Patent ID: 7345829

Claim:
An objective lens device of a single-lens construction, comprising: an objective lens element having a convex aspherical surface forming a first surface upon which light from a light source is incident; the objective lens element having a numerical aperture NA of at least 0.8; the objective lens element having an off-axis wavefront aberration at an angle of view of 0.5° and a standard wavelength λ which is equal to or less than 0.07 λrms; the first surface having an effective surface diameter of a radius R E (mm); the objective lens element having an outer diameter a radius R O (mm) and which is greater than said effective surface diameter of said first surface; the radius R O (mm) of the outer diameter and the radius R E (mm) of the effective surface diameter of the first surface satisfying the relationship 0.2≦( R O −R E )≦0.6.