Reflective laser-based particle detector
Inventors
Xi, Wenze • Geng, Rongli • Zorn, Carl • Kross, Brian J. • Weisenberger, Andrew G. • McKisson, Jack • Mckisson, John
Assignees
Jefferson Science Associates LLC
Publication Number
US-11041795-B2
Publication Date
2021-06-22
Expiration Date
2039-10-18
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Abstract
A reflective laser-based particle detector for detecting contamination particles moving through a vacuum. Laser light is directed through a vacuum access window in the containment vessel and toward a reflective surface on an inner surface opposite the window. A photonic detector is positioned to monitor reflected laser from the opposite inner surface inside the vessel and is capable of detecting perturbations of the reflected light. The system makes use of optical interferometry techniques embodied as a photonic integrated circuit to detect the particles. The reflective laser-based system can be placed entirely outside the vacuum thereby avoiding the need for breaking the vacuum environment to check for accumulation of contaminant particles.
Core Innovation
The invention is a reflective laser-based particle detector designed to detect contamination particles moving through a vacuum or other enclosed volume. The detector directs laser light through a vacuum access window toward a specular reflective surface on the inner surface opposite the window. A photonic sensor monitors the reflected laser light and detects perturbations caused by particles intersecting the laser beam. The sensor uses optical interferometry techniques embodied as a photonic integrated circuit, enabling detection of minute changes in amplitude and phase of the reflected light to indicate particle presence.
The background problem addressed is contamination from micrometer-sized metallic particles inside ultra-high vacuum beam-line components of particle accelerators, specifically caused by transportation of particulates via ion pumps and other vacuum devices. These contaminants interfere with accelerator cavity performance and currently can only be observed after shutdown and disassembly, causing operational downtime. The invention solves the need to detect and monitor contamination particles remotely and in real-time without breaking the vacuum environment.
The system can be located entirely outside the vacuum, avoiding vacuum interruption. Multiple laser beams arranged in coplanar arrays can enlarge the sensing volume and permit determination of particle direction and velocity. The invention overcomes limitations of conventional vacuum particle sensors that require in-vacuum equipment and rely on scattered light detection. No installation inside the vacuum is necessary beyond existing optical windows and reflective surfaces, which may be incorporated or inherently present.
Claims Coverage
The patent includes three independent claims describing reflective laser-based particle detectors with various features and configurations. The inventive features relate to the structural components and functional sensing capabilities of the system, including single and multiple laser beam arrangements and detection of particle characteristics.
Reflective laser-based detection system components
A particle detector comprising a volume containment device with near and far walls and a sensing volume; an optical access window in the near wall; a reflective surface on the far wall inner surface opposite the window; a laser beam directed through the optical window to the reflective surface with reflected beam returning along the same path; and a photonic detector that detects perturbations in the reflected light. The system detects charged and uncharged contamination particles.
Detection of micron and sub-micron particle sizes
A reflective laser-based particle detector incorporating the features of the single beam system and specifically capable of detecting micron and sub-micron sized contamination particles within the volume.
Multiple parallel and coplanar laser beam array for particle direction and velocity detection
A particle detector having a plurality of lasers each emitting a laser beam directed through the optical access window to the reflective surface, arranged parallel and coplanar. Each laser is paired with a photonic detector that detects perturbations in its reflected beam. This arrangement enables detection of micron and sub-micron sized particles and determination of particle direction and velocity. All lasers and detectors are positioned outside the sensing volume.
The claims cover a reflective laser particle detection system with a structured vacuum containment and optical setup, capable of detecting charged and uncharged particles including micron and sub-micron sizes. The inventive features include use of a reflective surface opposite an optical window for beam reflection, photonic detectors employing interferometry, and configurations involving single or multiple parallel coplanar laser beams for enlarged sensing volume and particle motion characterization.
Stated Advantages
The system can be placed entirely outside the vacuum, thereby avoiding the need to break the vacuum environment to check for contaminant particles.
It can monitor contamination particles in real-time while the accelerator is operating, avoiding downtime.
Allows remote contaminant monitoring from outside the radiation field surrounding the accelerator.
Capable of detecting micron and sub-micron sized charged and uncharged particles moving through a vacuum.
Eliminates installation challenges related to in-vacuum sensors.
The use of multiple parallel, coplanar laser beams enlarges the sensing volume and enables determination of particle direction and velocity.
Documented Applications
Detection of contamination particles inside ultra-high vacuum beam-line components of particle accelerators.
Particle detection within vacuums in nuclear reactors.
Clean room particle analysis.
Monitoring in manufacturing processes requiring vacuum conditions, such as integrated circuit production.
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