CCD imagers MTF enhanced filter design

In order to improve the imaging quality of the optical imagers, the modulation transfer function enhanced CCD signal filter circuit is designed. Firstly, the imager MTF transfer chain is discussed, and the impact to MTF causing by each part of imaging chain is introduced. Secondly, from frequency domain and time domain respectively the MTF enhanced filter principle and implementation method are analyzed, the filter minimum bandwidth is confirmed. By comparing the step response of the filter and the response of the camera to the Nyquist spatial frequency fringe imaging in simulation experiment, the optimum quality factor of the MTF enhancement filter is determined. Lastly, the camera MTF test was carried out using black and white stripe target, and the SNR of the camera was measured by integrating sphere. The test results show that MTF enhanced filter can improve the system MTF 30% when the quality factor is 1, and the noise suppression capability is comparable to that of the maximally flat filter in the pass-band. MTF enhancement filter can effectively improve the imaging performance of CCD camera.