OPTICAL SYSTEM FOR BROADBAND SECURITY CAMERA

摘要

An optical system is provided to enable the optical system to be used both during days and nights by enlarging an operation wavelength range of the optical system. A first lens(10) has a negative refractive power and includes a convex surface toward an object and a concave surface toward an upper side. A second lens(20) has a positive refractive power and includes a convex surface toward the object and a concave or convex surface toward the upper side. The second lens is a spherical lens with a high refractive index between 1.90 and 1.95. A third lens(30) has a positive refractive power and includes a convex or concave surface toward the object and a convex surface toward the upper side. A fourth lens(40) has a positive refractive power and includes convex surfaces toward the object and the upper side. A fifth lens(50) has a negative refractive power and includes a concave surface toward the object and a concave or convex surface toward the upper side. The fourth lens is a spherical lens with a high refractive index between 1.90 and 1.95. A diaphragm(60) adjusts an amount of incident light from the second lens. A UV(Ultra-Violet) filter(70) is arranged on the fifth lens.