38
1 Resonance Methods for Increasing Sensitivity of Interferometry …
Fig. 1.25 Dependence of current value on the temperature. Reprinted from [54] with permission
interfering beams provided the formation of high contract interference pattern for
wide spectrum radiation.
On the interferometer output, single telescopic system (2, 3) was placed. It
designed the localization region of interference fringes to the center of the cell (4)
with sodium vapors, which made it possible to save the shift of beams in the cell
under change of their convergence angle.
Outgoing from the cell beams was focused by the lens with the focal distance of
F = 200 mm on the slit of the spectrograph DFS-8. The spatial frequency of fringes
changed from 3 to 20 lines/mm that corresponded to beam convergence angle of 2
× 10
−3 –12 × 10
−3 rad. Intensity relations of beams on the interferometer output
vary from 1:1 to 1:30. Sodium atoms concentration in the cell changed from 10
14
to 10
16 cm
−3 , and the layer thickness (along the beams motion) was about 2 cm.
In the absence of sodium vapors in the cell in the focal plane of the spectrograph,
two horizontal fringes can be observed. They correspond to the spectra of initial
beams (see Fig. 1.26a). At space frequencies, which correspond to the recording of
a thin hologram, at radiation density of 10
5 W/cm
−2 , on spectrograms equidistant
fringes could be observed. The position of these fringes corresponded to the expected
diffraction grating pattern formed by initial beams. Figure 1.26b shows one of such
spectrograms produced under the beams convergence angle of 4 × 10
−3 rad. and
vapor concentration of 10
14 cm
−3 .
Additional beams disappeared when additional path difference exceeding 1.5 mm
was included into the interferometer. It corresponds to effective line width of 0.2–
0.3 nm, radiation spectrum assisted in forming dynamic grating (see Fig. 1.26c). And
when optical path difference increased from 0.1 to 1.5 mm, then additional beams
disappeared at first from long-wave and then from short-wave parts of both spectrum
components.
1 Resonance Methods for Increasing Sensitivity of Interferometry …
Fig. 1.25 Dependence of current value on the temperature. Reprinted from [54] with permission
interfering beams provided the formation of high contract interference pattern for
wide spectrum radiation.
On the interferometer output, single telescopic system (2, 3) was placed. It
designed the localization region of interference fringes to the center of the cell (4)
with sodium vapors, which made it possible to save the shift of beams in the cell
under change of their convergence angle.
Outgoing from the cell beams was focused by the lens with the focal distance of
F = 200 mm on the slit of the spectrograph DFS-8. The spatial frequency of fringes
changed from 3 to 20 lines/mm that corresponded to beam convergence angle of 2
× 10
−3 –12 × 10
−3 rad. Intensity relations of beams on the interferometer output
vary from 1:1 to 1:30. Sodium atoms concentration in the cell changed from 10
14
to 10
16 cm
−3 , and the layer thickness (along the beams motion) was about 2 cm.
In the absence of sodium vapors in the cell in the focal plane of the spectrograph,
two horizontal fringes can be observed. They correspond to the spectra of initial
beams (see Fig. 1.26a). At space frequencies, which correspond to the recording of
a thin hologram, at radiation density of 10
5 W/cm
−2 , on spectrograms equidistant
fringes could be observed. The position of these fringes corresponded to the expected
diffraction grating pattern formed by initial beams. Figure 1.26b shows one of such
spectrograms produced under the beams convergence angle of 4 × 10
−3 rad. and
vapor concentration of 10
14 cm
−3 .
Additional beams disappeared when additional path difference exceeding 1.5 mm
was included into the interferometer. It corresponds to effective line width of 0.2–
0.3 nm, radiation spectrum assisted in forming dynamic grating (see Fig. 1.26c). And
when optical path difference increased from 0.1 to 1.5 mm, then additional beams
disappeared at first from long-wave and then from short-wave parts of both spectrum
components.