Publication Date:
2013-02-19
Description:
Novel spherical aberration (Cs) and chromatic aberration (Cc) correctors, which correct aberrations using a new principle, were developed. The asymmetric Cs correctors were designed for use in the probe- and image-forming systems at 300 kV to diminish undesired parasitic aberrations. The correctors composed of non-equivalent multipoles connecting with a demagnifying transfer doublet in the system. The axial aberrations were corrected well up to the fifth order except 6-fold astigmatism ( A 6 ) experimentally. Next, we developed superior Cs correctors for probe- and image-forming systems of low voltage microscope that uses triple dodecapoles to correct 6-fold astigmatism ( A 6 ). An important feature of this system is the rotation of the 3-fold astigmatism azimuth at the second dodecapole. The optimum rotation of the three hexapole fields for the compensation of A 6 was derived from theoretical calculations. The experimental results confirmed the compensation of A 6 and the third-order Cs. Finally, a unique Cc corrector, which utilized the concave lens effect formed by a long quadrupole field, was designed. The performance of the Cc corrector was investigated using a 30-kV transmission electron microscope. The results confirmed that Cc correction was achieved.
Print ISSN:
0022-0744
Electronic ISSN:
1477-9986
Topics:
Electrical Engineering, Measurement and Control Technology
,
Natural Sciences in General
,
Physics
