The 47-904 is a Double-Convex Lens, a type of Spherical Lens, sourced from Edmund Optics. This lens, with a base shape of Circular, is designed for use within the visible light spectrum, specifically at a wavelength of 587.6nm. The lens features a diameter of 20mm and a thickness at the edge of 2.8mm, while the center thickness measures 5.3mm. The Effective Focal Length (EFL) is 40mm, and the Back Focal Length (BFL) is 38.44mm.
The lens is made from N-BK7 Schott, a popular optical glass due to its excellent optical properties and relatively low cost. The front and back surfaces of the lens are coated with the EDM VIS-0 Standard Curve coating, which is designed for use within the visible light spectrum (425-675nm). This coating enhances the lens's performance by reducing surface reflections, thereby increasing transmission.
The lens's geometry is characterized by its first and second radii of curvature, which are 40.67mm and -40.67mm, respectively. The Inner Radius and Outer Radius are both 0mm, indicating that this lens has no peripheral features that would affect its optical properties.