We report on experimental results and theoretical investigation on probing the structure of turbid medium using ultra low
coherence enhanced backscattering spectroscopy where the spatial coherence length of the incident line light is not greater
than 25 μm. The periodic structure contained in the low coherence enhanced backscattering spectroscopy is found to
decrease with the dominant scatterer size. A theoretical model is proposed to explain the observations and is verified by
Monte Carlo simulations.
The supercontinuum spectrum generated by femtosecond Ti:Sapphire laser in photonic crystal fiber (PCF) can be
increased into the UV by using small core diameter PCF with zero dispersion wavelength (ZDW) shorter 600nm. SC is
generated in the region 350 to 1200nm with modulation less than 10 dB and with maximum spectral intensity near 350-
450nm. It is further shown that spectral intensity in the UV spectral region can be increased by employing dualwavelength
pumping using the second harmonic of Ti:Sapphire laser beam as a second pumping wavelength.
The spectrum of the supercontinuum generated by a femtosecond Ti:Sapphire laser beam in photonic crystal fiber (PCF)
is increased into the UV using small core diameter PCF with zero dispersion wavelength (ZDW) shorter 600 nm. A flat
spectrum is generated that spans from 350 to 1000 nm. The SC was used as an excitation source for fluorescence
spectroscopy. Fluorescence spectra can be detected from dye molecules, and native molecules in tissues samples with
excitation from wavelengths extracted from ultrafast SC light in the spectral range between 350 to 500 nm using narrow
bandpass filters. A Streak Camera was used for time-resolved fluorescence measurements.
Recently microendoscopes are being developed as a tool to detection cancer or pre-cancerous lesions in the milk ducts of the human breast. The microendoscope can be inserted into the duct through the nipple. Integration of fluorescence spectroscopy into microendoscopy can provide an improved platform for real-time cancer detection followed by immediate intervention. Typically, the optical fibers employed by existing microendoscope systems transmit in the 450
to 900 nm range. A prototype system combining fluorescence spectroscopy with visible imaging by microendoscopy is described and preliminary measurements on ex vivo human breast tissues are presented. Image resolution and distortion are discussed.