Coherent Raman scanning fiber endoscopy.

Coherent Raman scattering methods allow for label-free imaging of tissue with chemical contrast and high spatial and temporal resolution. However, their imaging depth in scattering tissue is limited to less than 1 mm, requiring the development of endoscopes to obtain images deep inside the body. Here, we describe a coherent Raman endoscope that provides stimulated Raman scattering images at seven frames per second using a miniaturized fiber scanner, a custom-designed objective lens, and an optimized scheme for collection of scattered light from the tissue. We characterize the system and demonstrate chemical selectivity in mouse tissue images.