238
3 Holographic Interferometry for Studying …
6. The optical system for the formation of recording and restoration beams must
provide the formation of recording beams for λ = 694.3 nm and of restoration
beams for λ = 632.8 nm.
In both cases even exposure of the light-sensitive layer should be provided. The
number of relative distortions of reference beam wavefront must not exceed 0.1 λ
for λ = 632.8 nm at the change of the wavelength. There should be provided the
possibility of illumination with the laser radiation of not only the reversible carrier of
4 × 4 cm
2 , but also of the photographic plates of 30 × 40 cm
2 . The system of spatial
separation of reference beams is a part of the system of formation of recording and
reconstructing beams. It should provide the direction of the radiation generated in the
first pulse along the path different from the path of light radiation, which is generated
in the second pulse. For this KDP crystal (Pockels or Kerr cell) can be used, which
turns laser radiation polarization plane at sync pulse at 90° during generation of one
of the double-pulses. There should also be used two crossed polarizers or a polarizer,
which spatially separates radiation with orthogonally oriented electrical vectors (for
example, the Glan prism, etc.).
7. The system of hologram recording should provide hologram recording on the
reversible carrier for prompt formation of reconstructed images. The requirements for the reversible carrier for hologram recording are described separately.
The recording system should be capable of providing recording on holographic
plate of 9 × 12 cm
2 as well. There should also be provided the possibility of
fast removal of the plate for photoprocessing and putting it back into the same
place with high accuracy.
8. The system of interferogram formation should provide obtaining qualitative
contrast interferograms, which are the image of the human chest covered with
interference fringes. The size of the image should correspond to the size of
the receiving area of the registration system. There should be a possibility of
interferogram formation for several observation directions in order to determine
the spatial shifts (in case of utilization of large holographic plates).
9. The system of phase modulation should provide periodic changes with the set
phase frequency of one of the reconstructing beams for implementation of the
phase regime of interferogram processing. The phase change can be fulfilled
with oscillation of a piezoelectric flat mirror (the mirror 8 on the optical scheme
in Fig. 3.34).
10. The registration system should provide reliable registration of two-dimension
intensity distribution in set moments of time. A photodiode matrix, a vidicon,
a CCD matrix can be used.
11. The units of electronic processing of joining with a computer should provide
extraction of a desired signal of the set frequency, noise filtering, taking information in set moments of time and transmitting it to the computer, and displaying
the obtained image in real time.
12. The display must provide visualization of the holographic interference pattern
during the process of reconstruction of the two-exposure hologram.
3 Holographic Interferometry for Studying …
6. The optical system for the formation of recording and restoration beams must
provide the formation of recording beams for λ = 694.3 nm and of restoration
beams for λ = 632.8 nm.
In both cases even exposure of the light-sensitive layer should be provided. The
number of relative distortions of reference beam wavefront must not exceed 0.1 λ
for λ = 632.8 nm at the change of the wavelength. There should be provided the
possibility of illumination with the laser radiation of not only the reversible carrier of
4 × 4 cm
2 , but also of the photographic plates of 30 × 40 cm
2 . The system of spatial
separation of reference beams is a part of the system of formation of recording and
reconstructing beams. It should provide the direction of the radiation generated in the
first pulse along the path different from the path of light radiation, which is generated
in the second pulse. For this KDP crystal (Pockels or Kerr cell) can be used, which
turns laser radiation polarization plane at sync pulse at 90° during generation of one
of the double-pulses. There should also be used two crossed polarizers or a polarizer,
which spatially separates radiation with orthogonally oriented electrical vectors (for
example, the Glan prism, etc.).
7. The system of hologram recording should provide hologram recording on the
reversible carrier for prompt formation of reconstructed images. The requirements for the reversible carrier for hologram recording are described separately.
The recording system should be capable of providing recording on holographic
plate of 9 × 12 cm
2 as well. There should also be provided the possibility of
fast removal of the plate for photoprocessing and putting it back into the same
place with high accuracy.
8. The system of interferogram formation should provide obtaining qualitative
contrast interferograms, which are the image of the human chest covered with
interference fringes. The size of the image should correspond to the size of
the receiving area of the registration system. There should be a possibility of
interferogram formation for several observation directions in order to determine
the spatial shifts (in case of utilization of large holographic plates).
9. The system of phase modulation should provide periodic changes with the set
phase frequency of one of the reconstructing beams for implementation of the
phase regime of interferogram processing. The phase change can be fulfilled
with oscillation of a piezoelectric flat mirror (the mirror 8 on the optical scheme
in Fig. 3.34).
10. The registration system should provide reliable registration of two-dimension
intensity distribution in set moments of time. A photodiode matrix, a vidicon,
a CCD matrix can be used.
11. The units of electronic processing of joining with a computer should provide
extraction of a desired signal of the set frequency, noise filtering, taking information in set moments of time and transmitting it to the computer, and displaying
the obtained image in real time.
12. The display must provide visualization of the holographic interference pattern
during the process of reconstruction of the two-exposure hologram.