Claims
- 1. A distributed refractive index type optical transmission plastic article having a circular cross section of a radius r.sub.0 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 0.25r.sub.0 to 0.70r.sub.0 extending from a center axis toward a peripheral surface of the optical transmission article:
- n(r)=n.sub.0 {1-(g.sup.2 /2)r.sup.2 } (1)
- where n.sub.0 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.sup.-1) of the optical transmission article;
- r is a distance (mm) from the center axis toward the peripheral surface of the optical transmission article; and
- 1.4.ltoreq.n.sub.0 .ltoreq.1.6
- 0.4.ltoreq.r.sub.0 (mm).ltoreq.0.6
- 0.15.ltoreq.g (mm.sup.-1)<0.3
- 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.sub.max and a minimum value i.sub.min of light quantities of the image are measured, a modulation transfer function (MTF) calculated according to the following equation (2):
- MTF={(i.sub.max -i.sub.min)/(i.sub.max +i.sub.min)}.times.100 (2)
- is at least 55%.
- 2. 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 0.20r.sub.0 to 0.75r.sub.0 extending from the center axis toward the peripheral surface of the optical transmission article.
- 3. A method of manufacturing a distributed refractive index type optical transmission plastic article comprising the steps of preparing N (N.gtoreq.2) uncured liquid substances having a viscosity between 10.sup.3 and 10.sup.8 poises each and refractive indexes n of n.sub.1 >n.sub.2 >n.sub.3 . . . n.sub.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 thereafter, curing the uncured strand fiber.
- 4. 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 r.sub.0 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 0.25r.sub.0 to 0.70r.sub.0 extending from a center axis toward a peripheral surface of the optical transmission article:
- n(r)=n.sub.0 {1-(g.sup.2 /2)r.sup.2 } (1)
- where n.sub.0 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.sup.-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.ltoreq.n.sub.0 .ltoreq.1.6
- 0.4.ltoreq.r.sub.0 (mm).ltoreq.0.6
- 0.15.ltoreq.g (mm.sup.-1)<0.3
- 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.sub.max and a minimum value i.sub.min of light quantities of the image are measured, a modulation transfer function (MTF) calculated according to the following equation (2):
- MTF(%)={(i.sub.max -i.sub.min)/(i.sub.max +i.sub.min)}.times.100(2)
- is at least 55%.
Parent Case Info
This application is a continuation of application Ser. No. 07/689,880, filed on May 24, 1991, now abandoned.
PCT Information
Filing Document |
Filing Date |
Country |
Kind |
102e Date |
371c Date |
PCT/JP89/00991 |
9/29/1989 |
|
|
5/24/1991 |
5/24/1991 |
Publishing Document |
Publishing Date |
Country |
Kind |
WO91/05275 |
4/18/1991 |
|
|
US Referenced Citations (6)
Foreign Referenced Citations (3)
Number |
Date |
Country |
0208159 |
Jan 1987 |
EPX |
0242636 |
Oct 1987 |
EPX |
62-209402 |
Sep 1987 |
JPX |
Continuations (1)
|
Number |
Date |
Country |
Parent |
689880 |
May 1991 |
|