本文分析了薄凸透镜焦距测量中存在的问题，并利用消除视差的方式来测量薄透镜焦距，第一种用消视差自准直

法，用眼睛来代替目镜系统，将对像清晰程度的调节变为对横向的物与像视差的调节，可以大大的减少由焦深带来的误差.第二种用消视差共轭法，利用物与像的对称性，来测量焦距，同时巧妙的利用消除视差的方式.测量结果表明，利用消视差的方式得到的测量结果更精确，可达到0.4%.

This paper analyses the problems existing in the measurement of the foci of thin lens，and the method of parallax elimination is used to measure the focal length of thin lens. The first method uses self-collimation and eyes instead of eyepiece system，which can change the adjustment of the image clarity into the adjustment of the lateral object and image parallax，and can greatly reduce the error caused by the focal depth. The second method uses the conjugate method to measure the focal length by the symmetry of object and image，and at the same time skillfully uses the method of eliminating parallax. The measurement results show that the measurement results obtained by the method of parallax elimination are more accurate，reaching 0.4%.