科学级TDICCD相机的行频精度

Precision of row frequency of scientific grade TDICCD camera

从工程实际出发,以相机侧摆成像为例,系统分析了行频精度对TDICCD相机成像质量的影响。首先,推导了相机侧摆时焦平面各像元的像移速度求解公式,建立了侧摆角度与像移大小的一般关系式。在此基础上,采用调制传递函数(MTF)作为评价相机成像质量的指标,分析了像移失配对MTF的影响,计算导出了行频精度对成像质量的影响。结果表明,侧摆角度越大,积分级数越高,对行频精度的要求就越高,反之越低。在实际工程应用中(侧摆35°条件下),积分级数为64级和96级成像时,行频精度只要分别不低于0.54%和0.36%就能使MTFmatch≥0.95,满足系统对传递函数的要求。将实验结果与计算分析结果进行对比,验证了分析的正确性,该结论对实际工程应用和设计有指导作用。

In view of practical projects,this paper analyzed the influence of the precision of row frequency on the image quality of a TDICCD camera systematically by taking scroll imaging for an example.Firstly,the expression of the image motion of each pixel was deduced when the camera was scroll imaging,and the relationship between scroll angle and image motion velocity was established.Based on this,the Modulation Transfer Function（MTF）was used to evaluate the image quality.The influence of image motion mismatching on the MTF was analyzed in detail,and the dependence of image quality on the precision of row frequency was calculated.The results show that the bigger the scroll angle and the integral number of TDICCD are,the higher the precision of required row frequency is.Contrarily,the precision of row frequency is not required strictly.In engineering application（the scroll angle is 35°）,when the integral numbers of the camera are 64and 96,the precision of row frequency should be no less than 0.54%and 0.36%respectively for MTFmatch≥0.95,which meets the need of the system.Comparing the experimental results with the calculation analysis,it is proved that the analyzed results are correct and can provide the useful references for engineering application and designing.