1 Resonance Methods for Increasing Sensitivity of Interferometry …
3
to overcome this problem and to recover the full form of spatial coherence function
(SCF) between any laser edge points.
Though holographic and step methods enable to recover the full form of SCF, their
use is quite difficult and time-consuming experimental task. So, for example, the
number of measurements n necessary for SCF determining for points of laser end is
equal to N
2 (where N ≈ 100). At the same time in some cases, when behavior details
of |γ |
2 are insignificant, it is convenient to determine averaged values |γ |
2 (e.g., to
approximate |γ |
2 by homogeneous function) for the space coherent characteristic. For
the measuring laser edge-averaged SCF distribution, less time-consuming integral
method is proposed.
The possibilities of different methods, which are used in the radiation spatial
coherence investigations, have been studied. They are interference, holographic,
holographic with microphotometry of intensity initial distribution, integral under the
spatial coherence measurement of pulsed organic dye laser radiation with unstable
mode structure, particularly, rhodamine 6G laser with the laser pumping.
1.1 Rhodamine 6G Laser with Laser Pumping
for Holography, Resonance Interferometry
and Fluorescence
For the first time, dye solution generation was found in the USSR [45, 46], in the USA
and in FRG in 1966 [47, 48]. B. I. Stepanov, A. N. Rubinov, and V. A. Mostovnikov
contributed to the creation and development of these lasers; therefore, they were
honored with the USSR State Prize [49, 50].
Dye lasers are a special class of optical quantum generators [50–52]. Having broad
amplification band, organic dyes enable to carry out graduated frequency tuning in
the broad spectral region (up to 100 nm in one dye type). During the experimental
studies on resonance interferometry and dynamic resonance holography, “Raduga3M” dye laser-type [39, 53], which was developed in the Institute of Physics of
the Academy of Sciences of the BSSR, was assumed as a basis.
1 Using “Raduga3M,” it was possible to get quite high-power laser radiation in the spectral region
of 360–1200 nm. In the present work for radiation generation, the effective dye
1 The dye laser “Raduga-3M” with laser pumping was for the first time mounted by the author
from the separately developed drawings into the instrument version in the Institute of Physics of
the Academy of Sciences of the BSSR and was made in the optical mechanics departments of the
Leningrad Physics and Technology Institute named after A. E. Ioffe of the Academy of Sciences of
the USSR (1971). During the process of producing, several changes were added to this laser device.
In particular, the length of the resonator was increased, and the Fabry–Perot interferometer was
introduced in it with the basis of 100 μm, what gave the possibility to narrow the width of generator
spectrum up to 0.01–0.03 nm and carry out the regime of one-and four-frequency generation with
the pulse energy of 10 −3 J and power of about 0.1 mW. These changes made it appropriate for the
usage in holography purposes and resonance interferometry.
3
to overcome this problem and to recover the full form of spatial coherence function
(SCF) between any laser edge points.
Though holographic and step methods enable to recover the full form of SCF, their
use is quite difficult and time-consuming experimental task. So, for example, the
number of measurements n necessary for SCF determining for points of laser end is
equal to N
2 (where N ≈ 100). At the same time in some cases, when behavior details
of |γ |
2 are insignificant, it is convenient to determine averaged values |γ |
2 (e.g., to
approximate |γ |
2 by homogeneous function) for the space coherent characteristic. For
the measuring laser edge-averaged SCF distribution, less time-consuming integral
method is proposed.
The possibilities of different methods, which are used in the radiation spatial
coherence investigations, have been studied. They are interference, holographic,
holographic with microphotometry of intensity initial distribution, integral under the
spatial coherence measurement of pulsed organic dye laser radiation with unstable
mode structure, particularly, rhodamine 6G laser with the laser pumping.
1.1 Rhodamine 6G Laser with Laser Pumping
for Holography, Resonance Interferometry
and Fluorescence
For the first time, dye solution generation was found in the USSR [45, 46], in the USA
and in FRG in 1966 [47, 48]. B. I. Stepanov, A. N. Rubinov, and V. A. Mostovnikov
contributed to the creation and development of these lasers; therefore, they were
honored with the USSR State Prize [49, 50].
Dye lasers are a special class of optical quantum generators [50–52]. Having broad
amplification band, organic dyes enable to carry out graduated frequency tuning in
the broad spectral region (up to 100 nm in one dye type). During the experimental
studies on resonance interferometry and dynamic resonance holography, “Raduga3M” dye laser-type [39, 53], which was developed in the Institute of Physics of
the Academy of Sciences of the BSSR, was assumed as a basis.
1 Using “Raduga3M,” it was possible to get quite high-power laser radiation in the spectral region
of 360–1200 nm. In the present work for radiation generation, the effective dye
1 The dye laser “Raduga-3M” with laser pumping was for the first time mounted by the author
from the separately developed drawings into the instrument version in the Institute of Physics of
the Academy of Sciences of the BSSR and was made in the optical mechanics departments of the
Leningrad Physics and Technology Institute named after A. E. Ioffe of the Academy of Sciences of
the USSR (1971). During the process of producing, several changes were added to this laser device.
In particular, the length of the resonator was increased, and the Fabry–Perot interferometer was
introduced in it with the basis of 100 μm, what gave the possibility to narrow the width of generator
spectrum up to 0.01–0.03 nm and carry out the regime of one-and four-frequency generation with
the pulse energy of 10 −3 J and power of about 0.1 mW. These changes made it appropriate for the
usage in holography purposes and resonance interferometry.