论文部分内容阅读
为了满足工业TFT-LCD检测系统中显微镜对主动自动对焦的要求,提出了一种基于激光三角测距法主动自动调焦的方法,建立了相应的数学模型并进行了实验数据分析。该方法在可见光光路中加入一路808 nm波长的红外光,红外光在被检测物体表面反射后经过一系列光学器件投射在CCD相机上形成一个光斑,以对焦完成时CCD上光斑半径最小为基准,给出了离焦量δ与光斑信息探测量r之间的数学关系,据此实时控制PZT进行自动调焦。初步以50×物镜进行实验,结果显示其在焦平面±30μm范围内的实际测量值与理论值吻合,线性度优越,调焦精度达到0.2μm。与传统的显微镜调焦方法相比具有精度高、线性度好、调焦速度快等优点,满足工业检测自动化的实际需要。
In order to meet the requirement of microscope for active AF in industrial TFT-LCD inspection system, a method of active automatic focusing based on laser triangulation is proposed. The corresponding mathematical model is established and the experimental data are analyzed. The method adds an 808 nm wavelength of infrared light in the visible light path, the infrared light is reflected by the surface of the detected object and then is projected onto a CCD camera through a series of optical devices to form a light spot. Based on the smallest spot radius of the CCD on the completion of focusing, The mathematical relationship between the amount of defocus δ and the amount r of spot information is given, and the PZT is controlled in real time to perform automatic focusing. A preliminary experiment with a 50 × objective lens showed that the actual measured value in the focal plane ± 30μm coincided with the theoretical value and the linearity was excellent and the focusing accuracy reached 0.2μm. Compared with the traditional microscope focusing method with high precision, good linearity, focusing speed, etc., to meet the actual needs of industrial test automation.