| 摘要 |
<p>The invention provides a method of detecting sub-ppm lead impurity levels in a below 200 nm transmitting optical calcium fluoride crystal. The method includes providing a below 200 nm wavelength transmitting optical fluoride crystal having a crystal light transmission path length, providing a 200-210nm spectrophotometer having a light source for producing a transmission test wavelength in the range 200 to 210 nm and a transmission detector for measuring transmission of the test wavelength, and transmitting the transmission test wavelength in the range 200 to 210 nm through the below 200 nm wavelength transmitting optical fluoride crystal light transmission path length and measuring the transmission of the 200 to 210 nm test wavelength through the path length to provide a lead ppb impurity level measurement less than 500 ppb. The invention provides for improved manufacturing of below 200 nm wavelength optical elements and optical fluoride crystals such as ultralow lead contaminated calcium fluoride.</p> |
