Abstract

Current imaging systems for TEM place a variety of artificial limitations on efficiency, resolution, speed, dynamic range and field of view. Since these limitation are introduced primarily by the principle of operation of current detectors, little can be achieved by modifying the current cameras. New imaging systems based on new detection concepts are key in overcoming these limitations.

This seminar aims to introduce the main concepts in position sensitive particle detections and to provide an overview of the main detection systems in use, not only in electron microscopy, but also in other research areas, such as particle physics and astronomy. A number of detection systems will be compared, focusing on strip detectors, charge coupled devices and active pixel detectors. Direct and indirect detection, as well as counting and integration methods will be discussed, highlighting the advantages and disadvantages of each in relation with TEM .

Expected improvements in electron detection will be discussed, indicating the benefits for a number of TEM -based techniques. It will be shown that noiseless detection with a tremendous improvement in efficiency is possible, with great benefits in microscopy of electron sensitive materials, such as biological molecules and viruses. Detection speed will also be discussed, showing that frame rates in the range of kHz can be obtained, increasing the time resolution in TEM by a few orders of magnitude. It will also be shown that unlimited dynamic range can be obtained with new detectors, bringing significant advantages in quantitative electron diffraction and EELS .