A kind of optical fiber direct-fed vacuum inner particle on-line detection device

Abstract

The utility model relates to a kind of optical fiber direct feeding type vacuum internal particle online detection device, including vacuum chamber, laser generation and feed-in component, laser shaping component, particle detection and signal acquisition component, vacuum unit and cavity to be measured;Vacuum chamber side wall is equipped with laser feed-in and signal lead-out sealed interface, two ends are respectively sealed connection vacuum unit and cavity to be measured;Laser source is external in vacuum chamber, direct feeding laser is passed through transmission optical fiber to cavity;Laser shaping component is shaped laser in cavity to form detection zone;Particle detection and signal acquisition component contain optical filter element, photoelectric detection element and residual laser absorption element, photoelectric detection element is used to receive particle scattering signal, signal is led out by sealed interface.According to the optical fiber direct feeding type vacuum internal particle online detection device of the utility model, external beam expander is not needed, avoid external optical path interference, vacuum window reflection and visible light noise, realize stable vacuum internal particle real-time online monitoring.

Description

Technical Field

[0001] This utility model relates to the field of clean vacuum technology, and more specifically to an optical fiber direct-feed online particle detection device in vacuum. Background Technology

[0002] In beamline engineering projects, core work relies on high-frequency radiation sources (such as X-ray sources with frequencies ≥100kHz), which possess extremely high energy densities. In this context, particulate matter in the environment adhering to the surface of optical components can directly cause severe radiation damage. Simultaneously, pitting damage caused by larger dust particles can disrupt the optical coherence between the mirror and the crystal, thus affecting image quality. Therefore, accurate detection of particulate matter in the beamline engineering environment is a critical requirement for ensuring the project's stable progress.

[0003] To determine the size and quantity of particulate matter, various particle measurement methods have been developed in existing technologies. Traditional particle measurement methods include sieving, microscopy, sedimentation, and inductive methods. While these methods can achieve particle measurement in some conventional scenarios, they generally suffer from problems such as complex operation, inability to detect in real time, or limited detection accuracy. In recent years, with technological advancements, laser methods, computer image analysis technology, and particle size measurement technologies based on Brownian motion have been gradually applied. Among these, laser scattering, due to its non-invasiveness and real-time detection advantages, has become an important technological direction in the field of particle size analysis and detection. Its principle is suitable for the particle measurement needs within ultra-high vacuum systems and is considered one of the most promising detection technologies in this scenario.

[0004] Currently, optical particle counters based on laser scattering for atmospheric environment detection have achieved mature applications. The development of such devices began in the 1940s. Their core structure typically includes a light source, a detection zone, collecting optical components, and photoelectric detection equipment. During operation, they primarily measure the number of particles through the laser scattering effect. However, existing optical particle counters have significant limitations in structural design and applicable scenarios: their detection zone is usually small, smaller than the incident beam size, and a small amount of gas needs to be extracted from the environment during detection. This method is only suitable for scenarios where the particle number distribution in the sample is uniform and the overall number is small, failing to meet the comprehensive detection needs in complex environments.

[0005] For particle detection in vacuum environments, the traditional vacuum laser scattering detection devices used in existing technologies, although attempting to incorporate the principle of laser scattering, still have many technical shortcomings, making it difficult to achieve efficient and accurate detection.

[0006] First, such devices require a complex beam-expanding optical path to be set up outside the vacuum. The purpose is to adapt to the transmission path of "external optical path → vacuum window → internal detection area" and meet the needs of a large-area detection area. However, the external optical path is easily affected by vibration interference, which causes the beam to deflect and directly affects the detection accuracy.

[0007] Secondly, this type of device relies on a vacuum flange window to connect the external optical path with the internal detection area. The vacuum flange window introduces transmission loss and generates stray reflections. In addition, existing devices usually use a uniform light bar or a plano-concave lens to obtain a flat-top beam. The flat-top beam obtained by this method has poor uniformity and is prone to generating stray signals, which interfere with the detection results.

[0008] Furthermore, the detection process of such devices requires an external vacuum, and the detection light must pass through a vacuum isolation window to reach the detection surface. This not only weakens the intensity of the detection light but also causes further signal attenuation due to the long distance between the detection points. Therefore, a photomultiplier tube (PMT) is needed to amplify the detection signal. However, PMTs are not only expensive but also require high-voltage power, increasing the operating cost and safety risks of the device. In addition, traditional PMTs, due to the weak external detection signal, can only capture the scattered signals of particles larger than 5 μm, and have no detection capability for particles smaller than 5 μm. However, beamline engineering requires precise detection of particles in this size range to avoid damage to optical components.

[0009] In existing technologies, the sampling logic of atmospheric particle counters contradicts the rarefied characteristics of the vacuum environment. The design of the external optical path and PMT of traditional vacuum detection devices suffers from problems such as large interference, high cost, and blind spots in small particle detection. Neither of these can meet the core requirements of beamline engineering.

[0010] In summary, existing particle detection methods and traditional vacuum laser scattering detection devices cannot meet the needs of efficient, accurate, low-cost real-time detection of particulate matter in ultra-high vacuum environments in scenarios such as beamline engineering projects. There is an urgent need for a particle detection technology solution that is adaptable to vacuum environments, has stable performance, and is cost-controllable. Utility Model Content

[0011] Atmospheric particle counters use a method of pumping gas samples containing solid particles to their detection cross-section for detection. The diameter of the detection channel is typically less than the micrometer level. However, in a vacuum environment, due to the thin gas and small number of particles, it is impossible to pump a small amount of gas to the detection cross-section. Therefore, it is not possible to detect particulate matter in a vacuum pipeline using traditional particle counters. Based on this, this invention provides an optical fiber direct-feed online particle detection device in a vacuum.

[0012] According to this utility model, a fiber-optic direct-feed vacuum in-situ particle detection device includes a vacuum chamber with at least two sealed interfaces on its sidewall for laser feeding and detection signal output, respectively, and sealed interfaces for connecting external components at opposite ends; a laser generation and feeding component including a laser source and a transmission fiber, wherein the laser source is located outside the vacuum chamber, one end of the transmission fiber is connected to the output end of the laser source, and the other end passes through the sealed interface on the sidewall of the vacuum chamber for laser feeding and extends into the vacuum chamber to directly feed the laser output from the laser source into the vacuum chamber; a laser shaping component located inside the vacuum chamber and downstream of the extension end of the transmission fiber, for receiving the laser transmitted by the transmission fiber and shaping it to form a detection area for particle detection inside the vacuum chamber; and a particle detection and signal acquisition component. The vacuum chamber includes a filter element, a photoelectric detection element, and a residual laser absorption element. The photoelectric detection element is located beside the detection area and is used to receive the laser scattering signal generated when particles pass through the detection area. The filter element is located between the photosensitive surface of the photoelectric detection element and the detection area. The signal output end of the photoelectric detection element extends to the outside of the vacuum chamber through a signal transmission component through a sealed interface on the side wall of the vacuum chamber for signal extraction. The residual laser absorption element is located downstream of the detection area and is used to absorb residual laser light passing through the detection area. A vacuum unit and a test chamber are respectively sealed to the sealed interfaces at opposite ends of the vacuum chamber. The test chamber is the source channel for the particles to be detected. The vacuum unit is used to provide a vacuum environment for the vacuum chamber and the test chamber and guide the particles to be detected in the test chamber into the detection area of ​​the vacuum chamber with the airflow.

[0013] In a preferred embodiment, the sealing interface on the side wall of the vacuum chamber for laser feeding is a fiber optic vacuum flange, the sealing interface for signal output is a BNC vacuum flange, and the sealing interfaces at the upper and lower ends of the vacuum chamber for connection are both CF35 standard flanges.

[0014] In a preferred embodiment, the laser source is a single-mode fiber laser with an output laser wavelength of 808nm±30nm, excluding visible light in the wavelength range of 400-760nm.

[0015] In a preferred embodiment, the transmission optical fiber includes a vacuum-feed optical fiber and a vacuum-inner optical fiber. The vacuum-feed optical fiber is located outside the vacuum chamber, with one end connected to the laser source and the other end sealed to the sealing interface on the side wall of the vacuum chamber for laser feeding. The vacuum-inner optical fiber is located inside the vacuum chamber, with one end connected to the sealing interface on the side wall of the vacuum chamber for laser feeding and the other end extending upstream of the laser shaping component.

[0016] In a preferred embodiment, the laser shaping component includes a collimator, the input end of which is coaxially fixed with the extension end of the transmission optical fiber, for collimating the diverging laser output from the transmission optical fiber into parallel light.

[0017] In a preferred embodiment, the laser shaping component further includes a Powell prism, which is coaxially arranged with the output end of the collimator, for unidirectional beam expansion of parallel light in a direction perpendicular to the airflow to form a rectangular detection area.

[0018] In a preferred embodiment, the filtering element is a narrowband filter that allows light in the wavelength range of 808nm±30nm to pass through and has a cutoff rate of ≥99% for visible light in the wavelength range of 400-760nm.

[0019] In a preferred embodiment, the photoelectric detection element is a photodiode, which is disposed at 90°±2° in the detection area to capture laser scattering signals generated by particles of 5μm and below.

[0020] In a preferred embodiment, the signal transmission device is a shielded wire. One end of the shielded wire is connected to the signal output terminal of the photodiode, and the other end extends through the sealed interface on the side wall of the vacuum chamber for signal detection to the outside of the vacuum chamber and docks with an external signal processing unit.

[0021] In a preferred embodiment, the residual laser absorption element is a tail laser absorber, which is a conical metal cavity with its absorption surface facing the output end of the detection area, and its inner wall is coated with a black chrome coating.

[0022] According to this utility model, the fiber-optic direct-feed vacuum in-situ particle online detection device utilizes fiber-optic direct-feed laser and vacuum shaping detection, eliminating the need for external beam expanders and vacuum windows, thus avoiding external optical path interference and visible light noise. It replaces the PMT with a photodiode, reducing costs and enabling the detection of particles 5μm and smaller. Combined with the sealed connection between the vacuum unit and the chamber under test, it achieves online detection without sampling, ultimately solving the four core problems of traditional devices and realizing more stable, accurate, and low-cost real-time online monitoring of particles in a vacuum. Attached Figure Description

[0023] Figure 1 This illustrates the specific application environment of the fiber-optic direct-feed vacuum in-situ particle detection device according to this invention.

[0024] Figure 2 yes Figure 1 A schematic diagram of the structure of a fiber-optic direct-feed vacuum in-situ particle detection device. Detailed Implementation

[0025] The preferred embodiments of this utility model are given below with reference to the accompanying drawings and described in detail.

[0026] like Figure 1 As shown, the fiber-optic direct-feed online particle detection device in vacuum according to this utility model is based on laser scattering and is used in ultra-high vacuum environments (vacuum degree ≤10). -4 Real-time detection of large cross-section (detection cross-section ≥ 1mm × 1mm) particles (Pa) is achieved by using a vacuum chamber 7 as the core support. The vacuum unit 12 and the test chamber 13 are respectively sealed and connected to the vacuum chamber 7 to form a vacuum assembly. The particles in the test chamber 13 flow along the Z direction as the vacuum unit 12 pumps air, that is, they flow along the path of test chamber 13 → vacuum chamber 7 → vacuum unit 12.

[0027] Among them, vacuum chamber 7 is an all-metal encapsulated structure, meeting 10 -7 To meet the requirements of ultra-high vacuum, it is equipped with CF35 standard flange interfaces at both the top and bottom.

[0028] Among them, the test chamber 13 is a vacuum pipe for the particles to be detected. Different optical elements and optical element support and movement mechanisms are usually placed inside. It is located on the upper part of the vacuum chamber 7 and is sealed to the upper CF35 flange of the vacuum chamber 7.

[0029] The vacuum unit 12 is located at the lower part of the vacuum chamber 7 and is sealed to the lower CF35 flange of the vacuum chamber 7. It provides an ultra-high vacuum environment for the entire system (test chamber 13 + vacuum chamber 7). At the same time, through continuous evacuation, a stable airflow (airflow velocity 0.5-1m / s) is formed in the system, which drives the particles in the test chamber 13 to flow naturally into the detection area A of the vacuum chamber 7 (see...). Figure 2 This enables real-time online detection.

[0030] In addition to the vacuum chamber 7 mentioned above, the fiber-optic direct-feed vacuum particle online detection device according to this utility model includes a laser generation and feeding component 100, a laser shaping component 200, and a particle detection and signal acquisition component 300, such as... Figure 2As shown. The laser generation and feeding component 100 includes a fiber laser 1 (laser source) and transmission fibers (including a vacuum feed fiber 2 and a vacuum inner fiber 4). The transmission fiber is divided into an external section (vacuum feed fiber 2) and an internal section (vacuum inner fiber 4), enabling lossless laser transmission from the outside to the vacuum. The laser shaping component 200 includes a collimator 5 and a Powell prism 6, used to achieve precise shape control in the detection area A within the vacuum chamber 7. The particle detection and signal acquisition component 300 includes a filter element (narrowband filter 8), a photodetector element (photodiode 9), a residual laser absorption element (tail laser absorber 10), and a BNC vacuum flange 11, used for close-range internal detection to enhance signal strength. Specifically, the fiber vacuum flange 3 for introducing the laser and the BNC vacuum flange 11 for extracting the detection signal are fixed to the side wall of the vacuum chamber 7, with a leakage rate ≤ 1×10⁻⁶. - 10 The pressure of torr·l / s ensures the airtightness of the vacuum chamber 7. The optical fiber 4, collimator 5, Powell prism 6, narrowband filter 8, photodiode 9, and tail laser absorber 10 are set inside the vacuum chamber 7, forming a complete internal link of laser shaping-particle detection-signal acquisition. The fiber laser 1 is located outside the vacuum chamber 7 and is connected to the fiber vacuum flange 3 through the vacuum feed fiber 2. By reducing the number of external optical components, the overall structure of the device is simplified.

[0031] In this embodiment, fiber laser 1 is located outside the vacuum system and does not require vacuum encapsulation. Its output end is fixedly connected to one end of the vacuum-feed fiber 2 via a standard interface. Its output laser wavelength is 808nm ± 30nm (belonging to the near-infrared band > 760nm, with no visible light component), avoiding visible light noise interference at the signal source. There are no special limitations on the output power; it only needs to meet the required scattered signal intensity for detection. In this embodiment, fiber laser 1 is an 808nm single-mode fiber laser.

[0032] The vacuum-feed fiber 2 transmits the laser output from the fiber laser 1 to the entrance of the vacuum chamber 7 without loss, replacing the traditional "external beam expander" and avoiding beam deflection caused by vibration. The vacuum-feed fiber 2 is located outside the vacuum system, with one end connected to the laser 1 and the other end sealed to the external interface of the fiber vacuum flange 3.

[0033] The fiber optic vacuum flange 3 is installed on the side wall of the vacuum chamber 7, penetrating the chamber wall (metal-sealed). The fiber optic vacuum flange 3 includes a metal-sealed structure with a leakage rate ≤1×10⁻⁶. -10 The pressure of torr·l / s ensures that the vacuum chamber 7 is leak-proof while allowing for flexible disassembly of the internal optical fiber 4 for maintenance. The external interface of the optical fiber vacuum flange 3 is connected to the vacuum feed optical fiber 2, and the internal interface is connected to one end of the internal optical fiber 4 via a detachable FC / APC connector.

[0034] The vacuum fiber 4 is located inside the vacuum chamber 7. One end of it is connected to the internal interface of the fiber vacuum flange 3, and the other end is coaxially fixed to the input end of the collimator 5. It is used to transmit the laser to the collimator 5 inside the vacuum to ensure the stable transmission of the laser inside the vacuum.

[0035] The collimator 5 is located inside the vacuum chamber 7, near the output end of the vacuum fiber 4. Its input end is coaxially fixed with the vacuum fiber 4, and its output end faces the Powell prism 6. It is used to collimate the diverging laser output from the vacuum fiber 4 into parallel light. In a preferred embodiment, the collimator 5 has a focal length > 8mm, for example 15mm, a numerical aperture NA ≤ 0.5, and an adaptive wavelength of 808nm ± 30nm, providing a stable parallel light source for subsequent unidirectional beam expansion.

[0036] The Powell prism 6 is located inside the vacuum chamber 7, downstream of the collimator 5, and coaxial with the collimator 5. It is fixed to the inner wall support of the vacuum chamber 7, with its incident surface aligned with the output end of the collimator 5. The parallel light output from the collimator 5 (based on its focal length > 8mm and NA ≤ 0.5, the spot size is naturally ≥ 1×1mm) enters the Powell prism 6. The prism only expands the parallel laser beam in one direction, that is, it expands the beam along the X direction perpendicular to the airflow, but does not expand the beam along the Z direction of the airflow (the Z-direction size remains consistent with the incident parallel light, ≥ 1mm), ultimately forming a rectangular detection area A downstream, for example, 1mm×1mm to 10mm×10mm. The incident parallel light is ≥1×1mm, ensuring that after X-axis beam expansion, it covers most of the airflow cross-section of the cavity under test 13 (e.g., expanded to 10mm), and also ensuring that after Z-axis beam expansion, it still has a size of ≥1mm to control the particles passing through the time window, forming a clear scattered light pulse signal. This addresses the problems of small detection area and missed particle detection in existing devices. In a preferred embodiment, the vacuum pipe of the cavity under test 13 is typically a pipe with a diameter of 100mm, 63mm, or 35mm, and the detection cross-section of detection area A is ≥1mm×1mm.

[0037] The narrowband filter 8 is located inside the vacuum chamber 7, in front of the photosensitive surface of the photodiode 9 (close to the photosensitive surface). It is fixed on the bracket of the photodiode 9 and only allows near-infrared light of 808nm±30nm to pass through, while completely blocking visible light of 400-760nm and other stray wavelengths. Even if a small amount of external visible light enters the vacuum chamber 7 through the sealed gap, it will be filtered out, further eliminating optical noise.

[0038] The photodiode 9 is located inside the vacuum chamber 7, at a 90°±2° angle to the detection area A. It is fixed to the inner wall of the vacuum chamber 7 by a bracket, with its photosensitive surface facing the detection area A and a narrow-band filter 8 attached directly in front of it. The signal processing unit of the photodiode 9 performs the following actions: acquiring the peak value of the voltage pulse; when the peak value exceeds the threshold voltage V...th (V) th When the value is 3 × background noise σ, it is determined to be a valid particle signal; according to the calibration formula d = k(Vp - V), it is determined to be a valid particle signal. th The particle size is calculated (d is the particle size, Vp is the peak voltage, and k is the calibration coefficient). The signal output terminal of photodiode 9 is connected to the internal interface of BNC vacuum flange 11 through a shielded wire. It is used to receive the laser scattering signal generated when particles pass through detection area A (scattering signals of particles 5μm and below can be captured), replacing the traditional vacuum external photomultiplier tube (PMT). Its effective detection area is 10mm×10mm, it does not require high-voltage power supply, and its cost is only 1 / 5 of that of PMT. Moreover, because it detects at close range in a vacuum (without needing to pass through a vacuum window), the signal strength is improved.

[0039] The tail laser absorber 10 is located inside the vacuum chamber 7, downstream of the detection area A (directly facing the beam expansion direction of the Powell prism 6). It is fixed on the inner wall of the vacuum chamber 7, with the absorption surface facing the emission end of the detection area A. It adopts a conical metal cavity structure, and the inner wall is coated with a black chrome coating (absorption rate ≥98%@808nm). It completely absorbs the residual laser passing through the detection area A and avoids the laser reflecting back to the detection area A to form stray signals.

[0040] Among them, the BNC vacuum flange 11 is located on the side wall of the vacuum chamber 7 (staggered from the fiber optic vacuum flange 3). Its internal interface is connected to the shielding wire of the photodiode 9, and its external interface is connected to an external signal processing unit (such as a data acquisition card or computer) through a BNC wire, leading out the photodiode signal to the processing unit. This ensures the airtightness of the vacuum chamber 7 and avoids electromagnetic interference during signal transmission.

[0041] According to this utility model, the fiber-optic direct-feed vacuum particle online detection device measures the particle level inside the vacuum chamber based on scattering. Its working process includes: vacuum unit 12 evacuates the vacuum → fiber laser 1 outputs laser → fiber is directly fed to vacuum chamber 7 → internal collimation + unidirectional beam expansion forms detection area A → particles in the chamber to be tested 13 pass through detection area A with the airflow → scattered light is captured by photodiode 9 (filter 8 filters out stray light) → signal is extracted and processed through BNC flange 11 → particle size (corresponding to peak voltage) and quantity (corresponding to the number of peaks) are obtained.

[0042] Clearly, this invention, through its direct-feed structure of fiber laser 1 → vacuum-feed fiber 2 → fiber vacuum flange 3 → vacuum-inserted fiber 4, completely replaces the traditional external beam expander optical path + vacuum window, eliminating the external optical path and avoiding vibration and reflection interference. The core components of this invention, such as the collimator 5, Powell prism 6, and photodiode 9, are all integrated within the vacuum chamber 7, enabling unidirectional beam expansion and close-range detection. Internal integration of shaping and detection simplifies the structure and improves stability. Furthermore, this invention eliminates visible light noise through the fiber laser 1 (no visible light) and narrowband filter 8 (cut-off of visible light). Further, this invention replaces the PMT with a photodiode 9, eliminating the need for internal close-range detection through the vacuum window, solving the problem of high cost in traditional devices. Moreover, PMT testing can only detect particles larger than 5μm, while this invention solves the problem of lacking detection methods for particles smaller than 5μm in a vacuum. Moreover, this invention achieves direct communication between the test chamber 13 and the detection area A through the airflow guidance of the all-metal sealed vacuum chamber 7 and the vacuum unit 12, enabling online detection without sampling and solving the problem of traditional devices being unable to perform online detection.

[0043] The above description is merely a preferred embodiment of this utility model and is not intended to limit the scope of this utility model. Various variations can be made to the above embodiments of this utility model. That is, all simple and equivalent changes and modifications made based on the claims and description of this utility model fall within the protection scope of the claims of this utility model. Any aspects not described in detail in this utility model are conventional technical content.

Claims

1. A fiber-optic direct-feed vacuum in-situ particle detection device, characterized in that, This fiber-optic direct-feed vacuum in-circuit particle detection device includes: The vacuum chamber (7) has at least two sealed interfaces on its side wall, which are used for laser feeding and detection signal output, respectively, and sealed interfaces for connecting external components are provided at its opposite ends. The laser generating and feeding component (100) includes a laser source and a transmission optical fiber. The laser source is located outside the vacuum chamber (7). One end of the transmission optical fiber is connected to the output end of the laser source, and the other end passes through a sealed interface for laser feeding on the side wall of the vacuum chamber (7) and extends into the interior of the vacuum chamber, so as to feed the laser output from the laser source directly into the interior of the vacuum chamber. A laser shaping component (200) is disposed inside the vacuum chamber (7) and downstream of the extension end of the transmission optical fiber. It is used to receive the laser transmitted by the transmission optical fiber and shape it, forming a detection area (A) for detecting particles inside the vacuum chamber (7). A particle detection and signal acquisition component (300) is disposed inside the vacuum chamber (7) and includes a filter element, a photoelectric detection element, and a residual laser absorption element. The photoelectric detection element is disposed beside the detection area (A) and is used to receive the laser scattering signal generated when particles pass through the detection area (A). The filter element is disposed between the photosensitive surface of the photoelectric detection element and the detection area (A). The signal output end of the photoelectric detection element passes through the sealed interface for signal extraction on the side wall of the vacuum chamber (7) via a signal transmission component and extends to the outside of the vacuum chamber (7). The residual laser absorption element is disposed downstream of the detection area (A) and is used to absorb the residual laser passing through the detection area (A). The vacuum unit (12) and the test chamber (13) are respectively sealed to the sealing interfaces at opposite ends of the vacuum chamber (7). The test chamber (13) is the source channel for the particles to be detected. The vacuum unit (12) is used to provide a vacuum environment for the vacuum chamber (7) and the test chamber (13) and guide the particles to be detected in the test chamber (13) to enter the detection area (A) of the vacuum chamber (7) with the airflow.

2. The fiber-optic direct-feed vacuum in-situ particle detection device according to claim 1, characterized in that, The sealing interface for laser feed on the side wall of the vacuum chamber (7) is a fiber optic vacuum flange (3), and the sealing interface for signal output is a BNC vacuum flange (11). The sealing interfaces for connection at the upper and lower ends of the vacuum chamber (7) are both CF35 standard flanges.

3. The fiber-optic direct-feed vacuum in-situ particle detection device according to claim 1, characterized in that, The laser source is a single-mode fiber laser (1), whose output laser wavelength is 808nm±30nm and does not include visible light in the wavelength range of 400-760nm.

4. The fiber-optic direct-feed vacuum in-situ particle detection device according to claim 1, characterized in that, The transmission optical fiber includes a vacuum-feed optical fiber (2) and a vacuum-in-place optical fiber (4). The vacuum-feed optical fiber (2) is located outside the vacuum chamber, with one end connected to the laser source and the other end sealed to the sealing interface for laser feeding on the side wall of the vacuum chamber (7). The vacuum-in-place optical fiber (4) is located inside the vacuum chamber, with one end connected to the sealing interface for laser feeding on the side wall of the vacuum chamber (7) and the other end extending upstream of the laser shaping component.

5. The fiber-optic direct-feed vacuum in-situ particle detection device according to claim 1, characterized in that, The laser shaping component includes a collimator (5), whose input end is coaxially fixed with the extension end of the transmission fiber, and is used to collimate the diverging laser output from the transmission fiber into parallel light.

6. The fiber-optic direct-feed vacuum in-situ particle detection device according to claim 5, characterized in that, The laser shaping component also includes a Powell prism (6), which is coaxially arranged with the output end of the collimator (5) to expand the parallel light in a single direction perpendicular to the airflow to form a rectangular detection area (A).

7. The fiber-optic direct-feed vacuum in-situ particle detection device according to claim 1, characterized in that, The filter element is a narrowband filter (8), which allows light in the wavelength range of 808nm±30nm to pass through and has a cutoff rate of ≥99% for visible light in the wavelength range of 400-760nm.

8. The fiber-optic direct-feed vacuum in-situ particle detection device according to claim 1, characterized in that, The photoelectric detection element is a photodiode (9), which is positioned at 90°±2° in the detection area (A) to capture laser scattering signals generated by particles of 5μm and below.

9. The fiber-optic direct-feed vacuum in-situ particle detection device according to claim 1, characterized in that, The signal transmission device is a shielded wire. One end of the shielded wire is connected to the signal output terminal of the photodiode (9), and the other end extends through the sealed interface on the side wall of the vacuum chamber (7) for signal detection to the outside of the vacuum chamber (7) and docks with the external signal processing unit.

10. The fiber-optic direct-feed vacuum particle online detection device according to claim 1, characterized in that, The residual laser absorption element is a tail laser absorber (10), which is a conical metal cavity with the absorption surface facing the output end of the detection area (A), and its inner wall is coated with a black chrome coating.

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