This article considers the use of holographic interferometer to overwrite the holograms for distortion correction. Each optical system contains some deviations of the beam path, called aberrations of the optical system. They are considered in the resulting interference figure as a distortion of the bands. While increasing the sensitivity of the interference pattern, new aberrations caused by re-registration of the installation in addition to the aberrations already presented on the interferogram caused by the initial record, also multiplied by N times, are introduced N times. In this experiment we decided to use a modified setup with spatially combined interferograms with use of reflective SLM (spatial light modulator) LETO and digital image handling of the interferograms recorded by CCD or CMOS camera.
The article considers the use of holographic interferometer to overwrite the holograms for distortion correction. Each optical system contains some deviations of the beam path, called aberrations of the optical system. They are considered in the resulting interference figure as a distortion of the bands. While increasing the sensitivity of the interference pattern, new aberrations caused by re-registration of the installation in addition to the aberrations already presented on the interferogram caused by the initial record, also multiplied by N times, are introduced N times. In this experiment we decided to use a modified setup with spatially combined interferograms with use of reflective SLM (spatial light modulator) LETO and digital image handling of the interferograms recorded by CCD or CMOS camera.
The method of amplification of hologram was applied to the so-called Rozhdestvenskiy hooks, that were obtained in the Rozhdestvenskiy interferometer (Michelson interferometer, combined with a grating spectrograph). In such a device the absorption lines reveal themselves as specific “hooks”, whose curvature provides the information about the atomic oscillator force. The holographic amplification “smoothes” the hooks and thus makes their analysis much simpler.
The method of amplification of hologram was applied to the so-called Rozhdestvenskiy hooks, that were obtained in the Rozhdestvenskiy interferometer (Michelson interferometer, combined with a grating spectrograph). In such a device the absorption lines reveal themselves as specific “hooks”, whose curvature provides the information about the atomic oscillator force. The holographic amplification “smoothes” the hooks and thus makes their analysis much simpler.
The paper considers the use of holographic interferometer for hologram recording of the wide spectrum from the comb – generator of the femtosecond laser was applied for illuminating of Michelson interferometer with atomic vapor. The behavior of spectral interference fringes on the exit slit of spectrograph reflects the behavior of nonlinear refractive index. The method of holographic interferometry with increasing sensitivity using phase modulator was applied for digital hologram processing.
The paper considers the use of holographic interferometer for hologram re-recording with correction of distortions. Each
optical system contains some beam path deviations, called aberrations of the optical system. They are seen in the
resulting interference pattern as a distortion of fringes. While increasing the sensitivity of the interference pattern by N
times at the same time we introduce new aberrations, caused by re-recording setup in addition to aberrations that are
already presented on the interferogram, caused by initial recording, also multiplied by N times. In this experiment we
decided to use a modified setup with spatially combined interferograms with use of matrix spatial light modulator and
digital image processing of the interferograms recorded by CCD or CMOS camera.
The paper considers the dynamic holographic interferometry schemes with amplification (multiplication) of holographic fringes and with correction for distortions, imposed by the interferometer scheme elements. The use of digital microscope and of the matrix light modulator with direct addressing provides the completely digital closed-loop performance of the overall system for real-time evaluation of nano-scale objects size. Considered schemes were verified in the laboratory experiment, using the Michelson micro-interferometer, equipped by the USB-microscope and digital holography stage, equipped by the Holoeye spatial light modulator.
The method of holographic interferometry with the increased sensitivity was applied for measurements of height of nano-steps (from 10 nm and higher) with standard uncertainty about 0.5 nm. The increasing of sensitivity is obtained by interference of waves with mutually complex conjugated phases.
The method of holographic intereferometry with increased sensitivity was applied for measurements of height of nanosteps (from 10 nm and higher) with standard uncertainty about 0.5 nm. The initial microinterferogram with fringes of equal width was obtained in Michelson micro-interferometer with nano-step sample in one of legs. This interferogram was registered by CCD–camera and the digital interference pattern was reproduced on matrix phase modulator with spatial resolution 30 lines/mm. The matrix phase modulator was placed at the output of the two-beam Mach-Zehnder interferometer and illuminated by two plane laser beams. These two beams diffracted on phase modulator, were focused and spatially filtered by the pinholes in (+ 1-st ) and (– 1-st ) orders of diffraction. The second digital interferogram with twofold increase of sensitivity was obtained on CCD–camera and so on. The increase of sensitivity was obtained due to the interference of waves with complex conjugated phases. One can obtain the interference of higher orders too if working with the nonlinear interferogram. It is possible to obtain any carrier fringe space frequency by using of two plane waves in the interferometer. The increase of sensitivity may be obtained in research of flatness less than λ/100, and topography of surfaces with height difference less than few nanometers as well.
Coherent radiation of 3-level dense medium with strong polyharmonic driving field on adjacent transition has been
researched by numerical solving of density matrix equations together with Maxwell equations. The polarization spectrum
consists of coherent peaks on the frequencies separated from probe field frequency by modulation (beat) frequencies and
its harmonics.
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