Refractive-index measurement and inverse correction using optical coherence tomography

Area of Science:

• Biomedical Optics
• Materials Science
• Medical Imaging

Background:

• Accurate refractive index measurement is crucial for various applications, including medical imaging and materials characterization.
• Existing methods may have limitations in precision or applicability to certain sample types.

Purpose of the Study:

• To develop and validate a novel technique for precise refractive index determination using optical coherence tomography (OCT).
• To demonstrate the method's capability on both biological and technical non-opaque samples.

Main Methods:

• The study employs an inverse refractive-index correction (I-RIC) technique.
• This method corrects distorted feature geometry caused by refractive index boundaries to determine the real geometry.
• Refractive index is calculated by matching distorted and corrected images for known feature geometries.

Main Results:

• The technique successfully measured the refractive index of polymethylmethacrylate (PMMA) and ex vivo porcine cranial bone.
• Experimental results showed high precision and good agreement with reference data.
• The method proved effective for non-opaque technical samples and hard biological tissues.

Conclusions:

• The developed I-RIC OCT method offers a precise and versatile approach for refractive index determination.
• This technique holds potential for in vivo measurements of rigid biological tissues, aiding in robot-aided surgery.
• It can also be used to retrieve complex refractive index profiles of compound materials.