We first performed depth-resolved SHG imaging for control, SDB, DDB, and DB samples. To visualize structural differences of the dermal collagen fibers at high image contrast, the power of the laser light incident on the sample was adjusted to 10 mW for the control, 15 mW for SDB, 25 mW for DDB, and 40 mW for DB. The resulting series of depth-resolved SHG images are shown in Fig. 3 (, ). Furthermore, a series of more precisely, depth-resolved SHG images was given in Video 1 (, interval of scanning depth ). In this experiment, we defined the skin surface as a depth of 0 µm. The skin surface location was determined by confocal microscopy, which is a function included in the present SHG microscopy system (not shown in Fig. 2). It is interesting that the depths that the SHG light started to appear are different among different degrees of burn: 140 µm for control, 120 µm for SDB, 90 µm for DDB, and 40 µm for DB. This result indicated that the thickness of the epidermis was decreased due to the thermal shrink caused by the skin burn. If the probing depth of SHG microscopy is determined based on the skin surface, the actual probing depth of the dermis was different among the control, SDB, DDB and DB. Therefore, it is important to investigate depth dependency of the dermal collagen fiber for each burn sample. In the control sample, we observed that fine collagen fibers in the papillary dermis changed to thick collagen fibers in the reticular dermis with increasing probing depth [see Fig. 3(a)]. On the other hand, depth-resolved SHG images of the SDB, DDB, and DB samples indicated that each burn spread uniformly over the whole depth of the dermis. In the SDB sample, the SHG vanishing patterns discussed later were overlaid on the fiber structure of the dermal collagen [see Fig. 3(b)]. In the DDB sample, the SHG vanishing patterns became finer than those in the SDB sample [see Fig. 3(c)]. Furthermore, the fibrous structures of the dermal collagen were almost entirely lost and changed into amorphous structures. In the DB sample, a little SHG light was observed only from aggregates of degenerated collagen [see Fig. 3(d)]. Thus, there was no depth dependency of the SHG vanishing pattern for each burn sample within the probing depth range used in the present system.