Optical system with particular optical distortion

Abstract

An optical system satisfies conditions related to the optical distortion at the maximum image height and at eighty and sixty percent of the maximum image height in order to reduce the actual observed distortion of an image, for example, an image on a monitor, by balancing the optical distortion with TV distortion. The optical system may be a single focus lens that includes, in order from the object side: a diaphragm stop; and first and second lens components. An aspheric equation that includes a nonzero aspheric coefficient of order three or higher may determine an aspheric shape of a lens surface of the second lens component. Both lens components may be made of plastic.

Description

BACKGROUND OF THE INVENTION In recent years, along with the popularization of personal computers into homes, digital still cameras (hereinafter referred to simply as digital cameras) that enable input of picture image information, such as photographed landscapes and portraits, into a personal computer are rapidly becoming more popular. Additionally, with enhancements in portable telephone functions, portable cameras that include compact imaging modules are rapidly becoming more popular. Additionally, including an imaging module in compact information terminal equipment, such as PDAs (Personal Digital Assistants), is becoming popular. In such devices that include an imaging function, an image pickup element, such as a CCD (Charge Coupled Device) or a CMOS (Complementary Metal Oxide Semiconductor), is used to provide the imaging function. Recently, advancements in the miniaturization of such image pickup elements have been rapidly increasing. This has resulted in a desire for the ma...

AI Technical Summary

Benefits of technology

The present invention relates to an optical system that can be extremely compact, uses a small number of lens components and lens elements, and can achieve high optical performance with hardly noticeable distortion of an actual image. The present invention relates particularly to such a single focus lens that can be mounted in small information terminal equipment such as portable phones with a camera and in PDAs.

Problems solved by technology

However, as the number of lens components and lens elements is reduced, it becomes more difficult to achieve nearly ideal performance.

However, with a very small number of lens components and / or lens elements, such as only two or three, it is difficult to adequately correct all of the aberrations over the entire field of view.

However, a picture viewed on a monitor screen is also subject to TV distortion independent of the optical distortion of the imaging lens, and therefore TV distortion should also be considered in designing an imaging lens in order to minimize the distortion of a picture when viewed on a monitor screen.

For example, although optical distortion of the imaging lens may occur over the field of view, the perceived distortion of a viewed picture on a monitor screen may become unnoticeable by properly balancing optical distortion of the imaging lens and TV distortion.

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