Patent ID: 8014084

Claim:
An optical assembly, comprising: a first lens having positive refractive power and at least two aspheric surfaces, the first lens is located at a first distance from an aperture on an optical axis common to the first lens and the aperture, the optical axis being substantially cylindrically-symmetric; a second lens having negative refractive power and at least two aspheric surfaces, the second lens is meniscus-shaped near the optical axis and is located at a second distance from the first lens on the optical axis; and a third lens having positive refractive power and at least two aspheric surfaces, the third lens is meniscus-shaped near the optical axis and is located at a third distance from the second lens on the optical axis, wherein a real image of an object produced by the optical assembly has a defocus aberration coefficient greater than 0.1 at a focal plane of the optical assembly.