184
3 Holographic Interferometry for Studying …
The possibilities and spheres of application of the holographic interferometry
methods have significantly broadened as a result of powerful pulse solid lasers implementation in holographic systems. The studies and the development made in a number
of foreign companies (Rottencolber Holosystem (FRG), Apolo Laser Corp. (USA),
etc.) have shown good prospects of this school. Most significant results were obtained
during the implementation of specialized lasers in holographic systems. The lasers
operate in the generation mode of two giant pulses with regulated pulse-repetition
intervals and high spatial and time coherence of the radiation.
The peculiarity of the studies conducted in this chapter is the usage of unique
possibilities of pulsed dye lasers and ruby lasers that enabled to develop and implement the methods of two- and multi-long-wave holographic interferometry with
regulated spectral range and of two- and multi-exposure holographic interferometry
with regulated temporal interval between generation pulses, as well as the methods
of holographic contouring of surface relief using resonance, absorbing and optically
active media.
The holographic contouring methods are easy and suitable for obtaining contoured
maps of arbitrarily shaped objects. There exist different possibilities to form such
maps: The multi-long-wave method of recording a hologram of an object is conducted
in laser radiation containing several wavelengths [68, 69]; the immersion one—the
hologram is recorded when the object is placed in the camera [70] where the refractive
index of liquid or gas, which fill the camera, is changing between two exposures; the
several sources method—two sources spatially separated are used during recording
a hologram of an object [68], etc.
The method of holographic study of an object shape using several wavelengths
was most developed. In the work [69], it is shown that in the case of two point
sources emitting different wavelengths the interference fringes are formed when the
object crosses the family of paraboloids of revolution. It is pointed out that while
using collimated beams it is possible to obtain contour maps with plane equidistant
secant surfaces. It is ascertained [28–31] that the most perspective light source for
sensitivity regulating in this method is a dye laser. It allows smoothly converting the
wavelength in a wide range and implementing simultaneous generation of several
wavelengths. In the works [58, 71], the theoretical analysis of phase ratios under
holographic interferogram recording in several wavelengths is conducted.
Conditions of contour maps obtaining for Fresnel, quasi-Fourier and holograms
of a focused image are examined in the work [72], and for topograms of real and
virtual image—in the work [73].
Despite great possibilities of the holographic contouring method, it has its limitations and disadvantages. Two-long-wave interferometers require a rather complicated
adjustment procedure, though a number of decisions are found, which simplify it.
It is known that for multi-long-wave contouring ruby [74], pulse xenon [75] and
other ion gaseous lasers were implemented, which are characterized by high radiation
power and coherence length that enabled to get contours on real objects. Implementation of convertible along the wavelength radiation of dye lasers with continuous
pumping [71] and pulse pumping [28, 76] is most advantageous when there is need of
smooth regulating interval between broad bands. That is why dye lasers are of great
3 Holographic Interferometry for Studying …
The possibilities and spheres of application of the holographic interferometry
methods have significantly broadened as a result of powerful pulse solid lasers implementation in holographic systems. The studies and the development made in a number
of foreign companies (Rottencolber Holosystem (FRG), Apolo Laser Corp. (USA),
etc.) have shown good prospects of this school. Most significant results were obtained
during the implementation of specialized lasers in holographic systems. The lasers
operate in the generation mode of two giant pulses with regulated pulse-repetition
intervals and high spatial and time coherence of the radiation.
The peculiarity of the studies conducted in this chapter is the usage of unique
possibilities of pulsed dye lasers and ruby lasers that enabled to develop and implement the methods of two- and multi-long-wave holographic interferometry with
regulated spectral range and of two- and multi-exposure holographic interferometry
with regulated temporal interval between generation pulses, as well as the methods
of holographic contouring of surface relief using resonance, absorbing and optically
active media.
The holographic contouring methods are easy and suitable for obtaining contoured
maps of arbitrarily shaped objects. There exist different possibilities to form such
maps: The multi-long-wave method of recording a hologram of an object is conducted
in laser radiation containing several wavelengths [68, 69]; the immersion one—the
hologram is recorded when the object is placed in the camera [70] where the refractive
index of liquid or gas, which fill the camera, is changing between two exposures; the
several sources method—two sources spatially separated are used during recording
a hologram of an object [68], etc.
The method of holographic study of an object shape using several wavelengths
was most developed. In the work [69], it is shown that in the case of two point
sources emitting different wavelengths the interference fringes are formed when the
object crosses the family of paraboloids of revolution. It is pointed out that while
using collimated beams it is possible to obtain contour maps with plane equidistant
secant surfaces. It is ascertained [28–31] that the most perspective light source for
sensitivity regulating in this method is a dye laser. It allows smoothly converting the
wavelength in a wide range and implementing simultaneous generation of several
wavelengths. In the works [58, 71], the theoretical analysis of phase ratios under
holographic interferogram recording in several wavelengths is conducted.
Conditions of contour maps obtaining for Fresnel, quasi-Fourier and holograms
of a focused image are examined in the work [72], and for topograms of real and
virtual image—in the work [73].
Despite great possibilities of the holographic contouring method, it has its limitations and disadvantages. Two-long-wave interferometers require a rather complicated
adjustment procedure, though a number of decisions are found, which simplify it.
It is known that for multi-long-wave contouring ruby [74], pulse xenon [75] and
other ion gaseous lasers were implemented, which are characterized by high radiation
power and coherence length that enabled to get contours on real objects. Implementation of convertible along the wavelength radiation of dye lasers with continuous
pumping [71] and pulse pumping [28, 76] is most advantageous when there is need of
smooth regulating interval between broad bands. That is why dye lasers are of great