针对共聚焦型激光诱导荧光检测技术对微米尺度微流控芯片沟道检测存在对焦困难，检测精度受离焦影响严重的问题，本文提出了一种利用液体透镜连续变焦实现微沟道自动对焦的激光诱导荧光检测装置，并针对系统设计了基于图像清晰度评价的自动调焦算法。装置根据采集的微流控芯片沟道图像自动调整聚焦点位置，保证最优的激发光与诱导荧光收集。实验结果表明：本文设计的激光诱导荧光检测装置可实现对微流控芯片沟道的快速自动对焦，波动范围在0.5%之内，变异系数为1.5‰。它为提高微流控芯片的检测精度和设计灵活性提供了可能。

Laser Induced Fluorescence Detection (LIFD) technology is one of the most sensitive means for the microfluidic chip detection in which application field it is important to achieve accurate focus due to the small size of microfluidic chip. A novel LIFD based on liquid lens is proposed to obtain the optimal excitation light and the induced fluorescence collection, which is capable of adjusting focus position in three-dimension automatically according to the information provided by the images. The autofocus algorithm for LIFD is accomplished with the combination of SUSAN operator and the mountain climbing control algorithm. A tunable liquid lens based on LIFD experimental prototype is set up to testify the proposed system and algorithms. Experimental results show that the system can achieve the autofocus of microfluidic chip. The repeatability experimental results indicate that the evaluation of the last picture in each single experiment has a steady feature with a fluctuation of 0.5% and coefficient of variation of 1.5‰. It provides a solution to improving the detection accuracy and a design flexibility of microfluidic chip.