3.3 Laser-Holographic Complex …
243
providing the effective operation of the electronic system of signal processing.
Meanwhile, the mirror turns should be no more than 2
. The phase modulation
should be conducted at the stage of hologram reconstruction.
1.3.9. The device for the input of the set phase shift 21 should provide smooth
change of the optical path length of the transmitting light wave from λ 2 to ±
2 μm without oscillations of more than 0.05 λ.
For example, a compensator can be used as such a device. It is consisted of two
wedges put together in such a way that a plane-parallel plate is received, as it is shown
in the scheme. The thickness of the plate changes if one of the wedges is shifted. In
case the mirror 10 is slowly shifted in a set direction with the piezoelectric element
8 that leads to visual detection of the shift direction of the interference fringes, then
the device 21 is not necessary.
1.3.10. The plate λ/2 11 should provide the rotation of the polarization plane of the
transmitted radiation at 90°.
1.3.11. The telescopic systems 12, 13 should provide formation of plane fronts
of recording and reconstructing beams and even illumination of the lightsensitive surface of the reversible carrier 14 of the size 40 × 40 mm
2 .
Operative restructuring of the telescopic systems for wavelengths λ 1 and
λ 2 is acceptable. The difference of changing wavefront distortion passed
through the telescoping systems 12, 13, if λ 1 is replaced by λ 2 along the
whole front, should not exceed 0.05 λ.
The alternative variant can be the use of one illuminating lens achromatized for
λ 1 and λ 2 along the field of view. But the requirements to wave front distortions
remain the same over the whole active field of view.
1.3.12. The medium for hologram recording should provide reliable hologram
recording. As such a medium, it is suggested to use a reversible carrier,
the requirements to which are described additionally.
There should be a possibility to use holographic plates with the size of 9 × 12
cm
2 instead of the reversible carrier. In this case, instead of the telescopic systems
12, 13 lenses should be installed, which form spherical waves for even illumination
of large photoplates. There should be a possibility of fast removal of the plate for
photoprocessing and placing it into the same place with an accuracy of 0.005 mm.
1.3.13. The optical scheme for formation of the interferogram 15 should provide
construction of a qualitative image of the human chest (50 × 60 cm
2 ) on
the light-sensitive area of the registration system 16. The optical system 15
should have a possibility to change the aperture angle γ, at which the object
under study is observed within the limits from 1° to 2 arctg(l 0 /2l 1 ), where
l 0 is the size of the object; (l 0 = 60 cm), l 1 is the distance between the
object and the hologram. This can be implemented through changing the
diaphragm size situated in the focus of the first lens. The same diaphragm
can be used for filtering of phantom images, which are reconstructed by
each of the reconstructing waves.
243
providing the effective operation of the electronic system of signal processing.
Meanwhile, the mirror turns should be no more than 2
. The phase modulation
should be conducted at the stage of hologram reconstruction.
1.3.9. The device for the input of the set phase shift 21 should provide smooth
change of the optical path length of the transmitting light wave from λ 2 to ±
2 μm without oscillations of more than 0.05 λ.
For example, a compensator can be used as such a device. It is consisted of two
wedges put together in such a way that a plane-parallel plate is received, as it is shown
in the scheme. The thickness of the plate changes if one of the wedges is shifted. In
case the mirror 10 is slowly shifted in a set direction with the piezoelectric element
8 that leads to visual detection of the shift direction of the interference fringes, then
the device 21 is not necessary.
1.3.10. The plate λ/2 11 should provide the rotation of the polarization plane of the
transmitted radiation at 90°.
1.3.11. The telescopic systems 12, 13 should provide formation of plane fronts
of recording and reconstructing beams and even illumination of the lightsensitive surface of the reversible carrier 14 of the size 40 × 40 mm
2 .
Operative restructuring of the telescopic systems for wavelengths λ 1 and
λ 2 is acceptable. The difference of changing wavefront distortion passed
through the telescoping systems 12, 13, if λ 1 is replaced by λ 2 along the
whole front, should not exceed 0.05 λ.
The alternative variant can be the use of one illuminating lens achromatized for
λ 1 and λ 2 along the field of view. But the requirements to wave front distortions
remain the same over the whole active field of view.
1.3.12. The medium for hologram recording should provide reliable hologram
recording. As such a medium, it is suggested to use a reversible carrier,
the requirements to which are described additionally.
There should be a possibility to use holographic plates with the size of 9 × 12
cm
2 instead of the reversible carrier. In this case, instead of the telescopic systems
12, 13 lenses should be installed, which form spherical waves for even illumination
of large photoplates. There should be a possibility of fast removal of the plate for
photoprocessing and placing it into the same place with an accuracy of 0.005 mm.
1.3.13. The optical scheme for formation of the interferogram 15 should provide
construction of a qualitative image of the human chest (50 × 60 cm
2 ) on
the light-sensitive area of the registration system 16. The optical system 15
should have a possibility to change the aperture angle γ, at which the object
under study is observed within the limits from 1° to 2 arctg(l 0 /2l 1 ), where
l 0 is the size of the object; (l 0 = 60 cm), l 1 is the distance between the
object and the hologram. This can be implemented through changing the
diaphragm size situated in the focus of the first lens. The same diaphragm
can be used for filtering of phantom images, which are reconstructed by
each of the reconstructing waves.