A miniature fiber optic endomicroscope with built-in dynamic focus scanning capability is developed for the first time for 3-D two-photon fluorescence (TPF) imaging of biological samples. Fast2-D lateral beam scanning is realized by resonantly vibrating a double-clad fiber cantilever with a tubular piezoactuator. Slow axial scanning is achieved by moving the distal end of the imaging probe with an extremely compact electrically driven shape memory alloy (SMA). The 10-mm-long SMA allows 150-μm contractions with a driving voltage varying only from 50 to 100 mV. The response of the SMA contraction with the applied voltage is nonlinear, but repeatable and can be accurately calibrated. Depth-resolved imaging of acriflavine-stained biological tissues and unstained white paper with the endomicroscope is performed, and the results demonstrate the feasibility of 3-D nonlinear optical imaging with the SMA-based scanning fiber-optic endomicroscope.
- Focus scanning
- Shape memory alloy
- Two-photon fluorescence
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Atomic and Molecular Physics, and Optics
- Biomedical Engineering