NOTICE: Due to a lapse in annual appropriations, most of this website is not being updated. Learn more.
Form submissions will still be accepted but will not receive responses at this time. Sections of this site for programs using non-appropriated funds (such as NVLAP) or those that are excepted from the shutdown (such as CHIPS and NVD) will continue to be updated.
An official website of the United States government
Here’s how you know
Official websites use .gov
A .gov website belongs to an official government organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.
A Recommendation for an Inspection Standard to Control Sub-Surface Damage in Single-Crystal Sapphire Components
Published
Author(s)
Robert S. Polvani
Abstract
A variety of characterization techniques have been investigated to study surface and subsurface damage in single-crystal sapphire. To characterize the damage in ground surfaces we found that dimpling was the most useful tool. Surfaces with damage intermediate between that of ground surfaces and optically polished (specular) surfaces need to be addressed on a case by case basis. For optically polished surfaces an inspection protocol has been established consisting of optical characterization by bright light inspection, optical microscopy and surface finish measurements and x ray inspection using diffraction topography. A correlation was found between the microstructure imaged in topographs from a series of MOR bars and their fracture strength. Residual damage from the fabrication process reduced the average strength of the bars by 30%.
Citation
A Recommendation for an Inspection Standard to Control Sub-Surface Damage in Single-Crystal Sapphire Components
Polvani, R.
(2000),
A Recommendation for an Inspection Standard to Control Sub-Surface Damage in Single-Crystal Sapphire Components, A Recommendation for an Inspection Standard to Control Sub-Surface Damage in Single-Crystal Sapphire Components
(Accessed October 6, 2025)