Raman spectroscopy is a rapid nondestructive technique capable of assaying chemicals in human artery tissues and characterizing atherosclerotic plaques in vivo, but clinical applications through optical fiber-based catheters have been hindered by large background signals generated within the fibers. Previous workers realized that this background was reduced significantly in the high wavenumber (HWVN) Raman region (~2400 cm−1 to ~3800 cm−1), and with proper selection of optical fibers, one could collect quality Raman spectra remotely via a single optical fiber with no additional filters or optics. This study compared lipid concentrations in coronary artery tissue that were determined with chemical assay techniques to those estimated from HWVN Raman spectra collected through a single optical fiber. The standard error of predictions between the Raman and chemical assay techniques were small for cholesterol and esterified cholesterols, at 1.2% and 2.7%, respectively.
Despite the growing number of biomedical and micromachining applications enabled by ultra-short pulse lasers in
laboratory environments, realworld applications remain scarce due to the lack of robust, affordable and flexible laser
sources with meaningful energy and average power specifications. In this presentation, we will describe a laser source
developed at the eye-safe wavelength of 1552.5 nm around a software architecture that enables complete autonomous
control of the system, fast warm-up and flexible operation. Our current desktop ultra-short pulse laser system offers
specifications (1-5 microJ at 500 kHz, 800 fs-3 ps pulse width, variable repetition rate from 1 Hz to 500 kHz) that are
meaningful for many applications ranging from medical to micromachining. We will also present an overview of
applications that benefit from the range of parameters provided by our desktop platform. Finally, we will present a novel
scalable approach for fiber delivery of high peak power pulses using a hollow core Bragg fiber recently developed for
the first time by Raydiance and the Massachusetts Institute of Technology for operation around 1550 nm. We will
demonstrate that this fiber supports single mode operation for core sizes up to 100 micron, low dispersion and low
nonlinearities with acceptable losses. This fiber is a good candidate for flexible delivery of ultra-short laser pulses in
applications such as minimally accessible surgery or remote detection.