Fig. 2.

(a) and (b) are the lateral (x-y) SHG images of the ligament illuminated by excitations in LCP and RCP, respectively. The gray bars describe the SHG intensity counted by PMT. (c) is the SHG-CD image calculated pixel-wise from (a) and (b) with ImageJ software. The green and red colors indicate the SHG-CD value with positive sign and negative sign, respectively. (d) to (f) show results from different ligaments, demonstrating the reproducibility of SHG-CD responses. All scale bars are 5 μm. (g) θ is defined as the angle between the collagen molecular orientation z and the transverse XY-plane. Z denotes the direction of excitation. (h) Calculated SHG-CD responses as a function of the θ angle.