In order to measure the coordinate of moving target, the laser tracking system for moving target was proposed, in which the receiver of four-quadrant APD was adopted as the detector and the DC motor was used to drive the reflector to move in two dimensions. The principle of the measurement system was analyzed first. Then the main part of the system was introduced. The tracking experiment showed that, this system could realized the function of automatic tracking and measuring the coordinate of moving target according to the pulsed laser ranging and angle sensors.
An optical vortex is a beam of light with phase varying in a corkscrew-like manner along its direction of propagation and so has a helical wavefront. When such a vectorial vortex beam and the Gaussian beam with orthogonal polarization are focused by low NA lens, the Gaussian component causes a focal intensity distribution with a solid center and the vortex component causes a donut distribution with hollow dark center. The shape of the focus can be continuously varied by continuously adjusting the relative weight of the two components. Flat top focusing can be obtained under appropriate conditions. It is demonstrated through experiments with a liquid crystal spatial light modulator in such a beam, that flattop focus can be obtained by vectorial vortex beams with topological charge of +1 to achieve beam shaping vortex.