Low-cost and compact second harmonic laser for photoacoustic imaging

Area of Science:

• Optics and Photonics
• Biomedical Imaging
• Laser Technology

Background:

• Photoacoustic imaging (PAI) offers high contrast and resolution, valuable for vascular imaging and liver function reserve (LFR) assessment.
• Current PAI systems are limited by bulky, expensive pulsed lasers or low-energy, wide-pulse LEDs.
• A need exists for low-cost, compact, and efficient light sources for PAI commercialization and clinical application.

Purpose of the Study:

• To propose and validate a novel, low-cost, and compact PAI light source.
• To utilize a miniature laser and second-harmonic generation (SHG) for PAI excitation.
• To demonstrate the potential for vascular imaging and LFR assessment using the developed light source.

Main Methods:

• A miniature diode-pumped solid-state (DPSS) laser operating at 1535 nm was employed.
• A KTiOPO4 second-harmonic generation crystal was used to convert the 1535 nm output to 767.26 nm.
• PAI experiments were conducted on human finger and dorsal hand vasculature, and Indocyanine green (ICG) solutions.

Main Results:

• The SHG process yielded a compact light source with a 767.26 nm wavelength, 10 ns pulse width, and 0.68 mJ pulse energy.
• PAI of blood vessels in the human finger and dorsal hand was successfully demonstrated.
• PAI detection analysis showed sensitivity to varying concentrations of Indocyanine green (ICG).

Conclusions:

• The proposed low-cost, compact second-harmonic laser is a viable excitation source for PAI.
• This technology holds significant potential for advancing vascular imaging and LFR evaluation.
• The development contributes to miniaturized, portable PAI systems, facilitating wider application.