Zoom lens apparatus for recognizing eye iris mould

Abstract

The invention relates to a zoom lens apparatus used for an eye iris pattern recognition, consisting of a four-component mechanical compensation zoom lens and an eyeball alignment device. The zoom process requires air space on: D1 plus D2 equals C1, D3 plus l' equals C2, C1 and C2 are set values. By taking the measures of causing the distance TC equaling to C3 from the first surface of the lens to an image surface to be an invariable value, amending the cam curve pointwise, arranging two diaphragms to limit aperture beams and the like, that the image surface is stable without focusing can be ensured when object distance varies within the design range, leading the multiplying power value M and image space value NA of objective images to basically remain unchanged; an optical device also has to meet the following prerequisites: C1 / fC short' is more than 1.24 and less than 1.32; l' / fC short' is more than 0.8; C3 is less than 4fC short'; f variable' / fC short' is more than 0.39 and less than 0.43; and Td-T760nm is less than 6lambda / (NA)<2>micron. The lens apparatus can lead the image surface to be stable, the multiplying power value M and image space value NA of objective images not to change with object distance and images to be clear in the conditions of change of the object distance within certain range.

Description

technical field [0001] The invention relates to an optical lens device, which is used for image acquisition of an eye iris pattern recognition system, and is especially suitable for key departments, military security, financial industry, access control of special occasions, protection of key cultural relics, etc., which require high security, high reliability and other strict identities. In the field of authentication, it can also be used for security and anti-counterfeiting systems in other modes such as blood vessels on the back of the hand and finger veins. Background technique [0002] Because some parts and organs of the human body have obvious uniqueness, lifelong invariance and difficult to replicate biological characteristics, making them an important basis for identification. With the continuous development of fast computer image processing technology, identification based on these biological characteristics, such as face, fingerprint, blood vessel on the back of th...

AI Technical Summary

Problems solved by technology

Due to the simple structure and fewer correction parameters that can adapt to different object distances and environmental changes, it obviously has the following deficiencies: First, the active target must be constantly and timely adjusted to obtain a clear image

In addition, the currently selected fixed focal length lens can adapt to a relatively narrow spectral range, and cannot adapt to the environmental conditions required by visible light and near-infrared lighting at the same time.

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