An Aspheric lens focuses or collimates light without introducing spherical aberration into the transmitted wavefront. For monochromatic sources, spherical aberration is often what prevents a single spherical lens from achieving diffraction-limited performance when focusing or collimating light. Thus, an aspheric lens is often the best single element solution for many applications including collimating the output of a fiber or laser diode, coupling light into a fiber, spatial filtering, or imaging light onto a detector. The IR aspheric lens is also ideal for collimating light from MWIR and LWIR lasers, including Quantum Cascade Lasers (QCL).

If an unmounted aspheric lens is being used to collimate the light from a point source or laser diode, the side with the greater radius of curvature should face the point source or laser diode. To collimate light using one of our mounted aspheric lenses, orient the housing so that the externally threaded end of the mount faces the source.

The Black Diamond-2 material has several advantages over germanium, which is traditionally used for aspheric IR optics. BD-2's coefficient of thermal expansion (CTE) and thermally stable refractive index (n) result in a smaller change in focal length as a function of temperature. While germanium suffers from transmission loss as temperature increases, BD-2 aspheric lenses can be used in environments up to 130 °C. BD-2 is a chalcogenide made up of an amorphous mixture of germanium (28%), antimony (12%), and selenium (60%).

• EFL: 1.873 mm
• NA: 0.85
• CA: 4.00 mm
• WD: 0.72 mm
• DW: 9.5 µm
• Glass: BD-2
• M: Infinite