Research On Laser Feedback Confocal Tomography Technology

Biological tissue tomography belongs to strong scattering media imaging.In tomography of such media,the number of signal photons is small and the imaging signal-to-noise ratio is low.Therefore,biological tissue tomography has always been a challenging subject in the field of optical imaging.In biological tissue imaging,improving the sensitivity of the tomography system and the ability to suppress stray light is an effective method to solve this problem.The laser frequency-shifting feedback technology based on Nd: YVO4 microchip laser has extremely high optical gain,which can reach the order of 106.The micron-level laser beam waist acts as a natural spatial pinhole filter,which can effectively filter out stray photons.It is possible to achieve high resolution imaging and large depth tomography for biological tissue.Therefore,this paper studies the laser frequency-shift feedback confocal imaging technology based on Nd: YVO4 microchip laser.On the basis of systematic research on the frequency-shifted feedback technology of Nd:YVO4microchip laser,combined with the laser confocal tomography,a laser feedback confocal imaging method is proposed.The Nd:YVO4 laser feedback confocal tomography and the laser confocal tomography system with the same parameters are designed and built.The horizontal and vertical resolution,sensitivity and stability of both systems are tested,which proves that the laser feedback confocal tomography is consistent with laser confocal tomography in horizontal and vertical resolution,and has higher sensitivity and stability.Finally,a laser feedback confocal tomography system is used to scan the tissues of onion scales,and processed with 3D display and 2D tomographic image processing.Studies have shown that when object lens of NA=0.42,the horizontal resolution of the system is about 1.1?m,which is 1.4 times of optical imaging systems,the vertical resolution is about 20?m,which can be clearly detected the boundary structure of the onion scale epidermal tissue and prove that it has the ability of high-precision tomographic imaging of biological tissues.