Systems and methods for measuring light beam scattering
Inventors
Bak, Junhwi • Wu, Yue • Miles, Richard Bryant • Limbach, Christopher M.
Assignees
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Publication Number
US-12504372-B2
Publication Date
2025-12-23
Expiration Date
Abstract
A system for measurement of light scattering from a test article includes a light emitting device, configured to emit a light beam onto the test article along light axis, a collection assembly configured to collect scattered light from the test article along a measurement axis that is oriented at a non-zero angle from the light axis, wherein the collection assembly includes a first angular spectral filter, and a second angular spectral filter spaced from the first angular spectral filter along the measurement axis, wherein a position or orientation of at least one of the first angular spectral filter and the second angular spectral is adjustable relative to the measurement axis.
Core Innovation
The disclosed subject matter relates to laser light-scattering diagnostic systems for a test article in which scattered light is collected along a measurement axis oriented at a non-zero angle from a light axis. The collection assembly includes one or more angular spectral filters arranged along the measurement axis and positioned to form spectral transmissions at an image plane, with rejection and/or transmission features in an image-plane ring geometry that carries spectral information characteristic of the gaseous medium.
The system uses off-axis measurement combined with angular spectral filters implemented as volume Bragg gratings (VBGs) and/or notch filters. One or more VBGs are adjustable in position and/or orientation relative to the measurement axis, including adjustable pitch and/or yaw, and optionally rotation about the measurement axis, to form tunable rejection rings and ring overlap at the image plane.
In the described architectures, multiple angular spectral filters are spaced along the measurement axis so that separate rings form at the image plane with an offset relationship. Adjustable orientation of the first and second VBGs relative to the measurement axis enables tuning of the spatial relationship between the rings, including tangential ring geometry and mutual transmission regions, for spatially resolved measurements along a laser line and an extended 1D measurement region.
Claims Coverage
The document includes three independent claims that collectively focus on off-axis light-scattering measurement, ring-forming angular spectral filtering using VBGs, and adjustable orientation of one or more VBG angular spectral filters relative to the measurement axis. The inventive features center on non-zero-angle measurement geometry, image-plane ring spectral transmissions from VBGs, and filter adjusters that rotate VBGs to tune the ring geometry relative to the measurement axis.
Off-axis light axis and non-zero angle measurement axis geometry
A collection assembly is configured to collect scattered light along a measurement axis oriented at a non-zero angle from the light axis, where the light beam is emitted along the light axis into the gaseous medium from which light is scattered containing spectral information characteristic of the gaseous medium.
Ring-forming first and second angular spectral filters using VBGs
The collection assembly comprises a first angular spectral filter comprising a first volume Bragg grating (VBG) to produce a first spectral transmission forming a first ring at an image plane, and a second angular spectral filter spaced from the first angular spectral filter along the measurement axis and comprising a second VBG to produce a second spectral transmission forming a second ring at the image plane offset from the first ring.
Adjustable orientation of at least one VBG relative to the measurement axis
A position or orientation of at least one of the first VBG and the second VBG is adjustable relative to the measurement axis.
First angular spectral filter ring with a first filter adjuster for pitch/yaw
A first angular spectral filter positioned along the measurement axis comprises a first volume Bragg grating (VBG) to produce a first spectral transmission forming a first ring at an image plane, and a first filter adjuster coupled to the first angular spectral filter rotates the first angular spectral filter to adjust at least one of a pitch angle and a yaw angle of the first VBG relative to the measurement axis.
Method using emission, VBG ring formation, collection, and rotating filter adjuster
The method comprises emitting a light beam along a light axis from a light emitting device into the gaseous medium along a measurement axis that is at a non-zero angle to the light axis, passing scattered light through a first volume Bragg grating (VBG) of a first angular spectral filter positioned along the measurement axis to produce a first spectral transmission forming a first ring at an image plane, collecting the first spectral transmission by a collection assembly to capture the first ring at the image plane, and rotating by a first filter adjuster the first angular spectral filter to adjust at least one of a pitch angle and a yaw angle of the first VBG relative to the measurement axis.
Across the independent claims, the coverage centers on off-axis collection geometry using an image-plane ring-forming angular spectral filter based on VBGs, and on adjustable rotation of one or more VBGs via filter adjusters to tune the spectral ring relationship at the image plane.
Stated Advantages
Documented Applications
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