Mitsubishi Rayon Company, Limited

Masaaki Oda

Yoshihiko Mishina

Takashi Yamamoto

Yoshihiro Uozu

Teruta Ishimaru

Ryuji Murata

Nobuhiko Toyoda

Takayuki Tanaka

Yutaka Yamamoto

Distributed graded index type optical transmission plastic article and

An image-reading device comprises a lens unit array comprising an array of distributed refractive index plastic cylindrical lens elements and plastic plates, adhering the distributed refractive index plastic cylindrical lens elements therebetween, and a plastic case containing and holding the lens unit array. The difference in the thermal expansion coefficients of the plates of the lens unit array and the plastic case is 5.0.times.10.sup.-5 cm/cm/.degree. C. or below, or more preferably, 3.0.times.10.sup.-5 cm/cm/.degree. C. or below. The plastic case is formed by connecting, in a longitudinal arrangement, a plurality of case segments formed by an injection molding.

Image-reading device

Distributed refractive index type optical transmission plastic article

Disclosed is a graded index lens array which gives good resolution even if its end surfaces are not fully polished during its manufacture and which is less likely to suffer loss in resolution due to damage to its surfaces comprising a plurality of graded index lenses made of a synthetic resin and arranged in parallel, characterized in that at least one end surface of the lens array is coated with a cured film formed from a cross-linkable resin consisting essentially of a multifunctional compound having at least two (meth)acryloyloxy groups per molecule, and a fluorinated alkyl (meth)acrylate.

Graded index lens array

The graded-index optical transmission medium with a low transmission loss, a favorable index distribution and superior in softness etc. can be constituted by a mixture of polymers Pn having different refractive indices and by restricting the attenuation L.sub.F of the medium in accordance with the below inequality (I). The medium may advantageously be produced by way of admixing a thermoplastic polymer (A) and a monomer (B) able to form a polymer mutually soluble with the polymer (A), molding the mixture and volatilizing the monomer (B) from the surface of thus shaped substance. ##EQU1## wherein Wn are the respective proportions by weight of mixing of the polymers Pn to the whole of the mixture of the polymers Pn, and ##EQU2## Wn is equal to one.

Optical transmission medium and process for producing the same based on

A plastic optical transmission element having a body in which the refractive index varies continuously in a radial direction from the interior toward the surface of the body, may be free from the troubles derived from irregularity of the index distribution and flare by having a layer containing a light-absorbing substance under the surface thereof. Such a layer may be formed by contacting an untreated element with a solvent containing the light absorbing substance, when the solvent is selected so as to be capable of at least partially dissolving the plastic of the element.

Plastic optical transmission medium, process for producing the same and

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Otake, Japan

Masaaki Oda