Characterization and evaluation of a compact laser diode stack for full-aperture line illumination towards a handheld photoacoustic probe

Photoacoustic imaging uses a pulsed light source for excitation. Part of the energy is absorbed by the tissue and converted into heat, leading to temporary thermoelastic expansion and, consequently, broadband ultrasonic emission. Conventional systems rely on high-energy solid-state lasers at low repetition rates, increasing cost and size. We present a compact pulsed laser source for integration into handheld probes. An 808 nm laser diode stack (LDS) with post emission beam shaping tailors full-aperture line illumination. The LDS delivers 50 ns pulses at up to 3 kHz and energies reaching 2 mJ. Sliding window averaging improves signal-to-noise ratio (SNR) with a trade off against the effective frame rate. We demonstrate how pulse energy and pulse repetition frequency (PRF) affect signal amplitude and SNR in compliance with ANSI136.1 and IEC60825 standards.