Spatial coherence effect on layer thickness determination in narrowband full-field optical coherence tomography

Area of Science:

• Optical physics
• Biomedical imaging
• Metrology

Background:

• Longitudinal spatial coherence (LSC) is crucial for optical imaging resolution.
• High numerical aperture (NA) lenses in optical coherence tomography (OCT) typically reduce LSC.
• A shorter LSC than temporal coherence length is beneficial for high-resolution imaging of multilayered samples.

Purpose of the Study:

• To investigate the relationship between LSC and high-NA imaging in OCT.
• To develop a model for predicting interference signals in multilayered samples with high-NA objectives and narrowband light.
• To assess the feasibility of using low LSC for high-resolution 3D imaging.

Main Methods:

• Derivation of a simplified model for interference output signals.
• Experimental validation of the model using multilayered samples.
• Application of the method to strongly scattering media.

Main Results:

• A model was developed and experimentally verified, describing interference signals with high-NA lenses and narrowband light.
• An expression for a correction factor for layer thickness determination was derived and validated for high-NA objectives.
• The method demonstrated potential for high-resolution imaging of scattering media.

Conclusions:

• Low longitudinal spatial coherence, achieved with high-NA lenses and narrowband light, facilitates high-resolution 3D imaging.
• The developed model and correction factor enhance the accuracy of layer thickness measurements in OCT.
• This technique shows promise for imaging complex and scattering biological samples.