Illumination using light guide is isolated light source from luminescent part. Therefore the system shows easy maintenance and electrical insulating characteristics. However commercial light guide, glass or plastic optical bundle, have some problems, e.g. rigid, heavy weight, expensive or low heat -resistance. Then, a large diameter single core plastic light guide, is suitable for Illumination, has been developed. The light guide consist silicone rubber core and fluoro elastomer cladding. The core diameter is very large, 4-20mm, and the flexibility of light guide is excellent. And it shows not only good light transmission<0.2dB/m at 660nm but also high heat-resistance 130℃ 1000hrs after excess loss<0.2dB/m and side luminescent characteristics.
