Comb-calibrated laser ranging for three-dimensional surface profiling with micrometer-level precision at a distance.

Area of Science:

• Optics and Photonics
• Metrology
• Laser Technology

Background:

• Non-contact surface mapping is crucial for industrial metrology, manufacturing, forensics, and artifact preservation.
• Frequency Modulated Continuous Wave (FMCW) laser detection and ranging (LADAR) offers high precision, resolution, and sensitivity for remote sensing.

Purpose of the Study:

• To demonstrate a scanning imaging system utilizing frequency-comb calibrated FMCW LADAR for high-accuracy 3D surface mapping.
• To evaluate the system's performance in terms of accuracy, precision, and dynamic range at stand-off distances.

Main Methods:

• Development of a scanning imaging system based on frequency-comb calibrated FMCW LADAR.
• Implementation of real-time digital signal processing for data acquisition and analysis.
• Testing the system at stand-off distances up to 10.5 meters with various reflective surfaces.

Main Results:

• Achieved sub-micrometer accuracy and precision below 10 µm, limited by speckle noise.
• Demonstrated precise mapping of surfaces with diverse reflectivities (metal, dirt, vegetation) due to large dynamic range.
• Validated the system's capability for 3D imaging of diffusely scattering surfaces at extended distances.

Conclusions:

• The frequency-comb calibrated FMCW LADAR system provides highly accurate and precise non-contact 3D surface mapping.
• The system's shot-noise limited sensitivity and large dynamic range are advantageous for complex scenes.
• The fiber-optic based architecture is adaptable for future integrated, on-chip systems.