19 Sep 2016 For most situations, spherical optics are used to focus laser beams. For applications requiring a very short focal length, spherical aberrations can become an issue.
Aspheric lenses with at least one free-form surface produced using CNC polishing techniques can greatly reduce this effect. Ideally, aspherical lenses replace a system of several spherical lenses, thereby reducing weight and losses through surface scattering.
LASER COMPONENTS offers aspheric lenses for use in the FIR range in the following materials: ZnSe, Ge, Si, CaF2, Cu and Al. For a substrate with diameter 150mm a shape deviation of ½ fringe and a surface roughness is < 30 Å RMS can be achieved.
The aspheres can be coated according to customer request for all wavelengths from 2µm to 16µm.
http://www.lasercomponents.com/uk/optics/laser-optics/ir-laser-optics/ | 
