Abstract: An optical device with simple structure and low price is developed, which can adjust the laser beam parallel with the telescope axis conveniently and rapidly. The device is mainly composed of two optical wedge planes. The direction of the outgoing laser beam from this device can be changed arbitrarily by turning the two planes through two motors within a certain range, which depends on the wedge angle and the refractive index of the plane material. By using refraction law, the relationship between the rotation angles of two wedge planes and the direction of outgoing laser beam is deduced strictly. A lidar system adjustment is proposed with the device inserted into the transmitting optical path and spiral, circular and radial scans of the out beam, and the criterion and the process for alig