To provide a polyimide excellent in transparency, an isotropic property and crack resistance (without cracks on forming multilayers, easy for forming the multilayers and having a good processing property) and an optical part excellent in optical properties.
This polyimide having (a) ≤0.02 difference between the refractive indexes of a TE mode and TM mode, (b) ≥250°C glass transition temperature (Tg) and (c) ≤1 DB/cm light transmittance loss in 0.7-1.6 μm wave length, the polyimide having (b) ≥250°C glass transition temperature (Tg), (c) ≤1 DB/cm light transmittance loss in 0.7-1.6 μm wave length and (d) ≤22.6 wt.% fluorine content, or the polyimide having (a) ≤0.02 difference between the refractive indexes of the TE mode and TM mode, (b) ≥250°C glass transition temperature (Tg), (c) ≤1 DB/cm light transmittance loss in 0.7-1.6 μm wave length and (d) ≤22.6 wt.% fluorine content, and the optical part by using at least one of the polyimides are provided.
SASAKI HAN
NARA SHIGEO
SATO NINTEI
HAYASHIDA SHIGERU
TAYA MASATO
