オブジェクティブミニレンズ

objective mini lens

対物レンズの下におかれる弱いレンズ。対物レンズのように磁場を強めるポールピースを持たない。Low MAGモードで低倍率(～50～3000倍)を得るとき、対物レンズの励磁を切ってオブジェクティブミニレンズで制限視野絞り上に結像するために使われる。倍率は1～2倍。もう一つの使い方は、MAGモードで1000倍程度の低倍率を得るとき、対物レンズの性能(像質)を下げないために強励磁にしておき、オブジェクティブミニレンズを使って像を縮小（～0.5倍）し、広い視野を中間レンズに導くために使われる。

The "objective mini lens" is a weakly excited lens placed below the objective lens. This lens does not have a polepiece to strengthen a magnetic field as the objective lens does. This lens is used to form an image on the selector aperture in Low MAG mode (～50× to 3,000×) by stopping the excitation of the objective lens. The magnification at the objective mini lens is 1× to 2×. This lens is also used to obtain a high quality low magnification image of about 1,000× in the MAG mode. That is, the excitation of the objective lens is kept strong to maintain image quality of the objective-lens, and the image is demagnified (to ～0.5×) by the objective mini lens, thus a wide view image is formed on the object plane of the intermediate lens.