In this paper, for the first time, we consider theoretically all the potential orientations of dipoles for second harmonic generation (SHG) under crystallized type I collagen fiber. With high numerical aperture ( NA = 14), the effect of dipole orientation angle Φ on the SHG intensity, on the maximum SHG emergence angles (θ max , φ max ) and the action of these dipole sources on the ratio of forward to backward (F/B) SHG have been studied under different cases of fibrils diameter d1 and the QPM order (m, l) in the crystallized collagen fiber, and it is found that the influential patterns of the same Φ on SHG at different fibrils diameter d1 and the QPM order (m, l) are different. The dipoles arrangement is related to the characteristic changes in biological tissue so that our work may provide a helpful theoretical tool for pathological status detecting.
Second Harmonic Generation in 3-D Uniform Arrangement of Type I Collagen on Nonlinear Optics Microscopy