EP0447548A1
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Method of manufacturing a plastic graded-index optical transmission element
Assignee: Mitsubishi Chemical Corp
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Filing: 1989-09-29
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Granted: —
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Expires: 2009-09-29
Abstract
Abstract This invention relates to a refractive index distribution type plastic transfer member which has a round section having a radius r₀ of 0.4 ∼ 0.6 mm, has a refractive index distribution substantially approximate to a predetermined ideal refractive index distributtion curve in a region of at least from 0.25 r₀ ∼ 0.70 r₀ from its center axis to the outer peripheral surface, and has a refractive index n₀ of 1.4 ∼ 1.6 at its center, a refractive index distribution constant of 0.3 ∼ 0.7 mm-¹ and a modulation transfer function (MTF) of at least 55 %. This optical transfer member is produced by arranging N(N ≧ 3) uncured liquid materials whose viscosity is 10³ ∼ 10⁸ poises and whose refractive indices n are n₁ > n₂ > n₃ ... n N , when they are cured, in such a way that n becomes progressively lower from the center to the outer peripheral surface, shaping them in an uncured strand fiber consisting of a plurality of concentric laminated layers, and curing the uncured strand fiber while, or after, applying mutual diffusion treatment of the materials between the adjacent layers.
Inventors
- 👤 Nobuhiko Mitsubishi Rayon Co. Ltd. Toyoda
- 👤 Yoshihiko Mitsubishi Rayon Co. Ltd. Mishina
- 👤 Ryuji Mitsubishi Rayon Co. Ltd. Murata
- 👤 Yoshihiro Mitsubishi Rayon Co. Ltd. Uozu
- 👤 Masaaki Mitsubishi Rayon Co. Ltd. Oda
- 👤 Teruta Mitsubishi Rayon Co. Ltd. Ishimaru
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-04 08:01
CPC Classifications
G; G02; G02B; G02B6/00; G02B3/00; G02B3/0087; B; B29; B29C; B29C48/00; B29C48/03; B29C48/05; G02B6/02; G02B6/02033; G02B6/02038
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
223 words
A distributed refractive index type optical transmission plastic article having a circular cross section of a radius r₀ and a refractive index distribution which substantially approximates a refractive index distribution curve defined by the following equation (1) at least in a range of O.25r₀ to 0.70r₀ extending from a center axis toward a peripheral face of the optical transmission article: n(r) = n₀{1 - (g²/2)r²} (1) where n₀ is a refractive index at the center axis of the optical transmission article; n(r) is a refractive index at a position of radius r away from the center axis of the optical transmission article; g is a refractive index distribution constant (mm⁻¹) of the optical transmission article; r is a distance (mm) from the center axis toward the peripheral face of the optical transmission article; and 1.4 ≦ n₀ ≦ 1.6 0.4 ≦ r₀ (mm) ≦ 0.6 0.3 ≦ g (mm⁻¹) ≦ 0.7 wherein when a grid image of 4 line-pairs/mm is formed through the optical transmission article on a CCD line sensor and a maximum value i max and a minimum value i min of light quantities of the image are measured, a modulation transfer function (MTF) calculated according to the following equation (2): MTF(%) = {(i max - i min )/(i max + i min )} x 100 (2) is at least 55%.
Claim 2
Dependent Claim
60 words
A distributed refractive index type optical transmission plastic article as set forth in claim 1, wherein the refractive index distribution of the optical transmission article substantially approximates the refractive index distribution curve defined by the equation (1) at least in a range of 0.20r₀ to 0.75r₀ extending from the center axis toward the peripheral face of the optical transmission article.
Claim 3
Independent Claim
113 words
A method of manufacturing a distributed refractive index type optical transmission plastic article comprising the steps of preparing N (N ≧ 3) uncured liquid substances having a viscosity between 10³ and 10⁸ poises each and refractive indexes n of n₁ > n₂ > n₃ ... n N when cured, concentrically laminating the substances in such a way that the refractive indexes are successively reduced from the center toward the periphery of the laminated substances to form an uncured strand fiber, mutually diffusing the substances between adjacent layers in such a way that the refractive indexes are continuously distributed between the layers, and at the same time or thereafter, curing the uncured strand fiber.
Claim 4
Dependent Claim
37 words
A method of manufacturing a distributed refractive index type optical transmission plastic article as set forth in claim 3, wherein the uncured liquid substances are made of a mixture of poly(methyl methacrylate) and radical polymeric vinyl monomers.
Claim 5
Dependent Claim
254 words
An optical transmission article array comprising an assembly of a plurality of distributed refractive index type plastic optical transmission articles arranged in a single line or a plurality of lines, said distributed refractive index type optical transmission plastic articles each having a circular cross section of a radius r₀ and a refractive index distribution which substantially approximates a refractive index distribution curve defined by the following equation (1) at least in a range of 0.25r₀ to 0.70r₀ extending from a center axis toward a peripheral face of the optical transmission article: n(r) = n₀{1 - (g²/2)r²} (1) where n₀ is a refractive index at the center axis of the optical transmission article; n(r) is a refractive index at a position of radius r away from the center axis of the optical transmission article; g is a refractive index distribution constant (mm⁻¹) of the optical transmission article; r is a distance (mm) from the center axis toward the peripheral face of the optical transmission article; and 1.4 ≦ n₀ ≦ 1.6 0.4 ≦ r₀ (mm) ≦ 0.6 0.3 ≦ g (mm⁻¹) ≦ 0.7 wherein when a grid image of 4 line-pairs/mm is formed through the optical transmission article on a CCD line sensor and a maximum value i max and a minimum value i min of light quantities of the image are measured, a modulation transfer function (MTF) calculated according to the following equation (2): MTF(%) = {(i max - i min )/(i max + i min )} x 100 (2) is at least 55%.
Claim 6
Dependent Claim
41 words
An optical transmission article array as set forth in claim 5, wherein a lens for forming the array has a lens length (Z) between 5 and 15 mm and an image forming length (T c ) between 10 and 40 mm.
Claim 7
Dependent Claim
31 words
An optical transmission article array as set forth in claim 5 or 6, wherein the array of the optical transmission article has a modulation transfer function (MTF) of at least 40%.
Claim 8
Dependent Claim
23 words
An image sensor comprising an optical transmission article array and a CCD sensor connected to one face of the optical transmission article array.
References Cited (Backward Citations)
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