When optical images are used to measure the three-dimensional position of a target, it is necessary to project a laser source onto the object, and the center position of the pupil spot should be calculated. The laser light source has high application value, because the brightness of the spot is much higher than the brightness of the environment. When the camera is in a low exposure time, the spot will be in stark contrast to the surrounding environment, which can achieve the conditions of the image measurement. The laser can be divided into point laser, line laser and cross laser according to the simple emission shape. In this paper, the center positions of these lasers are solved separately. After calculating and testing, the stability and accuracy of the cross laser can be verified. The results can provide an important source of light source selection and new ideas for image measurement.