title: Efficient rejection of scattered light enables deep optical sectioning in turbid media with low-numerical-aperture optics in a dual-axis confocal architecture.
abstract: Miniature endoscopic microscopes, with subcellular imaging capabilities, will enable in vivo detection of molecularly-targeted fluorescent probes for early disease detection. To optimize a dual-axis confocal microscope (DACM) design for this purpose, we use a tabletop instrument to determine the ability of this technology to perform optical sectioning deep within tissue. First, we determine how tissue scattering deteriorates the diffraction-limited transverse and vertical responses in reflectance imaging. Specifically, the vertical response of a DACM to a plane reflector is measured at various depths in a scattering phantom and compared with diffraction theory and Monte Carlo scattering simulations. Similarly, transverse line scans across a knife-edge target are performed at various depths in a scattering phantom. Second, as a practical demonstration of deep-tissue fluorescence microscopy that corroborates the findings from our scattering experiments, 3-D fluorescence images are obtained in thick human gastrointestinal mucosal specimens. Our results demonstrate efficient rejection of scattered light in a DACM, which enables deep optical sectioning in tissue with subcellular resolution that can distinguish between normal and premalignant pathologies.
authors.affiliation: Stanford University, Department of Electrical Engineering, Ginzton Laboratory, and School of Medicine, James H. Clark Center for Biomedical Engineering and Science, Stanford, California 94305, USA. jonliu@stanfordalumni.org
authors.forename: Jonathan T C
authors.initials: JT
authors.lastname: Liu
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Mandella
authors.forename: James M
authors.initials: JM
authors.lastname: Crawford
authors.forename: Christopher H
authors.initials: CH
authors.lastname: Contag
authors.forename: Thomas D
authors.initials: TD
authors.lastname: Wang
authors.forename: Gordon S
authors.initials: GS
authors.lastname: Kino
mesh_terms: D005753:Gastric Mucosa / Q000166:cytology*; D006801:Humans; D007089:Image Enhancement / Q000295:instrumentation*; D066298:In Vitro Techniques; D007413:Intestinal Mucosa / Q000166:cytology*; D018613:Microscopy, Confocal / Q000295:instrumentation*; D008856:Microscopy, Fluorescence / Q000295:instrumentation*; D009391:Nephelometry and Turbidimetry / Q000295:instrumentation*; D055095:Optics and Photonics / Q000295:instrumentation*; D019047:Phantoms, Imaging