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Radio-active Camera Lenses!. By: Josh Ashman Pd: 8. What is the radio-active element in these lenses?. The radioactive element that is found in these older styled lenses is known as Thorium. Thorium occurs naturally in the Earth’s crusts, in very low concentrations. (10 parts per million)
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Radio-active Camera Lenses! By: Josh Ashman Pd: 8
What is the radio-active element in these lenses? • The radioactive element that is found in these older styled lenses is known as Thorium. • Thorium occurs naturally in the Earth’s crusts, in very low concentrations. (10 parts per million) • However, Of the 26 known isotopes of thorium, only 12 have half-lives greater than one second. • Thus, making it safe enough to use in such small amounts such as these lenses.
Why use Thorium in lenses? • By adding Thorium to lenses, the light is refracted in such a way that does not disperse as much light, and allows for a more focused, clear image. • The greater the index of refraction, the greater the bending of the light, which reduces the need for highly curved glass. This means the glass can be made thinner and lighter. • The first company to experiment with Thorium was Kodak, in the early 1900’s. • Also, many big name companies such as Nikon and Canon still use Thorium coated lenses.
