Optoacoustic imaging of subcutaneous microvasculature with a class one laser

We developed a combined imaging platform allowing optoacoustic and ultrasound imaging based on a low energy laser and a handheld probe. The device is based on a sensitive single element 35-MHz focused transducer, a 2-D piezoscanner and a dual-wavelength switchable Nd:YAG laser. Acoustical detection and optical illumination are confocal for optimization of optoacoustic signal-to-noise ratio. The system allows to scan over a range up to 12 mm ×12 mm in xy-direction with an isotropic lateral resolution of about 90 μm. Although the device is a class 1 laser product having pulse energies in the range, in vivo images of subcutaneous microvasculature could be obtained from human skin with signal-to-noise levels as good as 20 dB.