为了高精度地实现大量程的位移测量，采用传统激光三角法的测量原理，提出一种基于虚拟探测器的激光三角法来测量位移。该方法基于3个CCD分段测量的思想，将3个CCD互相独立且沿光轴均匀分布，以此扩大传统方法测量的范围。使用平面反射镜作为虚拟探测器进行探测，当成像光束经平面镜反射后在CCD上成像时，系统相当于增加了一个CCD，扩展了测量量程。由准直系统、偏振片、光阑组成准直滤光系统，缩小探测器光敏面上像点的直径，减小被测表面非理想光点对测量精度的影响，从而实现了较高精度下的大位移测量。最后通过实验验证了方法的可行性。

To realize the large-scale and high-precision displacement measurement, a new method based on a virtual detector was described according to the basic principles of traditional laser triangulation method. The CCD subsection measurement was used to enlarge the measuring range and to implement the displacement measurement. Three independent CCDs were distributed uniformly along the optical axis and a plain reflected mirror was regarded as the virtual detector.When the beam image was reflected by the plane mirror, the beam was imaged by CCDs. The designed system is equivalent to that a CCD is added, therefore, the measuring range is enlarged. Furthermore,the collimator filter is composed of a collimation system, a polarizer and a diaphragm. It shortens the diameter of the image spots on the photosensitive surface of the detector,and reduces the influent of unideal optical spots on the measured surface on the measuring accuracy.The high-precision measurement of large displacement is achieved. The results are in agreement with the experimental observation.