電圧軸

accelerating (acceleration) voltage center

[目次：レンズ系]

高圧ウォブラで加速電圧に変動を加えたとき電顕像が渦巻状に拡大縮小する。その拡大縮小の中心をいう。電圧軸の中心を二段偏向系を使って像観察用の蛍光板の中心に合わせることを電圧軸合わせという。高圧の変動は小さいので(10^-6以下)、高圧変動を対象とした調整というより試料による非弾性散乱（プラズモン散乱）を対象とした調整といえる。10万倍以下の中倍率の像の場合に必要な軸合わせ。

When fluctuations are added to accelerating voltage using a high-tension wobbler, a TEM image spirally enlarges and shrinks. The center of this enlargement and shrinkage is called "accelerating (acceleration) voltage center." Alignment of the accelerating voltage center is carried out to bring the accelerating voltage center to the center of the fluorescent screen for viewing the image by the use of a double-deflection coil system. Since the fluctuations of the high voltage are small (<10^-6), this alignment is used to minimize the effect of energy spread due to inelastic scattering (plasmon scattering) in a specimen rather than the effect of high-voltage fluctuations. This alignment is required when taking images at a medium magnification lower than 100,000×.

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