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Sound Clip: Watches by Mike Rooke
A DIY stereo laser vibrometer tour around the moving parts of a mechanical watch. The lasers track between the balance and escapement, oscillating back and forth. The device is a small telescope sight tube with a laser mounted inside it behind the main objective. The beam shines out from the telescope to the object of interest. Reflections are captured down the same telescope into the eye piece where two light dependent resistors are mounted. Working distance is 20-40 cm.