Distal-scanning common path probe for optical coherence tomography

In this paper,we present a distal-scanning common path probe for optical coherence tomography(OCT)equipped with a hollow ultrasonic motor and a simple and specially designed beam-splitter.This novel probe proves to be able to effectively circumvent polarization and dispersion mismatch caused by fiber motion and is more robust to a variety of interfering factors during the imaging process,experimentally compared to a conventional noncommon path probe.Furthermore,our design counteracts the attenuation of backscattering with depth and the fall-off of the signal,resulting in a more balanced signal range and greater imaging depth.Spectral-domain OCT imaging of phantom and biological tissue is also demonstrated with a sensitivity of∼100dB and a lateral resolution of∼3μm.This low-cost probe offers simplified system configuration and excellent robustness,and is therefore particularly suitable for clinical diagnosis as one-off medical apparatus.

RAMAN SPECTROSCOPY FOR IN VIVO TISSUE ANALYSIS AND DIAGNOSIS,FROM INSTRUMENT DEVELOPMENT TO CLINICAL APPLICATIONS

Raman spectroscopy is a noninvasive,nondestructive analytical method capable of determining the biochemical constituents based on molecular vibrations.It does not require sample preparation or pretreatment.However,the use of Raman spectroscopy for in vivo clinical applications will depend on the feasibility of measuring Raman spectra in a relatively short time period(a few seconds).In this work,a fast dispersive-type nearinfrared(NIR)Raman spectroscopy system and a skin Raman probe were developed to facilitate real-time,noninvasive,in vivo human skin measurements.Spectrograph image aberration was corrected by a parabolic-line fiber array,permitting complete CCD vertical binning,thereby yielding a 16-fold improvement in signal-to-noise ratio.Good quality in vivo skin NIR Raman spectra free of interference from fiber fluorescence and silica Raman scattering can be acquired within one second,which greatly facilitates practical noninvasive tissue characterization and clinical diagnosis.Currently,we are conducting a large clinical study of various skin diseases in order to develop Raman spectroscopy into a useful tool for non-invasive skin cancer detection.Intermediate data analysis results are presented.Recently,we have also successfully developed a technically more challenging endoscopic Laser-Raman probe for early lung cancer detection.Preliminary in vivo results from endoscopic lung Raman measurements are discussed.