AL2550 25 mm Dia. N-BK7 High-Precision; CNC Polished Aspheric Lenses; EFL=50 mm; NA=0.23 Uncoated

The AL2550 is a high-precision aspheric lens offered by Thorlabs, a leading global manufacturer of photonics equipment. This lens, crafted from N-BK7 Schott glass, boasts a 25 mm diameter and a focal length of 50 mm, making it ideal for a wide range of optical applications.

The lens's aspheric design, characterized by its non-spherical surface, offers superior image quality compared to traditional spherical lenses. This is achieved by reducing spherical aberration, a common issue in optical systems where light rays fail to converge at a single point. The aspheric shape ensures that light rays are correctly focused, resulting in sharper images and improved system performance.

The AL2550 features a numerical aperture (NA) of 0.23, which quantifies the lens's ability to gather light. A higher NA allows for greater light-gathering capability, making this lens suitable for applications requiring high light transmission.

The lens is uncoated, meaning it does not have any additional layers to enhance its optical properties. While coatings can reduce reflection, increase transmission, and protect the lens surface, an uncoated lens can be advantageous in certain applications where specific coating properties are not required.

This lens is CNC polished, ensuring a high level of precision and surface quality. The edge thickness is 3 mm, and the center thickness is 6 mm, providing robustness and stability.