According to the principle of photoacoustic imaging technology, it reflects the light absorption distribution of tissues, and the calculation formula of light intensity is I=Nhv/At, where I stands for the light intensity in optics, V stands for the frequency of light, A stands for the irradiation area, and n stands for the total number of photons irradiated on A in time interval T. The international unit is Candeira.
Photoacoustic imaging is a non-invasive imaging technology, which is very important for in vivo imaging. Because the power density of laser used is lower than the damage threshold of biological tissue, and the intensity of ultrasonic field generated in tissue is far lower than the damage threshold of tissue, photoacoustic imaging is a non-invasive, non-ionizing and non-invasive imaging technology.