1. Improper sample preparation: there are problems such as poor sample quality, too low or too high concentration, and aggregation during sample preparation. These problems make it impossible to obtain a clear image of the sample under the electron microscope.
2. Incorrect freezing process: During the freezing process, it is necessary to control the temperature and speed of the sample to ensure that the freezing process of the sample structure is uniform. If the freezing speed is too fast or too slow, or the temperature is unstable, it will lead to uneven freezing of samples, and thus high-quality images cannot be obtained.
3. Improper setting of electron microscope parameters: the electron microscope operator needs to set the electron microscope parameters reasonably according to the nature and requirements of the sample, such as voltage, magnification and contrast. If the parameters are not set properly, the image will be blurred or the contrast will be insufficient.