分析了红外成像系统随温度变化而离焦的原理, 提出一种线列红外无热化检测系统。分析了线列红外成像的特点, 针对传统的SMD, TenenGrad, Laplacian等方法容易受到线列红外条纹噪声干扰的问题, 结合所采用靶板的形状, 提出了一种基于7个方向改进的Sobel算子的清晰度评判的方法。实验结果表明,该方法能够有效克服线列红外成像系统条纹随机噪声对清晰度评价因子带来的干扰。和传统算法对比发现, 所提算法的响应曲线变化趋势明显、波动小, 能够更好地满足自动调焦的单调和无偏性要求。

The principle of the phenomenon that the infrared imaging system may defocus with the change of temperature is analyzed, and a linear infrared athermalization detection system is proposed. The characteristics of linear infrared imaging are analyzed. To solve the problem that the traditional methods of SMD, TenenGrad, Laplacian are prone to be disturbed by the stripe noise of the linear infrared system and considering the shape of the target plate, a method of definition evaluation based on the improved Sobel operator in seven directions is proposed. The experimental results show that this method can effectively overcome the interference of the stripe random noise of the linear infrared imaging system on the definition evaluation factor. Comparing with that of the traditional algorithms, the response curve of the proposed algorithm has obvious variation tendency and small fluctuation. It can better meet the monotonic and unbiased requirements of autofocusing.