244
3 Holographic Interferometry for Studying …
The distortion of the interference fringes under image transmitting should not
exceed 0.1 λ.
There should be a possibility of smooth turns of the optical system 15 with the
registration system 16 in the horizontal and the vertical planes in the range ±γ/2
around the axes, which pass through the central point of the reversible carrier 14 (γ
= 2 arctg(l 0 /2l 1 )).
There should be a possibility of smooth turns of the optical system 15 with the
registration system 16 in the horizontal and the vertical planes about axes, which
pass through the central point of the object. The length of the zones of the angle turn
± arctg(l 2 /2l 1 ) where l 2 is the size of the hologram.
1.3.14. The registration system 16 should have parameters (sensitivity, dynamic
range, inertia, etc.), which make it possible to safely register the oscillating
interference pattern in definite moments of time. A photodiode matrix, a
PEA-matrix or a vidicon can be used in the system.
1.3.15. As a source of continuous radiation 17, it is recommended to use He–Ne laser
LGN-215 or its later modifications. The oscillation plane of the electrical
vector of the generated radiation should be perpendicular to the plane of the
drawing.
1.3.16. The plane-parallel plate 18 should provide parallel shift of the laser beam
of He–Ne laser 17 in the plane perpendicular to the plane of the drawing
at h ± 2 mm. For this, it should have smooth inclinations in the plane
perpendicular to the plane of the drawing. The value of the inclination angle
can be calculated according to the formula
n = d sin α(1 − cos α/
n 2 − sin
2
α)
where d is the thickness of the plate; n is the refractive index.
1.3.17. The plate λ/4 19 is intended to obtain circularly polarized radiation of He–
Ne laser. This plate should be used in the case of the turn of one of the
polarizers 9 or 9
into 90° or deleting of both polarizers will lead to changes
of wavefront distortions more than 0.05 λ. In this case, the polarizers can
be left crossed.
1.3.18. The semitransparent plane-parallel plate 20 should have a possibility to be
put in and out the ray path for adjustment of the ruby laser 1. It should have
adjustment inclinations, which make it possible to join the reflected beam
with the incident one. The sensitivity of the angle adjustments should not
be worse than 2
.
1.3.19. All the elements of the optical scheme should be firmly fixed in the set states.
There should be no cutting of light beams. There should be boots protecting
the optical surfaces from dust and diaphragms for the elimination of spurious
glares.
1.3.20. The optical elements 7–14 should be located as compact as possible and be
firmly fixed to the common base. It is desirable to fulfill them with one block.
The distances between the beam splitter 7 and the mirror 10 and between
3 Holographic Interferometry for Studying …
The distortion of the interference fringes under image transmitting should not
exceed 0.1 λ.
There should be a possibility of smooth turns of the optical system 15 with the
registration system 16 in the horizontal and the vertical planes in the range ±γ/2
around the axes, which pass through the central point of the reversible carrier 14 (γ
= 2 arctg(l 0 /2l 1 )).
There should be a possibility of smooth turns of the optical system 15 with the
registration system 16 in the horizontal and the vertical planes about axes, which
pass through the central point of the object. The length of the zones of the angle turn
± arctg(l 2 /2l 1 ) where l 2 is the size of the hologram.
1.3.14. The registration system 16 should have parameters (sensitivity, dynamic
range, inertia, etc.), which make it possible to safely register the oscillating
interference pattern in definite moments of time. A photodiode matrix, a
PEA-matrix or a vidicon can be used in the system.
1.3.15. As a source of continuous radiation 17, it is recommended to use He–Ne laser
LGN-215 or its later modifications. The oscillation plane of the electrical
vector of the generated radiation should be perpendicular to the plane of the
drawing.
1.3.16. The plane-parallel plate 18 should provide parallel shift of the laser beam
of He–Ne laser 17 in the plane perpendicular to the plane of the drawing
at h ± 2 mm. For this, it should have smooth inclinations in the plane
perpendicular to the plane of the drawing. The value of the inclination angle
can be calculated according to the formula
n = d sin α(1 − cos α/
n 2 − sin
2
α)
where d is the thickness of the plate; n is the refractive index.
1.3.17. The plate λ/4 19 is intended to obtain circularly polarized radiation of He–
Ne laser. This plate should be used in the case of the turn of one of the
polarizers 9 or 9
into 90° or deleting of both polarizers will lead to changes
of wavefront distortions more than 0.05 λ. In this case, the polarizers can
be left crossed.
1.3.18. The semitransparent plane-parallel plate 20 should have a possibility to be
put in and out the ray path for adjustment of the ruby laser 1. It should have
adjustment inclinations, which make it possible to join the reflected beam
with the incident one. The sensitivity of the angle adjustments should not
be worse than 2
.
1.3.19. All the elements of the optical scheme should be firmly fixed in the set states.
There should be no cutting of light beams. There should be boots protecting
the optical surfaces from dust and diaphragms for the elimination of spurious
glares.
1.3.20. The optical elements 7–14 should be located as compact as possible and be
firmly fixed to the common base. It is desirable to fulfill them with one block.
The distances between the beam splitter 7 and the mirror 10 and between