Radiation imagery chemistry: process – composition – or product th – Imaging affecting physical property of radiation sensitive... – Radiation sensitive composition or product or process of making
Reexamination Certificate
2002-12-19
2004-09-07
Huff, Mark F. (Department: 1752)
Radiation imagery chemistry: process, composition, or product th
Imaging affecting physical property of radiation sensitive...
Radiation sensitive composition or product or process of making
C430S916000, C430S907000, C430S905000, C430S906000, C430S908000, C430S909000, C430S910000, C430S325000, C430S326000, C430S321000, C430S270100, C430S285100, C430S280100
Reexamination Certificate
active
06787289
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a radiation sensitive refractive index changing composition, a method of forming a refractive index pattern, a refractive index pattern and an optical material. More specifically, it relates to a novel radiation sensitive refractive index changing composition which is used in photoelectronic and display fields, a method of forming a refractive index pattern, a refractive index pattern and an optical material.
DESCRIPTION OF THE PRIOR ART
In the current society called “multi-media society”, refractive index distribution type optically molded products each consisting of different refractive index regions are in great demand. The products include not only optical fibers for transmitting information but also optical diffraction gratings having a periodical change in refractive index, optical memories in which information is written at sites having different refractive indices, optically coupled elements such as optical IC's having a fine refractive index pattern, optical control elements, optical modulation elements and optical transmission elements.
The refractive index distribution type optically molded products are divided into two types: one having a continuous refractive index distribution, such as GI type optical fibers in the molded products (to be referred to as “GRIN optically molded products” hereinafter) and the other having a discontinuous refractive index distribution, such as optical diffraction gratings and SI type optical waveguides.
The GRIN optically molded products are attracting much attention as the next-generation optically molded products. For example, a GI type optical fiber whose refractive index is reduced from the center axis of the core of the optical fiber to the periphery in a parabolic form can transmit a great volume of information. A GRIN lens whose refractive index continuously changes therein is used as a reading lens for use in copiers, spherical lens for connecting fibers, or micro-lens, making use of its characteristic features that it has refractive power even on a flat surface and that it is free from spherical aberration.
A large number of methods of producing the above GRIN optically molded products have been proposed up till now. For example, JP-A 9-133813, JP-A 8-336911, JP-A 8-337609, JP-A 3-192310, JP-A 5-60931 (the term “JP-A” as used herein means an “unexamined published Japanese patent application”), WO93/19505 and WO94/04949 disclose a method of obtaining a GI type optical fiber by dispersing a low-molecular weight compound or a monomer into a polymer and continuously distributing its concentration. JP-A 62-25705 discloses that a rod-like GI type optically molded product or optical fiber is obtained by photo-copolymerizing two or more vinyl monomers having different refractive indices and reactivity ratios. Further, JP-A 7-56026 discloses a method of obtaining a refractive index distribution by forming a polymer A having a photo-reactive functional group, dispersing a compound B having a lower refractive index than the polymer A into the polymer A to form the concentration distribution of the compound B and photo-reacting the polymer A with the compound B.
Some methods of producing GRIN optically molded products of an inorganic material have also been proposed. One of them is, for example, a method of producing a GI type rod by adding high refractive index thallium to rod-like glass essentially composed of silicon or lead, immersing the glass in a molten solution containing low refractive index potassium, and forming a potassium concentration distribution through ion exchange.
A GRIN lens can be obtained likewise by applying the above method to a short rod, that is, a lens-like optically molded product. Alternatively, the GI type rod produced by the above method may be sliced.
As one of the above methods of producing optically molded products having a fine refractive index pattern, such as an optical diffraction grating and optical IC, there is known a technology for obtaining a change in refractive index by causing a photochemical reaction in a molded product through exposure to light. For instance, in the case of an inorganic material, glass doped with germanium is exposed to light to change its refractive index so as to produce an optical diffraction grating. In the case of an organic material, the above technology is known as a photochromic reaction or photobleaching. JP-A 7-92313 discloses a technology for obtaining an optical diffraction grating by causing a change in the refractive index of a material containing a low-molecular weight compound having photochemical reactivity dispersed in a polymer through exposure to a laser beam. Further, JP-A 9-178901 has recently proposed the application of this technology to the production of a GRIN optically molded product. This method provides a continuous refractive index distribution in a depth direction with respect to irradiation, making use of the fact that light projected onto a molded product is absorbed and weakened in intensity.
However, in the refractive index distributions obtained with the above conventional materials, the maximum refractive index difference is only about 0.001 to 0.02 and it is difficult to provide a wider refractive index distribution for the purpose of preventing an optical loss and suppressing the malfunction of a circuit.
When the above conventional materials are used under the condition that light having a wavelength close to the wavelength used for changing the refractive index passes therethrough after a refractive index distribution is formed, it is impossible to prevent a phenomenon that a gradual change in refractive index occurs, thereby deteriorating the materials.
SUMMARY OF THE INVENTION
The present invention has been made in view of the above situation of the prior art.
That is, it is an object of the present invention to provide a radiation sensitive refractive index changing composition whose refractive index of a material is changed by a simple method, whose changed refractive index difference is sufficiently large, and which can provide a stable refractive index pattern and a stable optical material regardless of their use conditions.
It is another object of the present invention to provide a method of forming a refractive index pattern from the above composition of the present invention.
It is still another object of the present invention to provide a refractive index pattern or an optical material produced by the above method of the present invention.
Other objects and advantages of the present invention will become apparent from the following description.
According to the present invention, firstly, the above objects and advantages of the present invention are attained by a radiation sensitive refractive index changing composition which comprises (A) a polymerizable compound, (B) a non-polymerizable compound having a lower refractive index than the polymer of the polymerizable compound (A), and (C) a radiation sensitive polymerization initiator.
Secondly, the above objects and advantages of the present invention are attained by a method of forming a refractive index pattern by exposing a radiation sensitive refractive index changing composition comprising (A) a polymerizable compound, (B) a non-polymerizable compound having a lower refractive index than the polymer of the polymerizable compound (A), and (C) a radiation sensitive polymerization initiator to radiation through a pattern mask.
Thirdly, the above objects and advantages of the present invention are attained by a refractive index pattern formed by the above refractive index pattern forming method.
In the fourth place, the above objects and advantages of the present invention are attained by an optical material formed by the above refractive index pattern forming method.
In the present invention, the term “refractive index pattern” means a refractive index distribution type material formed in regions having different refractive indices. Comparison of the value of refractive indices is performed based on the refract
Bessho Nobuo
Konno Keiji
Kumano Atsushi
Yamada Kenji
Huff Mark F.
JSR Corporation
Lee Sin J.
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
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