New Test Method Of TDICCD Camera Machine Static MTF

Using modulation transfer function to evaluate the image quality of optical systems is the widely used method. How to get the more accurate value of the static MTF has been the direction of our research and development. For our research of TDICCD system, we also use MTF to evaluate the image quality. We usually choose the high frequency bar, which frequency matches the Nyquist frequency of the system ,to get the Contrast Transfer Function (CTF) of the image of the bar. The CTF of the image with the coefficient ofπ4 is equal to the Modulation Transfer Function (MTF) at high frequency.The traditional method mentioned above is limited to the production process of the high frequency bar target. It leads error into the result because of the approximate correction factor. With the development of science and technology, we require higher resolution of TDICCD camera and better testing technology. If we use the traditional method, the focal length of the collimator needed in the test should be longer or the bar target matched the system Nyquist frequency should be narrower. We know that, the collimator cannot be adjusted random as we want ,so the only way is to make high frequency bar target. According to the skill level at this stage, the requirement is hard to meet. The modulation of the high frequency bar target is hard to test accurately. The traditional method has encountered various restrictions. This article describes a method to extract MTF at specific frequencies from a single measurement of the line profile from a bar target. The MTF at Nyquist frequency also can be calculated. In the new method, a low frequency bar target is used, approximately parts of Nyquist, and the frequencies obtained by Fourier transfer of bar target and output signal are the odd harmonics of the target pattern. The MTF curve determined by the MTF values at the odd harmonics of the target pattern can be used to calculate the MTF at Nyquist frequency. The new method has better development in the present experimental conditions.This article analyses the theory of new test method, and make the simulation of the theory. By simulating the bar target pattern and output signal and calculating the MTF, we verify the correctness of the theory. We use the actual target to conduct an experiment and compare the experimental results with the traditional measurements in order to verify the applicability of the theory better.