Photoacoustic imaging (PAI) is a biomedical imaging technique that combines the high contrast of optical imaging with the high resolution of ultrasound imaging. It uses the absorption of electromagnetic (EM) energy, such as light or radio-frequency (RF) waves, to generate acoustic waves through thermoelastic expansion. These acoustic waves are then detected and used to create images of biological tissues. PAI has the potential to image organs like the breast and brain with high contrast and resolution. The technique involves the absorption of EM energy by tissues, which generates acoustic waves that are detected and processed to form images. PAI is particularly useful for imaging deep tissues where optical scattering limits resolution, as ultrasound has lower scattering and can provide better resolution in deeper tissues. The technique is non-invasive and non-ionizing, making it safe for in vivo applications. PAI can provide functional imaging by measuring optical absorption contrasts related to biochemical information, such as oxygen saturation and hemoglobin concentration. Recent advancements in PAI include the use of high-frequency ultrasound transducers, acoustic lenses, and computed tomography (CT) for improved resolution and depth. PAI has promising applications in cancer detection, early diagnosis, and imaging of superficial organs. The technique involves the use of various imaging methods, including depth profiling, scanning tomography, and CT, to reconstruct 3D images of tissues. The development of PAI has been driven by the need to overcome the limitations of traditional imaging modalities, such as optical imaging's limited depth and ultrasound's low contrast. PAI offers a unique combination of high contrast and resolution, making it a valuable tool in biomedical imaging.Photoacoustic imaging (PAI) is a biomedical imaging technique that combines the high contrast of optical imaging with the high resolution of ultrasound imaging. It uses the absorption of electromagnetic (EM) energy, such as light or radio-frequency (RF) waves, to generate acoustic waves through thermoelastic expansion. These acoustic waves are then detected and used to create images of biological tissues. PAI has the potential to image organs like the breast and brain with high contrast and resolution. The technique involves the absorption of EM energy by tissues, which generates acoustic waves that are detected and processed to form images. PAI is particularly useful for imaging deep tissues where optical scattering limits resolution, as ultrasound has lower scattering and can provide better resolution in deeper tissues. The technique is non-invasive and non-ionizing, making it safe for in vivo applications. PAI can provide functional imaging by measuring optical absorption contrasts related to biochemical information, such as oxygen saturation and hemoglobin concentration. Recent advancements in PAI include the use of high-frequency ultrasound transducers, acoustic lenses, and computed tomography (CT) for improved resolution and depth. PAI has promising applications in cancer detection, early diagnosis, and imaging of superficial organs. The technique involves the use of various imaging methods, including depth profiling, scanning tomography, and CT, to reconstruct 3D images of tissues. The development of PAI has been driven by the need to overcome the limitations of traditional imaging modalities, such as optical imaging's limited depth and ultrasound's low contrast. PAI offers a unique combination of high contrast and resolution, making it a valuable tool in biomedical imaging.