Achieving Precise Spectral Analysis and Imaging Simultaneously with a Mode-Resolved Dual-Comb Interferometer.

Area of Science:

• Optical Interferometry
• Spectroscopy
• Metrology

Background:

• Precise spectral analysis and surface imaging are crucial for various scientific and industrial applications.
• Existing methods often require separate measurements or lack simultaneous capabilities.
• Frequency comb interferometry offers high resolution and accuracy but requires advancements for combined functionalities.

Purpose of the Study:

• To develop and demonstrate a high-coherence dual-comb interferometer (DCI) for simultaneous spectral analysis and surface imaging.
• To achieve precise gas absorption spectroscopy and absolute distance measurements in a single setup.
• To evaluate the performance of the DCI for non-contact surface imaging and its potential in remote sensing applications.

Main Methods:

• Utilized two tightly phase-locking frequency combs to construct a high-coherence DCI operating from 188 to 195 THz.
• Integrated a reference arm for simultaneous gas absorption spectroscopy and absolute distance determination via time-of-flight (TOF).
• Employed 2D mechanical scanning for non-contact surface imaging and evaluated measurement precision and time.

Main Results:

• Achieved a spectral signal-to-noise ratio (SNR) of 159.7 with comb-tooth resolution.
• Demonstrated gas absorption spectroscopy of CO2 and CO.
• Obtained distance measurements with an RMS precision of 0.53 μm (1s averaging) and surface imaging with 40 μm lateral resolution (0.5s measurement).

Conclusions:

• The developed high-coherence DCI successfully enables simultaneous spectral analysis and surface imaging.
• The system offers high precision in both spectroscopy and distance measurements, suitable for various applications.
• The DCI shows significant potential for standoff detection, environmental monitoring, and remote sensing.