Three-dimensional nonlinear optical endoscopy.

The development of miniaturized nonlinear optical microscopy or endoscopy is essential to complement the current imaging modalities for diagnosis and monitoring of cancers. We report on a nonlinear optical endoscope based on a double-clad photonic crystal fiber and a two-dimensional (2-D) microelectromechanical system mirror, enabling the three-dimensional (3-D) nonlinear optical imaging through in vitro gastrointestinal tract tissue and human breast cancer tissue with a penetration depth of approximately 100 mum and axial resolution of 10 mum. The 3-D high-resolution and high-sensitive imaging ability of the nonlinear optical endoscope facilitates the visualization of 3-D morphologic and cell nuclei arrangement within tissue, and therefore will be important for histopathologic interpretation without the need of tissue excision.