CCD CAMERA CHARACTERIZATION FOR 400 KEV ELECTRON MICROSCOPY

葡萄糖包埋的紫色膜被用作测试样本， 评估400 kV点扫描恢复相位的可靠性 在Gatan制造的1024x1024慢扫描CCD相机上获得的图像。 选择这个标本是因为它代表了一个广泛的类别， 低对比度辐射敏感生物体及其结构 是公认的。 计算的反射的振幅， 这些图像受到调制传递函数的强烈衰减 摄像头的位置。 然而，它们的平均相位< 12-与亨德森的参考数据相差高达8.8
分辨率，相当于0.8的奈奎斯特频率的 相机 使用不同的相机也观察到类似的结果 由Tietz用100千伏电子制造。 这些结果表明，CCD 照相机可以是一种可行的记录介质， 记录晶体样品（如紫色）图像的胶片 膜的

Glucose-embedded purple membranes were used as a test specimen to evaluate the reliability of phases retrieved from 400 kV spot-scan images acquired on a 1024x1024 slow-scan CCD camera made by Gatan. This specimen was chosen because it represents a broad class of low-contrast radiation-sensitive biological objects and its structure is well established. The amplitudes of computed reflections from these images were strongly damped by the modulation transfer function of the camera. Nevertheless, their phases on average were < 12-different from the reference data of Henderson up to 8.8
resolution, which corresponds to 0.8 of the Nyquist frequency of the camera. Similar results are also observed with a different camera made by Tietz with 100 kV electrons. These results confirm that CCD camera can be a viable recording medium that can replace photographic film for recording images of crystalline specimens such as purple membrane.