在基于光学显微镜的微操作定位中,为了克服显微镜头在拍摄图像过程中的视场狭小、焦深短等问题,综合利用了基于梯度场的图像清晰度评价方法和基于小波变换的图像清晰度评价方法。将显微镜头安装在一维宏/微双精度定位平台上,用以保证显微镜头的运动精度。为了防止系统聚焦于面积最大的背景部分,采用了仅对目标区域进行清晰度评价计算的方法,保证系统仅对操作感兴趣的目标进行自动聚焦。通过以上技术实现定位机构的全闭环反馈控制。实验研究表明:系统的动态和稳定性能良好,系统的响应速度由0.3帧/s提高到3帧/s,同时根据清晰度确定的空间位置关系还可以进行防碰撞控制。
In order to avoid small field-of-view and limited depth-of-field of micro-vision,image definition based on gradient field and wavelet transformation was used.Microscope was set on the macro-micro dual-drive table in order to ensure the positioning precision.A selective focusing technique was developed to auto focus on the objects in different depth.Closed-loop feedback control was carried out.Experimental results showed that dynamic performance and stability of the system was satisfied,the response velocity of system increased from 0.3s-1 to 3s-1,meanwhile,collision-avoidance was executed according to vertical position relations computed by image definition.