68-236 25mm Dia. Germanium Infrared Aspheric Lens; EFL=15mm; NA=0.83 Uncoated

This is a 25mm diameter Germanium Infrared Aspheric Lens, catalog number 68-236, available from Edmund Optics. The lens is uncoated and designed for use at a wavelength of 4000nm. It has a high numerical aperture (NA) of 0.83, indicating a wide angle of acceptance for incoming light. The effective focal length (EFL) of this lens is 15mm, making it suitable for a variety of imaging applications.

The lens geometry includes an inner radius of 0mm, an outer radius of 0mm, and a thickness at the edge of 2.47mm. The first radius of curvature (r1) is 45.37mm, while the second radius (r2) is 0mm, indicating a purely aspheric surface. The back focal length (BFL) is 14mm, and the thickness at the center of the lens is 4mm. The lens does not have any coatings, as indicated by the empty 'coating' parameter in the item data.

The lens is available directly from the vendor's website, and the link provided in the item data indicates that it is currently in stock. This makes it a readily available option for users seeking a high-quality, uncoated germanium aspheric lens for infrared applications.