Power spectral density (PSD) is being used to evaluate the surface finish and wavefront errors in mid-spatial frequency
of optical components, but whether a PSD curve is credible or not is now a problem to be solved urgently. PSD curves
measured by different instruments make an influence on the estimate of optical components. In order to solve this
problem, we use system transfer function (STF) to find the relationships between different instruments and PSD
measurements. A mathematical model of STF and PSD measurement is established to stimulate and find the floor level
of STF to get a credible PSD. The experiment results that the instruments with STF at least 60% can be used in
mid-spatial frequency measurements.
The main method of the attitude measurement is to get series of graphs for analyzing the changing attitude of the
projectile by utilizing multiple shadowgraph-taking camera stations.However,the premise of accurate results is that
feature points on graphs must match its spatial coordinate in a certain spatial coordinate.Addressing to this
problem,combining the optical lever principle and the PSD,we propose a method of calibrating the spatial coordinate
coherence of the long distance and multiple shadowgraph-taking camera stations,and analyze the measurement accuracy
and repeatability of this method.According to the results,the accuracy of this calibration method is superior to 0.1mm .