成像法测量脉冲激光远场能量密度的模型及不确定度分析
Measurement model and uncertainty analysis of pulsed laser far field energy density based on CCD imaging
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摘要: 设计了基于漫反射成像法测量脉冲激光远场能量分布的方案，在相机标定的基础上建立了CCD图像灰度值与漫反射板上脉冲激光能量密度对应关系的数学模型，该模型考虑了漫反射板的漫反射率和CCD像元响应度的空间不一致性，并对不同测量位置的离轴角的影响进行了修正。分析表明:CCD灰度值、镜头透过率、漫反射率和CCD响应度的不确定度传播系数为1，镜头光圈数的不确定度传播系数为2,镜头焦距的不确定传播系数随离轴角增大而增大,成像中心像素坐标的不确定度传播系数在图像顶点处最大。针对相机标定实验中发现的利用Tsai单视角共面点标定相机得到的镜头焦距与实际存在较大偏差问题，指出对于定焦镜头，应该采用其它离线方法进行准确标定；对于变焦镜头，可采用单视角非共面点或多视角共面点进行在线标定。Abstract: A scheme is designed to measure the pulsed laser far field energy density based on CCD imaging, and the measurement model mapping the CCD gray value to the pulsed laser energy density on the reflective board is deduced based on radiometry and camera calibration, in which the influence of abaxial angle together with the nonuniformity of board’s diffuse reflection ratio and CCD sensor’s responsivity is considered and corrected. Uncertainty analysis shows that the uncertainty propagation coefficient of CCD’s gray value, lens’ transmittance, board’s diffuse reflection ratio and CCD sensor’s responsivity are all 1; that of lens’ iris diaphragm number is 2; that of lens’ focal length increases with the abaxial angle; and that of image center’s pixel coordinates reach the maximum at the
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Key words:
- pulsed laser /
- energy density /
- imaging /
- ccd /
- uncertainty
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