  Photoacoustic imaging is a new non-destructive medical imaging technology based on photoacoustic effect. It can reflect the difference of light absorption energy by detecting photoacoustic signal. At present, the analysis methods of photoacoustic signals in biological tissues can be divided into two categories, namely, time-domain analysis of signals and frequency-domain analysis of signals. In time domain analysis, the envelope of the received photoacoustic signal is usually used to reconstruct the image. However, due to the influence of various external factors, the time domain signal cannot accurately reflect the characteristics of the absorber itself. Here, photoacoustic spectrum analysis was performed by using k-Wave to obtains the relationship between the structure, size, density of the absorber and the photoacoustic spectrum. Firstly, the relationship between the size of absorber and the photoacoustic spectrum is studied, and the slope and intercept are used to analyze the spectrum. Conversely, the relationship was used to predict the size of the absorber Finally, we used this relationship to predict the size of blood vessels. 
Research on the photoacoustic spectrum analysis using k-Wave