This paper deals with the optical measurement of strain in electronic power
devices under normal operating conditions. This non-contact and non-invasi
ve method called shearography is based upon speckle interferometry. The tec
hnique developed produces images of normal displacement gradient of devices
. Numerical processing allows the determination of the surface displacement
and its related strain. The main advantages of the measuring tool are to b
e a simple optical set-up, to be very robust with a good sensitivity and to
measure directly strain. Therefore, his well suited to fit into an industr
ial environment. (C) 2000 Elsevier Science Ltd. Ail rights reserved.