Wide-angle lens

Abstract

The invention discloses a wide-angle lens, which comprises a first lens, a second lens, a third lens, a fourth lens and an aperture, wherein, the first lens, the second lens, the third lens, the aperture and the fourth lens are sequentially arranged from an object side. The first lens and the second lens are negative half-meniscus lenses with the convexities facing towards the object side; the third lens and the fourth lens are lenses with two convexities. With regard to the mirror faces of the first lens, the second lens and the third lens, at least four mirror surfaces are non-spherical surfaces, and the two mirror surfaces of the fourth lens are both non-spherical surfaces. When in use, even if the visual angle is as large as 140 degrees, the wide-angle lens can avoid the extreme distortion of the peripheral parts of imaging and ensure high sharpness of imaging, thus being fairly applicable to monitor and vehicle lenses.

Description

technical field The invention relates to a lens, in particular to a wide-angle lens. Background technique The biggest problem in the design of wide-angle lenses in the past is that the image of the object will be distorted after the optical action of the lens. In the past, there was only spherical glass, in order to compensate for the negative distortion of the image (or called barrel deformation) , that is, the closer to the edge in the imaging, the image will expand and the straight line will bend into an arc). It is necessary to configure multiple negative meniscus lenses and positive meniscus lenses at the front of the lens. When the lens viewing angle is 80°, 8 to 10 lenses are required, and 10 to 12 lenses are required when the lens angle of view exceeds 100°, which causes the problem that the overall length of the lens is too long and the weight is too heavy. Therefore, with the advancement of optical plastic materials and the popularization of aspheric lens manufac...

AI Technical Summary

Problems solved by technology

However, the problem of image distortion of these wide-angle lenses still exists. Ordinary lenses usually correct the distortion of imaging based on the projection method of y′=f·tanω, where y′ is the image height of a pixel, f is the focal length, and ω is Half angle of view, other projection methods include stereo projection method: y′=2f·tan(ω / 2), equidistant projection method: y′=f·ω, and equal solid angle projection method: y′=2f·sin(ω / 2) and the orthoprojection method: y′=2f·sinω, but from these formulas, it can be deduced that at a fixed focal length f, as the viewing angle and half viewing angle ω increase, the image height y′ of the pixel will also increase accordingly increase, when the value of y′ is too large, a complete image cannot be formed in the screen, and the surrounding images must be compressed to fully present the image in the screen, which makes it difficult to distinguish the surrounding images. If it is used on a monitor, it may be impossible to see the face of the prisoner due to the blurred surrounding image. If it is used on a car reversing monitoring system, the driver may ignore it due to the blurred surrounding image and bump into objects or children.

Although the current image processing technology is quite advanced, the distortion and aberration of the lens can be corrected by image processing technology, but the image after processing will inevitably be distorted. If the defect of peripheral image compression and blur can be directly avoided, the development of wide-angle lens is still a smooth road

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