Patent ID: 6414802
Filing Date: 2002-07-02
Classification: G02B

Abstract:
An optical system for producing an image of an object, said system having an object side, an image side, an overall positive focal length f0, and comprising in order from its object side to its image side of:(a) a first lens unit having: (i) a negative power or a weak positive power; and (ii) an object side surface and an image side surface; (b) a second lens unit having: (i) a positive power; and (ii) an object side surface and an image side surface; and (c) a third lens unit having a negative power, the magnitude of the focal length of the third lens unit being less than 1.5 times f0; â€ƒwherein: (i) each of the first, second, and third lens units comprises at least one aspherical surface; and (ii) said optical system has an aperture stop between the object side surface of the first lens unit and the image side surface of the second lens unit.