Lens system, fisheye lens and image acquisition device

Abstract

The application discloses a lens system, a fisheye lens and an image acquisition device, which are used to avoid virtual focus of the lens system in a working environment where the temperature is too low or too high, thereby improving the working stability of the lens system. A lens system provided in an embodiment of the present application, the lens system includes: a first lens group with a negative refractive power, a second lens group with a positive refractive power, and a lens group with a refractive power of Positive third lens group; the third lens group includes: the seventh lens with positive refractive power, the eighth lens with negative refractive power, and the ninth lens with positive refractive power arranged in sequence from the object side to the image side lens, and the tenth lens with positive refractive power; the dispersion coefficient Vd and the coefficient of refractive index variation with temperature dn / dt of the seventh lens, the ninth lens, and the tenth lens all meet the following conditions: Vd>68, dn / dt ≤‑5.6; where, the unit of the coefficient of variation of the refractive index with temperature dn / dt is 10 ‑6 / °C.

Description

technical field [0001] The present application relates to the field of optical instruments, in particular to a lens system, a fisheye lens and an image acquisition device. Background technique [0002] The fisheye lens is widely used in the field of security monitoring because of its field of view of more than 180 degrees. However, most of the fisheye lenses in the prior art cannot meet the requirements of 4K resolution, and a small number of products that can meet the 4K resolution have the problems of small target area and low utilization rate of sensors. Moreover, in the fisheye lens in the prior art, the ratio of the total length of the system to the focal length is too large, which makes it difficult to control the size of the lens, and the miniaturization of the lens cannot be realized. In addition, when the ambient temperature of the fisheye lens in the prior art is too low or too high, for example, in the extreme working environment where the temperature is -30 degr...

AI Technical Summary

Problems solved by technology

However, most of the fisheye lenses in the existing technology cannot meet the requirements of 4K resolution, and a small number of products can meet the requirements of 4K resolution, which has the problems of small target surface and low utilization rate of sensors.

Moreover, in the fisheye lens in the prior art, the ratio of the total length of the system to the focal length is too large, which makes it difficult to control the size of the lens, and it is impossible to realize the miniaturization of the lens

In addition, when the ambient temperature of the fisheye lens in the prior art is too low or too high, for example, in the extreme working environment where the temperature is -30 degrees Celsius or 70 degrees Celsius, there will be a virtual focus problem, and the image quality will be poor, which will affect the use of the product. reliability

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