06 September 2022
Researchers demonstrate chemically sensitive lidar method
New method could be used for chemical mapping and quality control
Rochester—Researchers have developed a new laser-based technique that can simultaneously perform lidar and remote chemical measurements. Lidar, which stands for light detection and ranging, uses a laser to measure distances, or ranges. Adding chemical information to lidar measurements could be useful for applications like remote chemical mapping, detecting trace amounts of chemicals, monitoring industrial processes and quality control.
“By mapping and identifying the composition of the environment, we can augment human interactions and industrial processes of the future with multi-dimensional object information beyond just ranging and detection,” detailed Bibek R. Samanta, technical staff at Nokia Bell Labs.
Samanta from Nokia Bell Labs will present the research at the Frontiers in Optics + Laser Science Conference (FiO LS) meeting being held in Rochester, New York and online 17 – 20 October 2022. Samanta’s presentation is scheduled for Monday, 17 October 2022 October at 12:00 EDT (UTC – 04:00).
Combining methods
The new technique, which combines photothermal spectroscopy and lidar, resolves chemical information by detecting sub-nanometer surface deformations due to photothermal absorption of a pump laser. These photothermal effects are caused by intensity modulations of the pump beam.
The researchers used a swept-source laser as a probe beam to perform a lidar scan in a frequency-modulated continuous wave configuration. The pump beam was a wavelength-stabilized infrared laser diode laser modulated using a chopper wheel. Both beams were collimated, combined and focused on the same spot about 8 centimeters away. For this setup, the researchers estimated an axial resolution of about 150 microns in air and an imaging depth of about 30 centimeters.
The investigators tested their new approach by using a 3D printed transparent plastic block with 500-micron deep channels containing epoxy resin mixed with either a green acrylic color or a near-infrared (NIR) absorbing dye. They were able to observe surface displacements of 0.2 to 0.3 nm that resulted from photothermal absorption of the epoxy containing the NIR dye. This agreed with estimated values and was about an order of magnitude greater than the system’s baseline noise.
By scanning the sample laterally, the researchers created a chemically sensitive lidar scan that showed the location of the NIR dye but not the green acrylic resin. Although an infrared laser was used in this demonstration, other wavelengths could be used to identify other materials.
“Using tunable laser systems and a fast-scanning integrated optical assembly, we plan on implementing spectroscopic identification of common household materials to create a 5D map of the environment,” Samanta further explains.
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About Frontiers in Optics + Laser Science
Frontiers in Optics, the annual meeting for Optica (formerly OSA) is presented with Laser Science, the annual meeting of the American Physical Society, Division of Laser Science. The two meetings unite communities from both societies for comprehensive and current research in a diverse collection of optics and photonics topics and across the disciplines of physics, biology and chemistry. The 2023 FiO LS Conference will be held as an in-person event featuring hundreds of live contributed and invited talks with additional on-demand content available for online viewing. Media registration is free with credential. Digital assets are available as requested.
About Optica
Optica (formerly OSA), Advancing Optics and Photonics Worldwide, is the society dedicated to promoting the generation, application, archiving and dissemination of knowledge in the field. Founded in 1916, it is the leading organization for scientists, engineers, business professionals, students and others interested in the science of light. Optica’s renowned publications, meetings, online resources and in-person activities fuel discoveries, shape real-life applications and accelerate scientific, technical and educational achievement. Discover more at: Optica.org
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