This book (Practical Electron Microscopy and Database) is a reference for TEM and SEM students, operators, engineers, technicians, managers, and researchers.
 

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Sasaki et al. [1-3] proposed that a delta corrector could simultaneously compensate for spherical aberration O₄ and 6-fold astigmatism A₆. Figure 2236 shows the photograph of a LVEM (low-voltage electron microscope) with delta C_s correctors operated in the range 30 - 60 kV. The CFEG stands for cold field emission gun installed on the top of the column. The delta correctors for STEM and TEM are integrated for both probe- and image-forming systems. An Enfina spectrometer is installed at the bottom of the column for EELS-based measurements.

Figure 2236. The photograph of a LVEM with delta C_s correctors operated in the range 30 - 60 kV. [3]

[1] Sawada H, Sasaki T, Hosokawa F, Yuasa S, Terao M, Kawazoe M, Nakamichi T, Kaneyama T, Kondo Y, Kimoto K, and Suenaga K
(2009) Correction of higher order geometrical aberration by triple 3-fold astigmatism field. J. Electron Microsc. 58: 341–347.
[2] Sawada H, Sasaki T, Hosokawa F, Yuasa S, Terao M, Kawazoe M, Nakamichi T, Kaneyama T, Kondo Y, Kimoto K, and Suenaga K
(2010) Higher-order aberration corrector for an image-forming system in a transmission electron microscope. Ultramicroscopy, doi:10.1016/j.
ultramic.2010.01.010.
[3] Takeo Sasaki, Hidetaka Sawada, Fumio Hosokawa, Yuji Kohno, Takeshi Tomita, Toshikatsu Kaneyama, Yukihito Kondo, Koji Kimoto, Yuta Sato, and Kazu Suenaga, Performance of low-voltage STEM/TEM with delta corrector and cold field emission gun, Journal of Electron Microscopy 59(Supplement): S7–S13 (2010).