An optical variable power module has a movable lens unit slidably mounted on a chassis, such that the lens unit is moved along an optical axis defined thereby, and a movable mirror unit slidably mounted on the chassis, such that the mirror unit is moved along the optical axis of the lens unit. The movable...http://www.google.es/patents/US5926330?utm_source=gb-gplus-sharePatente US5926330 - Optical variable power module
