An optical comparator is an instrument that projects a greatly magnified image of a part feature onto a screen for examination, to compare the shape, size, and location of its features.

这款光学比较仪，是一款可局部放大零件的设备。可用于检查设备，比较形状，尺寸和方位。主要应用于工业领域。

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"Size of Wales" was founded by Welsh environmentalists annoyed that their country was often used in the media as a comparator to gauge the scale of rainforest destruction.

BBC: Charity reaches rainforest goal