间距对图像传感器调制传递函数矩形模板接触测量的影响

Effect of Distance on Modulation Transfer Function of Imaging Sensor Using Rectangle Template Contact Method

为了简易、方便地测量图像传感器的调制传递函数,可以采用将模板直接投射在图像传感器上的办法来测量。实际测试中通常采用矩形模板,而且模板距离图像传感器光敏面有一定距离。从理论上分析了矩形模板和图像传感器光敏面不同间距情况下的光场分布,比较了用此光场分布函数测量图像传感器调制传递函数与采用正弦模板接触式测量法测得的调制传递函数值之间的差异。最后采用空间频率为50 mm-1的高对比矩形光栅进行了实验,测得调制传递函数为0.22,而修正后的调制传递函数值为0.18。结果表明修正后的调制传递函数值更准确,能更准确地评价图像传感器的性能。

In order to measure the modulation transfer function of the imaging sensor simply and expediently, the method with the template directly projecting on the imaging sensor has been adopted. Usually, the rectangle template is adopted, and there is a distance between the template and the photosensitive surface, which is critical in the measurement. The optical distribution on the rectangle template and the photosensitive surface with different distances are theoretically analyzed. Modulation transfer functions are derived with the optical distribution function and the sine template contact measurement respectively and compared. The experiment has been carried out, using rectangular grating with the spatial frequency 50 mm 1, and the experimental value of the modulation transfer function is 0.22, which is corrected to be 0.18. The result indicates that this modified modulation transfer function is more accurate, and the performance of the imaging sensor can be appraised more correctly.