68-237 25mm Dia. Germanium Infrared Aspheric Lens; EFL=20mm; NA=0.63 Uncoated

This is a 25mm diameter Germanium Infrared Aspheric Lens, catalog number 68-237, available from Edmund Optics. The lens has a focal length of 20mm and a numerical aperture of 0.63, making it suitable for a wide range of infrared applications. The lens is uncoated, which can be beneficial in certain applications where a specific coating is not required or desirable.

The lens geometry includes an inner radius of 0mm, an outer radius of 0mm, a thickness at the edge of 2.5mm, and a thickness at the center of 3.7mm. The back focal length is 19.08mm, and the aspheric surface is defined by a conic constant of 0 and a quadratic term of 0. The lens has no coating, as indicated by the empty "coating" parameter in the item data.

The lens is made of germanium, a material known for its high refractive index and transparency in the infrared region of the spectrum. This makes it an ideal choice for applications such as thermal imaging, night vision, and other infrared-based technologies.

The lens is currently in stock and can be purchased directly from the Edmund Optics website using the provided weblink. The link has been verified and is currently valid.