High resolution cellular imaging with nonlinear optical infrared microscopy.
We developed a nonlinear optical infrared microscope exploiting a thermally induced refractive index change in the mid-infrared regime and imaged a single biological cell with high spatial resolution that was not possible in conventional infrared microscopes. A refractive index change of a sample induced by infrared (~3.5 μm) absorption was probed by a visible (633 nm) laser beam. Thus the chemical specificity stems from the spectral absorbance of specimen and the spatial resolution from the short wavelength visible radiation. A reflecting objective (NA0.5) was used to focus the infrared and visible beams on the sample plane, and the sample was raster-scanned for 2-D imaging. The high resolution beyond the infrared diffraction limit was demonstrated by imaging fine grating lines made up of epoxy grooves (830 lines/mm). The probe wavelength dependence of the spatial resolution was investigated by imaging polystyrene beads. We found that the resolution was as small as 0.7 μm with 633 nm probe wavelength.
Division of Convergence Technology, Korea Research Institute of Standards and Science, Yuseong-Gu, Daejeon, South Korea.
Eun Seong
ES
Lee
Jae Yong
JY
Lee
D002478:Cells, Cultured / Q000166:cytology*; D004867:Equipment Design; D019544:Equipment Failure Analysis; D007089:Image Enhancement / Q000295:instrumentation*; D007259:Infrared Rays; D008853:Microscopy / Q000295:instrumentation*; D017711:Nonlinear Dynamics