In JoVE (1)
Articles by Florian Knorr in JoVE
Rejection of Fluorescence Background in Resonance and Spontaneous Raman Microspectroscopy Zachary J. Smith*1, Florian Knorr*1, Cynthia V. Pagba1, Sebastian Wachsmann-Hogiu1,2 1Center for Biophotonics Science and Technology, University of California, Davis, 2Department of Pathology and Laboratory Medicine, University of California, Davis We discuss the construction and operation of a complex nonlinear optical system that uses ultrafast all-optical switching to isolate Raman from fluorescence signals. Using this system we are able to successfully separate Raman and fluorescence signals utilizing pulse energies and average powers that remain biologically safe.
Other articles by Florian Knorr on PubMed
Development of a Time-gated System for Raman Spectroscopy of Biological Samples Optics Express. Sep, 2010 | Pubmed ID: 20940895 A time gating system has been constructed that is capable of recording high quality Raman spectra of highly fluorescing biological samples while operating below the photodamage threshold. Using a collinear gating geometry and careful attention to power conservation, we have achieved all-optical switching with a one picosecond gating time and 5% peak gating efficiency. The energy per pulse in this instrument is more than 3 orders of magnitude weaker than previous reports. Using this system we have performed proof-of-concept experiments on a sample composed of perylene dissolved in toluene, and the stem of a Jasminum multiflorum plant, the latter case being particularly important for the study of plants used in production of cellulosic biofuels. In both cases, a high SNR spectrum of the high-wavenumber region of the spectrum was recorded in the presence of an overwhelming fluorescence background.
Two-photon Excited Fluorescence Lifetime Measurements Through a Double-clad Photonic Crystal Fiber for Tissue Micro-endoscopy Journal of Biophotonics. Jan, 2012 | Pubmed ID: 22045513 This paper presents an endoscopic configuration for measurements of tissue autofluorescence using two-photon excitation and time-correlated single photon counting detection through a double-clad photonic crystal fiber (DC-PCF) without pre-chirping of laser pulses. The instrument performance was evaluated by measurements of fluorescent standard dyes, biological fluorophores (collagen and elastin), and tissue specimens (muscle, cartilage, tendon). Current results demonstrate the ability of this system to accurately retrieve the fluorescence decay profile and lifetime of these samples. This simple setup, which offers larger penetration depth than one-photon-based techniques, may be combined with morphology-yielding techniques such as photoacoustic and ultrasound imaging.