title: Reduction of distortion in photothermal microscopy and its application to the high-resolution three-dimensional imaging of nonfluorescent tissues.
abstract: A scheme for reducing image distortion in photothermal microscopy is presented. In photothermal microscopy, the signal shape exhibits twin peaks corresponding to the focusing or defocusing of the probe beam when a sample is scanned in the axial direction. This causes a distortion when imaging a structured sample in the axial plane. Here, we demonstrate that image distortion caused by the twin peaks is effectively suppressed by providing a small offset between two the focal planes of the pump and the probe beams. Experimental results demonstrate improvement in resolution, especially in the axial direction, over conventional optical microscopy-even with the focal offset. When a dry objective lens with a numerical aperture of 0.95 is used, the full width at half the maximum of the axial point spread function is 0.6 μm, which is 50% (62%) smaller than the focal spot sizes of the pump (probe) beam. Herein, we present high-resolution three-dimensional imaging of thick biological tissues based on the present scheme.
authors.affiliation: Advanced Ultrafast Laser Research Center, The University of Electro-Communications, 1-5-1 Chofugaoka, Chofu, Tokyo, 182-8585, Japan ; JST, CREST, K' Gobancho, 7, Gobancho, Chiyoda-ku, Tokyo 102-0076, Japan.
authors.forename: Jun
authors.initials: J
authors.lastname: Miyazaki
authors.affiliation: Department of Pathology, Juntendo University School of Medicine, 2-1-1, Hongo, Bunkyo-ku, Tokyo 113-8421, Japan.
authors.forename: Hiromichi
authors.initials: H
authors.lastname: Tsurui
authors.affiliation: Advanced Ultrafast Laser Research Center, The University of Electro-Communications, 1-5-1 Chofugaoka, Chofu, Tokyo, 182-8585, Japan ; JST, CREST, K' Gobancho, 7, Gobancho, Chiyoda-ku, Tokyo 102-0076, Japan ; Department of Electrophysics, National Chiao-Tung University, Hsinchu 300, Taiwan ; Institute of Laser Engineering, Osaka University, 2-6 Yamada-oka, Suita, Osaka 565-0971, Japan.
authors.forename: Takayoshi
authors.initials: T
authors.lastname: Kobayashi
keywords: (170.6900) Three-dimensional microscopy; (350.5340) Photothermal effects