The optical transmitted body null which was formed making use of the quartz glass element lump, and the aforementioned basic material in order to produce the said basic material the quartz glass basic material for the optical transmitted body, mainly

摘要

PURPOSE:To effectively suppress the fluctuation in refractive index by combining the OH group concn. distribution and C concn. distribution formed along a prescribed sectional direction and the virtual temp. distribution formed along the sectional direction by heating and cooling treatments. CONSTITUTION:Circular cylindrical synthetic quartz glass 1' is produced while high-purity silicon tetrachloride is brought into reaction in an oxyhydrogen flame by an oxyhydrogen flame hydrolysis method and the mixing ratios of both gases are adjusted to control the refractive index distribution added with the refractive index distribution determined by the OH group concn. in the section orthogonal with the circular columnar axis and the refractive index distribution determined by the Cl concn. in such a manner that as to attain the curve which indicates the max. value in the central area and indicates the value gently decreasing toward the outer edge part. The produced synthetic quartz glass is cut along the inside of the section orthogonal with the symmetrical axis of the OH group concn. and Cl concn. distribution to form the quartz glass stock lump 1. This stock lump is held at a specified temp. for a prescribed period of time in an electric furnace and is slowly cooled while the difference in the virtual temp. distribution is so controlled as to attain in the prescribed difference. The highly homogeneous glass base material which is small in the fluctuation width of the refractive index is obtd. in this way.