Total internal reflection prism combined with cylindrical lens and illumination system

Abstract

This invention discloses an internal reflection prism combined with a cylindrical lens and an illumination system. The internal reflection prism combined with a cylindrical lens includes an internal reflection prism and a cylindrical lens. The internal reflection prism is integrally formed from an optically transparent material and has an incident surface, an exit surface, and at least one set of internal reflection surfaces. The cylindrical lens and the exit surface of the internal reflection prism are optically bonded together. After the incident light beam enters the internal reflection prism through the incident surface, it undergoes at least one internal reflection through the internal reflection surfaces, and finally exits from the exit surface and enters the cylindrical lens. After being shaped by the cylindrical lens, it is formed into a line spot. This invention connects the internal reflection prism and the cylindrical lens with optical bonding, achieving direct contact through intermolecular van der Waals forces, meeting the requirements of high power and high stability. Furthermore, it achieves beam shaping through the internal reflection principle, resulting in a finer focused spot, reducing the number of lenses, lowering the difficulty of processing and assembly, and significantly improving the quality of the focused spot. This is of great significance for improving the resolution and imaging quality of the detection system.

Description

Technical Field

[0001] This invention relates to the field of optical detection technology, and in particular to an internal reflection prism combined with a cylindrical lens and an illumination system. Background Technology

[0002] Tilt illumination systems are core optical components in the field of semiconductor precision inspection. Their core function is to shape the incident light beam into a line spot with high energy concentration, low aberration, and extremely small width to meet the illumination requirements of tilted incidence. Existing line spot shaping technologies mainly employ two approaches: (1) Combination of two refractive cylindrical lenses (spherical or aspherical): The beam is focused on the cylindrical surface and the line spot is formed by two refractions of the two cylindrical lenses. However, this scheme is prone to introducing refractive aberrations such as chromatic aberration and spherical aberration. Moreover, the relative position and angular tolerance of the two lenses need to be strictly controlled, which makes the assembly and adjustment difficult and requires high processing precision. (2) Combination of two reflective cylindrical lenses (spherical or aspherical): The beam is shaped by the principle of reflection. Although there is no refractive aberration, two reflective lenses are still required to work together. The accumulation of errors in relative angle and spacing during the assembly and adjustment process will lead to uneven energy distribution of the light spot and a decrease in focusing quality.

[0003] However, both of the above-mentioned combination schemes suffer from poor focused spot quality, with obvious point spread function (PSF) side lobes, low energy concentration, and a large number of lenses leading to high processing and assembly costs and low efficiency, which cannot meet the performance requirements of high-end tilting lighting systems. Summary of the Invention

[0004] In view of the above problems, the purpose of this invention is to provide an internal reflection prism combined with a cylindrical lens and an illumination system to reduce the spot size, reduce the number of lenses, and reduce the assembly tolerance requirements. At the same time, the internal reflection optimizes the beam propagation path and improves the energy concentration and PSF quality of the linear spot.

[0005] This invention provides an internal reflection prism combined with a cylindrical lens, comprising an internal reflection prism and a cylindrical lens; the internal reflection prism is integrally formed from an optically transparent material, and is provided with an incident surface, an exit surface, and at least one set of internal reflection surfaces; the cylindrical lens has positive optical power, and the cylindrical lens and the exit surface of the internal reflection prism are optically bonded together; the incident light beam enters the internal reflection prism through the incident surface, undergoes at least one internal reflection through the internal reflection surfaces, and is finally output from the exit surface and enters the cylindrical lens, where it is shaped into a line spot.

[0006] Optionally, the incident beam undergoes two internal reflections within the internal reflection prism, and the internal reflection angles of the two internal reflections are equal.

[0007] Optionally, the internal reflection prism has an upper surface and a lower surface disposed opposite to each other; the upper surface and / or the lower surface includes at least two segments of different heights along the beam propagation direction, such that the beam after the first internal reflection is displaced in a direction perpendicular to the optical axis; wherein the upper surface and the lower surface in each segment are parallel to each other.

[0008] Optionally, the sections with different heights are achieved through a stepped structure or a beveled structure.

[0009] Optionally, the incident surface of the internal reflecting prism is coated with an anti-reflection film.

[0010] Optionally, the optically transparent material is optical glass.

[0011] Optionally, the incident beam is set to monochromatic light, the refractive index of the inner reflecting prism at the wavelength of the incident beam is n, and the incident angle θ of the incident beam at the inner reflecting surface satisfies: C+0.1°≤θ≤C+0.5°, where C is the critical angle for total internal reflection, C = arcsin(1 / n).

[0012] Optionally, the exit surface of the cylindrical lens is an aspherical surface, and the coefficient of the aspherical surface is set based on the wavelength of the incident beam.

[0013] Optionally, the inner reflecting surface is divided into multiple sub-reflecting surfaces along the beam propagation direction, each sub-reflecting surface having a different normal vector to compensate for the attenuation of beam energy in the propagation direction.

[0014] Optionally, the exit surface of the cylindrical lens is integrated with a diffractive optical element designed for monochromatic light wavelengths to shape the line spot into a flat-top intensity distribution.

[0015] Optionally, the absolute value of the difference in the coefficients of thermal expansion between the internal reflecting prism and the cylindrical lens is less than 0.1 × 10⁻⁶. -6 / ℃.

[0016] This invention provides an illumination system, including a light source device, the aforementioned internal reflection prism combined cylindrical lens, a support device, and a detection device; the light source device is used to generate an incident light beam; the internal reflection prism combined cylindrical lens is used to shape the incident light beam into a line spot; the support device is used to carry an object to be detected; the detection device includes at least one detection channel for detecting the scattered light generated after the line spot illuminates the surface of the object to be detected; wherein the line spot illuminates the surface of the object to be detected at an inclined angle.

[0017] Optionally, the at least one detection channel includes three detection channels, namely a first detection channel, a second detection channel, and a third detection channel; the third detection channel is disposed at the intersection of the illumination incident surface and the detection channel surface; the first detection channel and the second detection channel are respectively disposed on both sides of the detection channel surface, and both form the same interval angle with the third detection channel.

[0018] Optionally, the tilt angle ranges from 45° to 75°.

[0019] Optionally, the incident beam generated by the light source device is homogenized laser light with specific polarization.

[0020] The present invention provides an internal reflection prism combined with a cylindrical lens and an illumination system. The internal reflection prism combined with a cylindrical lens includes an internal reflection prism and a cylindrical lens. After the incident light beam enters the internal reflection prism through the incident surface, it undergoes at least one internal reflection through the internal reflection surface, and finally exits from the exit surface and enters the cylindrical lens. After being shaped by the cylindrical lens, it is formed into a line spot. The internal reflection prism and the cylindrical lens are optically bonded, i.e., a direct surface contact bonding without an intermediate medium, relying on intermolecular forces (van der Waals forces). This ensures no air gaps in the optical path, maintains wavefront phase consistency, and meets the requirements of high-power and high-stability applications. Simultaneously, beam shaping through the internal reflection principle yields a finer focused spot, reduces the number of lenses, lowers the difficulty of processing and assembly, and significantly improves the quality of the focused spot. This is of great significance for improving the resolution and imaging quality of the detection system. Attached Figure Description

[0021] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 This is a front view of the internal reflection prism combined cylindrical lens according to an embodiment of the present invention.

[0023] Figure 2 This is a top view of the internal reflection prism combined with a cylindrical lens according to an embodiment of the present invention.

[0024] Figure 3 This is an optical path diagram of an internal reflection prism combined with a cylindrical lens according to an embodiment of the present invention.

[0025] Figure 4 This is an intensity distribution diagram in the Y direction of an internal reflection prism combined cylindrical lens according to an embodiment of the present invention.

[0026] Figure 5 This is a schematic diagram of the structure of a lighting system according to an embodiment of the present invention.

[0027] Figure 6 This is a schematic diagram of the structure of a lighting system according to another embodiment of the present invention. Detailed Implementation

[0028] The foregoing and other technical contents, features, and effects of the present invention will be clearly presented in the following detailed description of preferred embodiments with reference to the accompanying drawings. Through the description of the specific embodiments, a more in-depth and specific understanding can be gained of the technical means and effects adopted by the present invention to achieve its intended purpose. However, the accompanying drawings are for reference and illustration only and are not intended to limit the present invention; some well-known parts may not be shown. In the various drawings, the same elements are represented by similar reference numerals. For clarity, the various parts in the drawings are not necessarily drawn strictly to scale.

[0029] It is important to understand that the terms "first," "second," etc., are used merely to distinguish elements or circuits with similar properties, and do not indicate or imply relative importance or a specific order. The terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, which includes not only the listed elements but also other elements not expressly listed.

[0030] Figure 1 This is a front view of the internal reflection prism combined cylindrical lens according to an embodiment of the present invention. Figure 2 This is a top view of the internal reflection prism combined with a cylindrical lens according to an embodiment of the present invention. Figure 1 and 2 As shown, this embodiment provides an internal reflection prism combined cylindrical lens, which includes an internal reflection prism 10 and a cylindrical lens 20. The internal reflection prism 10 is integrally formed from an optically transparent material and is provided with an incident surface, an exit surface, and at least one set of internal reflection surfaces. The cylindrical lens 20 has positive optical power, and the cylindrical lens 20 and the exit surface of the internal reflection prism 10 are connected by optical bonding. After the incident beam enters the internal reflection prism 10 through the incident surface, it undergoes at least one internal reflection through the internal reflection surfaces in sequence, and is finally output from the exit surface and enters the cylindrical lens 20, where it is shaped into a line spot.

[0031] Specifically, the internal reflecting prism 10 is integrally molded from an optically transparent material, and contains one or more sets of parallel internal reflecting surfaces. After the incident beam enters the prism from the incident surface, it is not directly transmitted, but undergoes at least one total internal reflection between two opposing reflecting surfaces. This internal reflecting optical path design allows the beam to be repeatedly folded longitudinally within the prism, significantly extending the equivalent propagation path of the beam without adding external optical components. The longer path, combined with the refractive index distribution of the prism material itself, more effectively homogenizes the incident light field, while utilizing the angular accuracy of the reflecting surfaces to compress the beam to a narrower lateral dimension. Since the parallelism between the internal reflecting surfaces is guaranteed by the integral molding process, and the reflection process does not rely on additional mirrors, the entire optical path folding function is fully integrated into a single prism, eliminating the need for multiple independent lenses or mirrors as in traditional beam expanders, thus directly reducing the total number of lenses.

[0032] Meanwhile, the cylindrical lens 20 is directly connected to the exit surface of the inner reflecting prism 10 via optical bonding, eliminating air gaps and requiring no additional mechanical clamping or fine-tuning structures. This integrated assembly method fundamentally eliminates tilt, eccentricity, or spacing errors that may occur between discrete components, significantly reducing assembly tolerances. More importantly, the beam emitted from the inner reflecting prism 10 already tends to be compressed or shaped in a certain dimension, and the cylindrical lens 20 only needs to provide positive optical power to further converge this beam into a thin, elongated line spot. Compared to traditional separate lens groups that first expand and then focus the beam, the synergistic effect of the inner reflecting prism 10 and the cylindrical lens 20 ensures that the beam is precisely constrained throughout its transmission, resulting in minimal energy loss and the formation of a line spot with extremely high energy concentration on the target plane.

[0033] The multiple reflection paths within the internal reflecting prism 10 are not simply folds back. By carefully designing the length and spacing of the reflecting surfaces, the beam can be incident at an angle close to the critical angle during each reflection, thus achieving near-lossless total internal reflection. Since there are no transmission elements between the reflecting surfaces, interface reflection and scattering are avoided, resulting in minimal wavefront distortion of the emitted beam.

[0034] In this invention, "optical bonding" specifically refers to the direct contact bonding of two optical surfaces without an intermediate medium achieved after ultra-precision processing. Its core characteristics are fundamentally different from traditional adhesive bonding, as detailed below: (1) Adhesive medium: Optical bonding has no intermediate layer; while adhesive bonding requires optical glue as an intermediate layer.

[0035] (2) Adhesion principle: Optical bonding relies on intermolecular forces (van der Waals forces); adhesive bonding relies on the physical connection after the glue has cured.

[0036] (3) Optical performance: Photopolymerization achieves perfect light transmission (with almost no reflection and absorption loss); although adhesive bonding has high light transmission, there is still about 0.1% reflection loss.

[0037] (4) Precision requirements: The light bonding process is extremely strict; the bonding is relatively lenient.

[0038] (5) Process difficulty: The light bonding process is complex and has high environmental requirements; the adhesive bonding is relatively mature and easy to mass-produce.

[0039] (6) Environmental tolerance: It has strong photo-bonding, high resistance to extreme temperature differences and high threshold for laser damage; but poor bonding and adhesion, and is prone to aging and yellowing.

[0040] (7) Main applications: Photopolymerization is used in cutting-edge fields such as high-energy lasers, aerospace, and national defense; adhesive bonding is mostly used in consumer electronics and general optical instruments.

[0041] Therefore, in this embodiment, the internal reflection prism combined with the cylindrical lens uses optical bonding to connect the internal reflection prism 10 and the cylindrical lens 20. This means that there is no intermediate medium and the bonding is achieved through direct surface contact relying on intermolecular forces (van der Waals forces). This ensures that there are no air gaps in the optical path and maintains wavefront phase consistency, meeting the requirements of high-power and high-stability applications. At the same time, beam shaping achieved through the internal reflection principle can produce a finer focused spot, reduce the number of lenses, reduce the difficulty of processing and assembly, and significantly improve the quality of the focused spot. This is of great significance for improving the resolution and imaging quality of the detection system.

[0042] In one embodiment, the incident beam undergoes two internal reflections within the internal reflection prism 10, with the internal reflection angles of the two reflections being equal. This symmetrical design causes a definite deflection of the beam direction through two reflections, while simultaneously achieving beam compression and aberration control, ensuring that the beam enters the cylindrical lens 20 precisely at the designed angle.

[0043] In one embodiment, the internal reflection prism 10 has an upper surface and a lower surface arranged opposite each other; the upper surface and / or the lower surface includes at least two segments with different heights along the beam propagation direction, such that the beam after the first internal reflection is displaced in a direction perpendicular to the optical axis; wherein the upper surface and the lower surface within each segment are parallel to each other. Specifically, this longitudinal offset structure, by changing the geometric height of the prism between the two internal reflections, causes the beam to undergo a translation perpendicular to the optical axis after completing the first internal reflection and before entering the second internal reflection, the amount of which is precisely controlled by the height difference between the two segments. This design not only achieves spatial adjustment of the beam path but also maintains the stability of the beam propagation within each segment, ensuring that the beam enters the cylindrical lens 20 at the optimal position, thereby improving the beam quality and focusing accuracy of the system.

[0044] In one embodiment, the segments with different heights are implemented using a stepped structure or a beveled structure. The stepped structure can take the form of vertical steps, allowing for precise control of the step height to achieve beam displacement. This method is relatively easy to manufacture and the displacement is precisely controllable. The beveled structure can use an inclined surface to connect two segments with different heights, enabling a smooth transition of the beam during height changes and reducing beam disturbance and scattering loss.

[0045] In one embodiment, the incident surface of the internal reflection prism 10 is coated with an antireflection film. The antireflection film can be a multilayer dielectric film structure. By precisely controlling the refractive index and thickness of each layer, the reflected light can be destructively interfered using the thin-film interference principle, which significantly improves the energy transmission efficiency of the optical system and reduces the impact of stray light on imaging quality, thus meeting the needs of high-energy-density laser applications.

[0046] In one embodiment, the optically transparent material is optical glass. The optically transparent material can also be an optical crystal or optical plastic, such as quartz glass, fused silica, BK7 glass, or other different types of materials, to meet the needs of different wavelengths and application scenarios.

[0047] Table 1 shows the basic parameters of the internal reflection prism combination cylindrical lens, including key parameters such as the surface type, radius of curvature, thickness, material, clear semi-diameter, mechanical semi-diameter, and the conic constant of the aspherical surface. The units for radius of curvature, thickness, clear semi-diameter, and mechanical semi-diameter are all millimeters (mm).

[0048]

[0049] In this diagram, the first row (STOP) is the aperture stop, the second row is the first optical surface, specifically the incident surface of the internal reflection prism 10, the third row is the second optical surface, specifically the focusing surface of the aspherical surface of the cylindrical lens 20, and the fourth row is the image plane.

[0050] Figure 3 This is an optical path diagram of an embodiment of the internal reflection prism combined with a cylindrical lens. (See diagram below.) Figure 3 As shown, the incident beam enters the internal reflection prism and cylindrical lens combination parallel from the left. After passing the stop, it enters the internal reflection prism 10 from the incident surface 11. After passing through the internal reflection prism 10 and the cylindrical lens 20, it reaches the aspherical focusing surface 21 of the cylindrical lens 20. All incident rays are shaped into a line spot after passing through the focusing surface of the cylindrical lens 20.

[0051] Figure 4This is an intensity distribution diagram in the Y direction of an internal reflection prism combined cylindrical lens according to an embodiment of the present invention. Figure 4 As shown, the curve reaches its peak at Y=0, with a relative irradiance close to 1.0. It then drops rapidly, reaching close to 0 at Y≈±0.45 micrometers, followed by a very small secondary peak, exhibiting typical diffraction spot intensity distribution characteristics. The imaging quality of the optical system is close to the ideal diffraction limit, demonstrating a high-quality focusing effect.

[0052] In one embodiment, the incident beam is set to monochromatic light, the refractive index of the internal reflecting prism at the wavelength of the incident beam is n, and the incident angle θ of the incident beam at the internal reflecting surface satisfies: C + 0.1° ≤ θ ≤ C + 0.5°, where C is the critical angle for total internal reflection, C = arcsin(1 / n). Specifically, this design is designed for single-wavelength (e.g., 193nm, 365nm, or 633nm) applications. By precisely locking the incident angle within an extremely narrow optimal range above the critical angle, it ensures 100% total internal reflection of the beam at the internal reflecting surface, avoiding any energy transmission loss, and effectively avoids higher-order wavefront distortions excited by excessively large incident angles. This precise matching strategy can completely compress the sidelobes of the point spread function (PSF) and eliminate... Figure 4 The weak secondary peak at Y≈±0.45μm significantly improves the defect identification accuracy in high-resolution wafer inspection and avoids signal crosstalk between adjacent micro- and nano-structures.

[0053] In one embodiment, the exit surface of the cylindrical lens is aspherical, and the coefficients of the aspherical surface are set based on the wavelength of the incident beam. Specifically, unlike general designs for a wide spectrum, this embodiment abandons compromise solutions and instead performs a dedicated reconstruction and iterative optimization of the aspherical equation of the cylindrical lens for the specific physical characteristics of the working monochromatic light. This process aims to precisely eliminate higher-order aberrations such as residual spherical aberration and coma inherent at this single wavelength. After this single-wavelength-specific optimization, the energy concentration of the resulting line spot can reach over 99% within an extremely small range of 0.5 μm, and its performance approaches the theoretical diffraction limit at this monochromatic light wavelength, providing a near-perfect illumination source for ultra-high precision optical detection.

[0054] In one embodiment, a deformable mirror is also included; the deformable mirror is disposed between the exit surface of the inner reflecting prism and the cylindrical lens to correct wavefront aberrations of the light beam. Specifically, the deformable mirror is configured for single-wavelength use and forms a closed-loop control system with the wavefront sensor. In actual operation, the system detects wavefront aberrations introduced by micro-processing errors of the inner reflecting surface or environmental disturbances in real time, and feeds the data back to the controller, driving the actuator array of the deformable mirror to generate a conjugate phase distribution, thereby dynamically and actively correcting these aberrations. This active correction mechanism not only further improves the energy concentration of the light spot but also significantly improves its uniformity, ensuring the system's excellent imaging stability under long-term, complex operating conditions.

[0055] In one embodiment, the inner reflecting surface is divided into multiple sub-reflecting surfaces along the beam propagation direction, each with a different normal vector to compensate for the attenuation of beam energy in the propagation direction. Specifically, addressing the inherent defect of the linear spot in the prior art being "bright in the middle and dark at both ends" along its length, this embodiment solves this problem by finely segmenting the reflecting surface of the inner reflecting prism. The normal vector (i.e., reflection angle) of each sub-reflecting surface is independently calculated and finely adjusted, allowing the beam to obtain differentiated reflection gain at different lateral positions, thereby accurately compensating for the uneven energy distribution of the laser beam in the lateral direction and the natural attenuation during propagation. Through this method, the uniformity error of the light intensity of the final linear spot along its long axis can be strictly controlled within ±2%, ensuring a high degree of consistency in the global detection sensitivity of the wafer.

[0056] In one embodiment, a diffractive optical element (DOE) is integrated on the exit surface of the cylindrical lens. This DOE is configured to shape the line spot into a top-hat intensity distribution. Specifically, the DOE is a homogenizing element specifically designed for the specific monochromatic light wavelength used in the system. When the line spot, initially focused by the cylindrical lens, passes through this integrated DOE, its lateral intensity distribution undergoes precise phase modulation. This modulation efficiently converts the Gaussian or quasi-Gaussian intensity profile into a strictly top-hat distribution without sacrificing the original narrow width and high energy density of the line spot, providing ideal light source conditions for applications requiring constant illumination intensity, such as precision lithography or quantitative detection.

[0057] In one embodiment, a height difference formed by a stepped structure exists between the incident and exit surfaces of the internal reflecting prism. The height of the stepped structure is configured to compensate for the optical path difference of the beam at different positions, thereby improving the phase uniformity of the line spot. Specifically, in applications highly sensitive to the phase of the light source, such as interferometric detection of wafer thin film thickness or surface morphology, the phase inhomogeneity of the line spot directly degrades the quality of the interference fringes. To address this, this embodiment employs precise optical design of the height difference of the stepped structure within the internal reflecting prism, ensuring that the beam passing through different regions of the prism undergoes precisely calculated and differentiated geometric paths. This design effectively compensates for the optical path difference introduced by the optical path itself, thereby eliminating the phase gradient of the line spot and outputting a line light source with highly consistent phase characteristics, significantly improving the imaging quality and measurement accuracy in interferometric detection scenarios.

[0058] In one embodiment, for optical materials selected for single-wavelength applications (such as fused silica or BK7), a composite processing technology combining ultra-precision single-point diamond turning (SPDT) and ion beam polishing is employed. Specifically, the SPDT process first achieves high-precision shaping of the macroscopic geometry of the inner reflective surface, with angular tolerances controlled within ±0.05°; subsequently, ion beam polishing performs atomic-level finishing of the surface, improving the surface accuracy to better than λ / 20 (λ being the operating wavelength) and reducing the surface roughness Ra to below 0.5 nm. This process combination effectively suppresses scattering loss and wavefront distortion, meeting the stringent surface quality requirements of single-wavelength high-coherence illumination, while significantly improving the processing yield of complex stepped or beveled structures, providing process assurance for large-scale mass production.

[0059] In one embodiment, the internal reflecting prism integrates submicron-level machining reference holes or surfaces, and is equipped with dedicated assembly and adjustment fixtures. Specifically, these reference features are manufactured simultaneously with the optical functional surfaces during the ultra-precision machining stage, ensuring extremely high repeatability in their position and orientation. During system assembly, the cylindrical mirror module can be quickly and accurately aligned to the internal reflecting prism body using these references, achieving efficient calibration of coaxiality and parallelism between the two, simplifying the complex assembly and adjustment process that traditionally relies on repeated iterative adjustments into a single positioning operation. This not only significantly reduces assembly difficulty and time costs but also ensures a high degree of consistency in optical performance between different batches of products, improving the robustness of the overall manufacturing process.

[0060] In one embodiment, the cylindrical mirror and the internal reflecting prism are made of materials with highly matched coefficients of thermal expansion, the difference between their coefficients of thermal expansion being less than ±0.1 × 10⁻⁶. -6 / ℃. Specifically, when fused silica is used for the internal reflection prism, ultra-low expansion glass (such as ULE or Zerodur) is used for the cylindrical mirror. This single-wavelength-specific material matching strategy fundamentally eliminates the accumulation of interfacial thermal stress caused by changes in ambient temperature, avoiding the risk of cracking or delamination of the photoadhesive layer due to material deformation differences during long-term use. Even in the temperature fluctuation environment common in semiconductor testing equipment, this design ensures the long-term mechanical and optical stability of the photoadhesive bonding interface, providing the system with a reliable service life of over 10 years.

[0061] In one embodiment, the photoresist bonding between the internal reflecting prism and the cylindrical mirror employs a process combining vacuum photoresist bonding and low-temperature annealing. Specifically, photoresist filling and curing are performed in a high-vacuum environment to completely eliminate the formation of microbubbles at the interface; subsequently, a precisely controlled low-temperature annealing process is applied to effectively release residual stress within the adhesive layer. This optimized process ensures that no visible interference fringes or phase noise are generated at the photoresist interface under single-wavelength high-coherence illumination conditions, thereby maintaining the purity of the line spot and imaging quality. Accelerated aging tests have verified that this bonding structure exhibits long-term optical and mechanical stability for over 10 years under standard operating conditions, meeting the stringent reliability requirements of high-end testing equipment.

[0062] In one embodiment, a fiber Bragg grating (FBG) sensor is embedded within the photoadhesive interface. Specifically, this miniature FBG sensor is precisely positioned in key stress concentration areas before the photoadhesive cures, enabling real-time, in-situ monitoring of micro-strains at the interface caused by temperature changes, mechanical vibrations, or material aging. The monitoring signal is transmitted via optical fiber to an external demodulation unit, where the system can intelligently analyze abnormal stress growth based on preset thresholds and issue early warnings before the risk of debonding occurs. This proactive health monitoring mechanism transforms the traditional "post-failure maintenance" model into "predictive maintenance," significantly improving equipment operational continuity and maintenance efficiency, and is particularly suitable for unattended or high-value production line scenarios.

[0063] In one embodiment, the stepped structure of the internal reflecting prism is designed with an adjustable height to achieve continuous adjustment of the line spot tilt angle within the range of 45° to 75°. Specifically, by replacing the precision displacement mechanism or modular stepped components, the equivalent reflection path of the incident beam on the internal reflecting surface is changed, thereby dynamically controlling the illumination tilt angle of the ray spot relative to the wafer surface. This adjustable angle design enables the system to optimize illumination conditions for defects of different depths or morphological features (such as shallow scratches and deep trenches), improve the contrast and signal-to-noise ratio of the scattered signal, significantly enhance the adaptability and detection rate of the detection system, and meet the comprehensive detection needs of multiple types of defects in advanced processes.

[0064] In one embodiment, a switchable spherical lens module is integrated at the cylindrical lens end for rapid switching between line spot and point spot illumination modes at a single wavelength. Specifically, this module seamlessly switches between the cylindrical lens optical path and the spherical focusing lens optical path via a high-precision motorized turntable or sliding rail mechanism. In line spot mode, the system is suitable for large-area, high-speed wafer scanning; when switched to point spot mode, it can perform high numerical aperture (NA) fine focusing and positioning of suspected defect areas, achieving sub-micron spatial resolution. Both modes share the same single-wavelength light source and main optical path, ensuring wavelength consistency and system stability during switching, significantly improving the flexibility and efficiency of the inspection process.

[0065] In one embodiment, the optical path structure of the internal reflection prism is specifically optimized to ensure that the output line spot meets the coherence and phase consistency requirements of interference illumination. Specifically, through precise calculation and control of the arm lengths, material thicknesses, and step heights of each optical path within the prism, a highly uniform phase distribution in both the transverse and longitudinal directions is ensured, resulting in stable interference with the reference beam. This design allows the system to be directly applied to interference detection scenarios such as wafer thin film thickness measurement, surface flatness assessment, and three-dimensional topography reconstruction, without the need for complex heterodyne or phase-shifting devices. This maintains a compact structure while expanding the versatility of a single-wavelength optical system.

[0066] In one embodiment, both the reflecting and transmitting surfaces of the internal reflection prism are coated with a high damage threshold thin film optimized for specific high-power single-wavelength lasers (such as a 193nm excimer laser). Specifically, this coating uses a multilayer fluoride dielectric material and is prepared by an ion-assisted deposition process. Its laser damage threshold (LIDT) exceeds 20 J / cm²@193nm (10 ns pulse), far exceeding the level of conventional commercial coatings. This design effectively suppresses damage mechanisms such as color center formation, ionization ablation, and thermal cracking induced by high-energy ultraviolet photons, ensuring that the optical surface maintains high reflectivity, low absorptivity, and excellent surface stability under long-term high-power irradiation, guaranteeing reliable operation of the system in harsh industrial environments.

[0067] In one embodiment, the internal reflecting prism integrates a microchannel water-cooling structure for efficiently dissipating heat generated by high-power laser irradiation. Specifically, the cooling channels are arranged along the areas with the highest heat flux density (such as near the incident and reflecting surfaces), employing a combination of high thermal conductivity materials (such as fused silica doped or metal inserts) and a deionized water circulation system to achieve rapid heat dissipation from localized hotspots. This thermal management design controls the prism temperature rise within ±0.1°C, effectively suppressing optical surface deformation caused by thermal lensing effects or thermal stress, thereby maintaining the positional stability, width consistency, and wavefront quality of the line spot, meeting the requirements of high-power continuous or high-repetition-rate pulsed laser applications.

[0068] In one embodiment, a dedicated single-wavelength beam homogenizer is integrated at the incident end of the internal reflection prism. Specifically, this homogenizer can employ a microlens array (MLA) or fiber bundle homogenization structure, and is optimized for radiation resistance and low scattering at the operating wavelength (e.g., 193 nm). Its function is to homogenize the inherent spatial intensity noise of the high-power laser source (such as "hot spots" or mode inhomogeneity) into a smooth near-field distribution before inputting it to the prism system. This not only improves the intensity stability and temporal consistency of the final line spot but also reduces the risk of damage to subsequent optical components from local peak power, providing a cleaner and more reliable illumination foundation for high-power single-wavelength detection systems.

[0069] Figure 5 This is a schematic diagram of the structure of a lighting system according to an embodiment of the present invention.

[0070] This invention provides a lighting system, such as Figure 5 As shown, the lighting system includes a light source device, an internal reflection prism combined with a cylindrical lens, a carrier device, and a detection device as described in the above embodiment; the light source device is used to generate an incident light beam; the internal reflection prism combined with a cylindrical lens is used to shape the incident light beam into a line spot; the carrier device is used to carry the object to be detected; the detection device includes at least one detection channel 30 for detecting the scattered light generated after the line spot illuminates the surface of the object to be detected; wherein the line spot illuminates the surface of the object to be detected at an inclined angle.

[0071] Specifically, the light source generates an incident light beam, which is shaped into a line spot by an internal reflecting prism combined with a cylindrical lens. A support device holds the object to be detected, and a detection device includes a detection channel 30 for receiving scattered light generated when the line spot illuminates the object's surface. The incident light is projected at an angle θ onto the illumination spot at the center of the detection channel 30, forming a complete optical path from the light source to the detector. Through the design of the angled illumination, the system optimizes the collection efficiency of scattered light, achieving efficient optical detection of the object.

[0072] In one embodiment, the tilt angle θ ranges from 45° to 75°. Setting the tilt angle θ to 45° to 75° effectively balances the efficiency of scattered light collection with the quality of the detection signal, ensuring sufficient signal strength for the detection device while avoiding optical interference between the incident light and the detection channel, thus achieving optimal detection results.

[0073] In one implementation, such as Figure 1 and Figure 5 As shown, the incident angle of the light on the inner reflecting surface and the tilt angle of the linear light spot illuminating the surface of the object to be detected can be the same angle θ, which can help control the incident direction of the incident light, thereby improving the resolution and imaging quality of the detection system.

[0074] In one embodiment, the incident light beam generated by the light source device is a homogenized laser beam with specific polarization. The homogenized laser beam ensures a uniform and stable light intensity distribution; simultaneously, the use of specific polarized light improves the focusing accuracy and imaging quality of the optical system by controlling the beam polarization characteristics, thus meeting the requirements of high-precision detection.

[0075] Figure 6 This is a schematic diagram of the structure of a lighting system according to another embodiment of the present invention.

[0076] In one implementation, such as Figure 6 As shown, at least one detection channel 30 includes three detection channels: a first detection channel 31, a second detection channel 32, and a third detection channel 33. The third detection channel 33 is located at the intersection of the illumination incident surface and the detection channel surface. The first detection channel 31 and the second detection channel 32 are respectively located on both sides of the detection channel surface, and both form the same interval angle with the third detection channel 33. All three detection channels point towards the central illumination spot, and the symmetrical layout enables multi-angle scattered light reception, ensuring the comprehensiveness and reliability of the detection signal and improving the detection accuracy and efficiency of the optical system.

[0077] The above are merely specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the appended claims.

Claims

1. An internally reflecting prismatic lenticular characterized in that, The internal reflection prism combined cylindrical lens includes an internal reflection prism and a cylindrical lens; The internal reflection prism is integrally formed from an optically transparent material, and the internal reflection prism is provided with an incident surface, an exit surface, and at least one set of internal reflection surfaces. The cylindrical lens has positive optical power, and the exit surface of the cylindrical lens and the internal reflecting prism are connected by optical bonding. The incident beam enters the internal reflecting prism through the incident surface, undergoes at least one internal reflection through the internal reflecting surface, and is finally output from the exit surface and enters the cylindrical lens, where it is shaped into a line spot.

2. The total-internal-reflection prism combined cylindrical lens according to claim 1, characterized by The incident light beam undergoes two internal reflections within the internal reflection prism, and the internal reflection angles of the two internal reflections are equal.

3. The total-internal-reflection prism combined cylindrical lens according to claim 1, wherein The internal reflection prism has an upper surface and a lower surface arranged opposite to each other; the upper surface and / or the lower surface includes at least two segments of different heights along the beam propagation direction, such that the beam after the first internal reflection is displaced in a direction perpendicular to the optical axis; wherein the upper surface and the lower surface in each segment are parallel to each other.

4. The total-internal-reflection prism combined cylindrical lens according to claim 1, wherein The different height sections are achieved through stepped or oblique cut structures.

5. The total-internal-reflection prism combined cylindrical lens according to claim 1, wherein The incident beam is set to monochromatic light, the refractive index of the inner reflecting prism at the wavelength of the incident beam is n, and the incident angle θ of the incident beam at the inner reflecting surface satisfies: C+0.1°≤θ≤C+0.5°, where C is the critical angle for total internal reflection, C = arcsin(1 / n).

6. The total-internal-reflection prism combined cylindrical lens according to claim 1, wherein The exit surface of the cylindrical lens is an aspherical surface, and the coefficient of the aspherical surface is set based on the wavelength of the incident beam.

7. The total-internal-reflection prism combined lenticular lens according to claim 1, wherein The inner reflecting surface is divided into multiple sub-reflecting surfaces along the beam propagation direction, and each sub-reflecting surface has a different normal vector to compensate for the attenuation of beam energy in the propagation direction.

8. The total-internal-reflection prism combined cylindrical lens according to claim 1, wherein The cylindrical lens has a diffractive optical element designed for monochromatic light wavelength integrated on its exit surface to shape the line spot into a flat-top intensity distribution.

9. The total-internal-reflection prism combined lenticular lens according to claim 1, wherein The inner reflection prism and the cylindrical lens have an absolute value of a difference in a thermal expansion coefficient of less than 0.1 x 10 -6 / °C.

10. A lighting system, characterized by include A light source device used to generate an incident light beam; The internal reflection prism combined with a cylindrical lens as described in any one of claims 1 to 9 is used to shape the incident beam into a line spot; A support device used to support the object to be tested; The detection device includes at least one detection channel for detecting the scattered light generated after the line spot illuminates the surface of the object to be detected; The line light spot illuminates the surface of the object to be detected at an oblique angle.

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