Measurement model and uncertainty analysis of pulsed laser far field energy density based on CCD imaging
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 image corners.In order to decrease the unacceptable error of calibrated lens' focal length with Tsai's mono-view coplanar calibration technique,two feasible calibrating ways are pointed out: offline calibration for focus fixed lens,and mono-view non-coplanar or multi-view coplanar online calibration for zoom lens.