Table 1. Experimental results of deeply penetrating PA imaging in biological tissues.

	Depth [cm]	SNR	Image contrast	NESb [mM]	FWHM [μm]
Topa	4.5	7.5	3.4	4	~400
Bottoma	5.2	2.7	0.6	11	N/Ac

^aTop and bottom denote the top and bottom boundaries of the tube.

^bNES: Noise equivalent sensitivity.

^cDue to low SNR, it was difficult to estimate the FWHM from the bottom surface of the tube.