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The resolution of aerial camera lens is one of the most important camera's performance indexes. The
measurement and calibration of resolution are important test items in in maintenance of camera. The
traditional method that is observing resolution panel of collimator rely on human's eyes using
microscope and doing some computing. The method is of low efficiency and susceptible to artificial
factors. The measurement results are unstable, too. An auto-measurement system of aerial camera lens'
resolution, which uses orthogonal linear CCD sensor as the detector to replace reading microscope, is
introduced. The system can measure automatically and show result real-timely. In order to measure the
smallest diameter of resolution panel which could be identified, two orthogonal linear CCD is laid on
the imaging plane of measured lens and four intersection points are formed on the orthogonal linear
CCD. A coordinate system is determined by origin point of the linear CCD. And a circle is
determined by four intersection points. In order to obtain the circle's radius, firstly, the image of
resolution panel is transformed to pulse width of electric signal which is send to computer through
amplifying circuit and threshold comparator and counter. Secondly, the smallest circle would be
extracted to do measurement. The circle extraction made using of wavelet transform which has
character of localization in the domain of time and frequency and has capability of multi-scale analysis.
Lastly, according to the solution formula of lens' resolution, we could obtain the resolution of
measured lens. The measuring precision on practical measurement is analyzed, and the result
indicated that the precision will be improved when using linear CCD instead of reading microscope.
Moreover, the improvement of system error is determined by the pixel's size of CCD. With the
technique of CCD developed, the pixel's size will smaller, the system error will be reduced greatly too.
So the auto-measuring system has high practical value and wide application prospect.
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