Three-dimensional optical reconstruction using two-dimensional optical flow measured on the rotating groove surfaces of gramophone recordings will enhance our ability to preserve this valuable audio legacy without depending on mechanical contact playback. A modified microscope overcame the limitation of a shallow depth of field by using a thin glass plate to obtain an image at a second focal length. Sound is decoded from the orientation of the groove surface. The algorithm has been tested and validated using both damaged and undamaged records. Informal listening tests confirmed a subjective reduction of pops and other degradations.
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