Results 221 to 230 of about 10,061 (256)
Some of the next articles are maybe not open access.
Finite difference nearfield errors for a baffled vibrating piston
The Journal of the Acoustical Society of America, 1984Two-microphone finite difference errors for velocity, intensity, and radiated power were analyzed in the near- and farfield of a vibrating piston in a baffle. Since a closed form solution is not available for nearfield radiation, numerical solutions were used to obtain the sound pressure, velocity, and intensity.
openaire +1 more source
Retrieving Inter-Segment Piston Error Using Broadband Light
Frontiers in Optics 2016, 2016Traditional phase retrieval methods fail to retrieve piston errors greater than 0.5 waves in segmented systems because of 2π ambiguities. We present and characterize an algorithm that uses broadband light to determine such piston errors.
Scott W. Paine, James R. Fienup
openaire +1 more source
Effect Of Piston And Tilt Bias Errors In Multiple Wavefront Interference
Optical Engineering, 1989The impact of tilt bias errors in multiple wavefront interferometry is assessed in terms of its effect on the ability to determine piston phase differences between wavefronts from such interferometry. The error in such piston phase determination due to tilt bias has been found to be substantial.
Petras V. Avizonis +2 more
openaire +1 more source
Cross-fringe technique for sensing piston errors of segmented mirror telescope
Space Telescopes and Instrumentation 2020: Optical, Infrared, and Millimeter Wave, 2020For the disaster prevention and mitigation, large segmented Earth observation telescope in the geostationary orbit is studied in JAXA. In order to obtain diffraction limited performance with the segmented telescope, it is necessary to co-phase the segmented primary mirrors with sub-wavelength accuracy.
Seichi Sato +3 more
openaire +1 more source
Experimental determination of errors in piston manometers at high pressures
Measurement Techniques, 1959The suggested method of comparing piston manometers of high pressures by means of a differential instrument is also applicable for determining experimentally the differences between the errors as functions of pressure. The experiments carried out up to pressures of 7000 kg/cm2 confirmed the previously obtained formulas of corrections for strains in ...
openaire +1 more source
Error analysis of the piston estimation method in dispersed fringe sensor
Chinese Physics B, 2017Dispersed fringe sensor (DFS) is an important phasing sensor of next-generation optical astronomical telescopes. The measurement errors induced by the measurement noise of three piston estimation methods for the DFS including least-squared fitting (LSF) method, frequency peak location (FPL) method and main peak position (MPP) method, are analyzed ...
Yang Li, Sheng-Qian Wang, Chang-Hui Rao
openaire +1 more source
MTF non-redundant distribution for multi-piston errors detection of segmented telescopes
2019 International Conference on Optical Instruments and Technology: Optoelectronic Measurement Technology and Systems, 2020We propose a MTF non-redundant distribution method, with which the multi-piston errors of segmented telescope can be detected simultaneously. A mask with a sparse multi-subaperture configuration is set in the exit pupil of the segmented telescope. One subaperture matches to one segment and samples the wave-front reflected by this segment.
Weirui Zhao +3 more
openaire +1 more source
Tolerance Analysis for Piston and Tilt Error in Hexagonal Laser Phased Array
2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC), 2019Coherent Beam Combining is an alternative approach to the construction of high-power lasers, which mitigates the thermo-optic problems occurring in the classic laser construction [1]. However, phased array requires the control of a larger number of parameters, which results in easier beam quality degradation.
Przemyslaw Gontar, Jan K. Jabczynski
openaire +1 more source
Estimation of the GMT inter-segment piston error from deformable mirror commands
SPIE Proceedings, 2011ABSTRACT The Giant Magellan Telescope (GMT) will place seven prim ary mirror segments of 8.4 m diameter on a common mount to form a single co-phased aperture of 25 m. 1 High order adaptive optics (AO) using an adaptive secondary mirror that is segmented in the same way as the primary will correct the telescopes imaging to the diffraction limit in the ...
Michael Hart +5 more
openaire +1 more source