Hayk Soghomonyan | Searcharxiv

arXiv2025

3D in-situ profiling in a laser micromachining station using dual-comb LiDAR

One of the main challenges in laser micromachining is the complexity of the process development. The available monitoring capabilities are mostly limited to external measurement systems, significantly slowing down this step. We address this limitation by integrating a coaxial dual-comb LiDAR system directly into a laser micromachining station, enabling in-situ, non-destructive 3D profiling without removing the workpiece. The sub-micron raw axial precision of the system, the operation without mechanical delay scanning and a large working range make the system well-suited for profiling a large variety of micromachined structures. By providing in-situ feedback this approach will significantly accelerate laser micromachining process development.

physics.optics↗

arXiv2024

Long-range and dead-zone free dual-comb ranging for the interferometric tracking of moving targets

Dual-comb ranging has emerged as an effective technology for long-distance metrology, providing absolute distance measurements with high speed, precision, and accuracy. Here, we demonstrate a dual-comb ranging method that utilizes a free-space transceiver unit, enabling dead-zone-free measurements and simultaneous ranging with interchanged comb roles to allow for long-distance measurements even when the target is moving. It includes a GPU-accelerated algorithm for real-time signal processing and a free-running single-cavity solid-state dual-comb laser with a carrier wavelength $λ_c \approx$ 1055 nm, a pulse repetition rate of 1 GHz and a repetition rate difference of 5.06 kHz. This combination offers a fast update rate and sufficient signal strength to reach a single-shot time-of-flight precision of around 0.1 $μ$m (i.e. $< λ_c/4$) on a cooperative target placed at a distance of more than 40 m. The free-running laser is sufficiently stable to use the phase information for interferometric distance measurements, which improves the single-shot precision to $<$20 nm. To assess the ranging accuracy, we track the motion of the cooperative target when moved over 40 m and compare it to a reference interferometer. The residuals between the two measurements are below 3 $μ$m. These results highlight the potential of this approach for accurate and dead-zone-free long-distance ranging, supporting real-time tracking with nm-level precision.

physics.optics↗