Photoacoustic (optoacoustic) imaging bridges optical contrast and ultrasound resolution: a pulsed laser is absorbed by tissue chromophores such as hemoglobin, the sudden thermoelastic expansion launches an acoustic pressure wave, and a surface transducer array times its arrival to localize the absorber — the same principle used in preclinical photoacoustic microscopy and clinical breast/vascular imaging research. This simulator renders a 3D tissue cross-section with embedded absorbing vessels, fires a real laser pulse whose initial pressure follows p₀ = Γ·μₐ·F, animates the resulting spherical pressure wavefronts at the true speed of sound in tissue, and reconstructs the image on a second panel using genuine delay-and-sum backprojection — including the array-density and sound-speed-mismatch artifacts that challenge real photoacoustic scanners.