Research On Optical Microscopy Imaging Method Based On Photoacoustic Transmission Matrix

After the laser passes through scattering media such as biological tissue,milk,and scattering sheets,the refractive index of these scattering media is not uniform,which will cause multiple scattering of the laser light during the propagation of these scattering media.The scattered laser light is very difficult to use in optical imaging experiments due to the large reduction in light intensity and the lack of concentration of light intensity.The emergence of wavefront shaping technology can well solve the problem of laser scattering through scattering media.Wavefront shaping technology can modulate the amplitude and phase of the laser before it is incident on the scattering medium to eliminate the light distortion caused by light scattering,so that the laser can still be focused after passing through the scattering medium.Since the laser light is affected by scattering as it propagates through the biological tissue,this greatly hinders the focusing of the laser light through the biological tissue.Taking advantage of the weak scattering of photoacoustic signal in biological tissue and the fact that wavefront shaping technology can counteract the scattering,photoacoustic signal and wavefront shaping technology are combined to form photoacoustic front shaping technology,which can realize the focusing of laser in biological tissue.The photoacoustic wavefront shaping method based on the photoacoustic effect can realize light focusing and imaging inside biological tissue.The difference between the photoacoustic wavefront shaping method and the traditional wavefront shaping method is that an ultrasonic transducer is used to collect the photoacoustic signal as a feedback signal.In this paper,we propose a new method for photoacoustic wavefront shaping and photoacoustic imaging.The photoacoustic transmission matrix is used as the wavefront shaping algorithm,and the amplitude and phase of the incident light are modulated by the superpixel method with the Digital Micromirror Device(DMD),so that the enhancement factor of the photoacoustic signal reaches 10.75.Then,the above absorber is moved by moving the two-dimensional moving platform,which is used to realize photoacoustic scanning imaging.Compared with the inability to image the initial photoacoustic signal before photoacoustic wavefront shaping,the photoacoustic signal after photoacoustic wavefront shaping can obtain a clear photoacoustic image with a contrast ratio of 16.85.Our photoacoustic wavefront shaping and photoacoustic imaging methods have promising applications in the imaging of weaker photoacoustic signals.