Figure 2 shows the results of depth measurement of each absorption layer by using digital micrometer calipers (MDQ-30, Mitsutoyo, Kanagawa, Japan) and PA imaging for two types of phantoms: a simple three-layered model and a six-layered model, in which mesh patterns were not printed on the second and fifth layers. For the three-layered model, the depths at which signals arose for the first (depth measured by calipers, 0.70 mm), second (1.48 mm), and third (2.29 mm) absorption layers were 0.62 to 0.68 mm (maximum error for the depth measured by calipers, ), 1.45 to 1.60 mm (), and 2.25 to 2.40 (), respectively. For the six-layered model, the depths at which signals arose for the first (depth measured by calipers, 0.67 mm), second (2.08 mm), third (2.88 mm), and fourth (4.36 mm) absorption layers were 0.65 to 0.70 mm (maximum error for the depth measured by calipers, ), 2.05 to 2.15 mm (), 2.85 to 2.90 mm (), and 4.40 to 4.50 mm (), respectively. Thus, the maximum imaging depth error for the phantoms was , although this value may be affected by the compression with a sensor for soft material and biological tissue. Since the deepest absorption layer at can be visualized with high contrast, the results show the capability of visualizing vasculatures in full-thickness human skin tissue with the present imaging system.