| In laser ranging scenarios involving non-cooperative targets, the complex and diverse surface characteristics of these targets often result in low reflectivity and scattering of reflected light in various directions. Consequently, the optical energy returning to the measurement system is weak. To effectively collect the return optical energy and achieve precise focusing of the laser spot under such conditions, a high-precision laser zoom optical-mechanical system and auto-focusing control system have been designed. This system optimizes the optical structure by incorporating a combination of collimating lens group, front lens group, movable lens group, rear lens group, and compensating lens group. This design ensures efficient beam focusing and maximizes energy, thereby enhancing the signal-to-noise ratio and stability across different ranging distances. Additionally, the system improves focusing consistency through optimized optical axis stability and mechanical structure layout. In terms of control methodology, an image recognition-based auto-focusing strategy is introduced. A high-resolution camera captures real-time images of the target laser spot. Image processing techniques are employed to extract key features such as spot diameter, shape, and clarity. These features are used to dynamically calculate optimal focal length adjustment parameters, enabling automatic closed-loop focusing via a stepper motor. Experimental results indicate that within a measuring range of 0.5 meters to 30 meters, the system has a centroid offset of no more than 65 μ m within a working distance of 0.5m to 30m, which meets the design requirements and can effectively achieve spot focusing. |
