Sumita Optical Glass, Inc.

Hideaki Takaku

Takashi Watanabe

Naruhito Sawanobori

Masaaki Otsuka

Masaaki Yamazaki

Koichi Tsuchiya

Nahoe Sumita

Nobuhito Takahashi

An optical glass is provided which does not contain components negatively affecting the environment as environmental loads, and is less colored while having a refractive index maintained moderately high. The optical glass has a composition including, in % by mass, 30% or more and 47% or less of SiO, 0% or more and 10% or less of BO, 3% or more and 12% or less of NaO, 0% or more and 5% or less of LiO, 0% or more and 3.8% or less of CaO, 28% or more and 43% or less of BaO, 3% or more and 16% or less of ZnO, 0% or more and 8% or less of ZrO, 0% or more and 15% or less of LaO, where SbOis excluded from the composition, wherein the optical glass does not contain any of PbO, AsO, and KO.

Optical glass and optical element

Provided is an optical fiber illumination device in which optical fibers produced without using a special method is used and the amount of light emitted from the side surface is improved. An optical fiber illumination deviceincludes: an optical fiber bundlehaving a plurality of optical fibers, a resin jacketthat covers a bundle of the plurality of optical fibers and emits light, a first end, and a second end, the first end and the second end being polished; and a first light source placed close to the first end so as to emit light in a range of angles larger than an angular aperture of the plurality of optical fibers toward the optical fiber bundle.

Optical fiber illumination device

Provided is an image guide fiber that improves image quality while preventing a manufacturing problem. The image guide fiber according to the present disclosure has a numerical aperture NA in the range of 0.70 to 0.90. A linear thermal expansion coefficient difference &#x394;&#x3b1;, which is a value obtained by subtracting a linear thermal expansion coefficient &#x3b1;at from 100 to 300&#xb0; C. of clad glass, from a linear thermal expansion coefficient &#x3b1;at from 100 to 300&#xb0; C. of core glass, is in the range of &#x2212;3&#xd7;10&#xb0; C. to 15&#xd7;10/&#xb0; C. A glass-transition temperature Tgof the core glass is higher than a glass-transition temperature Tgof the clad glass. A core occupancy area ratio is 25% or more. A pixel density is 0.1 pixel/&#x3bc;mor more.

Image guide fiber

A glass material is provided which is capable of exhibiting fluorescence in the visible region by ultraviolet ray excitation. This glass material is represented, in term of atoms for making up the glass, by the following chemical composition (mol %):

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Saitama, Japan

Hideaki Takaku