Du Hong, Voss Kenneth J
Department of Physics, University of Miami, 1320 Campo Sano Drive, Coral Gables, Florida 33124, USA.
Appl Opt. 2004 Jan 20;43(3):665-70. doi: 10.1364/ao.43.000665.
The point-spread function (PSF) of a camera can seriously affect the accuracy of radiometric calibration and measurement. We found that the PSF can produce a 3.7% difference between the apparent measured radiance of two plaques of different sizes with the same illumination. This difference can be removed by deconvolution with the measured PSF. To determine the PSF, many images of a collimated beam from a He-Ne laser are averaged. Since our optical system is focused at infinity, it should focus this source to a single pixel. Although the measured PSF is very sharp, dropping 4 and 6 orders of magnitude and 8 and 100 pixels away from the point source, respectively, we show that the effect of the PSF as far as 100 pixels away cannot be ignored without introducing an appreciable error to the calibration. We believe that the PSF should be taken into account in all optical systems to obtain accurate radiometric measurements.
相机的点扩散函数（PSF）会严重影响辐射校准和测量的准确性。我们发现，在相同光照条件下，PSF会使两块不同大小斑块的表观测量辐亮度产生3.7%的差异。通过用测量得到的PSF进行反卷积可以消除这种差异。为了确定PSF，对来自氦氖激光器的准直光束的许多图像进行平均。由于我们的光学系统聚焦于无穷远，它应该将这个光源聚焦到单个像素上。尽管测量得到的PSF非常尖锐，分别在距离点光源4和6个数量级以及8和100个像素处下降，但我们表明，在不引入明显校准误差的情况下，距离点光源100像素处的PSF效应不能被忽略。我们认为，在所有光学系统中都应考虑PSF，以获得准确的辐射测量结果。
