Petal-like Bessel beam based high-resolution optical ranging for hypersonic turbulence

Area of Science:

• Electromagnetics and Wave Propagation
• Aerospace Engineering
• Plasma Physics

Background:

• Hypersonic vehicles generate plasma sheath turbulence (PST) due to air friction and ionization.
• PST significantly obstructs electromagnetic wave transmission, challenging target detection.
• Conventional time-domain ranging methods are inadequate for PST environments.

Purpose of the Study:

• To develop a novel spatial-domain ranging method for target detection in PST.
• To enhance ranging accuracy and stability under severe plasma turbulence conditions.
• To introduce an angle recognition neural network (ARNN) for improved performance.

Main Methods:

• Utilized petal-like Bessel beams, generated via coherent superposition of vortex phases, for stable propagation in PST.
• Leveraged the relationship between Bessel beam rotation angle and propagation distance for high-precision ranging.
• Implemented an angle recognition neural network (ARNN) to overcome limitations of traditional correlation intensity methods.

Main Results:

• Achieved over 90% accuracy with 1 mm resolution in various plasma turbulence conditions.
• Demonstrated high prediction accuracy and strong generalization capabilities of the ARNN.
• Validated the method's effectiveness across different refractive index fluctuation variances.

Conclusions:

• The developed spatial-domain ranging method offers a viable solution for target detection in PST.
• Petal-like Bessel beams provide stable propagation and enable precise distance measurement.
• The ARNN significantly improves accuracy and robustness in complex turbulent media.