Large-volume, low-cost, high-precision FMCW tomography using stitched DFBs.

Area of Science:

• Optics and Photonics
• Metrology
• Imaging Systems

Background:

• Optical frequency-modulated continuous-wave (FMCW) reflectometry offers long-range, high-resolution distance measurements.
• Swept-source optical coherence tomography (SS-OCT) provides high-resolution depth imaging at high scan speeds over shorter distances.
• Existing technologies present trade-offs between range, resolution, speed, and cost.

Purpose of the Study:

• To develop a low-cost, low-bandwidth 3D imaging system.
• To achieve high axial resolution imaging over extended FMCW ranging depths.
• To enable long-distance, high-resolution surface interrogation in a compact package.

Main Methods:

• Integration of 12 distributed feedback laser (DFB) elements from a single butterfly module.
• Implementation of active sweep linearization to reduce signal processing.
• Combination of FMCW reflectometry principles with SS-OCT imaging capabilities.

Main Results:

• Achieved an axial resolution of 27.1 μm.
• Demonstrated imaging over a depth of 6 meters and a volume of up to 14 cubic meters.
• Successfully generated sub-surface OCT-style tomograms and 3D maps of various objects.

Conclusions:

• The developed system bridges the gap between FMCW reflectometry and SS-OCT.
• It offers a unique combination of long-range, high-resolution 3D imaging at a low cost.
• Potential applications include non-destructive testing, metrology, and remote sensing.