(color online) (a) In vivo imaging of single gold nanorods in mouse ear blood vessels. Overlay of transmission image (light blue) and single-frame TPL image. Two single nanorods (red spots) superimposed by a line scan (white). Image size is 175 μm × 175 μm (from Ref. [16], Fig. 5(c)). (b) Topographic images of gold nanorods and two-photon-induced photoluminescence images of gold nanorods (from Ref. [74], Fig. 2)). (c) The process of reshaping gold nanorods in the focal volume of focusing objective. Some nanorods that couple with light can be reshaped for optical recording (from Ref. [15], Fig. 2(a)).