Patent ID: 6621642
Filing Date: 2003-09-16
Classification: G02B

Abstract:
An optical device comprising:a zoom lens system; and an image sensor for converting an optical image formed by said zoom lens system into an electrical signal; wherein said zoom lens system comprises, from an object side thereof to an image side thereof, a first lens unit having a negative optical power, a second lens unit having a positive optical power, and a third lens unit having a positive optical power; wherein said zoom lens system achieves zooming by varying unit-to-unit distances; wherein each of said first lens unit, said second lens unit, and said third lens unit is comprised of a single lens element; wherein at least said first lens unit and said second lens unit are moved along an optical axis during zooming, and the following conditional formula is fulfilled: 0.22-3/fW<1.2 â€ƒwhere tW2-3 represents an optical path length from a most image-side lens surface in said second lens unit to a most object-side lens surface in said third lens unit at a wide-angle end; and fW represents a focal length of the entire zoom lens system at the wide-angle end.