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Abstract:
Image plates (IP) can be used for electron detection in the EM like conventional negative material [N. Mori et al., Ultramicroscopy 25 (1988) 195]. The stored information can later be retrieved by a scanning process in form of a digitized image. Although the physics of the electron storage process of the IPs in theory predicts electron detection with high spatial resolution, high detection efficiency and high dynamic range, in practice the scanning process limits resolution and detection efficiency. At present the scanners yield only moderate spatial resolution — about 100 μm effective pixel size (i.e. about 200 μm line resolution [S. Isoda et al., Ultramicroscopy 41 (1992) 99]. Data on the detection efficiency have not been published so far. Here we report a scanner of novel design with an improved optical detection device which gives highly increased spatial resolution (40 μm effective pixel size) and an optimal detection efficiency with a DQE of about 0.9. These properties are comparable to values published on slow-scan CCD cameras. Using subsequent scans of the same IP (which could register an image, an electron diffraction pattern or a parallel EELS recording) a linear dynamic detection range of almost 5 orders of magnitude is possible. We discuss how these properties of the IP scanner system could be utilized in future applications.
