Compact high resolution athermal objective lens with front aperture stop

A method of detecting an image of a scene with an objective lens assembly, the method comprising:

• directing visible light through a first lens group of the objective lens assembly, the first lens group being configured to have a positive refractive power and positioned to receive visible light along an optical path extending through the objective lens assembly;
• directing visible light from the first lens group through a center lens to a second lens group of the objective lens assembly, the second lens group being configured to have a negative refractive power and being positioned along the optical path to receive the visible light from the first lens group and the center lens;
• and
• detecting an image from the visible light with an optical receiver centered along the optical path and positioned to receive the visible light from the second lens group,
• wherein an aperture stop is centered along the optical path and positioned in front of the first lens group to direct visible light from the scene to the first lens group.