Velocity synchronized Fourier transform hologram camera system
Hologram camera system recording hypervelocity particles by velocity synchronized Fourier transform method, employing interferometer
Dyes, W. A.↗
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Results for “Fourier”
Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.
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A new method for the inverse Laplace transformation via the fast Fourier transform
Algorithm for inverse Laplace transformation of irrational transfer function via fast Fourier transform
Chen, C. F.↗
Factorization of spectra by discrete Fourier transforms
Discrete Fourier transform method for factoring spectral density functions, calculating absolute error
Rino, C. L.↗
Some applications and limitations of the fast Fourier transform
Using fast Fourier transforms for analysis of structural vibration
Hopper, E.↗
Fourier transformable properties of paraboloidal mirror segments
Fourier transformable properties of paraboloidal mirror segments also experimental results of spatial filtering
Husain-Abidi, A. S.↗
Fourier and statistical analysis at random waveforms, part D Final project report
Computer programming formulas for frequency and statistical analysis of random waveform signals including Fourier analysis, probability density functions, and autocorrelation
Luckinbill, D. L.↗
High precision moments for the Fourier coefficients of arbitrary functions
High precision moments for fourier coefficients of arbitrary functions
Zohar, S.↗
Spatial registration of multispectral and multitemporal digital imagery using fast Fourier transform techniques
Multispectral and multitemporal digital imagery spatial registration using fast Fourier transform techniques, applying to earth resources satellite imagery preprocessing
Anuta, P. E.↗
Fourier spectroscopy with a one-million-point transformation
A new type of interferometer for use in Fourier spectroscopy has been devised at the Aime Cotton Laboratory of the National Center for Scientific Research (CNRS), Orsay, France. With this interferometer and newly developed computational techniques, interferograms comprising as many as one million samples can now be transformed. The techniques are described, and examples of spectra of thorium and holmium, derived from one million-point interferograms, are presented.
Connes, J.↗
Vlasov equation eigenvalues and eigenvectors for Fourier-Hermite dispersion matrices of order greater than 1,000
The connection between the Van Kampen and Landau representations of the Vlasov equations has been extended to Fourier-Hermite expansions containing more than 1000 terms by taking advantage of the properties of tridiagonal matrices. These numerical results are regarded as conclusive indications of the nonuniformly convergent behavior of the approximation curve in the limit of an infinite number of terms and represent an extension of work begun by Grant (1967) and by Grant and Feix (1967).
Grant, F. C.↗
An interim report on remote sensing of environmental pollutants with a Fourier interference spectrometer.
A small Fourier interference spectrometer for sensing environmental pollutants from spacecraft has been developed at the Jet Propulsion Laboratory. The instrument is intended for obtaining high spectral resolution infrared absorption spectra in the 1.2 to 5.5 micron region at speeds sufficiently high for medium altitude orbital satellite surveys. The paper reviews basic details of the instrument servo and infrared detection systems, previously described, as well as recent developments. In particular, the data-handling system, data reduction techniques and optical tolerance problems are discussed. Preliminary results are included.
Schindler, R. A.↗
Jones's matrix representation of optical instruments. II - Fourier interferometers /spectrometers and spectropolarimeters/.
Our method of matrix synthesis of optical components and instruments is applied to the derivation of Jones's matrices appropriate for Fourier interferometers (spectrometers and spectropolarimeters). These matrices are obtained for both the source beam and the detector beam. In the course of synthesis, Jones's matrices of the various reflectors (plane mirrors; retroreflectors: roofed mirror, trihedral and prism cube corner, cat's eye) used by these interferometers are also obtained.
Fymat, A. L.↗
Fourier transform C-13 NMR analysis of some free and potassium-ion complexed antibiotics.
Fourier transforms of the noise-decoupled, natural abundance C-13 NMR free induction decays of the cyclic antibiotic valinomycin and its potassium-ion complex have been obtained at 25.2 MHz. Comparisons are made with C-13 NMR spectra taken at 22.6 MHz of the cyclic antibiotic nonactin and the synthetic polyether dicyclohexyl-18-crown-6 and their potassium complexes. The results obtained suggest that conformational rearrangements of the molecule as a whole can compete with direct interactions between carbons and the potassium ion in determining C-13 chemical shift differences between the free and complexed species.
Ohnishi, M.↗
Fourier spectrum of beams chopped by circular apertures.
The circular apertures in the case investigated are uniformly spaced. It is assumed that modulation does not alter beam collimation and that diffraction from aperture edges can be neglected. It is also assumed that the diameter of the apertures is equal to the spacing between the trailing edge and the leading edge of successive apertures. The motion of apertures across the beam is rectilinear. Calculations have been performed for both homogeneous and bivariate normal intensity distributions. The absolute values of the first six Fourier coefficients are plotted as a function of the beam radius normalized to aperture radius.
Cohen, S. C.↗
Fourier plane filters
An electrically addressed liquid crystal Fourier plane filter capable of real time optical image processing is described. The filter consists of two parts: a wedge filter having forty 9 deg segments and a ring filter having twenty concentric rings in a one inch diameter active area. Transmission of the filter in the off (transparent) state exceeds fifty percent. By using polarizing optics, contrast as high as 10,000:1 can be achieved at voltages compatible with FET switching technology. A phenomenological model for the dynamic scattering is presented for this special case. The filter is designed to be operated from a computer and is addressed by a seven bit binary word which includes an on or off command and selects any one of the twenty rings or twenty wedge pairs. The overall system uses addressable latches so that once an element is in a specified state, it will remain there until a change of state command is received. The drive for the liquid crystal filter is ? 30 V peak at 30 Hz to 70 Hz. These parameters give a rise time for the scattering of 20 msec and a decay time of 80 to 100 msec.
Oliver, D. S.↗
A high-resolution Fourier Transform Spectrometer for planetary spectroscopy
The employment of a high-resolution Fourier Transform Spectrometer (FTS) is described for planetary and other astronomical spectroscopy in conjunction with the 88-inch telescope at Mauna Kea Observatory. The FTS system is designed for a broad range of uses, including double-beam laboratory spectroscopy, infrared gas chromatography, and nuclear magnetic resonance spectroscopy. The data system is well-suited to astronomical applications because of its great speed in acquiring and transforming data, and because of the enormous storage capability of the magnetic tape unit supplied with the system. The basic instrument is outlined 2nd some of the initial results from the first attempted use on the Mauna Kea 88-inch telescope are reported.
Cruikshank, D. P.↗
A simple Fourier analysis technique for measuring the dynamic response of manual control systems.
From a practical standpoint most dynamic response analysis techniques are complicated, expensive, and time consuming to mechanize and operate. Adaptive parameter tracking techniques partially overcome these faults, but they have prescribed forms which is an undesirable restriction for basic research. To overcome these drawbacks, an on-line Fourier analysis technique has been developed which deals only with the input and error signals in a manual feedback control system. Several sine waves are used for the input, and the on-line data measurement includes the error variance and a simple means for obtaining the sine and cosine transforms of the error signal at each of the input frequencies. From this relatively small amount of data, we show simple ways to compute the open- and closed-loop dynamic response at input frequencies and the relative amount of linearly correlated power in the error signal.
Allen, R. W.↗
A high-resolution Fourier-transform infrared spectrometer.
We have developed a Fourier-transform infrared spectrometer having a resolution of 0.5/cm over the range of wavelength from 1 to 5.5 microns. It has been used to observe the sun over this wavelength range from a Lear Jet flying at an altitude of 14 km, and to observe a number of stars from the ground, using the 229-cm telescope of the Steward Observatory and the 152-cm aluminum-mirror telescope at the Observatorio Astronomico Nacional in the Sierra de San Pedro Martir, Baja California, Mexico. The solar spectrum is given here, while the ground-based spectra are being published separately.
Johnson, H. L.↗