The use of compact and cost-effective visible light emitting diodes (LEDs) as an alternative to Q-switched lasers, the conventional photoacoustic excitation source, has been explored for vascular imaging applications [T. J. Allen and P. C. Beard, “Light emitting diodes as an excitation source for biomedical photo-acoustics,” Proc. SPIE8581, 85811F (2013)]. This research motivated our work. Experiments used a 619 nm LED (Luminus SST-90-R-F11-HH100) pulsed for 450 ns with period 34 ms utilizing a pulse generator, MOSFET driver and power MOSFET switch, discharging a bank of capacitors (990 μF) with 36 A peak current. A pair of 2.5 cm diameter aspherical acrylic lens focused the LED—with an emitting area of 3mm × 3 mm—onto the surface of a vertical capillary tube (1.19 mm ID, 1.75 mm OD) filled with 5% McCormick Green food coloring or 5% Higgins India Ink and placed in the 10 cc acrylic water tank. An Olympus emersion transducer (1.27 cm diameter circular plane array, 1 MHz with 0.4MHz bandwidth) was amplified using four home-made low noise amplifiers (87 dB overall gain, 0.5–30 MHz bandwidth). An Agilent DSO 7014 B oscilloscope recorded the photoacoustic signal pulse averaging 8196 trials.