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Tavrov AV Kobayashi Y Tanaka Y Shioda T Otani Y Kurokawa T Takeda M 《Optics letters》2005,30(17):2224-2226
A three-dimensional common-path interferometer is proposed, which can achromatically null out an on-axis source while it maintains the detectability of an off-axis source. A geometric phase in the three-dimensional interferometer introduces an achromatic pi-phase shift to the light from the on-axis source, such that destructive interference nulls out the axial light at one of the ports of the interferometer. Light from the off-axis source, which is exempt from the pi-phase shift, comes out from both ports with equal intensity. The common-path scheme makes the system highly immune to environmental disturbances. 相似文献
2.
Tavrov A Korablev O Ksanfomaliti L Rodin A Frolov P Nishikwa J Tamura M Kurokawa T Takeda M 《Optics letters》2011,36(11):1972-1974
To suppress starlight for direct exoplanet observation, we propose a common-path achromatic rotational-shearing coronagraph (CP-ARC), which is an interferocoronagraph with an angular-adjustable field rotator. The CP-ARC aims to maintain unwanted detection of stellar light, which can be suppressed incompletely by interference because of the finite diameter of the star. Compared to the previous interferocoronagraph, which had a nonadjustable 180° field rotation, the proposed CP-ARC can improve the coronagraphic contrast by several orders if the CP-ARC is combined with medium or large telescopes where the companion-star separation is optically resolved by more than a few Airy radii. The CP-ARC is made robust against mechanical disturbances due to the common-path interferometer principle. 相似文献
3.
R Nirmala V Sankaranarayanan K Sethupathi AV Morozkin T Geethakumary Y Hariharan 《Pramana》2002,58(5-6):1101-1104
New R
2Ti3Ge4 (R=Dy, Ho and Er) intermetallic compounds have been synthesized and characterized by X-ray diffraction and low temperature ac
magnetic susceptibility, electrical resistivity and thermoelectric power measurements were carried out. The compounds crystallize
in the parent, Sm5Ge4-type orthorhombic structure (space group Pnma) and lanthanide contraction is observed as one moves along the rare-earth series.
The changeover from paramagnetic to antiferromagnetic phase happens at low temperatures and the ordering temperature scales
with the de Gennes factor. The electrical resistivity is metallic with a negative curvature above 100 K. Thermopower displays
a weak maximum at temperatures less than 50 K signifying the possible phonon and magnon drag effects. 相似文献
4.
A. V. Tavrov 《Technical Physics》2010,55(3):400-408
A common-path interferometer that is intended for observation of a faint off-axis light source against the background of an
intense on-axis source is suggested. The on-axis source and its replicated image acquire an achromatic phase shift of 180°
and interfere in antiphase. The achromatic phase shift is due to the geometrical phase in the configuration of a 3D interferometer.
Interference spatially separates the dark and bright fields of the on-axis source by directing them to different sides of
a beam splitter. At the same time, interference does not attenuate the field of the off-axis source, directing it to different
sides of the beam splitter with equal intensities. Such a configuration of the common-path interferometer provides mechanical
stability. 相似文献
5.
A. V. Tavrov 《Journal of Experimental and Theoretical Physics》2009,108(6):963-976
We propose a new scheme of an achromatic nulling interferometer-coronagraph to gain a higher contrast in the star-planet model. Two successive rotational shearing interferometers improve the interference contrast limited by insufficient spatial coherence of a physically extended source, a star. The theory and simulations have been confirmed by an experiment. The theoretical value of the coronagraphic contrast has been improved from 104 to 1010 for an angular size of the extended source of 10?2λ/D, where λ is the wave-length and D is the telescope’s aperture diameter. 相似文献
6.
A. V. Tavrov 《Journal of Experimental and Theoretical Physics》2008,107(6):942-951
We propose an achromatic interferometer for the observation of a faint off-axis light source against the background of a bright on-axis light source. The on-axis source and its copy acquire an achromatic phase shift by 180° and interfere with a phase difference of π. The achromatic phase shift is attributable to the geometric phase in the three-dimensional interferometer scheme. Interference spatially separates the nulled and bright fields of the on-axis source, redirecting them on opposite sides of the beamsplitter. Interference does not attenuate the field of the off-axis source and redirects it with an equal intensity on both sides of the beamsplitter. We consider the principle of operation of the nulling interferometer and constraints on the attenuation of an extended source due to the decrease in coherence. The laboratory breadboard and experiment are briefly described. 相似文献
7.
Resonant ultrasound spectroscopy was used to measure the elastic constants of bcc Ta0.33V0.67 over the temperature range 3.5–300?K; the results were compared to earlier measurements on C15 TaV2. The temperature dependence of the polycrystalline shear modulus is completely different in the two phases; that of the bcc phase decreases with temperature whereas that of the C15 phases increases in an anomalous fashion. This difference is consistent with a model involving doubly-degenerate levels at the X point of the Brillouin zone in the C15 phase with the Fermi level lying near the doubly degenerate level. This model accounted for the unusual behaviour of the C15 phase. Debye temperatures were determined from the ultrasonic measurements: 295?K for the C15 phase and 315?K for the bcc phase. 相似文献
8.
Nulling interferometry aims to perform destructive interference achromatically. It is used to detect a faint source near a bright one and to provide dark field, an annular pupil, and rotational shear. A nulling out-of-plane interferometer that utilizes the geometric phase of spin redirection is proposed. The degree of nulling is determined by beam collimation and angular orientation of mirrors. Simulations and experiments are in reasonable agreement. 相似文献
9.
A novel scheme for an interferometric microscope with which to visualize a geometrical spin-redirection phase image that represents the local inclination of microsurface structures of an object is proposed. The observed phase depends on the state of polarization and the optical constants of the object material, which enable one to distinguish the spin-redirection phase from the conventional dynamical-phase. A preliminary experiment was performed, and the phase images obtained were found to be consistent with those predicted by computer simulation based on a theoretical model. 相似文献
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