Thoriated glass

Thoriated glass is a glass material used in the manufacture of optical systems, specifically photographic lenses. It is useful to this process due to its high refractive index. Thoriated glass is radioactive due to the inclusion of thorium dioxide, oxide of radioactive element thorium. It has therefore been succeeded as a material of choice by glass including lanthanum oxide. Thoriated glass can contain up to 30% by weight of thorium.[1] The thoriated glass elements in lenses over time develop a yellow tint reducing transmission and interfering with neutral color reproduction.

References

  1. ↑ http://www.irpa.net/irpa3/cdrom/VOL.3B/W3B_13.PDF Robert C. McMillan & Steven A. Horne: Eye Exposure from Thoriated Optical Glass (U.S. Army memo)
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