A broadband light source

Abstract

The application provides a broadband light source, belonging to the field of light source of industrial vision, and the broadband light source comprises a laser pumping module, a light beam shaping module, a light source chamber, a light splitting glass ellipsoidal mirror, a bulb, a spherical mirror, a high-voltage driving module and a light source output window; an aberration correction plate is arranged between the light splitting glass ellipsoidal mirror and the light source output window, and is used for correcting the distorted light beam wave front of the light splitting glass ellipsoidal mirror, so as to offset the system aberration generated in the transmission process of the ellipsoidal mirror. The application provides a light splitting working mechanism with high reflection of pumping laser and high transmission of target broadband light, and a spherical mirror is arranged behind to form a positive straight-through + backward folding full-range double-path light collecting system, so that the pumping NA and the collecting NA are maximized, the aberration correction plate is arranged to correct the distortion and reduce the system aberration, the quality of the outgoing light is high, and the broadband light source can be used in the fields of semiconductor precision detection, sensor high-precision calibration, embedded integrated detection equipment and biochemical spectrum analysis.

Description

Technical Field

[0001] This invention belongs to the field of industrial vision light sources, especially the field of laser-driven plasma light source technology, and specifically relates to a broadband light source. Background Technology

[0002] In fields such as semiconductor testing, optical calibration, precision optical testing, and biochemical spectroscopy analysis, there is an urgent need for wide-bandwidth, high-brightness, and high-stability laser-driven light sources. Laser-driven light sources possess advantages such as an ultra-wide continuous spectrum from ultraviolet to visible to infrared, good stability, and long lifespan, and have gradually replaced traditional lamp light sources, finding widespread application in high-precision optical testing scenarios. As testing equipment continues to evolve towards miniaturization and integration, the industry demands that light sources, while retaining features such as large NA pumping, high laser utilization, high saturation threshold, and high brightness output, further improve overall compactness, reduce light output height, and enhance spatial adaptability.

[0003] Current mainstream high-brightness laser-driven light sources generally adopt large numerical aperture pumping and large-angle light collection structure, which effectively improves laser focusing efficiency, energy utilization and light source saturation threshold, and solves the defects of insufficient brightness and low light efficiency of traditional small NA light sources, thus meeting the basic light emission requirements of high-precision detection.

[0004] However, the existing large NA light source optical path structure design is fixed. In order to ensure the large-angle pumping and large solid angle light collection effect, a large structural redundancy and device installation spacing are required. The optical layout is loose and the space utilization is low, resulting in a large overall size, low integration and high light output window height. It is difficult to adapt to miniaturized embedded devices and narrow space integration scenarios, which greatly limits the application range of the light source.

[0005] Existing compact light source solutions mostly achieve miniaturization by reducing the pump angle and sacrificing the pump NA. Although the overall size of the machine is reduced, it will cause problems such as decreased laser utilization, lower saturation threshold, insufficient plasma excitation, and decreased output brightness. It cannot meet the multiple requirements of large NA pump, large NA light collection, high brightness and small compact structure.

[0006] In addition, one of the applicant's own solutions is to place the spherical reflector behind the ellipsoidal mirror and arrange them on the same side. However, the glass ellipsoidal mirror is prone to introducing wavefront aberrations during the transmission of broad-spectrum light, causing beam wavefront distortion and reducing the adaptability of the external collection optical path (the above are not necessarily existing technologies, but are only used as background technology introduction).

[0007] In summary, the industry currently lacks a laser-driven light source that can fully retain the advantages of large NA high-efficiency pumping, large solid angle high-efficiency light collection, high saturation threshold, and high brightness output, while also possessing a highly compact optical path, low distortion, low light output height, and wide applicability, and can reduce problems such as wavefront aberration introduction. This makes it difficult to meet the development needs of high-end miniaturized and integrated detection equipment.

[0008] Therefore, the development of this type of novel compact high-brightness laser-driven light source has significant engineering application value and market significance. Summary of the Invention

[0009] To address the technical bottlenecks of traditional large-NA laser-driven light sources, which struggle to simultaneously achieve lossless pumping across the entire range, ultra-wide-angle full-range light collection, compact structure, and light output distortion, this invention proposes a broadband light source.

[0010] Design Principle: This invention retains the advantages of large numerical aperture pumping, large solid angle light collection, high laser utilization, high saturation threshold, and compact optical path layout. It also features a completely new optimized design for the material and optical film system of the core pumping and focusing device, the ellipsoidal mirror. Furthermore, by placing the ellipsoidal mirror and the spherical mirror on opposite sides and adding an aberration correction plate, it is possible to simultaneously achieve ultra-large NA laser pumping and ultra-large NA broadband light collection. This simplifies the optical path structure, improves the output brightness of the light source and the structural integration, and effectively solves the technical pain point of existing technologies that cannot simultaneously achieve high pumping performance, high light collection efficiency, and a minimalist and compact structure. It also addresses the problems of wavefront aberration easily introduced during the transmission of broadband light by the glass ellipsoidal mirror, which leads to beam wavefront distortion and reduces the adaptability of the external collection optical path.

[0011] A broadband light source includes a laser pumping module, a beam shaping module, a light source chamber, a beam-splitting glass ellipsoid, a lamp, a spherical reflector, a high-voltage driving module, and a light source output window. The beam-splitting glass ellipsoid is arranged on the same side as the light source output window, and a spherical reflector is correspondingly arranged on the opposite side of the beam-splitting glass ellipsoid. An aberration correction plate is arranged between the beam-splitting glass ellipsoid and the light source output window to correct the distorted beam wavefront of the beam-splitting glass ellipsoid, thereby compensating for the system aberrations generated during the transmission process of the ellipsoid.

[0012] Furthermore, the beam-splitting glass ellipsoid uses optical glass as the substrate for the ellipsoidal reflector and coats the mirror surface with a spectrally selective medium film; the front of the beam-splitting glass ellipsoid faces the lamp to focus the light, and the aberration correction plate is set on the back side of the beam-splitting glass ellipsoid; the beam-splitting glass ellipsoid constructs a beam-splitting optical path with high laser reflection and high transmission of broad-spectrum light.

[0013] Furthermore, the spectrally selective medium film of the beam-splitting glass ellipsoid includes a central high-transmittance spectral film and an outer high-reflectance laser film. The laser beam output after beam shaping by the beam shaping module is directed entirely towards the high-reflectance laser film and reflected and converged to the central region of the bulb. One effective wavelength of the spectral light emitted by the bulb's plasma is directly transmitted through the high-transmittance spectral film, while the other spectral light from the bulb first directly illuminates the spherical reflector, which reflects this portion of the spectral light back to the high-transmittance spectral film of the beam-splitting glass ellipsoid. The spectral light after passing through the high-transmittance spectral film is optically corrected by a subsequent aberration correction plate and then directly emitted from the light source output window arranged on the same side.

[0014] Furthermore, a beam-splitting glass ellipsoidal mirror combined with a spherical reflector constructs an all-angle light collection and output system. This all-angle light collection and output system includes two output paths: a direct transmission output path and a refracted transmission output path. The direct transmission output path involves the effective wavelength light generated by the plasma directly passing through the beam-splitting glass ellipsoidal mirror, undergoing optical correction by a subsequent aberration correction plate, and then exiting directly through the light source output window located on the same side. The refracted transmission output path involves the back-radiated light from the plasma incident on the spherical reflector located on the opposite side, precisely refracted back by the spherical reflector, passing through the plasma luminescent area again, and then transmitting through the beam-splitting glass ellipsoidal mirror. After undergoing optical correction by a subsequent aberration correction plate, it exits directly through the light source output window located on the same side.

[0015] Furthermore, the laser pumping module includes a laser and an optical path coupling mirror assembly for supplying a laser beam into the light source cavity.

[0016] Furthermore, the beam shaping module includes diffractive optical elements, apertures, spatial light modulators, and micromirror arrays.

[0017] Furthermore, the high-voltage drive module is connected to the two electrodes of the bulb, and applies high voltage to the inside of the bulb through the electrodes, causing the working gas filled in the center of the bulb to be pre-ionized to form a plasma light-emitting region; the pump laser focused out by the beam-splitting glass ellipsoid mirror continuously excites the plasma, causing the plasma to generate a broad spectrum of continuous light covering the ultraviolet, visible and infrared bands.

[0018] Furthermore, an output window is embedded in the output window of the light source chamber, and the output window is made of flat glass or curved glass. An anti-reflective coating is deposited on the glass surface of the output window.

[0019] Compared to existing technologies, this application innovatively uses a glass-based spectrally selective dielectric film ellipsoidal mirror to replace the traditional metal-plated aluminum mirror, breaking through the limitation of traditional mirrors that can only reflect pump light. By utilizing the spectral frequency division characteristics of the dielectric film, a beam splitting mechanism is achieved that enables high reflectivity of the pump laser and high transmittance of the target's broad spectrum of light. This invention eliminates the need for openings in the ellipsoidal mirror, fully preserving its ultra-large angle receiving range and ensuring lossless ultra-large NA throughout the pump light path. Simultaneously, by utilizing the light transmission characteristics of the ellipsoidal mirror in conjunction with a rear spherical mirror, a folding light receiving path is constructed, forming a full-domain dual-path light receiving system with forward direct access and backward folding. Without increasing the complexity of the optical path structure, this invention maximizes both the pump NA and the collecting NA, resolving the inherent contradiction of traditional structures that either sacrifice pump performance for light receiving efficiency or have limited light receiving angles that hinder brightness improvement. Meanwhile, the ellipsoidal and spherical reflectors are set up opposite each other, which improves the structural regularity. The aberration correction plate is set up to correct distortion and reduce inefficient system aberrations. The quality of the emitted light is high, which greatly improves the miniaturization and spatial adaptability of the equipment. It can be widely used in various scenarios such as semiconductor precision testing, high-precision sensor calibration, embedded integrated testing equipment and biochemical spectral analysis, with a wider range of applications and stronger engineering practicality. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the broadband light source of this application; Figure 2 for Figure 1 A schematic diagram of the optical path for collection; Figure 3 This is a schematic diagram of the laser pupil distribution after passing through the beam shaping module.

[0021] In the diagram, 1. Beam-splitting glass ellipsoid; 2. Bulb; 3. Output window; 4. Source cavity; 5. Laser beam; 6. Output beam; 7. Spherical mirror; 8. Aberration correction plate; 9. Beam shaping module; 10. Laser. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0023] A broadband light source, see Figures 1-3The broadband light source includes a laser pump module, a beam shaping module 9, a light source chamber 4, a beam-splitting glass ellipsoid mirror 1, a bulb 2, a spherical mirror 7, a high-voltage drive module, and a light source output window. The laser pump module includes a laser 10 and an optical path coupling mirror assembly, and the beam shaping module 9 includes diffractive optical elements, an aperture, a spatial light modulator, and a micromirror array.

[0024] Arrangement: A beam-splitting glass ellipsoid 1, a bulb 2, a spherical reflector 7, and an aberration correction plate 8 are installed within the light source chamber 4. An output window 3, made of flat or curved glass, is embedded at the light source output window of the chamber 4. The beam-splitting glass ellipsoid 1 is positioned on the same side as the light source output window, with the spherical reflector 7 positioned opposite it. An aberration correction plate 8 is placed between the beam-splitting glass ellipsoid 1 and the light source output window to correct the distorted beam wavefront of the beam from the beam-splitting glass ellipsoid 1, thereby compensating for system aberrations generated during ellipsoidal transmission. This scheme achieves both ultra-large NA pumping and ultra-large NA full-area light collection without any pump NA loss or mirror openings. The core of this scheme lies in optimizing and improving the overall optical path layout and optical correction structure based on the dual ultra-large NA, dielectric film beam-splitting ellipsoid light source structure, and optimizing wavefront aberration correction through the aberration correction plate 8.

[0025] Unlike traditional aluminized metal ellipsoidal mirror optical path structures, this invention uses optical glass as the ellipsoidal reflector substrate and coats the mirror surface with a spectrally selective dielectric film, replacing the traditional aluminized metal substrate structure. Within this field, it achieves an ultra-large aperture index value (NA) ≥ 0.9.

[0026] The laser pupil of the laser beam 5, shaped by the beam shaping module 9, is approximately semi-circular. The beam shaping module 9 precisely shapes the laser pupil distribution and beam profile, ensuring that the output beam shape and spot size perfectly match the effective reflecting surface of the beam-splitting glass ellipsoidal mirror 1 (i.e., the glass ellipsoidal reflector). This guarantees that the pump laser is incident on the ellipsoidal mirror surface at full aperture and with high efficiency, eliminating beam deviation and energy waste. The shaped pupil distribution is as follows: Figure 3 As shown.

[0027] Furthermore, in an optional example, an anti-reflection coating is deposited on the glass surface of the output window 3 to improve the transmittance of the output beam 6.

[0028] The beam-splitting glass ellipsoid 1 uses optical glass as the ellipsoidal reflector substrate and is coated with a spectrally selective medium film on the mirror surface. The front of the beam-splitting glass ellipsoid 1 faces the bulb 2 to focus the light, and the aberration correction plate 8 is set on the back side of the beam-splitting glass ellipsoid 1. The beam-splitting glass ellipsoid 1 constructs a beam-splitting optical path with high laser reflection and high broadband light transmission. The lateral receiving angle of the beam-splitting glass ellipsoid 1 is 180°.

[0029] The spectrally selective medium film of the beam-splitting glass ellipsoid 1 includes a high-transmittance spectral film in the middle and a high-reflectance laser film on the periphery. The laser beam 5 output by the beam shaping module 9 is directed entirely toward the high-reflectance laser film and reflected and converged to the central region of the bulb 2. One effective wavelength of the spectral light emitted by the plasma of the bulb 2 is selected and directly transmitted through the high-transmittance spectral film. Another spectral light from the bulb 2 first directly illuminates the spherical reflector 7, which reflects this portion of the spectral light back toward the high-transmittance spectral film of the beam-splitting glass ellipsoid 1. The spectral light after passing through the high-transmittance spectral film is optically corrected by the subsequent aberration correction plate 8 and then directly emitted from the light source output window arranged on the same side.

[0030] The shape of the high-transmittance film of the beam-splitting glass ellipsoid 1 matches the central region of the approximately semi-circular laser pupil, and the high-reflectance film of the laser of the beam-splitting glass ellipsoid 1 matches the annular region of the laser pupil.

[0031] Omnidirectional light collection and output optical path setup: A beam-splitting glass ellipsoid 1 combined with a spherical reflector 7 constructs an omnidirectional light collection and output system. This system includes two output paths: a direct transmission output path and a retrograde transmission output path. The direct transmission output path involves the effective wavelength light generated by the plasma directly passing through the beam-splitting glass ellipsoid 1, undergoing optical correction by the subsequent aberration correction plate 8, and exiting directly through the light source output window on the same side. The retrograde transmission output path involves the back-radiated light from the plasma incident on the spherical reflector 7 on the opposite side, precisely reflected back by the spherical reflector 7, passing through the plasma luminescent area again, and then through the beam-splitting glass ellipsoid 1. After optical correction by the subsequent aberration correction plate 8, it exits directly through the light source output window on the same side. These two light paths work together to fully preserve the ultra-large solid angle light collection capability, ensuring ultra-high luminous flux and output brightness of the light source.

[0032] Two spectral beams are emitted from the light source output window as output beam 6, providing a light source for subsequent processing or detection with an effective wavelength.

[0033] The bulb 2 is a high-pressure sealed bulb filled with working gas. The high-pressure drive module is connected to the two electrodes of the bulb 2 and applies high pressure to the inside of the bulb 2 through the electrodes, causing the working gas in the center of the bulb to be pre-ionized to form a plasma light-emitting region. The pump laser focused out by the beam-splitting glass ellipsoid 1 continuously excites the plasma, causing the plasma to produce a broad spectrum of continuous light covering the ultraviolet, visible and infrared bands.

[0034] like Figure 1 As shown, the beam-splitting glass ellipsoid 1 and the light source output window are arranged on the same side, and a spherical reflector 7 is arranged on the opposite side of the beam-splitting glass ellipsoid 1. The whole adopts a beam-splitting working mechanism of a non-perforated ellipsoid, high laser reflectivity and high broadband light transmittance.

[0035] To address the issues of wavefront aberrations introduced during the transmission of broad-spectrum light by an ellipsoidal mirror, leading to beam wavefront distortion and reduced adaptability to the external collection optical path, this application adds an aberration correction plate 8 between the beam-splitting glass ellipsoidal mirror 1 and the output window on the same side. Utilizing the optical compensation characteristics of the aberration correction plate 8, the distorted beam wavefront of the ellipsoidal mirror is precisely corrected, offsetting the systematic aberrations generated during the ellipsoidal mirror transmission process. This ensures that the wavefront of the final emitted beam approximates a standard spherical wave, significantly optimizing the beam output quality. This allows the emitted light to perfectly adapt to the external large numerical aperture collection optical path outside the cavity, improving the coupling efficiency and detection accuracy of the external optical path.

[0036] Based on the advantages of dual large NA optical paths, high laser utilization, compact structure, controllable cost, and wide applicability, the proposed solution further optimizes the overall structural regularity through same-side integrated layout. At the same time, the addition of an aberration correction plate solves the beam distortion problem of the transparent ellipsoidal mirror, effectively improving the output beam quality and optical path coupling adaptability of the light source. Under the premise of ensuring constant output light intensity, the optical performance and engineering practicality of the light source are further improved.

[0037] In an application example, the present invention also provides a wafer quantity inspection system, including a wafer motion stage, an optical inspection station and a processor, wherein the light source of the optical inspection station adopts the aforementioned broadband light source.

[0038] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A broadband light source, characterized in that, The broadband light source includes a laser pumping module, a beam shaping module (9), a light source chamber (4), a beam-splitting glass ellipsoid mirror (1), a bulb (2), a spherical reflector (7), a high-voltage driving module, and a light source output window; The beam splitter glass ellipsoid (1) is arranged on the same side as the light source output window, and a spherical reflector (7) is set on the opposite side of the beam splitter glass ellipsoid (1); an aberration correction plate (8) is set between the beam splitter glass ellipsoid (1) and the light source output window to correct the distorted beam wavefront of the beam splitter glass ellipsoid (1).

2. The broadband light source according to claim 1, characterized in that: The beam-splitter glass ellipsoid (1) uses optical glass as the substrate of the ellipsoidal reflector and a spectrally selective medium film is coated on the mirror surface; the front side of the beam-splitter glass ellipsoid (1) faces the light bulb (2) to focus the light, and the aberration correction plate (8) is set on the back side of the beam-splitter glass ellipsoid (1); the beam-splitter glass ellipsoid (1) constructs a beam-splitter optical path with high laser reflection and high transmission of broad spectrum light.

3. The broadband light source according to claim 2, characterized in that: The spectrally selective medium film of the beam-splitting glass ellipsoid (1) includes a high-transmittance spectral film in the middle and a high-reflectance laser film on the periphery. The laser beam (5) output by the beam shaping module (9) is directed towards the high-reflectance laser film and reflected and converged to the central region of the bulb (2). One of the spectral rays emitted by the plasma of the bulb (2) is selected to directly transmit the effective wavelength light through the high-transmittance spectral film. The other spectral ray of the bulb (2) is first directly irradiated by the spherical mirror (7). The spherical mirror (7) reflects this part of the spectral ray back to the high-transmittance spectral film of the beam-splitting glass ellipsoid (1). The spectral ray after passing through the high-transmittance spectral film is optically corrected by the subsequent aberration correction plate (8) and then directly emitted from the light source output window arranged on the same side.

4. The broadband light source according to claim 1, characterized in that: The beam-splitting glass ellipsoid (1) combined with the spherical reflector (7) forms an all-angle light collection and output path. The all-angle light collection and output path includes two light paths: a direct transmission output path and a folded-back transmission output path. The direct transmission output path is as follows: the effective wavelength light generated by the plasma is directly transmitted through the beam-splitting glass ellipsoid (1), and after optical correction by the subsequent aberration correction plate (8), it is directly emitted from the light source output window arranged on the same side. The folded-back transmission output path is as follows: the light radiated from the back of the plasma is incident on the spherical reflector (7) arranged on the opposite side, and is accurately folded back by the spherical reflector (7). After passing through the plasma luminescent area again, it is transmitted through the beam-splitting glass ellipsoid (1), and after optical correction by the subsequent aberration correction plate (8), it is directly emitted from the light source output window arranged on the same side.

5. The broadband light source according to claim 1, characterized in that: The laser pumping module includes a laser (10) and an optical path coupling mirror assembly for supplying a laser beam (5) into the light source chamber (4).

6. The broadband light source according to claim 1, characterized in that: The beam shaping module (9) includes diffractive optical elements, apertures, spatial light modulators and micromirror arrays.

7. The broadband light source according to claim 1, characterized in that: The lateral receiving angle of the beam-splitting glass ellipsoid (1) is 180°.

8. The broadband light source according to claim 1, characterized in that: The bulb (2) is a high-pressure sealed bulb, and the bulb is filled with working gas.

9. The broadband light source according to claim 1, characterized in that: The high-voltage drive module is connected to the two electrodes of the bulb (2). The electrodes apply high voltage to the inside of the bulb (2), causing the working gas filled in the center of the bulb to be pre-ionized to form a plasma light-emitting area. The pump laser focused out by the beam splitter glass ellipsoid (1) continuously excites the plasma, causing the plasma to generate a broad spectrum of continuous light covering the ultraviolet, visible and infrared bands.

10. The broadband light source according to claim 1, characterized in that: An output window (3) is embedded in the light source output window of the light source chamber (4), and the output window (3) is made of flat glass or curved glass.

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