Use of adaptive optics to increase nonlinear imaging signal in mouse bone morrow

Abstract

In a recent effort, researchers from Wellman Center of Photomedicine use fluorescence signal provided by single- or two-photon excitation, second harmonic generation and coherent anti-Stokes Raman spectroscopy (CARS) to illustrate the cell level detail of mouse bone marrow [1]. However, the several non-linear imaging techniques suffered on a common base: signal degradation with deeper light penetration. The fluorescence signal weakening from the mouse skull is caused by the decreased excitation light intensity. With deeper imaging depth, the excitation light suffers tissue scattering, absorption and optical aberration. The last one of the causes spreads the light intensity away from its diffraction limited focal spot. In consequence, less fluorescence light is produced in the enlarged focal volume. In this paper, I will introduce Adaptive Optics (AO), a system for real time optical aberration compensation, to improve the non-linear fluorescence signal in the mouse bone marrow imaging. A parallel stochastic gradient decent algorithm based on Zernike polynomial is employed to control the deformable mirror in real time aberration compensation.