Rod lens array, optical device, image sensor, printer, inspection apparatus, composition, and method for manufacturing refractive index distribution type rod lens

By forming an upright, equal-magnification rod lens array with an opening angle of 3–6° in glass wire and performing ion exchange treatment, the problem of small depth of field in the prior art is solved, realizing a rod lens array with large depth of field, improving the resolution and accuracy of image acquisition, adapting to the thickness deviation of the measured object, and reducing the cost of the device and its operation.

CN115836234BActive Publication Date: 2026-03-17NIPPON SHEET GLASS CO LTD
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Patent Information

Application Number
CN202180041961.5
Authority / Receiving Office
CN · China
Patent Type
Patents(China)
Current Assignee / Owner
Priority Date
2020-06-25
Filing Date
2021-06-14
Publication Date
2026-03-17
Estimated Expiration
2041-06-14

AI Technical Summary

Technical Problem

In the existing technology, the large aperture angle of the refractive index distribution rod lens results in a small depth of field, which makes it difficult to meet the needs of high-resolution image acquisition. In particular, when there is a deviation in the thickness of the object being measured, the focus is easily misaligned, resulting in unclear images or missed or misidentified defects.

Method used

An upright, equal-magnification rod lens array with an aperture angle of 3–6° is employed. The refractive index distribution is formed through ion exchange treatment in the glass wire, ensuring a modulation transfer function (MTF) value of over 30% at a spatial frequency of 6 lp/mm, a depth of field of 1.5–3.0 mm, and an imaging distance of 45–75 mm. Ion exchange treatment is performed using a base glass composition with specific glass compositions such as SiO2, TiO2, MgO, ZnO, and Li2O.

Benefits of technology

A large depth-of-field rod lens array was achieved, which improved the resolution and accuracy of image acquisition, adapted to the thickness deviation of the measured object, reduced the phenomenon of focus misalignment, and reduced the cost of the device and its operation.

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Abstract

A rod lens array (10a) has a plurality of refractive index distribution type rod lenses (1b) arranged in parallel with their optical axes, forming a positive erect equal magnification image. The refractive index distribution type rod lens (1b) has a refractive index distribution in the radial direction. The radius of the refractive index distribution type rod lens (1b) is denoted as r0. The refractive index at the center of the refractive index distribution type rod lens (1b), that is, the central refractive index, is denoted as n0. The refractive index distribution constant of the refractive index distribution type rod lens (1b) is denoted as A such that the refractive index at a distance r from the center of the refractive index distribution type rod lens (1b) is approximated as n(r) = n0·{1-(A / 2)·r 2}. The opening angle θ represented by the formula is 3-6°. The imaging distance of the rod lens array (10a) is 45-75 mm. The depth of field in which the value of the modulation transfer function (MTF) at a spatial frequency of 6 lp / mm is 30% or more is 1.5-3.0 mm.
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Citation Information

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