Continuous-wave photoacoustic microscopy

Abstract

We have built a photoacoustic microscope (PAM) using an amplitude-modulated continuous-wave (CW) laser source, which is an inexpensive 120-mW laser diode. By using a bowl-shaped piezoelectric transducer, whose numerical aperture is 0.85 and resonance frequency is 2.45 MHz, we have experimentally demonstrated a lateral resolution of 600 µm, an axial resolution of 700 µm, and a signal-to-noise ratio (SNR) as high as 43 dB. Although the SNR in the CW PAM system is an order of magnitude worse than that of the pulsed-laser-based PAM system, CW PAM shows potential for biomedical applications as it uses durable and inexpensive semiconductor lasers, which will significantly reduce operation costs of the PAM systems.

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