3.3 Laser-Holographic Complex …
241
polarizer 9, broadens with the telescopic system 12 and illuminates the hologram 14
as well. The reconstructed holographic image of the object, which is covered with
the interference fringes is transferred onto the light-sensitive area of the registration
system 16 with the help of the optical system of interferogram formation.
The mirror 10 should be capable of harmonic oscillations with the help of the
piezoelectric element 8 in the direction, which is perpendicular to its reflecting surface
to provide interferogram processing in the phase regime.
Ellipticity can appear under reflection of circularly polarized radiation from the
beam splitters and the mirrors that will lead to intensity inequality of the reconstructed
waves. To compensate this, a reverse set radiation ellipticity can be introduced with
the photoplate λ/4 19. It is obvious that chromatic aberrations can appear if λ 1 is
replaced by λ 2 during reconstruction. Moreover, the aberrations will appear because
of diameter difference of laser beams and different divergence. It is required to
eliminate them, for example, by filtering the radiation. But if the values of such
aberrations are equal for both reconstructing beams it should not lead to distortions
of the interference pattern.
The plane-parallel semitransparent plate 20 serves for adjustment and matching
of the lasers.
As the localization surface of the interference fringes cannot coincide with the
surface under study and be located at essential distance from it, then it is necessary
to use the small aperture optical system to simultaneously observe the image of the
surface and of the interference fringes. But the size of the speckles increases and that
considerably diminishes the quality of the interference pattern. To find a compromise
it is important to have the possibility of changing the aperture of the interferogram
forming system. As the field of view is narrowing if the aperture decreases, then
the system turns around the axis, which passes through the central hologram point,
should be considered to provide the possibility of analysis of the whole human chest
surface under study.
1.3. Technical requirements to the elements of the optical scheme.
1.3.1. Ruby laser
a. the wavelength of the laser radiation should be 694.3 nm,
b. the width of the spectral line of each pulse of the laser radiation should be
not more than 300 MHz;
c. the operation mode: single-mode generation of pair monopulses with the
regulated limits of 100–700 μs with intervals between the pulses.
d. the energy of each of the two radiation pulses of the driving generator should
reach 0.01 J, of the two-stage amplifier—0.25 J, of the total one—0.5 J;
e. the duration of each pulse of the laser radiation should reach 20–120 ns;
f. the radiation is polarized in the vertical plane.
The electrical vector oscillations of the generated radiation should be in the plane
perpendicular to the incidence plane on the beam splitter 2.
241
polarizer 9, broadens with the telescopic system 12 and illuminates the hologram 14
as well. The reconstructed holographic image of the object, which is covered with
the interference fringes is transferred onto the light-sensitive area of the registration
system 16 with the help of the optical system of interferogram formation.
The mirror 10 should be capable of harmonic oscillations with the help of the
piezoelectric element 8 in the direction, which is perpendicular to its reflecting surface
to provide interferogram processing in the phase regime.
Ellipticity can appear under reflection of circularly polarized radiation from the
beam splitters and the mirrors that will lead to intensity inequality of the reconstructed
waves. To compensate this, a reverse set radiation ellipticity can be introduced with
the photoplate λ/4 19. It is obvious that chromatic aberrations can appear if λ 1 is
replaced by λ 2 during reconstruction. Moreover, the aberrations will appear because
of diameter difference of laser beams and different divergence. It is required to
eliminate them, for example, by filtering the radiation. But if the values of such
aberrations are equal for both reconstructing beams it should not lead to distortions
of the interference pattern.
The plane-parallel semitransparent plate 20 serves for adjustment and matching
of the lasers.
As the localization surface of the interference fringes cannot coincide with the
surface under study and be located at essential distance from it, then it is necessary
to use the small aperture optical system to simultaneously observe the image of the
surface and of the interference fringes. But the size of the speckles increases and that
considerably diminishes the quality of the interference pattern. To find a compromise
it is important to have the possibility of changing the aperture of the interferogram
forming system. As the field of view is narrowing if the aperture decreases, then
the system turns around the axis, which passes through the central hologram point,
should be considered to provide the possibility of analysis of the whole human chest
surface under study.
1.3. Technical requirements to the elements of the optical scheme.
1.3.1. Ruby laser
a. the wavelength of the laser radiation should be 694.3 nm,
b. the width of the spectral line of each pulse of the laser radiation should be
not more than 300 MHz;
c. the operation mode: single-mode generation of pair monopulses with the
regulated limits of 100–700 μs with intervals between the pulses.
d. the energy of each of the two radiation pulses of the driving generator should
reach 0.01 J, of the two-stage amplifier—0.25 J, of the total one—0.5 J;
e. the duration of each pulse of the laser radiation should reach 20–120 ns;
f. the radiation is polarized in the vertical plane.
The electrical vector oscillations of the generated radiation should be in the plane
perpendicular to the incidence plane on the beam splitter 2.