The advantage of using a diode laser instead of a Q-switched laser in photoacoustic imaging of tissues

Photoacoustic (PA) imaging of biological tissues using laser diodes instead of conventional Q switched pulsed systems provides an attractive alternative for biomedical applications. However, the relatively low energy of laser diodes operating in the pulsed regime, results in generation of very weak acoustic waves, and low signal-to-noise ratio (SNR) of the detected signals. This problem can be addressed if optical excitation is modulated using custom waveforms and correlation processing is employed to increase SNR through signal compression. This work investigates the effect of the parameters of the modulation waveform on the resulting correlation signal and offers a practical for optimizing PA signal detection. The advantage of coherent signal averaging is demonstrated using theoretical analysis and a numerical model of PA generation. It was shown that an additional 5–10dB of SNR can be gained through waveform engineering by adjusting the parameters and profile of optical modulation waveforms. Also Diode lasers are also more intense and have more power output Therefore, the data can be combined quickly and provide more precise control and are absorbed by the pigment cells such as hemoglobin, because of their proximity to the infrared spectrum. And due to the presence of blood flow throughout the body, it is very useful in the treatment of diseases.