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In recent years, photoacoustic imaging is a new imaging technology which combines the advantages of high resolution and rich contrast of optical imaging and high penetration depth of acoustic imaging. Therefore, photoacoustic imaging is widely used in biomedical fields, such as brain imaging, tumor detection and so on. As an important branch of photoacoustic imaging, photoacoustic microscopy imaging of optical resolution can reach the submicron level and can meet the needs of multi-scale imaging from cell to tissue. However, the strongly focused Gaussian beam is usually used in the traditional system of photoacoustic microscopy imaging of optical resolution, and so the depth of imaging is small, which makes it difficult to achieve fast imaging of large volume. In order to solve this problem, researchers have proposed many schemes, one of which is to use non-diffracted beams instead of Gaussian beams for imaging. As a nondiffracted beam, Bessel beam is applied to photoacoustic microscopy imaging of optical resolution in this study because it has the characteristic of large depth of field. However, in practice, the cost of building the system of photoacoustic microscopy imaging of optical resolution is high and its structure is complex, so there is an urgent need for the technology of virtual simulation for photothermal simulation analysis of the imaging system. In order to achieve this goal, a virtual simulation platform of photoacoustic microscopy imaging system of Bessel beam based on finite element analysis was built by using simulation software COMSOL Multiphysics. In COMSOL, the Bessel beam realized by compound axicon was constructed and then irradiated the human brain tissue. The propagation of the Bessel beam in the brain tissue was simulated by solving the diffusion equation. And the temperature changes of gray matter and blood vessel were obtained by solving the equation of biological heat transfer. This study is helpful to understand the propagation of Bessel beam in human brain and the interaction between them, and has a certain theoretical significance for the optical imaging of human brain.
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