摘要 |
A system includes a measuring tool, a fixture, and a rotatable target. The measuring tool includes a light source, an imaging device, and an electronic circuit. The fixture allows the rotatable target to rotate about an axis. The rotatable target includes a surface having microscopic asperities. The imaging device is mounted to provide a sequence of images derived from said microscopic asperities. The electronic circuit is connected to the imaging device for measuring rotation of the rotatable target from the sequence of images.
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