Optical distortion evaluation of an aerodynamically heated window using the interfacial fluid thickness concept

Area of Science:

• Optics and Photonics
• Aerodynamics
• Materials Science

Background:

• Aerodynamically heated windows experience significant refractive index gradients.
• Accurate optical distortion evaluation is crucial for their performance.
• Existing methods may require extensive refractive index data.

Purpose of the Study:

• To develop a method for reconstructing the refractive index field of heated windows.
• To evaluate the optical distortion of reconstructed refractive index fields.
• To assess the efficiency of the proposed method in reducing required data.

Main Methods:

• Utilized the interfacial fluid thickness (IFT) concept.
• Developed a harmonic-mean refractive index gradient magnitude threshold.
• Reconstructed the refractive index field using retrieved high-gradient regions.
• Performed numerical 3D optical distortion evaluation using ray-tracing and a recursive algorithm.

Main Results:

• The IFT-based methodology successfully retrieved high refractive index gradient regions.
• Reconstructed refractive index fields allowed for optical distortion evaluation.
• Wave aberration results indicated reduced refractive index information requirements.
• The method accurately captured essential optical distortion characteristics.

Conclusions:

• The IFT concept provides an effective threshold for identifying critical refractive index gradients.
• The developed method simplifies the process of optical distortion evaluation for heated windows.
• This approach offers a computationally efficient way to assess optical performance.