METHOD FOR NONDESTRUCTIVE TESTING OF OPTICAL DISCONTINUITIES IN MONOLITHIC TRANSPARENT POLYCRYSTALLINE CERAMIC ARTICLES

摘要

A method of non-destructive detection of solid inclusions with varying sensitivities but highly congruent positional identification by both short-wavelength and long-wavelength methods. The short-wavelength method consists of lateral scatter (LS) and the long-wavelength method consists of THz imaging. The LS method was able to detect all agglomerated inclusions, transparency variations, voids, and localized phase differences. The THz imaging was able to routinely detect solid inclusions and index inhomogeneity. In combination, the LS and THz imaging methods were able to detect all relevant types of material variation, so that the combination of the two non-destructive testing methods provides a synergistic solution capable of detecting the full array of critical material variations in transparent polycrystalline ceramic materials.

主权项

1. A method of testing for optical discontinuities in a monolithic substantially transparent article comprising:
A) subjecting the article to a short-wavelength inspection including
1) laterally sweeping a narrow collimated sub-millimeter (sub-mm) beam of laser light across the article;2) digitally recording photographic images at each sequential cross-section illuminated by the collimated beam of laser light;3) digitally combining the separate cross-sectional images into a fully three-dimensional lateral scatter (LS) map of the optical properties of the article; and B) subjecting the article to a long-wavelength inspection including
1) illuminating the article with focused terahertz (THz) radiation while mechanically or optically scanning the article;2) sweeping the time delay for a range of sequential pulses in a first direction to create a one-dimensional depth profile of reflection/scattering amplitude at each inspection point; and3) mechanically or optically scanning in the other two dimensions to create a full-volume three-dimensional THz map of dielectric discontinuities within the article.