Near-infrared laser focusing lens and laser printing device

Abstract

A near-infrared laser focusing lens and a laser printing device are provided. The lens comprises a first lens, a second lens, a third lens, a fourth lens and a fifth lens (L, L, L, L, L) which are coaxially arranged along a transmission direction of incident light rays, wherein the first lens (L) is a negative plane-concave lens; the second lens and the third lens (L, L) are positive biconvex lenses; and the fourth lens and the fifth lens (L, L) are positive meniscus lenses; and a concave surface (S) of the first lens (L) is opposite to the second lens (L), and the middle parts of the fourth lens and the fifth lens (L, L) both reversely protrude towards the transmission direction of light beams. After the shapes and the relative locations of the lenses are designed, the near infrared light can be clearly imaged, and the geometrical aberration of the lens can be effectively corrected, so as to obtain a clear flat field. In addition, because of having a large relative aperture and visual field and a long working distance, the lens is a microscope objective simultaneously having a large visual field, a large relative aperture, a long working distance and a flat field, and is capable of improving printing precision and clarity, so that the color rendition is truer and the operation is more convenient.