Gc. Jin et al., APPLICATION OF NONDESTRUCTIVE TESTING METHODS TO ELECTRONIC INDUSTRY USING COMPUTER-AIDED OPTICAL METROLOGY, Optics and lasers in engineering, 25(2-3), 1996, pp. 81-91
A novel application of NDT to the electronic industry using computer-a
ided optical metrology that includes Electronic Speckle Pattern Interf
erometer (ESPI), Electronic Shearing Speckle Pattern Interferometer (E
SSPI) and Digital Speckle Correlation Method (DSCM) was described. The
theoretical analysis based on interferometry and the deformation theo
ry was presented and the relationship between fringe-distribution and
defect-geometry was given. An important technique-computer-controlled
polarization phase shifting-was developed for improving the fringe qua
lity and the sensitivity of ESPI and ESSPI. In order to improve the se
nsitivity for NDT of small object like electronic elements, a new NDT
method using DSCM was first introduced. Two key techniques, the cross-
search algorithm and double-lens optical arrangement, were developed t
o provide the possibility of high processing speed and small object me
asurement. These new techniques will make DSCM the most powerful NDT t
ool in electronic engineering. Several applications are presented as e
xamples in this paper; they include the electrosound elements, miniatu
rized multilayer ceramic capacitor (MLC), compact disk (CD) and optica
l fibers. The findings have demonstrated that computer-aided optical m
etrology is a powerful tool for NDT applications in electronic enginee
ring.