Interferometric velocity measurements through a fluctuating gas-liquid interface employing adaptive optics

Area of Science:

• Optical Physics
• Fluid Dynamics
• Metrology

Background:

• Optical transmission is hindered by distortions at fluctuating interfaces between media with different refractive indexes.
• Temporal fluctuations in these distortions degrade the accuracy of optical measurements, posing challenges for flow velocity determination.

Purpose of the Study:

• To introduce an adaptive optics-enhanced interferometric technique for precise flow velocity measurements.
• To address the limitations of optical measurements in dynamic and complex environments with fluctuating interfaces.

Main Methods:

• Implementation of a low-order adaptive optics system utilizing a fast deformable mirror.
• Integration of a high frame-rate Hartmann-Shack camera for distortion correction.
• Development of an interferometric velocity measurement technique embedded with adaptive optics.

Main Results:

• Demonstrated the first application of adaptive optics in an interferometric velocity measurement for air-water interfaces.
• Achieved precise flow velocity measurements despite fast fluctuations at the media interface.
• Attained a high control bandwidth for effective real-time distortion correction.

Conclusions:

• Adaptive optics significantly enhance the capability of optical flow measurements through fluctuating interfaces.
• This methodology offers a robust solution for optical metrology in challenging, dynamic environments.
• The technique has broad applicability for various optical flow measurements in complex settings.