2.1 Holographic Microscopy for the Study of Phase, Diffusive …
67
It follows that holographic microscopes, based on different methods of hologram recording, can simultaneously operate as holographic interferometers using
the method of two-base exposure or real time, multiple longwave or immersion
[142]. And these holographic microinterferometers differ from the traditional ones
by new principal possibilities such as the comparison of wave fronts scattered by an
object during different periods of time (for example, microobject initial state and its
strained state in the result of mechanical, chemical and electromagnetic effects), and
they also enable to carry out the comparison of wave fronts of any complicated form
(including diffusely scattered objects). Moreover, such microinterferometers enable
to carry out interference comparison of waves of different frequencies that makes it
possible to detect microobjects dispersion characteristics or to study wave interference scattered by microobjects in the range of hologram aperture. It should be noted
that precise overlapping of the compared microobjectives state using holographic
interferometry is doing automatically, while their identification in traditional interferometry is carried out with lower accuracy only during complicated comparison,
for example, when photographing two different states of a microobject. There is also
a set of other practical advantages. So, for the visualization of phase object relief,
for the detection of deviation sign of the interference fringe and for the quantitative processing of microobjects interferograms making small phase incursions, the
interferograms in fringes of final width appear to be convenient. For producing such
an interferogram, the fringe period should be lower than a microobject sizes. Holographic interferometers without any difficulties enable to produce reference fringes
with the frequency higher than the frequency of traditional industrial interference
microscopes, and thus, using them makes it more convenient to get quantitative
information about phase microobjects.
Figure 2.4a shows the interferogram with the limiting for traditional interference
microscope band frequency, and Fig. 2.4b shows the interferogram of the same object
produced in holographic microscope. These interferograms were recorded during the
Fig. 2.4 Nerve fiber interferograms under traditional (a) and holographic (b) interference
microscopes. Reprinted from [136] with permission
67
It follows that holographic microscopes, based on different methods of hologram recording, can simultaneously operate as holographic interferometers using
the method of two-base exposure or real time, multiple longwave or immersion
[142]. And these holographic microinterferometers differ from the traditional ones
by new principal possibilities such as the comparison of wave fronts scattered by an
object during different periods of time (for example, microobject initial state and its
strained state in the result of mechanical, chemical and electromagnetic effects), and
they also enable to carry out the comparison of wave fronts of any complicated form
(including diffusely scattered objects). Moreover, such microinterferometers enable
to carry out interference comparison of waves of different frequencies that makes it
possible to detect microobjects dispersion characteristics or to study wave interference scattered by microobjects in the range of hologram aperture. It should be noted
that precise overlapping of the compared microobjectives state using holographic
interferometry is doing automatically, while their identification in traditional interferometry is carried out with lower accuracy only during complicated comparison,
for example, when photographing two different states of a microobject. There is also
a set of other practical advantages. So, for the visualization of phase object relief,
for the detection of deviation sign of the interference fringe and for the quantitative processing of microobjects interferograms making small phase incursions, the
interferograms in fringes of final width appear to be convenient. For producing such
an interferogram, the fringe period should be lower than a microobject sizes. Holographic interferometers without any difficulties enable to produce reference fringes
with the frequency higher than the frequency of traditional industrial interference
microscopes, and thus, using them makes it more convenient to get quantitative
information about phase microobjects.
Figure 2.4a shows the interferogram with the limiting for traditional interference
microscope band frequency, and Fig. 2.4b shows the interferogram of the same object
produced in holographic microscope. These interferograms were recorded during the
Fig. 2.4 Nerve fiber interferograms under traditional (a) and holographic (b) interference
microscopes. Reprinted from [136] with permission