Methods and devices for standoff differential Raman spectroscopy with increased eye safety and decreased risk of explosion
Inventors
Vakhshoori, Daryoosh • Blanchard, Romain • Chen, Peili • Azimi, Masud • Mansuripur, Tobias • Krishnamurthy, Kalyani • Bibby, Arran M. • Huettig, III, Fred R. • Ulu, Gokhan • Vander Rhodes, Greg
Assignees
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Publication Number
US-11885681-B2
Publication Date
2024-01-30
Expiration Date
Abstract
A compact, portable Raman spectrometer makes fast, sensitive standoff measurements at little to no risk of eye injury or igniting the materials being probed. This spectrometer uses differential Raman spectroscopy and ambient light measurements to measure point-and-shoot Raman signatures of dark or highly fluorescent materials at distances of 1 cm to 10 m or more. It scans the Raman pump beam(s) across the sample to reduce the risk of unduly heating or igniting the sample. Beam scanning also transforms the spectrometer into an instrument with a lower effective safety classification, reducing the risk of eye injury. The spectrometer's long standoff range automatic focusing make it easier to identify chemicals through clear and translucent obstacles, such as flow tubes, windows, and containers. And the spectrometer's components are light and small enough to be packaged in a handheld housing or housing suitable for a small robot to carry.
Core Innovation
The patent describes Raman spectroscopy in which a telescope illuminates a sample with ranging beams to form a first spot and a second spot. A distance between the first spot and the second spot is detected, and a focus of the telescope is adjusted based on the distance. After the focus adjustment, the sample is illuminated with a Raman pump beam propagating along the optical axis of the telescope and a Raman signal scattered by the sample is measured.
The patent also describes Raman spectroscopy in which a camera acquires an image of a scene. A processor identifies a target in the scene based on the image, and a laser emits a Raman pump beam that is directed to the target by a beam-steering element. A detector detects a Raman signal scattered by the target in response to the Raman pump beam, while electronics determine an angular deviation in an aim point of the Raman pump beam based on the image of the scene and control the beam-steering element to compensate for the angular deviation.
Further, the patent describes a method in which an image of a scene is acquired and a target is identified based on the image. An angular deviation in an aim point of the Raman pump beam is determined based on the image of the scene, and the aim point is automatically adjusted to compensate the angular deviation. The target is then illuminated with the Raman pump beam and the Raman signal scattered by the target is detected in response to the Raman pump beam.
Claims Coverage
The partial content includes three independent claims (clm-00001, clm-00005, clm-00015). Across these claims, the coverage centers on distance-based focus adjustment using telescope ranging spots for Raman spectroscopy, and camera-based target identification with angular deviation determination and beam-steering compensation to measure Raman signals.
Telescope-based ranging spots for focus adjustment
Illuminating the sample, via a telescope, with a first ranging beam propagating along an optical axis of the telescope to form a first spot on the sample; illuminating the sample, via the telescope, with a second ranging beam propagating along a marginal ray of the telescope to form a second spot on the sample; detecting a distance between the first spot and the second spot; adjusting a focus of the telescope based on the distance between the first spot and the second spot; illuminating the sample, via the telescope, with a Raman pump beam propagating along the optical axis of the telescope; and measuring a Raman signal scattered by the sample in response to the Raman pump beam.
Camera-guided target identification with aim compensation
A Raman spectroscopy system comprising a camera to acquire an image of a scene; a processor, operably coupled to the camera, to identify a target in the scene based on the image of the scene; a laser to emit a Raman pump beam; a beam-steering element, in optical communication with the laser and the target, to illuminate the target with the Raman pump beam; a detector, in optical communication with the target, to detect a Raman signal scattered by the target in response to the Raman pump beam; and electronics, operably coupled to the camera and the beam-steering element, to determine an angular deviation in an aim point of the Raman pump beam based on the image of the scene and to control the beam-steering element to compensate the angular deviation.
Automatic Raman pump aim adjustment based on scene-image angular deviation
Acquiring an image of a scene; identifying a target in the scene based on the image of the scene; determining an angular deviation in an aim point of a Raman pump beam based on the image of the scene; automatically adjusting the aim point of the Raman pump beam to compensate the angular deviation; illuminating the target with a Raman pump beam; and detecting a Raman signal scattered by the target in response to the Raman pump beam.
Overall, the claim coverage relates Raman spectroscopy methods and systems that integrate telescope or camera-based ranging or scene imaging with adjustments to focus or aim, so that Raman pump illumination is properly directed and Raman signals scattered by the target or sample can be measured.
Stated Advantages
Not explicitly described in patent.
Documented Applications
Not explicitly described in patent.
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