208
3 Holographic Interferometry for Studying …
Fig. 3.9 Scheme of
multi-angle method of
contouring. Reprinted from
[94] with permission
I =
sin
π
λ
zαm(tgβ cos α − sin α
sin
π
λ
zα(tgβ cos α − sin α
2
.
(3.36)
The main maxima on the half-height is m/2 times narrower than under traditional
beam contouring that leads correspondingly to accuracy increase during detection of
band location.
This interference pattern has a period between the main maxima set by the depth
interval calculated as
z =
λ cos β
αsin(α − β)
.
(3.37)
Due to the wave phase in (3.35) is proportional not to the angle α m itself, phase
mismatch can occur, and the interference pattern will loose regularity and can get
blurred under certain conditions. Due to this reason, the maximal rotation angle must
satisfy the condition
α
2tgα
m
.
(3.38)
The interferograms of the model object (bolt) for cases of twofold and sevenfold interference correspondingly demonstrating the narrowing of the bands and
increasing determination accuracy of their location in 3.5 times are presented in
Fig. 3.10a, b. But in these experiments, it was proved on the model objects that the
increase of exposures of the same hologram leads to reduction of its diffractive efficiency, which is expressed in intensity decrease in the maxima of the interference
pattern. As it is known, this effect is caused by two factors: time of one exposure
3 Holographic Interferometry for Studying …
Fig. 3.9 Scheme of
multi-angle method of
contouring. Reprinted from
[94] with permission
I =
sin
π
λ
zαm(tgβ cos α − sin α
sin
π
λ
zα(tgβ cos α − sin α
2
.
(3.36)
The main maxima on the half-height is m/2 times narrower than under traditional
beam contouring that leads correspondingly to accuracy increase during detection of
band location.
This interference pattern has a period between the main maxima set by the depth
interval calculated as
z =
λ cos β
αsin(α − β)
.
(3.37)
Due to the wave phase in (3.35) is proportional not to the angle α m itself, phase
mismatch can occur, and the interference pattern will loose regularity and can get
blurred under certain conditions. Due to this reason, the maximal rotation angle must
satisfy the condition
α
2tgα
m
.
(3.38)
The interferograms of the model object (bolt) for cases of twofold and sevenfold interference correspondingly demonstrating the narrowing of the bands and
increasing determination accuracy of their location in 3.5 times are presented in
Fig. 3.10a, b. But in these experiments, it was proved on the model objects that the
increase of exposures of the same hologram leads to reduction of its diffractive efficiency, which is expressed in intensity decrease in the maxima of the interference
pattern. As it is known, this effect is caused by two factors: time of one exposure