We report the numerical analysis of gradient index (GRIN) lens-based optical coherence tomography imaging probes to derive optimal design parameters. Long and short working distance probes with a small focal spot are considered. In each model, the working distance and beam waist are characterized and compared for different values of length and refractive index of the probe components. We also explore the influence of the outer tubing and refractive index of the sample media. Numerical results show that the adjustment of the maximum beam diameter and focusing angle at the end of the GRIN lens surface is very important for determining the optical performance parameters of the probe.
We validate a molecular imaging technique called Nonlinear Interferometric Vibrational Imaging (NIVI)
by comparing vibrational spectra with those acquired from Raman microscopy. This broadband coherent
anti-Stokes Raman scattering (CARS) technique uses heterodyne detection and OCT acquisition and design
principles to interfere a CARS signal generated by a sample with a local oscillator signal generated
separately by a four-wave mixing process. These are mixed and demodulated by spectral interferometry. Its
confocal configuration allows the acquisition of 3D images based on endogenous molecular signatures.
Images from both phantom and mammary tissues have been acquired by this instrument and its spectrum is
compared with its spontaneous Raman signatures.