257
9
9.4.8 Holography
In holographic evaluation, which is also referred to as holographic
interferometry, the image (interferogram) of the composite is evalauted for deformation. Holography already has been proven to be
an effective technique in the nondestructive testing of composites.
A schematic of holographic testing of composites is shown in
. Fig. 9.21. The principle of holographic evaluation is based on the
local modification of the surface of the composite produced by a
. Fig. 9.20 Thermographic image of a building [26]
Variable
wavelength
filter
Camera
Rotated coarse
2D grating
l = l(q)
or l(x)
x
y
a
j
b
z
Unknown
pulse
Reference
pulse
. Fig. 9.21 Schematic of holographic testing of composites [27]
9.4 · Advanced Test Methods for Composites
9
9.4.8 Holography
In holographic evaluation, which is also referred to as holographic
interferometry, the image (interferogram) of the composite is evalauted for deformation. Holography already has been proven to be
an effective technique in the nondestructive testing of composites.
A schematic of holographic testing of composites is shown in
. Fig. 9.21. The principle of holographic evaluation is based on the
local modification of the surface of the composite produced by a
. Fig. 9.20 Thermographic image of a building [26]
Variable
wavelength
filter
Camera
Rotated coarse
2D grating
l = l(q)
or l(x)
x
y
a
j
b
z
Unknown
pulse
Reference
pulse
. Fig. 9.21 Schematic of holographic testing of composites [27]
9.4 · Advanced Test Methods for Composites