Microball lens integrated fiber probe for optical frequency domain imaging

An integrated microball lens fiber catheter probe is demonstrated, which has better lateral resolution and longer working distance than a corresponding bare fiber probe with diverging beam for Fourier domain optical coherence tomography （FDOCT）. Simulation results are shown to gain the effect of the distance between the mieroball lens and the bare fiber to the focusing plane and beam width. The freedom of modifying the working distance and lateral resolution is shown. This is achieved by changing the gap distance between the single-mode fiber and the microball lens within the packaged surgical needle catheter without using an additional beam expander having a fixed length. The probe successfully acquired crosssectional images of ocular tissues from an animal sample with the proposed miniaturized imaging probe.

A NOVEL SWEPT LASER SOURCE BASED ON COMBINED TUNABLE FILTERS FOR OCT

A novel broad tunable bandwidth and narrow instantaneous line-width linear swept laser source using combined tunable filters working at 1,300 nm center wavelength is proposed.The combined filters consist of a fiber Fabry
Perot tunable filter and a tunable filter based on diffractive grating with scanning polygon mirror.In contrast to traditional method using single tunable filter,the trade-off between bandwidth and instantaneous line-width is alleviated.Parallel implementation of two semiconductor optical amplifiers with different wavelength range is adopted in the laser resonator for broadband light amplification.The Fourier domain mode locking swept laser source with combined tunable filters offers broadband tunable range with narrow instantaneous line-width,which is especially benefiting for high-quality optical frequency domain imaging.The proposed Fourier domain mode locking swept laser source provides a tuning range of 160 nm with instantaneous line-width of about 0.01nm at sweeping rate of 15 kHz,a finesse of 16,000 is thus achieved.

Three-dimensional quantication of protoporphyrin IX in photodynamic therapy using SFDI/DFT:A pilot experimental validation

Photodynamic therapy(PDT)dosimetry,induding light dose,photosensitizer dose and tissue oxygen,has been a research focus in PDT.In this work,we present a three-dimensional(3D)quantification of protoporphyrin X(PpIX)using combined spatial frequency domain imaging(SFDI)and diffuse fuorescence tomography(DFT).The SFDI maps both the distributions of tissue absorption and scattering properties at three wavelengths and accordingly provides the optical background for DFT and extracts the tissue oxygenation for assessing the therapeutic outcomes,while DFT dynamically monitors the 3D distribution of PpEX dose from measured fluorescence signals for the procedure optimization.A pilot in vrivo application in tumor nude models showed that the proposed SFDI/DFT is able to dynamically trace changes in the PpX concentration and tissue oaxygen during the treatment,rendering it a potentially powerful tool for PDT to improve clinical eficacy.