AL1225 12.5 mm Dia. N-BK7 High-Precision; CNC Polished Aspheric Lenses; EFL=25 mm; NA=0.23 Uncoated

The AL1225 is a high-precision aspheric lens offered by Thorlabs, boasting a 12.5 mm diameter and a focal length of 25 mm. This lens is crafted from N-BK7, a popular glass type known for its excellent optical properties, making it an ideal choice for various applications.

The lens's asphere is CNC polished, ensuring high-quality surfaces and accurate shaping. This aspheric design helps minimize spherical aberration, a common issue in traditional spherical lenses, thereby improving image quality and resolution. The lens's NA (numerical aperture) is 0.23, which is a good balance between depth of field and light-gathering capability.

The lens is uncoated, which means it does not have any anti-reflective coatings. While this may result in higher reflective losses, it also means the lens is more cost-effective and simpler to use, making it suitable for applications where such losses are acceptable or can be mitigated.

The lens's geometry includes a 2.5 mm thickness at the edge and a 4 mm thickness at the center, with the inner and outer radii being 0. It also features a series of aspheric coefficients (k1, a2, a4, a6, a8, a10, a12, a14, and a16) that define its precise shape.