Chemically Sensitive LiDAR – New Method

Researchers have developed a new laser-based technique that can perform LiDAR and remote chemical measurements at the same time. LiDAR (light detection and ranging) uses a laser to measure distances or ranges. Chemically sensitive LiDAR measurements could be useful for remote chemical mapping, detecting trace amounts of chemicals, monitoring industrial processes, and quality control.

Researchers can augment future human interactions and industrial processes with multi-dimensional object information beyond ranging and detection by mapping and identifying the composition of the environment.

The new chemically sensitive LiDAR method combines photothermal spectroscopy and LiDAR. It resolves chemical information by detecting sub-nanometer surface deformations caused by a pump laser’s photothermal absorption. The intensity modulations of the pump beam cause these photothermal effects.

The researchers performed a LiDAR scan in a frequency-modulated continuous wave configuration using a swept-source laser as a probe beam. A wavelength-stabilized infrared diode laser modulated by a chopper wheel provided the pump beam. Both beams were collimated, combined, and focused on the same 8-centimeter-distance target. The researchers estimated an axial resolution of about 150 microns in air and an imaging depth of about 30 centimeters.

The researchers intend to use tunable laser systems and a fast-scanning integrated optical assembly to create a 5D map of the environment by implementing spectroscopic identification of common household materials.

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