Table 2.

Summary of PA imaging experimental setups.

	Imaging resolution	Imaging depth	Imaging speed	Laser type	Wavelength	Energy used	Typical applications
OR-PAM	The lateral and axial resolutions were 3 μm and 15 μm in clear media*.	0.7 mm (through an intact skull with the scalp removed)*.	About 15 s when imaged the region at the size of 5 × 10 mm2*.	Single wavelength lasers with 3-ns and 3-ps pulse width*.	532 nm*.	<20 mJ/cm2 (Li B. et al., 2023; Li D. et al., 2023).	Noninvasively imaging human microvasculature (Li B. et al., 2023; Li D. et al., 2023).
AR-PAM	The lateral and axial resolutions were 57 μm and 38 μm by imaging a 6 μm carbon fiber**.	3.2 mm (through the intact skin and skull of a mouse in situ)**.	Image acquisition time of whole brain was about 4 min**.	OPO laser with 8-ns pulse width**.	560–580 nm**.	~12.1 mJ/cm2**.	Used to study skin diseases (Fakhoury et al., 2024).
PACT with ring UTA	The spatial resolution was 125 μm***.	11 mm (in a coronal view of the rat whole brain)***.	A frame rate of 50 Hz***.	Single wavelength lasers with 5–9 ns (1,064 nm) and 12-ns (720 nm) pulse width; OPO laser with 6-ns pulse width (630 and 680 nm)***.	630, 680, 720, and 1,064 nm***.	~8 mJ/cm2 for 630, 680, and 720 nm; ~18 mJ/cm2 for 1,064 nm***.	Small animal whole body imaging***.
PACT with linear UTA	The lateral resolution was 75 μm****.	The whole mouse brain was covered (sectioning thickness is ~0.5 mm within the depth of focus)****.	A frame rate of 10 Hz****.	Single wavelength laser with 4–6 ns pulse width****.	1,064 nm****.	~64 mJ/cm2****.	Small animal deep brain imaging****.

^{*,**,***,****}Annotated information comes from the references of Yao et al. (2015), Yao et al. (2013), Li et al. (2017), and Zhang et al. (2018), respectively. OR-PAM, optical-resolution photoacoustic microscopy; AR-PAM, acoustic-resolution photoacoustic microscopy; PACT, photoacoustic computed tomography; UTA, ultrasonic transducer array, ns, nanosecond; ps, picosecond; OPO, optical parametric oscillator.