backscattering thickness gage

backscattering thickness gage

[′bak¦skad·ə·riŋ ′thik·nəs ‚gāj]
(engineering)
A device that uses a radioactive source for measuring the thickness of materials, such as coatings, in which the source and the instrument measuring the radiation are mounted on the same side of the material, the backscattered radiation thus being measured.