生物样品图像边缘增强与提取是医学图像处理的关键技术之一, 是进行生物样品形态分析的基础。图像边缘增强通常是通过计算机编程对原始图像进行后期处理来实现的, 然而, 这里应用共焦空间微分显微镜系统, 实现了在获得样品共焦显微图像的同时直接获取对应的边缘增强显微图像, 且图像分辨率与对比度较高。实验不仅获取了掩膜板与标准分辨率板RTA-07的边缘增强图像, 说明系统分辨率达到1.5 μm, 而且实现了生物细胞的边缘增强图像的获取, 如血红细胞与口腔上皮细胞, 图像可用于样品尺度与面积等形态的分析与计算, 在生物医学研究中有实际应用意义。

We demonstrate the feasibility of simultaneous multi-probe detection for an optical-resolution photoacoustic microscopy (OR-PAM) system. OR-PAM has elicited the attention of biomedical imaging researchers because of its optical absorption contrast and high spatial resolution with great imaging depth. OR-PAM allows label-free and noninvasive imaging by maximizing the optical absorption of endogenous biomolecules. However, given the inadequate absorption of some biomolecules, detection sensitivity at the same incident intensity requires improvement. In this study, a modulated continuous wave with power density less than 3mW/cm² (1/4 of the ANSI safety limit) excited the weak photoacoustic (PA) signals of biological cells. A microcavity transducer is developed based on the bulk modulus of gas five orders of magnitude lower than that of solid; air pressure variation is inversely proportional to cavity volume at the same temperature increase. Considering that a PA wave expands in various directions, detecting PA signals from different positions and adding them together can increase detection sensitivity and signal-to-noise ratio. Therefore, we employ four detectors to acquire tiny PA signals simultaneously. Experimental results show that the developed OR-PAM system allows the label-free imaging of cells with weak optical absorption.