Gatan CCD相机调节

如果发现拍的图片有六方形的暗影或者图片有问题的时，点prepare gain reference ，样品远离观察视野，将光斑散开满屏，然后抬屏就可以点了
prepare dark reference，将荧光屏放下，使得CCD无光源信号，即可操作
说明文件的原文如下：
3.2. Prepare dark reference image
This section only applies to DualVision 600 CCD camera which do not have a TEM shutter control. The DualVision 600 camera is shutterless. Since CCD dark current depends upon the temperature, CCD must reach its set target temperature before acquiring the dark reference image. Before starting the preparation procedure, lower the TEM viewing screen (make sure no electron beam illuminates the CCD sensor during the procedure). Under the Camera menu, choose Prepare Dark Reference and follow the screen instructions.
3.3. Prepare gain reference image
It is important to prepare a new gain reference image after the CCD has reached the equilibrium temperature (normally this takes about 1 -2 hours). The gain reference image should be checked daily. To prepare gain reference image, remove specimen from the field of view, evenly spread the illumination across the CCD sensor; for wide angle CCD cameras, this could mean that the illumination is evenly spread across the entire viewing screen in the TEM. Under the Camera menu, choose Prepare Gain Reference. Set the target intensity to the value of about half the dynamic range. For example, for 14-bit cameras, set the value to 8000 and 12-bit camera to 2500. Normally it is sufficient to set the frames to average to 4. Then simply follow the instructions on the screen.

恩恩我试试，谢谢啦！！

谢谢，又学了一招

应助达人

请教 二者的先后顺序有影响吗？

Dark reference 随便什么时候都可以做，一般相机不过热机器稳定时候都可以做。gain reference 需要相机调教好的时候做，过程比较长，可能在不同焦段gain reference还不同。参考相机的维护手册，没个型号的gain reference value不同。

两者为独立的功能，无先后，也并不是都需要做一遍，根据具体情况操作，这是gatan的ccd，其他品牌的ccd操作可能会有些许的不同