fixed focus lens

Abstract

The invention discloses a fixed-focus lens. The fixed-focus lens comprises in sequence from the object side to the imaging surface: a first lens with negative refractive power, the object side of the first lens is a convex surface, and the image side is a concave surface; A second lens with positive refractive power, the object side of the second lens is a convex surface, and the image side is a plane; a diaphragm; a third lens with positive refractive power, the object side and the image side of the third lens are convex surfaces ; The fourth lens with negative refractive power, the object side of the fourth lens is convex, and the image side is concave; the fifth lens with positive refractive power, the object side of the fifth lens is concave, and the image side is A convex surface; a sixth lens with negative refractive power, the object side and the image side of the sixth lens are both concave at the near optical axis, and the object side and the image side of the sixth lens both have inflection points. The fixed-focus lens has uniform distribution of pixels in the full field of view, and has the advantages of small size, large imaging surface, small distortion, good thermal stability and high image quality.

Description

technical field [0001] The invention relates to the technical field of optical lenses, in particular to a fixed-focus lens. Background technique [0002] Distortion exists in all optical lenses. Distortion belongs to the geometric distortion of imaging. It is a phenomenon of image distortion and deformation caused by different magnifications of images in different areas on the focal plane. The degree of deformation increases from the center of the image to the edge of the image. Reflected more clearly at the edge of the screen. Distortion is usually divided into two types, barrel distortion and pincushion distortion; due to the distortion of the lens, the image formed by the subject passing through the optical system and projected onto the imaging chip will become barrel or pincushion. [0003] In order to reduce the image distortion caused by lens distortion, the camera usually has its own software to cut the circle around the imaging chip, and restore the image to a new i...

AI Technical Summary

Problems solved by technology

Although this method of stretching the image can solve the problem of image distortion caused by distortion, the image quality will be greatly affected by the large stretching changes, such as the sharpness and brightness of the image around the image will be reduced, and it cannot solve the problem of a part of the chip around the chip. The problem with unused pixels

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