typically close to an ideal conjugate position, used as the initial state. The specific position can be set according to actual needs without undue limitation. Positioning the two optical elements at conjugate positions and ensuring strict parallelism provides a stable geometric reference for the entire assembly and adjustment process, avoiding systematic errors caused by reference drift and improving the controllability of subsequent alignment. Only by ensuring that the two image sensors face their corresponding light-transmitting surfaces can the acquired images of the optical element apertures be free of perspective distortion, providing accurate raw data for subsequent image cross-comparison. The calibration process establishes a unified image acquisition reference coordinate system, eliminating the impact of image sensor installation errors on measurement accuracy and laying the foundation for subsequent high-precision image comparison. The two optical elements, designated as the first and second optical elements respectively, are positioned in conjugate positions and strictly parallel, providing a stable geometric reference for the entire assembly and adjustment process. This avoids systematic errors caused by reference drift and improves the controllability of subsequent alignment. Optical conjugation requires that the two optical elements not only be conjugate in directions perpendicular to their respective light-transmitting surfaces, but their own planar directions must also be perpendicular to the optical axis, i.e., parallel to the light-transmitting surfaces. If the plane of the optical element is not parallel to the light-transmitting surface, it is equivalent to the optical element being tilted relative to the ideal optical path, which will cause the light beam to be unable to pass through the optical element or the light beam passing through the optical element to be distorted and have uneven energy distribution, thus destroying the conjugate imaging quality. By adjusting the parallelism of the two optical elements, the attitude foundation for achieving high-precision image overlap is laid. A beam splitter includes four light-transmitting surfaces around its perimeter and non-light-transmitting surfaces at both ends. Taking a double-slit assembly scenario in a coaxial spectral confocal system as an example, two optical elements correspond to two slits. The first light-transmitting surface corresponds to the first optical element. The light beam passes through the first optical element, the first light-transmitting surface, the beam splitting surface of the beam splitter, and the dispersive lens to reach the surface of the object under test. After reflection, it passes through the dispersive lens, the beam splitting surface of the beam splitter, and the second light-transmitting surface to reach the second optical element.

[0025] The light source is illuminated, emitting a uniform beam that travels towards a beam splitter. This beam passes through two optical elements and reaches two image sensors, resulting in two through-hole images of the optical elements. The optical axis of the light source is aligned with the optical axis of the beam splitter, and the uniform beam exhibits consistent illuminance at any position on a plane perpendicular to the optical axis of the light source. The light source is positioned either to the side of the first or second light-transmitting surface. The light emitted after illumination passes through the two optical elements via reflection and refraction at the beam splitter surface. The through-hole shapes of the optical elements are projected onto the corresponding image sensors, resulting in two through-hole images: the first optical element through-hole image and the second optical element through-hole image. The intersection-union ratio (IUGR) of the first and second optical element through-hole images in the same image coordinate system directly and accurately reflects the physical conjugate state of the two optical elements within the beam splitter's optical path. This step transforms the invisible and abstract "optical conjugate" relationship into an intuitive and quantifiable "image coincidence" problem. It enables real-time precision detection, eliminating reliance on operator visual observation and providing accurate feedback signals (image differences) for subsequent adjustments, which is the technical prerequisite for the entire automated precision adjustment.

[0026] One of the two optical elements is fixed as a reference. During the adjustment of the other optical element, the plane of that optical element is kept parallel to the photosensitive surface of the corresponding image sensor until the intersection-over-union ratio of the through-hole images of the two optical elements is within a preset threshold range. For example, the first optical element is used as a reference and fixed on the first light-transmitting surface of the beam splitter. Fixing can be done using any method as needed, such as bonding, clamping, magnetic attraction, or vacuum adsorption. After fixing the first optical element, only the second optical element needs to be adjusted, reducing the adjustment freedom from six degrees of freedom for two elements to six degrees of freedom for one element. This greatly simplifies the complexity and optimization difficulty of the adjustment model and improves the determinism and efficiency of the adjustment. In specific operation, a glass pad of customized thickness is used as a positioning aid to bond the first optical element to the conjugate position of the first light-transmitting surface of the beam splitter. By controlling the thickness of the glass pad, the initial distance between the first optical element and the surface of the beam splitter strictly conforms to the optical design dimensions; at the same time, a height gauge can be used to check the flatness of the first optical element to ensure that its parallelism deviation with the reference surface of the beam splitter is less than 10μm. The beam-splitting prism assembly with the first optical element already bonded is fixed to the air-floating platform where the six-axis controller is located to ensure positional stability during subsequent adjustments. Based on the through-hole images of the first and second optical elements extracted from the acquired images, the second optical element is adjusted by a control system such as the six-axis controller, allowing for fine adjustments to its position and orientation at the micron or even sub-micron level. The ultimate goal of the adjustment is to ensure that the intersection-union ratio (CIU) of the two optical element through-hole images is within a preset threshold range, meaning that the real-time images of the two optical elements completely overlap on the display screen. The CIU refers to the ratio of the intersection to the union of the two optical element through-hole images, that is, the ratio of the area of ​​the overlapping portion of the two optical element through-hole images to the total area covered by the two optical element through-hole images. The closer the CIU is to 1, the better the overlap effect. A specific preset threshold range can be set according to the actual situation. According to geometric optics and aberration theory, when the two optical elements are in ideal positions in the conjugate optical path of the beam-splitting prism, the images formed by them after passing through the prism are completely identical in space. Conversely, if two images are misaligned in the same image coordinate system, it directly indicates that the physical positions of the two optical elements deviate from the ideal conjugate state. Therefore, "image coincidence" is an accurate mapping of "physical conjugate" in image space. By continuously adjusting the second optical element and observing the image, a negative feedback loop is formed until the cross-union ratio is within a preset threshold range, thus achieving high-precision conjugate alignment.

[0027] Through the above steps, this invention achieves the following effects: First, by fixing the first optical element in advance as a reference, only the six degrees of freedom of the second optical element need to be adjusted in subsequent processes, simplifying the complexity of the adjustment model. Second, by using two pre-calibrated image sensors, the through-hole images of the first and second optical elements can be compared in the same image coordinate system, thereby adjusting the spatial pose of the second optical element. Simultaneously, the displacement, rotation, and optical axis movement of the plane containing the second optical element can be monitored in real time.

[0028] As a specific embodiment of the present invention, calibrating two image sensors includes: A calibration object is placed between the light source and the beam splitter, with the plane of the calibration object parallel to either the first or second light-transmitting surface. The calibration object is a reference object with known feature points, which can be edge features of an opaque object or feature points of a translucent object. At this point, the parallel relationship between the calibration object and the beam splitter ensures that the imaging positions of each feature point on the two image sensors have a definite theoretical correspondence after beam splitting.

[0029] The light source is illuminated, and the emitted beam passes sequentially through the calibration object and the beam splitter before entering the two image sensors, resulting in two images of the calibration object. At this point, the two image sensors can simultaneously obtain the corresponding images of the calibration object. Based on all feature point data in the same image coordinate system, the positional relationship between the two image sensors can be accurately determined.

[0030] Two image sensors are adjusted separately to ensure that the difference in sharpness values ​​of all feature points in the calibration object image corresponding to each image sensor is less than a preset threshold. The calibration object contains at least three non-collinear feature points. Consistent feature point sharpness means that the plane of the calibration object is precisely parallel to the target surface of the image sensor. If they are not parallel, feature points at different locations on the calibration object will exhibit different sharpness due to varying degrees of defocus. These three non-collinear feature points provide reliable data support for adjusting the image sensors, avoiding a situation where all feature points have consistent sharpness but the parallelism of the image sensor cannot be guaranteed. By iteratively adjusting to achieve consistent sharpness across the entire field of view, the parallelism of the image sensor target surface to the plane of the calibration object is ensured, which in turn is parallel to the light-transmitting surface of the beam splitter. This achieves high-precision spatial calibration of the two image sensors relative to the light-transmitting surface of the beam splitter, providing a benchmark guarantee for the accurate acquisition of subsequent through-hole images of optical components.

[0031] Since this invention utilizes two image sensors, it is necessary to process the data from one of them to unify the image coordinate system. The method for determining whether the cross-over ratio (CUP) of the two optical element aperture images is within a preset threshold range is as follows: After calibration, extract all feature point data from each calibrated object image.

[0032] Establish a mapping model between all feature point data in two calibration object images, and fit the corresponding mapping relationship.

[0033] Based on the mapping relationship, the through-hole image of any optical element is corrected, and the corrected through-hole image of the optical element is compared with the through-hole image of another optical element until the cross-comparison ratio is within a preset threshold range.

[0034] Two image sensors may have inherent systematic errors such as differences in pixel size, rotation deviation, and distortion. By establishing a mapping model using calibrated feature points, the coordinate transformation relationship between the two imaging systems can be quantitatively described. The corrected image eliminates these systematic errors, allowing image comparison to directly reflect the actual spatial position deviation of the optical elements, thereby improving the accuracy and reliability of cross-comparison (CCOM) determination.

[0035] As a specific embodiment of the present invention, fixing any one of the two optical elements as a reference includes: bonding a glass gasket to the optical element to be fixed as a whole, and bonding and fixing the glass gasket to the conjugate position of the first or second light-transmitting surface of the beam splitter. After the optical adhesive cures, there is an optimal adhesive layer thickness range (e.g., 30μm). Too thin or too thick a layer will affect strength and stability, and direct application of adhesive cannot precisely control the gap. The glass gasket provides a precise and rigid physical separation. The glass gasket has precise thickness tolerance and flatness, allowing for standardized control of the distance between the optical element and the prism, replacing the vague method of manual adhesive application for thickness control. The fixed thickness of the gasket enables precise preset of the adhesive layer distance, while ensuring the flatness of the assembly plane of the optical element. By precisely controlling the gap between the bottom surface of the first optical element and the light-transmitting surface of the prism using the gasket, the thickness of the subsequent adhesive layer is equal to the thickness of the gasket, achieving precise and quantitative control of the adhesive layer thickness. This avoids the problems of spacing deviation and uneven adhesive layer thickness caused by manual bonding, improving the consistency and stability of the reference end assembly.

[0036] To ensure a reasonable spacing between the optical elements and the beam splitter, before fixing the reference component, the following steps are taken: the reference component is moved perpendicular to the plane of its location until the width of the corresponding optical element image falls within a preset width range. A glass spacer of appropriate thickness is then selected based on the spacing between the reference component and the beam splitter. The width of the through-hole images of the two optical elements depends not only on the physical width of the optical elements themselves but also on their defocusing amount in the optical path. Only when the two optical elements are located near the optimal conjugate image plane will the image be sharpest, with the smallest width equal to the theoretical value. By finding the "minimum width" position, the optimal focal plane position can be precisely located.

[0037] To ensure the parallelism of the two optical elements, adjustments are made to make the planes containing the two optical elements parallel to the photosensitive surfaces of the two image sensors. This includes: using a telecentric lens facing the non-light-transmitting surface of the beam splitter to photograph the two optical elements, obtaining side view images of the two optical elements; adjusting the two optical elements respectively until the intersection lines of the non-light-transmitting surface of the beam splitter with the first and second light-transmitting surfaces are parallel to the length direction of the side view images corresponding to the first and second optical elements, respectively, and the width of the two side view images is equal to the imaging width under the theoretical orientation; wherein, the non-light-transmitting surface is simultaneously perpendicular to the first and second light-transmitting surfaces. The imaging width under the theoretical orientation is pre-calculated based on optical design parameters. The telecentric lens has the advantages of parallel light imaging and no perspective distortion, and can accurately capture the lateral attitude deviation of the optical elements; the lateral shooting angle can intuitively reflect the pitch and yaw angles of the optical elements, compensating for the deficiency of frontal imaging in identifying attitude tilt angles, and providing a basis for subsequent adjustments. This step accurately acquires the lateral attitude information of the second optical element without imaging distortion. It can efficiently identify minute tilt errors of the second optical element, providing accurate image data for the parallelism calibration of the optical element plane and improving the accuracy of attitude adjustment. When the planes containing the two optical elements are completely parallel to the first and second light-transmitting surfaces of the beam splitter, the length direction of the side view images of the two optical elements will be parallel to the edge of the beam splitter, and the imaging width of the two optical elements will be consistent. If there is a tilt angle, the imaging will be tilted and the width will be widened. This can be used as a basis for accurate attitude calibration. This step decomposes the complex spatial parallelism adjustment into two intuitive image feature comparisons (parallel edges and equal width), making the adjustment process data-driven, enabling automated judgment and closed-loop control, and ensuring the accuracy and efficiency of parallelism adjustment.

[0038] As shown above, after adjusting the plane of the second optical element to be parallel to the second light-transmitting surface of the beam splitter, the pose of the second optical element needs to be adjusted along the optical axis and the plane of the second optical element. Specifically, adjusting the second optical element includes: moving the adjusted optical element along a direction perpendicular to the plane of the adjusted optical element until, through the known coordinate mapping relationship between the two image sensors, the widths of the aperture images of the two optical elements are consistent in the corrected unified coordinate system; calculating the slope difference of the same feature direction in the aperture images of the two optical elements, and rotating the adjusted optical element according to the slope difference; calculating the centroid offset of the aperture images of the two optical elements, and translating the adjusted optical element along the plane of the adjusted optical element according to the centroid offset; wherein, the mapping relationship between the centroid offset and the corresponding translation is known. The same feature direction is the straight line direction formed by connecting any two identical feature points in the images of the two optical elements. The process of adjusting the second optical element to achieve image overlap is decomposed into two ordered steps: rotation and translation. The inconsistency in image width is essentially caused by the different defocus amounts of the two optical elements. By moving the second optical element along a direction perpendicular to the second light-transmitting surface (i.e., along the optical axis), the distance between the second optical element and the beam splitter can be changed, allowing its image width to match the fixed image width of the first optical element's aperture image. This corresponds to the two achieving conjugation in the optical axis direction. Based on this consistent width (i.e., confocal), further displacement or rotation along the plane of the second optical element is needed to make the outlines of the first and second optical element's aperture images coincide, thus achieving complete spatial conjugation. This step first resolves the main contradiction (defocus) through a one-dimensional search, then addresses the coincidence problem in the two-dimensional plane. This avoids complex coupled searches in six-degree-of-freedom space, greatly simplifying the complexity of the control algorithm and improving adjustment speed and success rate.

[0039] To further address the curing misalignment issue during dispensing, after adjusting another optical element, the process includes: measuring the distance between the adjusted optical element and the beam splitter; selecting a shim of appropriate thickness for dispensing onto the adjusted optical element by subtracting the reserved adhesive layer thickness; adjusting the optical element during the dispensing curing process to maintain the cross-section over union (CUB) of the through-hole images of the two optical elements within a preset threshold range. After achieving precise alignment, the remaining gap, corresponding to the reserved adhesive layer thickness, is observed through a side telecentric lens; dispensing is then performed only if the expected CUB thickness is met. After bonding, the optical element pose may undergo slight changes due to the adhesive layer, necessitating further fine-tuning until the images re-align. This step resolves the contradiction between "precise alignment" and "adhesive layer thickness control." Through alignment, measurement, shim selection, and re-alignment, it ensures both the accuracy of the final conjugate state and precise control of the adhesive layer thickness within the design value, balancing optical performance and mechanical reliability. Secondary fine-tuning compensates for deformation errors, locking in a high-precision assembly state. During UV curing, the alignment status of the two optical elements is continuously observed. Once a slight offset is detected due to glue flow or curing shrinkage, it can be immediately compensated and corrected using a six-axis controller to ensure that the established high-precision conjugate relationship is not changed during the curing process.

[0040] As a specific application scenario of the present invention, the above-mentioned optical element is a slit, which effectively solves the assembly and adjustment problem of double slits in the coaxial spectral confocal system and improves the reliability and consistency of slit adjustment. Example 2

[0041] As a second embodiment of the assembly method of the present invention, the present invention also provides an optical element assembly method based on multiple sensors, comprising: Two flat optical elements with arbitrarily shaped through holes of the same shape are set up and located at the conjugate positions between the two calibrated image sensors and the flat beam splitter, respectively. The planes of the two optical elements are adjusted so that they are parallel to the photosensitive surfaces of the two image sensors. The light source is lit, causing it to emit a uniform beam of light that is directed toward the flat beam splitter. The beam passes through two optical elements and reaches two image sensors, resulting in through-hole images of the two optical elements. One of the two optical elements is fixed as a reference. During the adjustment of the other optical element, the plane of the optical element is kept parallel to the photosensitive surface of the corresponding image sensor until the cross-over ratio of the through-hole images of the two optical elements is within a preset threshold range. The photosensitive surfaces of the two calibrated image sensors are perpendicular to each other, aligned with the two sides of the flat beam splitter, and each forms a 45-degree angle with the plane of the flat beam splitter. The coordinate mapping relationship between the two image sensors is known. The optical axis of the light source is consistent with the optical axis of the flat beam splitter, and the illuminance of the uniform beam is consistent at any position on the plane perpendicular to the optical axis of the light source.

[0042] The difference between Example 2 and Example 1 is that the beam splitter is replaced with a flat beam splitter. Although it is still a beam splitter, since the light-transmitting surface of the beam splitter is missing for parallel calibration, a new alignment method is adopted: "the photosensitive surfaces of the two calibrated image sensors are perpendicular to each other, aligned with the two sides of the flat beam splitter, and both are at a 45-degree angle to the plane of the flat beam splitter." From a pose perspective, the plane of the flat beam splitter is equivalent to the beam-splitting surface of the beam splitter in Example 1; they are essentially the same and will not be described further here. Example 3

[0043] As a third embodiment of the assembly method of the present invention, the present invention also provides an optical element assembly method based on multiple sensors, comprising: At least three flat optical elements with through holes of arbitrary shapes and the same through hole shape are provided, respectively located at the conjugate positions between at least three calibrated image sensors and multi-beam splitters, and adjusted so that the planes of at least three optical elements are parallel to the photosensitive surfaces of the corresponding image sensors. Lighting up the light source causes it to emit a uniform beam of light, which is directed toward the incident surface of the multi-beam splitter. The beam passes through each optical element via the multi-beam splitter and reaches the corresponding image sensor, resulting in at least three through-hole images of the optical elements. Fix any one of the optical elements as a reference, and while adjusting the other optical elements, keep the plane of the adjusted optical element parallel to the photosensitive surface of the corresponding image sensor until the cross-over ratio of the through-hole images of all optical elements is within a preset threshold range. In this configuration, the photosensitive surfaces of at least three calibrated image sensors are parallel to and directly opposite the exit surfaces of the multi-beam splitter, and the coordinate mapping relationship between all image sensors is known. The multi-beam splitter is used to split the light beam entering the incident surface into at least three exit beams through the exit surfaces. The optical axis of the light source is consistent with the optical axis of the multi-beam splitter, and the uniform beam has consistent illuminance at any position on a plane perpendicular to the optical axis of the light source.

[0044] The difference between Example 3 and Example 1 is that the method involves an installation scenario with at least three optical elements and a multi-beam splitter prism. The multi-beam splitter prism is no longer a traditional dichotomous prism, but rather one capable of splitting the beam entering the incident surface into at least three exit beams through various exit surfaces, such as a dichroic lens composed of three different prisms available on the market. From the core principle of the invention, it still uses one optical element corresponding to one image sensor, and the adjustment principle remains the same, which will not be elaborated further here. Example 4

[0045] like Figure 2 As shown, to achieve the above assembly method, the present invention also provides an optical element assembly device based on multiple sensors, which uses the above assembly method to achieve adjustment, and is used to respectively set two flat optical elements at the conjugate positions of the first light-transmitting surface 11 and the second light-transmitting surface 12 of the beam splitter 1, wherein the beam splitter 1 is a cubic structure formed by cementing two right-angled triangular prisms, the first light-transmitting surface 11 and the second light-transmitting surface 12 are adjacent and are respectively located on both sides of the beam splitting surface 13 of the beam splitter 1, and the assembly device includes: Two calibrated image sensors are provided, with their photosensitive surfaces parallel and directly facing the first light-transmitting surface 11 and the second light-transmitting surface 12 of the beam splitter 1, respectively. The coordinate mapping relationship between the two image sensors is known. The two image sensors include a first image sensor 4 and a second image sensor 5, with the first image sensor 4 facing the first light-transmitting surface 11 and the second image sensor 5 facing the second light-transmitting surface 12.

[0046] Light source 6, positioned opposite the first light-transmitting surface 11 or the second light-transmitting surface 12, emits a uniform light beam that is directed towards beam splitter 1. This beam passes through two optical elements via beam splitter 1 and is captured by two image sensors to obtain images of the through-holes in the two optical elements. Both optical elements have identical through-holes of arbitrary shape, positioned at conjugate positions between the two image sensors and beam splitter 1. The planes containing the two optical elements are parallel to the photosensitive surfaces of the two image sensors. The optical axis of light source 6 is aligned with the optical axis of beam splitter 1, and the uniform light beam exhibits consistent illuminance at any position on a plane perpendicular to the optical axis of light source 6. The two optical elements include a first optical element 2 and a second optical element 3. The first optical element 2 is fixed to the conjugate position between the first image sensor 4 and the first light-transmitting surface 11, and the plane of the first optical element 2 is parallel to the first light-transmitting surface 11. The second optical element 3 is installed to the conjugate position between the second image sensor 5 and the second light-transmitting surface 12, and is adjusted so that the plane of the second optical element 3 is parallel to the second light-transmitting surface 12 of the beam splitter 1, thereby realizing that the planes of the two optical elements are parallel to the photosensitive surfaces of the two image sensors respectively.

[0047] The adjustment mechanism includes a translation adjustment module and a rotation adjustment module. The translation adjustment module is used to translate the optical element perpendicularly to the plane of the optical element being adjusted, and the rotation adjustment module is used to rotate the optical element along the plane of the optical element being adjusted, while keeping the plane of the optical element being adjusted parallel to the photosensitive surface of the corresponding image sensor, until the intersection-to-jump ratio of the two optical element images is within a preset threshold range. The adjustment mechanism as a whole can be adjusted directly using a six-axis controller, or the translation adjustment module and the rotation adjustment module can be selected separately. For example, the translation adjustment module can be a guide rail type translation adjustment mechanism such as a lead screw drive, piezoelectric ceramic drive, or motor drive, and the rotation adjustment module can achieve the rotation by driving the rotation of the shaft to drive the corresponding connecting parts.

[0048] The specific operational details of this device can be found in the assembly method described above, and will not be repeated here. Example 5

[0049] The present invention also provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the above-described assembly method.

[0050] In practical applications, a computer-readable storage medium can be any combination of one or more computer-readable media. A computer-readable medium can be a computer-readable signal medium or a computer-readable storage medium. A computer-readable storage medium can be, but is not limited to, an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any combination thereof. More specific examples of a computer-readable storage medium may include: an electrical connection having one or more wires, a portable computer disk, a hard disk, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fiber, portable compact disk read-only memory (CD-ROM), optical storage device, magnetic storage device, or any suitable combination thereof. In this embodiment, a computer-readable storage medium can be any tangible medium containing or storing a program that can be used by or in conjunction with an instruction execution system, apparatus, or device.

[0051] Computer-readable signal media may include data signals propagated in baseband or as part of a carrier wave, carrying computer-readable program code. Such propagated data signals may take various forms, including but not limited to electromagnetic signals, optical signals, or any suitable combination thereof. Computer-readable signal media may also be any computer-readable medium other than computer-readable storage media, capable of sending, propagating, or transmitting programs for use by or in connection with an instruction execution system, apparatus, or device.

[0052] Program code contained on a computer-readable medium may be transmitted using any suitable medium, including but not limited to wireless, wire, optical fiber, RF, or any suitable combination thereof.

[0053] Computer program code for performing the operations of this application can be written in one or more programming languages ​​or a combination thereof, including object-oriented programming languages ​​such as Java, Smalltalk, and C++, as well as conventional procedural programming languages ​​such as "C" or similar programming languages. The program code can be executed entirely on the user's computer, partially on the user's computer, as a standalone software package, partially on the user's computer and partially on a remote computer, or entirely on a remote computer or server. In cases involving remote computers, the remote computer can be connected to the user's computer via any type of network, including a local area network (LAN) or a wide area network (WAN), or it can be connected to an external computer (e.g., via an Internet service provider).

[0054] In the description of this specification, references to terms such as "an embodiment," "example," and "specific example" indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0055] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed invention.

Claims

1. A method for assembling optical components based on multiple sensors, characterized in that, include: Two flat optical elements with arbitrary-shaped through holes of the same shape are set up and located at the conjugate positions between the two calibrated image sensors and the beam splitter, respectively. The planes of the two optical elements are adjusted to be parallel to the photosensitive surfaces of the two image sensors. Lighting up the light source causes it to emit a uniform beam of light, which is directed toward the beam splitter. The beam passes through the beam splitter and two optical elements, reaching two image sensors to obtain images of the through holes of the two optical elements. One of the two optical elements is fixed as a reference. During the adjustment of the other optical element, the plane of the optical element is kept parallel to the photosensitive surface of the corresponding image sensor until the cross-over ratio of the through-hole images of the two optical elements is within a preset threshold range. In this configuration, the photosensitive surfaces of the two calibrated image sensors are parallel to and directly opposite the first and second light-transmitting surfaces of the beam splitter, respectively, and the coordinate mapping relationship between the two image sensors is known; the first and second light-transmitting surfaces are adjacent to each other and are located on opposite sides of the beam splitter surface of the beam splitter; the optical axis of the light source is consistent with the optical axis of the beam splitter, and the uniform beam has consistent illuminance at any position on a plane perpendicular to the optical axis of the light source.

2. The method for assembling optical components based on multiple sensors according to claim 1, characterized in that, Calibrating two image sensors includes: Place a calibration object between the light source and the beam splitter, so that the plane of the calibration object is parallel to the first or second light-transmitting surface; The light source is turned on, so that the beam emitted by the light source passes through the calibration object and the beam splitter in sequence and then enters the two image sensors respectively, thus obtaining two images of the calibration object; Adjust the two image sensors respectively so that the difference in sharpness values ​​of all feature points in the calibration image corresponding to each image sensor is less than a preset threshold; The calibration object contains at least three non-collinear feature points.

3. The method for assembling optical components based on multiple sensors according to claim 2, characterized in that, The method for determining whether the cross-over ratio (CUP) of the through-hole images of the two optical elements is within a preset threshold range is as follows: After calibration, extract all feature point data from each calibrated object image; Establish a mapping model between all feature point data in two calibration object images, and fit the corresponding mapping relationship; Based on the mapping relationship, the through-hole image of any optical element is corrected, and the corrected through-hole image of the optical element is compared with the through-hole image of another optical element until the cross-comparison ratio is within a preset threshold range.

4. A method for assembling optical elements based on multiple sensors according to any one of claims 1-3, characterized in that, Adjustments were made to ensure that the planes containing the two optical elements were parallel to the photosensitive surfaces of the two image sensors, including: A telecentric lens is used to face the non-light-transmitting surface of the beam splitter to photograph the two optical elements, resulting in side view images of the two optical elements; Adjust the two optical elements separately until the intersection of the non-light-transmitting surface of the beam splitter and the first light-transmitting surface and the second light-transmitting surface is parallel to the length direction of the side view image corresponding to the first optical element and the second optical element, and the width of the two side view images is equal to the imaging width under the theoretical posture. The non-light-transmitting surface is perpendicular to both the first light-transmitting surface and the second light-transmitting surface.

5. A method for assembling optical elements based on multiple sensors according to any one of claims 1-3, characterized in that, Adjusting another optical element includes: The optical element being adjusted is moved along a direction perpendicular to the plane of the optical element being adjusted until the coordinate mapping relationship between the two image sensors is known, so that the width of the through-hole images of the two optical elements is consistent in the corrected unified coordinate system. Calculate the slope difference in the same feature direction in the through-hole images of two optical elements, and rotate the adjusted optical element according to the slope difference; Calculate the centroid offset of the through-hole images of the two optical elements, and translate the optical element being adjusted along the plane of the optical element being adjusted based on the centroid offset; The mapping relationship between the centroid offset and the corresponding translation is known.

6. A method for assembling optical elements based on multiple sensors according to any one of claims 1-3, characterized in that, After adjusting another optical element, the following is also included: Measure the distance between the optical element being adjusted and the beam splitter, and select a shim of the corresponding thickness and apply adhesive to the optical element being adjusted by deducting the reserved adhesive layer thickness. Adjust the optical elements during the dispensing and curing process to keep the cross-over ratio of the through-hole images of the two optical elements within a preset threshold range.

7. A method for assembling optical elements based on multiple sensors, characterized in that, include: Two flat optical elements with arbitrarily shaped through holes of the same shape are set up and located at the conjugate positions between the two calibrated image sensors and the flat beam splitter, respectively. The planes of the two optical elements are adjusted so that they are parallel to the photosensitive surfaces of the two image sensors. The light source is lit, causing it to emit a uniform beam of light that is directed toward the flat beam splitter. The beam passes through two optical elements and reaches two image sensors, resulting in through-hole images of the two optical elements. One of the two optical elements is fixed as a reference. During the adjustment of the other optical element, the plane of the optical element is kept parallel to the photosensitive surface of the corresponding image sensor until the cross-over ratio of the through-hole images of the two optical elements is within a preset threshold range. The photosensitive surfaces of the two calibrated image sensors are perpendicular to each other, aligned with the two sides of the flat beam splitter, and each forms a 45-degree angle with the plane of the flat beam splitter. The coordinate mapping relationship between the two image sensors is known. The optical axis of the light source is consistent with the optical axis of the flat beam splitter, and the illuminance of the uniform beam is consistent at any position on the plane perpendicular to the optical axis of the light source.

8. A method for assembling optical components based on multiple sensors, characterized in that, include: At least three flat optical elements with through holes of arbitrary shapes and the same through hole shape are provided, respectively located at the conjugate positions between at least three calibrated image sensors and multi-beam splitters, and adjusted so that the planes of at least three optical elements are parallel to the photosensitive surfaces of the corresponding image sensors. Lighting up the light source causes it to emit a uniform beam of light, which is directed toward the incident surface of the multi-beam splitter. The beam passes through each optical element via the multi-beam splitter and reaches the corresponding image sensor, resulting in at least three through-hole images of the optical elements. Fix any one of the optical elements as a reference, and while adjusting the other optical elements, keep the plane of the adjusted optical element parallel to the photosensitive surface of the corresponding image sensor until the cross-over ratio of the through-hole images of all optical elements is within a preset threshold range. Among them, the photosensitive surfaces of at least three calibrated image sensors are parallel to and directly opposite each exit surface of the multi-beam splitter, and the coordinate mapping relationship between all image sensors is known. The multi-beam splitter is used to split the light beam entering the incident surface into at least three outgoing beams through each exit surface; the optical axis of the light source is consistent with the optical axis of the multi-beam splitter, and the uniform beam has consistent illuminance at any position on a plane perpendicular to the optical axis of the light source.

9. A multi-sensor-based optical element assembly apparatus, using the assembly method according to any one of claims 1-6 to achieve adjustment, for respectively positioning two flat optical elements at conjugate positions on the first and second light-transmitting surfaces of a beam splitter, wherein... The first light-transmitting surface and the second light-transmitting surface are adjacent and located on opposite sides of the beam-splitting surface of the beam-splitting prism, characterized in that the assembly device includes: Two calibrated image sensors are provided, with their photosensitive surfaces parallel and directly facing the first and second light-transmitting surfaces of a beam splitter, respectively. The coordinate mapping relationship between the two image sensors is also known. A light source, positioned on either the side of the first or second light-transmitting surface, is used to emit a uniform light beam and direct it toward a beam splitter. The light beam passes through two optical elements via the beam splitter and is captured by two image sensors to obtain images of the through-holes of the two optical elements. The optical axis of the light source is aligned with the optical axis of the beam splitter, and the uniform light beam has consistent illuminance at any position on a plane perpendicular to the optical axis of the light source. The adjustment mechanism includes a translation adjustment module and a rotation adjustment module. The translation adjustment module is used to translate the optical element in the direction perpendicular to the plane where the optical element is located. The rotation adjustment module is used to rotate the optical element in the plane where the optical element is located, while keeping the plane where the optical element is located parallel to the photosensitive surface of the corresponding image sensor, until the intersection ratio of the two optical element images is within a preset threshold range. Both optical elements have through holes of arbitrary shape and the through holes are identical. They are respectively set at the conjugate position between the two image sensors and the beam splitter, and the planes on which the two optical elements are located are parallel to the photosensitive surfaces of the two image sensors.

10. A computer-readable storage medium storing a computer program, characterized in that, When the computer program is executed by the processor, it implements the assembly method as described in any one of claims 1-8.

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