标本在暗背景下即呈现出光亮。

The specimen thus appears bright against a dark background.

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比如，在暗背景的微距拍摄时，直方图会显示在左侧有很多像素。

For instance, a macro shot with a black background will have a histogram that has a lot of pixels at the extreme left end of the graph.

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本文讨论了影响等厚条纹对比度的原因，指出了暗背景光学元件的优点。

The causes of interfering with the contrast of equal thickness fringes are discussed. The advantages of optical components of dark background are presented.

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