中間レンズ

intermediate lens

対物レンズと投影レンズの間にあるレンズ。励磁電流を調整して中間レンズの焦点距離を変えて、対物レンズによって作られる回折図形またはTEM像に焦点を合わせて、それらを拡大し投影レンズの物面にそれらの像を作る。通常、中間レンズは3段構成で、1段目は主に焦点合わせに、2段目は像の拡大に、3段目は主に無回転像を作るために使われる。中間レンズの倍率は～0.5～100倍。倍率100倍のときの内訳は1段目 4～5倍、2段目～10倍、3段目 2～3倍。

The "intermediate lens" is placed between the objective lens and the projector lens. The intermediate lens works in the following way. The intermediate lens changes focusing position either on a diffraction pattern or a TEM image produced by the objective lens by adjusting its excitation, and forms the magnified pattern or image on the object plane of the projector lens. Normally, the intermediate lens consists of three parts: The first part mainly selects focusing position, the second part magnifies the focused pattern or image, and the third part mainly achieves rotation-free condition. The magnification of the intermediate lens is varied from ～0.5× to ～100×. When the total magnification is 100×, the magnifications for the first, second and third parts are 4× to 5×, ～10×, and 2× to 3×, respectively.