対物絞り

objective aperture

[目次：レンズ系]

明視野像や暗視野像を得るために透過波や回折波のひとつを取り込むための絞り。対物レンズの後焦点面に挿入される。 絞りの直径は5～100μm。以前は格子像、構造像をとるときにも挿入されたが、最近は使わないことが多い。絞りを使って急なカットを入れたデータを使ってコンピュータ処理をするとアーティファクトが現れることがあるためである。

The "objective aperture" is used for accepting a transmitted wave or one of diffracted waves to obtain a bright-field image or a dark-field image. The objective aperture is inserted into the back focal plane of the objective lens. The diameter of the objective aperture is 5 μm to 100 μm. It is noted that this aperture was inserted when obtaining a lattice image or a structure image, but recently, it has not been used. The reason for this is as follows. If computer processing is applied to the data which has a sharp cut due to the aperture, artifacts can appear in the processed image.

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