66-325 50 mm Dia. L-BAL35 Precision Aspheric Lens; EFL=37.5mm; NA=0.66 BBAR 425-675nm

The 66-325 is a high-precision aspheric lens offered by Edmund Optics, boasting a 50 mm diameter and a numerical aperture of 0.66. This lens is designed for use in the visible spectrum, with a wavelength of 587.6 nm.

The lens is made from L-BAL35, a material from Ohara, and features a broadband anti-reflection (BBAR) coating, optimized for the 425-675 nm range. This coating enhances the lens's performance by reducing surface reflections, thereby improving transmission and image quality.

The lens's geometry is carefully designed, with an inner radius of 0 mm, an outer radius of 0 mm, and a thickness at the edge of 3.23 mm. The effective focal length (EFL) is 37.5 mm, and the back focal length (BFL) is 25.74 mm. The lens's center thickness is 19.4 mm, and it has a high refractive power, thanks to its short focal length and large diameter.

The lens's aspheric shape is defined by its first and second radii of curvature (R1 and R2), which are 22.781 mm and 500 mm, respectively. The lens's conic constant (K1) is -0.632106, indicating a slightly hyperbolic shape. This shape helps correct spherical aberration, a common issue in traditional spherical lenses, thereby improving the image quality.