Ensiklopedia Dunia

From Wikipedia, the free encyclopedia

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.^[2] The thoriated glass elements in lenses over time develop a brown tint reducing transmission and interfering with neutral color reproduction.

Many Kodak, Fuji and Asahi Takumar lenses that were produced prior to the 1970s are radioactive.^[3]^[4]

Radiation browning

Over extended time periods, thoriated glass may develop significant discoloration. This is due to induced F-centers forming in the glass as the radioactive decay of the thorium progresses.^[5] The formation of F-centers is due to the ionizing effect of the high energy thorium decay products. This process can potentially be reversed by annealing the glass or exposing it to light.^[6]

References

^ Frame, Paul. "Thoriated Camera Lens (ca. 1970s)". ORAU Museum of Radiation and Radioactivity. Retrieved 17 August 2024.
^ 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)
^ "Radioactive Camera Lenses from the recent past". Archived from the original on 2016-12-26. Retrieved 2023-12-01.{{cite web}}: CS1 maint: bot: original URL status unknown (link)
^ Kautz, Robert Allen. "Radioactive Lenses". Robert Allen Kautz Photography. Retrieved 17 August 2024.
^ Bach, Hans; Neuroth, Norbert (1998-08-06). The Properties of Optical Glass. Springer Science & Business Media. ISBN 9783540583578.
^ "Radiation-induced Discoloration" (PDF). www.sealandair.fr. BIRNS, Inc .

v t e Glass science topics
Basics	Glass Glass transition Supercooling
Formulation	AgInSbTe Bioglass Borophosphosilicate glass Borosilicate glass Ceramic glaze Chalcogenide glass Cobalt glass Cranberry glass Crown glass Flint glass Fluorosilicate glass Fused quartz GeSbTe Gold ruby glass Lead glass Milk glass Phosphosilicate glass Photochromic lens glass Silicate glass Soda–lime glass Sodium hexametaphosphate Soluble glass Tellurite glass Thoriated glass Ultra low expansion glass Uranium glass Vitreous enamel Wood's glass ZBLAN
Glass-ceramics	Bioactive glass CorningWare Glass-ceramic-to-metal seals Macor Zerodur
Preparation	Annealing Chemical vapor deposition Glass batch calculation Glass forming Glass melting Glass modeling Ion implantation Liquidus temperature sol–gel technique Viscosity Vitrification
Optics	Achromat Dispersion Gradient-index optics Hydrogen darkening Optical amplifier Optical fiber Optical lens design Photochromic lens Photosensitive glass Refraction Transparent materials
Surface modification	Anti-reflective coating Chemically strengthened glass Corrosion Dealkalization DNA microarray Hydrogen darkening Insulated glazing Porous glass Self-cleaning glass sol–gel technique Tempered glass
Diverse topics	Conservation and restoration of glass objects Glass-coated wire Safety glass Glass databases Glass electrode Glass fiber reinforced concrete Glass ionomer cement Glass microspheres Glass-reinforced plastic Glass cloth Glass-to-metal seal Porous glass Pre-preg Prince Rupert's drops Radioactive waste vitrification Windshield Glass fiber

This glass engineering or glass science related article is a stub. You can help Wikipedia by expanding it.

Categories:

Hidden categories: