A heterogeneous rectangular homogenizing rod and a light source shaping system for wafer detection

Abstract

This invention discloses a heterogeneous rectangular beam homogenizer and a light source shaping system for wafer inspection. The beam homogenizer includes two symmetrically spliced ​​optical path folding units, each unit having an optical path unfolding section and an optical path convergence and integration section. The optical path unfolding section horizontally unfolds the light beam through its first deflection surface, while the optical path convergence and integration section vertically converges the light beam through its second deflection surface, together heterogeneously integrating and uniformly filling the light from the square light inlet to the rectangular light outlet. The system includes a light source module with a single-row, double-column LED chip array and the aforementioned beam homogenizer. The beam homogenizer shapes the square light spot of the light source into a rectangular uniform light spot that matches the target surface of a linear array TDI camera. This invention solves the problem of shape mismatch between the light-emitting surface of the light source and the target surface of the linear array detector without changing the LED chip arrangement.

Description

Technical Field

[0001] This invention relates to the field of light source shaping technology, and in particular to a heterogeneous rectangular light-diffusing rod and a light source shaping system for wafer inspection. Background Technology

[0002] In fields such as projection display and precision optical inspection, efficiently shaping the light spot emitted by a light source into a uniform illumination area of ​​a specific shape is a critical requirement. Traditionally, for systems such as LCD projection, compound eye lens arrays or Köhler illumination structures are often used to achieve uniform illumination. However, these methods typically involve a large number of optical components, resulting in bulky, complex, and costly systems. Another common approach is to use integrating square bars, especially in DLP projection systems, where multiple reflections of light within the square bar form a uniform rectangular light spot. However, standard square bars usually require the incident and exit light spot shapes to be similar, limiting their ability to change the aspect ratio of the light spot. Furthermore, the system still requires a condenser lens assembly, making it difficult to meet the growing demands for miniaturization and integration.

[0003] In recent years, with the widespread adoption of high-brightness LEDs in lighting and projection, homogenization technology for LED surface light sources has been developed. For example, structures using conical homogenizing rods have emerged, with their emitting ends designed as rectangles such as 4:3 or 16:9 to match the display chip. These solutions simplify the system to some extent, but are typically designed to achieve conventional projection ratios, and their optical path transformations are relatively simple. Meanwhile, special homogenizing elements exist that convert square light spots into circular light spots to meet the customary requirements of certain lighting scenarios. These solutions often achieve shape transitions through two-segment splicing or freeform surfaces, but the conversion process may introduce a loss of optical spread or increase manufacturing difficulty.

[0004] Especially in precision industrial fields such as wafer inspection and line scan imaging, linear TDI cameras are commonly used, with their target surfaces being elongated rectangles. LEDs, as a common light source, are often arranged in compact arrays (single row, double column, etc.) to form square or near-square emitting surfaces due to packaging, heat dissipation, and standardized production considerations. This leads to a direct contradiction where the shape of the light source's emission pattern is severely mismatched with the shape of the detector's photosensitive area. Simply using an optical system to image this square spot results in a significant amount of light energy being wasted outside the detector's target surface; customizing specially arranged LED chips to match the target surface shape significantly increases costs and presents challenges in heat dissipation design. Existing irregularly shaped light guides or homogenizing solutions often struggle to simultaneously achieve high light energy utilization, accurate two-dimensional shape transformation capabilities, structural compactness, and broad compatibility with standard LED light sources. Therefore, a simple, efficient, and low-cost solution remains lacking for addressing such demanding shape-matching lighting problems. Summary of the Invention

[0005] To address the aforementioned shortcomings, this invention proposes a heterogeneous rectangular light-diffusing rod and a light source shaping system for wafer inspection, which solves the problem of shape mismatch between the light-emitting surface of the light source and the target surface of the linear array detector without changing the LED chip arrangement.

[0006] The present invention provides the following technical solution: a heterogeneous rectangular light-diffusing rod for shaping a beam of light emitted from a square light source into a rectangular illumination spot, comprising a first optical path folding unit and a second optical path folding unit symmetrically arranged along a splicing surface; The first optical path folding unit and the second optical path folding unit each have: The optical path unfolding section includes an inclined incident section for receiving light from a partial square light source. The inclined incident section has a first deflection surface, which causes the incident light beam to be deflected in a direction away from the splicing surface in a first plane perpendicular to the optical axis and realizes horizontal optical path unfolding. The optical path convergence and integration section is connected to the optical path unfolding section. It includes a transition reflection section and a rectangular light-emitting section. The transition reflection section includes a second deflection surface for receiving the unfolded light beam and deflecting the light beam in a direction closer to the splicing surface in a second plane that is perpendicular to the optical axis and perpendicular to the first plane, thereby achieving vertical optical path convergence and finally guiding it to the rectangular light-emitting section. The first optical path folding unit and the second optical path folding unit together define a square light inlet, and the rectangular light outlet sections of the first optical path folding unit and the second optical path folding unit are placed side by side along the splicing surface to form a rectangular light outlet. Through the horizontal expansion of the optical path expansion section and the vertical convergence of the optical path convergence integration section, the light rays incident from different areas of the square light inlet are heterogeneously guided and integrated, and uniformly filled into the entire rectangular light outlet.

[0007] Compared with the prior art, the advantages of the present invention are as follows: This heterogeneous rectangular beam homogenizer achieves efficient and precise two-dimensional transformation of the beam shape through its unique optical structure. At its core, the shape of the final emitted light spot is entirely determined by the designed rectangular exit port, completely eliminating the reliance on the original arrangement of LED chips. This fundamentally solves the problem of mismatch between the shape of the light-emitting surface and the target illumination area, and significantly improves light energy utilization.

[0008] Specifically, this design can be directly adapted to most standard LED light source modules without changing the inherent arrangement of LED chips, such as the common single-row and double-row arrangement. Through the heterogeneous light path in the two symmetrical light path folding units, which first expands horizontally and then converges vertically, the light from different areas of the square light inlet is redistributed and integrated, uniformly filling the entire rectangular outlet. This gives the light-diffusing rod good versatility and makes it suitable for complex light-emitting surfaces composed of multiple LEDs arranged in different arrays, effectively shaping and homogenizing them as a whole.

[0009] This device achieves excellent light shaping while ensuring efficient light energy transmission. Light propagates primarily through total internal reflection via a precisely designed tilted reflective surface. The entire optical path transformation is accomplished through a simple geometric structure, eliminating the need for complex lens assemblies or mechanical moving parts. This not only minimizes light loss but also results in a compact, stable, reliable, and low-cost overall structure. Symmetrically arranged folding units further simplify design and manufacturing, and ensure the uniformity of the emitted light spot.

[0010] Ultimately, this homogenizing rod enables the use of standard-arranged LED light source modules to generate a uniform rectangular illumination spot that highly matches the target surface shape of the linear scanning detector, without any chip-level rearrangement or customization. This significantly improves the light energy coupling efficiency from the light source to the detector surface, making it particularly suitable for precision optical systems such as wafer inspection autofocus systems with stringent requirements for spot shape, uniformity, system cost, and integration.

[0011] As an improvement, the first and second optical path folding units have a geometric structure that is mirror-symmetrical with respect to the splicing surface and are formed as a single component. Alternatively, the first and second optical path folding units can be two independent mirror-symmetrical components that are combined into a uniform light bar by aligning their respective splicing surfaces. The two optical path folding units are mirror-symmetrical with respect to the splicing surface, ensuring that the light from both sides of the light source undergoes the same optical processing. This fundamentally guarantees the uniformity of the light intensity distribution on both sides of the symmetry axis of the emitted light spot, eliminating aberrations or uneven illumination that may be caused by asymmetrical design. When the two units are formed as a single component, they are integrally molded, completely eliminating any assembly gaps or alignment errors that may exist on the splicing surface. This results in higher structural rigidity and stability. The internal optical interface is completely continuous, effectively avoiding light scattering, leakage, or energy loss caused by interface discontinuities, thus optimizing the efficiency of light energy transmission during total internal reflection. When using two independent components for docking, this design significantly reduces the processing difficulty of complex three-dimensional irregular structures. Each independent mirror-symmetric component has a relatively regular shape, making it easier to form through injection molding, compression molding, or precision machining. Through precise splicing, the two components can be combined to form a complete and accurate optical path channel, improving production flexibility and maintainability while ensuring optical performance, and potentially reducing manufacturing costs. Whether as a single component or in a modular combination, this mirror-symmetric architecture provides a solid and reliable physical basis for achieving efficient and uniform rectangular beam shaping. It makes the overall performance of the beam do not depend on stringent assembly and adjustment, facilitating stable mass production and ensuring that the final lighting system obtains high-quality, highly uniform rectangular beam output.

[0012] As an improvement, the first and second deflecting surfaces are constructed as reflecting planes for deflecting the optical path. The first deflecting surface is configured to reflect the beam away from the splicing surface in a first plane to achieve horizontal optical path expansion. The second deflecting surface is configured to reflect the beam closer to the splicing surface in a second plane to achieve vertical optical path convergence. The first deflecting surface reflects the beam away from the splicing surface, actively pushing the light energy to both sides in the horizontal dimension, thereby effectively expanding the width of the light spot and solving the problem of concentrated light energy in the width direction of a square light source, which needs to be dispersed to fill the long side of the rectangle. Then, the second deflecting surface reflects the beam closer to the splicing surface, converging and regularizing the expanded beam in the vertical dimension, reducing its height and improving the parallelism and boundary sharpness of the beam in the vertical direction. This configuration of reflection directions, one close and one near, constitutes a deterministic optical path transformation sequence of expansion followed by convergence. The two reflecting planes in... The different planes, each with its own function and working collaboratively, ensure that the beam width expansion and height convergence processes proceed sequentially without interference, achieving a high degree of controllability and determinism in the shaping of complex two-dimensional light spots. Through this active directional reflection control, light rays from different positions of the square light inlet are precisely guided to the corresponding areas of the rectangular light outlet, thus ensuring the uniformity of energy distribution and the integrity of filling of the emitted light spot while completing the shape transformation. All functions of this structure are realized through two static reflective planes, making the optical path conversion efficient and direct, without relying on the complex coordination of dynamic elements or multiple sets of lenses. The planar configuration of the reflective surfaces facilitates high-precision processing and inspection, which helps to ensure the consistency and stability of mass production. At the same time, it provides an ideal interface for light to propagate through total internal reflection, minimizing light energy loss. Ultimately, with a simple and reliable structure, the core function of efficiently and uniformly reshaping a square light spot into a rectangular light spot is achieved.

[0013] As an improvement, the splicing structure of the optical path unfolding section and the optical path beam convergence section ensures that light rays incident from any point on the square light inlet can propagate to the rectangular light outlet without vignetting. Through the precise splicing structure between the optical path unfolding section and the beam convergence section, it is ensured that the entire beam cross-section defined by the square light inlet, after undergoing complex horizontal unfolding and vertical beam convergence transformations, can be transmitted intact to the rectangular light outlet. This means that during the entire beam shaping process, no part of the light is lost due to unexpected mechanical obstruction or aperture cutting by the internal structure of the beam homogenizer. All light rays entering from the effective emitting surface of the light source are guided in an orderly manner by the structural wall of the irregularly shaped light guide in a controllable total internal reflection manner, with none wasted or forming vignetting. The absence of stray light and vignetting directly ensures that the original light energy of the light source is preserved and utilized to the maximum extent, achieving the conservation or near-conservation of optical extension, thus obtaining extremely high optical efficiency. At the same time, this effect also ensures the high uniformity of the illuminance of the emitted rectangular light spot, because the loss or obstruction of light energy often leads to dark areas or uneven illuminance distribution, while the vignetting-free propagation ensures the continuity and integrity of the light energy filling the target surface, which is crucial for applications such as wafer inspection autofocus that require highly uniform illumination. Finally, this structural characteristic allows the light-diffusing rod to perfectly achieve the transformation of the light spot shape from square to rectangular without sacrificing luminous flux, meeting the precision illumination requirements that must simultaneously achieve high brightness and high uniformity.

[0014] As an improvement, the first and second deflection surfaces are optical interfaces where light undergoes total internal reflection at their interface. This allows the light beam to propagate primarily through total internal reflection within the homogenizer. By constructing the first and second deflection surfaces as optical interfaces with total internal reflection, the propagation of the light beam within the device relies mainly on the physical phenomenon of total internal reflection. This ensures high efficiency in light energy propagation. Since total internal reflection is a theoretically energy-loss-free form of reflection, light will not escape to the outside due to transmission at the interface, thus greatly reducing light attenuation in the transmission path. This allows most of the incident light energy to be retained and ultimately... The output from the light outlet directly improves the luminous flux utilization of the entire optical system, which is crucial for applications requiring high-brightness illumination. Secondly, this design offers significant advantages in reliability and stability. The performance of total internal reflection does not depend on any additional metal or dielectric reflective coatings, thus completely avoiding problems such as decreased adhesion, film aging, poor thermal stability, or insufficient reflectivity in specific wavelength bands that may occur with coatings. Its optical performance is determined by the inherent properties of the homogenizing rod material and the precise interface geometry, thus possessing inherent environmental stability and long lifespan characteristics. At the same time, this characteristic simplifies the manufacturing process and reduces costs. The elimination of high-precision coatings on complex inner surfaces reduces the requirements for process equipment and the complexity of production steps, improving production yield and consistency. Finally, relying primarily on the propagation mechanism of total internal reflection, combined with precisely calculated deflection plane angles, the path of light within the homogenizing rod is strictly and accurately controlled. This not only provides the physical basis for achieving the preset square-to-rectangular optical path transformation but also ensures that the emitted light spot has good uniformity and clear boundaries, thereby meeting the core requirements for illumination quality in high-precision applications such as wafer inspection.

[0015] As an improvement, the beam homogenizer is designed such that the incident angle of edge rays incident from the square entrance aperture at the maximum divergence angle U on the first or second deflection surface is greater than or equal to the critical angle of total internal reflection. The angle I between the deflection plane and the reference plane perpendicular to the optical axis satisfies: ,and , and The refractive indices of the homogenizer material and the surrounding medium, respectively, establish a clear and mandatory physical law for homogenizer design: the tilt angle I of the deflection surface must be controlled within a strict upper limit determined by both material properties and light source characteristics. This design law ensures absolute performance robustness while also granting the design a high degree of customizability and flexibility. It ensures that even for the edge rays with the largest divergence angle and the most difficult to control in the light source, when they propagate to the critical deflection surface, their angle of incidence is at least equal to, and usually greater than, the critical angle of total internal reflection. This eliminates the risk of light energy loss due to light leakage, providing a solid and quantifiable guarantee for the characteristic that light propagates mainly through total internal reflection inside the homogenizer. This transforms high-efficiency light energy transmission from a design goal into a deterministic result enforced by structural parameters. This worst-case-based design philosophy and its quantifiable constraints bring significant advantages to the engineering of actual products. It establishes a calculable bridge between optical design and material selection, forming a clear design methodology. Designers can use this methodology to flexibly select suitable homogenizer materials for different target applications, such as based on the luminous characteristics of a specific light source, such as the divergence angle U, and the system's limitations on volume and cost. Based on this, key structural parameters such as the tilt angle I of the deflection surface and the length of each segment are accurately calculated. This not only improves the scientific nature of the design and the success rate, and achieves the reliability and consistency of performance, but also enables the beam uniformr to be flexibly adapted to the needs of different fields, from general lighting to wafer inspection, by adjusting the design. While meeting stringent optical requirements, it optimizes the overall size and cost of the system. As long as the manufacturing precision meets the requirements, any product manufactured according to this relationship can stably achieve a high-efficiency total internal reflection optical path, thereby reliably completing the predetermined beam shaping function and outputting a highly uniform rectangular light spot, meeting the stringent requirements of precision applications such as wafer inspection for the stability and efficiency of the lighting system.

[0016] As an improvement, to transform a square light inlet with side length B into a rectangular light outlet with a long side of A and a short side of B, the optical path unfolding section is constructed to cause a horizontal translation of size A / 2. This provides a clear, direct, and necessary structural implementation path for achieving the specific shape transformation from a square with side length B to a rectangle with a long side of A: the optical path unfolding section needs to generate a horizontal translation of size A / 2, which simplifies and anchors the complex two-dimensional shape transformation problem; the translation amount of A / 2 is not arbitrarily chosen, but is a geometrically necessary requirement in the horizontal direction for this specific size transformation, i.e., B→A. This clarifies the specific tasks that the optical path unfolding section needs to complete, quantifying the concept of unfolding into a definite physical displacement directly linked to the target size. This provides a basis for the specific structural design of the optical path unfolding section. The length and angle of the inclined surface provide the fundamental design basis and optimization target. By forcibly achieving this precise translation, the structure ensures that light rays from both sides of the center line of the square light inlet can be symmetrically and fully guided to the predetermined areas on both sides of the rectangular light outlet, thus filling the entire rectangular range of length A without omission. This avoids insufficient illumination or dark areas on both sides of the light outlet due to insufficient expansion, and also prevents light energy waste or structural redundancy caused by excessive expansion. Therefore, this feature not only defines the function, but also ensures the sufficiency and accuracy of the function through quantification. It enables the light-diffusing rod to strictly and predictably reshape the square light spot into a rectangular light spot with a specified aspect ratio, laying a solid geometric foundation for achieving precise matching with the target surface of the linear array detector, thereby reliably improving the utilization efficiency of the light source.

[0017] As an improvement, the height dimension C of the optical path expansion section in the optical axis direction satisfies the following approximate relationship. This study reveals that the axial height C required for the optical path unfolding section to achieve a specified horizontal translation A / 2 directly depends on the tilt angle I of the deflection surface. This tightly couples three key structural parameters with a simple formula. Given that the translation A / 2 is determined by the target beam conversion, the height C of the optical path unfolding section can be actively controlled by selecting or optimizing the tilt angle I. This effectively regulates the volume and compactness of the entire beam homogenizer. The formula means that once the target rectangle size A is determined and the tilt angle I that satisfies the total internal reflection condition is selected, the basic longitudinal profile of the optical path unfolding section is determined. This not only simplifies the design process and improves design efficiency, but more importantly, it ensures that the determined structure can accurately realize the predetermined optical path translation function in terms of geometry. It provides a reliable dimensional basis for achieving the expected square-to-rectangular beam shaping. Therefore, this feature not only defines a dimensional relationship but also provides a controllable and calculable design method. It empowers designers to optimize the axial dimensions of the device by adjusting the angle I, providing a theoretical basis and implementation method for the miniaturization and integration design of beam homogenizer structures while ensuring optical functionality.

[0018] As an improvement, the material of the light homogenizing rod is optical glass, which is chosen to satisfy the total internal reflection condition inside the light homogenizing rod and ensure high light transmission efficiency. The primary purpose of choosing optical glass is to fundamentally ensure that the total internal reflection condition is stably and reliably satisfied. Optical glass typically has a high and stable refractive index, which directly determines the size of the critical angle for total internal reflection. A higher refractive index results in a smaller critical angle, making it easier for light to enter at the interface at an angle greater than the critical angle. This provides a more relaxed and reliable geometric design space for achieving efficient total internal reflection. Simultaneously, the optical glass refracts... The consistency and uniformity of the light transmittance ensure the accuracy of optical path prediction and the stability of the output beam quality. Secondly, optical glass possesses high light transmittance in commonly used wavelengths such as visible and near-infrared, with few internal impurities and low scattering. Light loss due to absorption and scattering is minimal as it passes through the material. This characteristic, combined with the lossless nature of total internal reflection, ensures that light energy is transmitted and transformed with extremely low attenuation throughout the entire transmission process from the light inlet to the outlet. Therefore, this material constraint ensures that the beam homogenizer possesses both low transmission loss and high reflection efficiency at the physical level. This allows the optical efficiency of the entire beam shaping process to reach the optimal level for engineering applications, providing the necessary material basis for achieving high-brightness, highly uniform rectangular beam output. This choice also eliminates materials such as ordinary glass or plastics that may suffer performance degradation due to insufficient refractive index, poor uniformity, or low transmittance, thus clarifying the preferred technical path for achieving the best results of this invention.

[0019] A light source shaping system for wafer inspection, used to solve the problem of mismatch between the shape of the LED light source's emitting surface and the target surface shape of a linear TDI camera, comprising: At least one LED light source module has a square or quasi-square light-emitting surface composed of an array of LED chips arranged in a single row and two columns; As described above, a heterogeneous rectangular light-diffusing rod has a square light inlet optically coupled to the light-emitting surface of an LED light source module, used to shape the light beam emitted from the square light-emitting surface into a rectangular uniform light spot with a predetermined aspect ratio. The size and shape of the rectangular uniform light spot are configured to adapt to the size and shape of the target surface of the linear TDI camera, so as to improve the light energy utilization without changing the LED chip arrangement.

[0020] By integrating a specially designed beam homogenizer with a standard LED light source, a complete and efficient solution was constructed, directly addressing and solving the inherent shape mismatch problem between LED light sources and linear TDI cameras in wafer inspection. The system uses LED modules arranged in a common single-row, double-column configuration as the light source. A heterogeneous rectangular beam homogenizer actively optically shapes the square light spot emitted from these modules. The core function of the beam homogenizer is to redistribute and integrate the light beam coupled into its square entrance into a rectangular light spot with a predetermined aspect ratio and uniform illumination through a heterogeneous optical path that first expands horizontally and then converges vertically. The size and shape of the spot are precisely configured to achieve optical matching with the geometric features and light-gathering characteristics of the elongated target surface of the TDI camera. Without changing the original arrangement of the LED chips or requiring a custom light source, high-efficiency light energy coupling from the light source to the detector target surface is achieved. This allows standardized LED light sources to be directly applied to high-precision wafer inspection scenarios, significantly improving the target surface fill factor and light energy utilization of the illumination spot. Ultimately, the system provides ideal illumination with uniform brightness and shape matching for inspection processes such as autofocus, thereby reducing the complexity and cost of the system while ensuring inspection accuracy and stability. Attached Figure Description

[0021] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments: Figure 1 A schematic diagram of a heterogeneous rectangular light homogenizing rod from a first-view perspective; Figure 2 A schematic diagram of a heterogeneous rectangular light homogenizing rod from a second-view perspective; Figure 3 A side view of a heterogeneous rectangular uniform light rod structure; Figure 4 A schematic diagram of the working state of a heterogeneous rectangular light-monitoring rod; Figure 5 This is a schematic diagram of a light source shaping system for wafer inspection. Figure 6 This is a schematic diagram of the LED chip array distribution; Figure 7 This is a schematic diagram simulating the luminous flux input of a light source; Figure 8 A schematic diagram showing the light flux output through a heterogeneous rectangular light-diffusing rod; Figure 9 This is a schematic diagram of the LED light source module distribution.

[0022] The markings in the above figure are as follows: 1. Inclined incident section; 1.1. First deflection surface; 2. Transition reflection section; 2.1. Second deflection surface; 3. Rectangular light exit section; 4. Light entrance; 5. Light exit; 6. Splicing surface. Detailed Implementation

[0023] In this invention, it should be understood that the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "planar direction", "circumferential", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0024] like Figures 1 to 4 As shown, a heterogeneous rectangular light-diffusing rod is used to shape a beam emitted from a square light source into a rectangular illumination spot. It includes a first optical path folding unit and a second optical path folding unit symmetrically arranged along a splicing surface 6. Each of the first and second optical path folding units has an optical path unfolding section and an optical path convergence and integration section. The optical path unfolding section includes an inclined incident section 1 for receiving a portion of the light from the square light source. The inclined incident section 1 has a first deflection surface 1.1, causing the incident beam to deflect away from the splicing surface 6 in a first plane perpendicular to the optical axis, thus achieving horizontal optical path unfolding. The optical path convergence and integration section is optically connected to the optical path unfolding section. The optical path convergence and integration section includes a transition reflection section 2 and a rectangular light-emitting section 3. 2 includes a second deflection surface 2.1, which is used to receive the expanded light beam and deflect the light beam in a direction close to the splicing surface 6 in a second plane that is perpendicular to the optical axis and perpendicular to the first plane, thereby achieving vertical optical path convergence and finally guiding it to the rectangular light-emitting section 3; the inclined incident section 1 of the first optical path folding unit and the second optical path folding unit together define a square light-emitting port 4, and the rectangular light-emitting section 3 of the first optical path folding unit and the second optical path folding unit are placed side by side along the splicing surface 6 to form a rectangular light-emitting port 5; through the horizontal expansion of the optical path expansion part and the vertical convergence of the optical path convergence integration part, the light rays incident from different areas of the square light-emitting port 4 are heterogeneously guided and integrated, and uniformly filled into the entire rectangular light-emitting port 5.

[0025] The first optical path folding unit and the second optical path folding unit have a geometric structure that is mirror-symmetrical with respect to the splicing surface 6 and are formed as a single component, or the first optical path folding unit and the second optical path folding unit are two independent mirror-symmetrical components that are combined into a uniform light rod by aligning their respective splicing surfaces 6.

[0026] The first deflection surface 1.1 and the second deflection surface 2.1 are constructed as reflecting planes for deflecting the optical path. The first deflection surface 1.1 is configured to reflect the light beam away from the splicing surface 6 in the first plane to achieve horizontal optical path expansion. The second deflection surface 2.1 is configured to reflect the light beam closer to the splicing surface 6 in the second plane to achieve vertical optical path convergence.

[0027] The splicing structure of the optical path expansion section and the optical path convergence integration section ensures that light rays incident from any point on the square light inlet 4 can propagate to the rectangular light outlet 5 without vignetting.

[0028] The first deflection surface 1.1 and the second deflection surface 2.1 are optical interfaces where light undergoes total internal reflection at their interface, so that the light beam propagates mainly through total internal reflection inside the homogenizer.

[0029] The beam homogenizer is designed such that the incident angle of edge rays from the square entrance 4 at the maximum divergence angle U on the first deflection surface 1.1 or the second deflection surface 2.1 is greater than or equal to the critical angle of total internal reflection. The angle I between the deflection plane and the reference plane perpendicular to the optical axis satisfies: ,and , and These are the refractive indices of the homogenizing rod material and the surrounding medium, respectively.

[0030] To transform the square light inlet 4 with side length B into a rectangular light outlet 5 with long side A and short side B, the optical path expansion section is constructed to cause the optical path to be translated by a magnitude of A / 2 in the horizontal direction.

[0031] The height dimension C of the optical path expansion section along the optical axis satisfies the following approximate relationship. .

[0032] The material of the light homogenizing rod is optical glass, which is selected to meet the total internal reflection conditions inside the light homogenizing rod and ensure high light transmission efficiency. Preferably, the material of the light homogenizing rod is fused silica.

[0033] like Figure 5 , Figure 6 As shown, a light source shaping system for wafer inspection is used to solve the problem of mismatch between the shape of the LED light source's emitting surface and the target surface shape of a linear TDI camera, comprising: At least one LED light source module has a square or quasi-square light-emitting surface composed of an array of LED chips arranged in a single row and two columns; A heterogeneous rectangular light-electrode, with its square light inlet 4 optically coupled to the light-emitting surface of an LED light source module, is used to shape the light beam emitted from the square light-emitting surface into a rectangular uniform light spot with a predetermined aspect ratio. The size and shape of the rectangular uniform light spot are configured to adapt to the size and shape of the target surface of the linear TDI camera, so as to improve the light energy utilization without changing the LED chip arrangement.

[0034] like Figures 7 to 9As shown, taking A=2 and B=1 as an example, after calculating and designing the overall size of the light-diffusing rod, the luminous flux input of the LED light source module simulates the light source as 2.00000E+00 watts, and the luminous flux output through the heterogeneous rectangular light-diffusing rod is 1.87237E+00 watts, which can make the transmittance reach 93.62%.

[0035] The greater the ratio of the distance between the light inlet 4 and the light outlet 5 to the width of the light outlet 5, the more times the light is reflected and the better the uniformity. However, if the distance is too long, it will increase the volume and light loss.

[0036] The shaping process of the light source shaping system used for wafer inspection is as follows: First, the LED light source module is activated, and its single-row, double-column LED chip array emits light, forming a square or quasi-square initial light-emitting surface. This light-emitting surface is directly optically coupled to the square light inlet 4 of the heterogeneous rectangular light-diffusing rod, through which the light enters the interior of the light-diffusing rod.

[0037] Upon entering the homogenizing rod, the light beam is received by two symmetrically arranged optical path folding units. In each optical path folding unit, the light beam first reaches its optical path unfolding section. The inclined incident section 1 of the optical path unfolding section, through its first deflection surface 1.1, deflects the light beam in a direction away from the splicing surface 6 between the two units in a first plane perpendicular to the optical axis. This process achieves symmetrical unfolding of the light beam in the horizontal direction, the amount of which is determined by the design. For example, to transform a square with side length B into a rectangle with long side A, the horizontal optical path translation contributed by each unit is approximately A / 2.

[0038] Subsequently, the horizontally expanded beam enters the optical path convergence and integration section. The transition reflection section 2 of this section, through its second deflection surface 2.1, deflects the beam towards the splicing surface 6 in a second plane perpendicular to the optical axis and the first plane, thereby achieving vertical beam convergence and regularization. During this process, the beam is guided to the final rectangular beam exit section 3.

[0039] Throughout the optical path, light propagates primarily through total internal reflection occurring at the first deflection surface 1.1 and the second deflection surface 2.1. The homogenizing rod is made of optical glass (such as fused silica), and its refractive index and the tilt angle of the deflection surfaces are designed to ensure that even for edge rays incident at the maximum divergence angle, the angle of incidence on the deflection surfaces satisfies the condition of total internal reflection, thereby guaranteeing extremely high light transmission efficiency and vignetting-free light energy transmission.

[0040] Finally, the emitted beams from the two optical path folding units converge at the splicing surface 6 and exit from the rectangular light-emitting port 5 of the homogenizing rod, forming a uniform rectangular light spot whose size, shape, and aspect ratio are highly matched to the target surface of the linear TDI camera. This system thus efficiently solves the shape mismatch problem between the light source and the detector without altering the original arrangement of the LED chips, significantly improving the light energy utilization and illumination quality in processes such as wafer inspection autofocus.

[0041] LED light source modules include, but are not limited to, those arranged in a diamond shape or in a 3×3 square.

[0042] The above description only illustrates the preferred embodiments of the present invention and should not be construed as limiting the scope of the claims. The present invention is not limited to the above embodiments, and variations in its specific structure are permitted. All modifications made within the scope of the independent claims of this invention are also within the scope of protection of this invention.

Claims

1. A heterogeneous rectangular homogenizing rod for shaping a light beam emitted by a square light source into a rectangular illumination spot, characterized in that, It includes a first optical path folding unit and a second optical path folding unit symmetrically arranged along a splicing surface (6); The first optical path folding unit and the second optical path folding unit each have: The optical path unfolding section includes an inclined incident section (1) for receiving part of the light from the square light source. The inclined incident section (1) has a first deflection surface (1.1) such that the incident light beam is deflected in a direction away from the splicing surface (6) in a first plane perpendicular to the optical axis and thus achieves horizontal optical path unfolding. The optical path convergence and integration section, which is connected to the optical path unfolding section, includes a transition reflection section (2) and a rectangular light-emitting section (3). The transition reflection section (2) includes a second deflection surface (2.1) for receiving the unfolded light beam and deflecting the light beam in a direction close to the splicing surface (6) in a second plane that is perpendicular to the optical axis and perpendicular to the first plane, thereby achieving vertical optical path convergence and finally guiding it to the rectangular light-emitting section (3). Among them, the inclined incident section (1) of the first optical path folding unit and the second optical path folding unit together define a square light inlet (4), and the rectangular light outlet section (3) of the first optical path folding unit and the second optical path folding unit are placed side by side along the splicing surface (6) to form a rectangular light outlet (5). Through the horizontal expansion of the optical path expansion section and the vertical convergence of the optical path convergence integration section, the light rays incident from different areas of the square light inlet (4) are heterogeneously guided and integrated, and uniformly filled into the entire rectangular light outlet (5).

2. The heterogeneous rectangular homogenizing rod of claim 1, wherein, The first optical path folding unit and the second optical path folding unit have a geometric structure that is mirror-symmetrical with respect to the splicing surface (6) and are formed as a single component, or the first optical path folding unit and the second optical path folding unit are two independent mirror-symmetrical components that are combined into a uniform light rod by connecting their respective splicing surfaces (6).

3. The heterogeneous rectangular homogenizing rod of claim 1, wherein, The first deflection surface (1.1) and the second deflection surface (2.1) are configured as reflective planes for deflecting the optical path. The first deflection surface (1.1) is configured to reflect the light beam away from the splicing surface (6) in the first plane to realize the horizontal optical path expansion. The second deflection surface (2.1) is configured to reflect the light beam closer to the splicing surface (6) in the second plane to realize the vertical optical path convergence.

4. The heterogeneous rectangular homogenizing rod of claim 3, wherein, The splicing structure of the optical path expansion section and the optical path convergence integration section ensures that light rays incident from any point of the square light inlet (4) can propagate to the rectangular light outlet (5) without vignetting.

5. The heterogeneous rectangular homogenizing rod of claim 1, wherein, The first deflection surface (1.1) and the second deflection surface (2.1) are optical interfaces where light undergoes total internal reflection at their interface, so that the light beam propagates mainly through total internal reflection inside the homogenizing rod.

6. The heterogeneous rectangular homogenizing rod of claim 5, wherein, The homogenizing rod is designed such that the edge rays incident from the square light inlet (4) with the maximum angle of divergence U have an angle of incidence on the first deflection surface (1.1) or on the second deflection surface (2.1) greater than or equal to the critical angle of total reflection where the angle I between the deflection surface and the reference plane perpendicular to the optical axis satisfies: and , and are the refractive indices of the homogenizing rod material and the ambient medium, respectively.

7. The heterogeneous rectangular homogenizing rod of claim 6, wherein, In order to convert the square light inlet (4) with side length B into the rectangular light outlet (5) with long side A and short side B, the light path expansion section is configured to cause the light path to be translated by a magnitude of A / 2 in the horizontal direction.

8. The heterogeneous rectangular homogenizing rod of claim 7, wherein, The height dimension C of the light path expansion portion in the optical axis direction satisfies the following approximate relationship .

9. The heterogeneous rectangular homogenizing rod of claim 1, wherein, The material of the light homogenizing rod is optical glass, which is selected to meet the total internal reflection condition inside the light homogenizing rod and ensure high light transmission efficiency.

10. A light source shaping system for wafer detection, used to solve the problem of the shape mismatch between the LED light source emitting surface and the linear array TDI camera target surface, characterized in that, include: At least one LED light source module has a square or quasi-square light-emitting surface composed of an array of LED chips arranged in a single row and two columns; A heterogeneous rectangular light-regulating rod as described in any one of claims 1 to 9, wherein its square light inlet (4) is optically coupled to the light-emitting surface of the LED light source module, for shaping the light beam emitted from the square light-emitting surface into a rectangular uniform light spot with a predetermined aspect ratio; The size and shape of the rectangular uniform light spot are configured to adapt to the size and shape of the target surface of the linear TDI camera, so as to improve the light energy utilization rate without changing the LED chip arrangement.

Images