Phase object data obtained by pulsed TV holography and defocused laser speckle displacement.
Transient events in optically transparent media occur in many engineering applications. Using pulsed TV holography to capture a laser speckle field propagated through an optical disturbance makes it possible to obtain both the position and the phase gradients of the disturbance. The technique depends on the fact that speckles transmitted through an optical disturbance will be displaced by an amount that depends on the relation of the defocus to the object. First the speckle field is captured holographically, without and with disturbance present. Then the recorded fields are numerically refocused in a computer to a number of different focal planes. With a cross-correlation technique a number of speckle displacement fields are obtained, and from them the data about the disturbance are obtained. So far the technique has been shown to work for thin objects.
Johansson
Eva-Lena
EL
Division of Experimental Mechanics, Luleå University of Technology, SE-971 87 Luleå, Sweden. eva-lena.johansson@sirius.luth.se
Benckert
Lars
L
Sjödahl
Mikael
M