47-645 25 mm Dia. N-BK7/N-SF5 Achromatic Doublet; EFL=200mm VIS 0° 425-675nm

The 47-645 is a high-quality achromatic doublet lens, boasting a 25 mm diameter and an effective focal length (EFL) of 200mm, specifically designed for the visible light spectrum ranging from 425 to 675nm. This lens is sourced from the renowned optical vendor, Edmund Optics, and is available for purchase through their website.

The lens is constructed from two types of glass: N-BK7 and N-SF5, both from Schott, ensuring excellent optical performance. The front and back surfaces of the lens are coated with the EDM VIS-0 standard curve coating, providing improved light transmission and protection against environmental factors.

The lens geometry is intricately designed with precise radii and thicknesses. The edge thickness is 11.56mm, while the center thickness is 8.5mm. The lens features three distinct radius values: r1 at 124.12mm, r2 at -87.26mm, and r3 at -253.1mm. The inner and outer radii are both zero, indicating a circular shape.

This achromatic doublet lens is a multiplet, meaning it is composed of multiple optical elements. The multiplet design helps to correct chromatic aberration, a common issue in lens systems where different colors of light focus at different points. This lens is specifically designed to bring two wavelengths into focus on the same plane, ensuring sharp and clear images.