Polarization effect on the depth resolution of optical coherence tomography

Area of Science:

• Optical Engineering
• Biomedical Imaging
• Physics

Background:

• Optical Coherence Tomography (OCT) is a vital non-invasive imaging technique.
• Depth resolution in OCT is crucial for detailed biological tissue imaging.
• The polarization state of light in OCT systems can be affected by system components and samples.

Purpose of the Study:

• To investigate the effect of polarization mismatch between sample and reference arms in fiber-based OCT.
• To determine the impact of light source polarization on OCT depth resolution.
• To establish methods for optimizing depth resolution in OCT imaging.

Main Methods:

• Experimental setup of a fiber-based OCT system.
• Systematic variation of polarization states in the sample and reference arms.
• Measurement and analysis of the Point Spread Function (PSF) and depth resolution.
• Evaluation of the effect of the Degree of Polarization (DOP) of the light source.

Main Results:

• Polarization mismatch significantly degrades OCT depth resolution when the light source is partially polarized (DOP<1).
• Matched polarization states yield depth resolution close to theoretical predictions.
• When the light source is fully polarized (DOP=1), depth resolution becomes independent of polarization mismatch.

Conclusions:

• Controlling polarization is critical for achieving high-resolution OCT imaging, especially with partially polarized light sources.
• Achieving a Degree of Polarization (DOP) of 1 ensures uniform depth resolution throughout the sample.
• This finding is fundamental for advancing OCT applications in biological tissue analysis.