为了更好地实现无创、实时、动态的皮肤层析成像, 提高成像信噪比, 需要对反射式激光共聚焦系统性能进行全面的评价。在此引入结构函数进行变尺度波前评价。首先对结构函数的基本数学性质进行了推导, 着重分析了不同尺度的波像差在结构函数中的体现; 之后, 利用数值仿真对Zernike多项式进行了分析, 验证了结构函数对低阶像差的表征能力。由于显微镜在使用时必然需要穿过皮肤组织, 故在检测过程也需要考虑人体组织的影响, 分析了其对系统信噪比的影响; 最后, 对实际显微镜系统的波前进行了分析, 得到系统标校后的信噪比为95.7 dB, 验证了方法的正确性与可行性。通过变尺度评价方法, 可以对无创成像系统进行更加全面的评价, 并可以有效地指导类似设备的检测装调工作。

In order to better realize non-invasive, real-time and dynamic skin tomographic imaging and improve the imaging signal-to-noise ratio (SNR), the performance of the reflective laser confocal system was evaluated comprehensively. Structure function as variable metric for wave front was introduced, and the basic mathematical properties was analyzed. The wave aberration of different scales in the structure function was analyzed emphatically. After that, the numerical simulation for low order aberration presented by Zernike polynomials was investigated. The ability of structure function to characterize low order aberrations was verified. Because confocal microscopy was required to pass through the skin, it was important to think about the effects of human tissue in the pre-test process and analyze its effects on the system′s SNR; Finally, the wavefront of the actual skin lens system was analyzed, and a SNR of 95.7 dB was obtained after system calibration, and the correctness and feasibility of the method were verified. By means of the variable scale evaluation method, the non-invasive imaging system can be evaluated more comprehensively and it can effectively guide the detection and adjustment of similar equipment.