18-749 15mm Dia. N-FK58 NIR Aspheric Lens; EFL=15mm; NA=0.5 Uncoated

This is the 18-749 model from Edmund Optics, a high-quality 15mm Dia. N-FK58 NIR Aspheric Lens with an effective focal length of 15mm and a numerical aperture of 0.5, uncoated. The lens is made of N-FK58 Schott material, a popular choice for its excellent optical properties in the near-infrared (NIR) region.

The lens features a circular base shape with a diameter of 15mm, and a thickness of 3.31mm at the edge and 8mm at the center. The inner and outer radii are not specified, indicating that they may not be relevant for this particular lens design. The lens has a high numerical aperture (NA) of 0.5, which is beneficial for applications requiring high light-gathering capability or high resolution.

The aspheric design of this lens is a significant advantage over traditional spherical lenses. It provides superior image quality by reducing spherical aberration, coma, and other optical aberrations. The lens has a conic constant of -1.021 and a second-order aspheric coefficient of 0, indicating a relatively simple aspheric surface.

The uncoated version of this lens is suitable for applications where anti-reflection coating is not required or desired. However, for applications where high transmission and low reflection are critical, coated versions are available.