Patent ID: 8687472

Claim:
An apparatus comprising: a light source configured to produce light; a lens configured to focus the light on an optical disc, wherein the lens is configured to i) focus on a data layer of the optical disc while in a first position relative to the optical disc, and ii) focus on an outer surface of the optical disc while in a second position relative to the optical disc, wherein the first position is a first distance from the outer surface of the optical disc, and the second position is a second distance from the outer surface of the optical disc that is different from the first distance; a photo detector configured to obtain a measurement of the light reflected by the optical disc while the lens is in the second position; and a controller configured to i) control movement of the lens to the second position to focus the lens on the outer surface of the optical disc, and ii) determine a cleanliness of the lens based on the measurement of the light reflected by the optical disc while the lens is focusing the light on the outer surface of the optical disc.