Flow visualization in the Langley 0.3-meter Transonic Cryogenic Tunnel and preliminary plans for the National Transonic Facility

Design problems associated with the integration of flow visualization in cryogenic facilities are discussed. The possible effects from the cryogenic environment (i.e., window distortion due to thermal contraction both in the mounts and in the window material itself and turbulence in the flow due to injected LN2) are examined. The flow visualization techniques studied are schlieren, shadowgraph, moire deflectometry, and holographic interferometry. The test beds for this work are a Langley in-house cryogenic test chamber and the 0.3-Meter Transonic Cryogenic Tunnel

The radius and mass of the close solar twin 18 Sco derived from asteroseismology and interferometry

The growing interest in solar twins is motivated by the possibility of comparing them directly to the Sun. To carry on this kind of analysis, we need to know their physical characteristics with precision. Our first objective is to use asteroseismology and interferometry on the brightest of them: 18 Sco. We observed the star during 12 nights with HARPS for seismology and used the PAVO beam-combiner at CHARA for interferometry. An average large frequency separation $134.4\pm0.3$ $\mu$Hz and angular and linear radiuses of $0.6759 \pm 0.0062$ mas and $1.010\pm0.009$ R$_{\odot}$ were estimated. We used these values to derive the mass of the star, $1.02\pm0.03$ M$_{\odot}$.Comment: 5 pages, 5 figure

Achieving diffraction-limited performance on the Berkeley MET5

The Berkeley MET5, funded by EUREKA, is a 0.5-NA EUV projection lithography tool located at the Advanced Light Source at Berkeley National Lab. Wavefront measurements of the MET5 optic have been performed using a custom in-situ lateral shearing interferometer suitable for high-NA interferometry. In this paper, we report on the most recent characterization of the MET5 optic demonstrating an RMS wavefront 0.31 nm, and discuss the specialized mask patterns, gratings, and illumination geometries that were employed to accommodate the many challenges associated with high-NA EUV interferometry

Interferometric tracking system for the tracking and data relay satellite

This report documents construction and testing of the Interferometric Tracking System project developed under the NASA SBIR contract NAS5-30313. Manuals describing the software and hardware, respectively entitled: 'Field Station Guide to Operations' and 'Field Station Hardware Manual' are included as part of this final report. The objective of this contract was to design, build, and operate a system of three ground stations using Very Long Baseline Interferometry techniques to measure the TDRS orbit. The ground stations receive signals from normal satellite traffic, store these signals in co-located computers, and transmit the information via phone lines to a central processing site which correlates the signals to determine relative time delays. Measurements from another satellite besides TDRS are used to determine clock offsets. A series of such measurements will ultimately be employed to derive the orbital parameters, yielding positions accurate to within 50 meters or possibly better

Correlated flux densities from VLBI observations with the DSN

Correlated flux densities of extragalactic radio sources in the very long baseline interferometry (VLBI) astrometric catalog are required for the VLBI tracking of Galileo, Mars Observer, and future missions. A system to produce correlated and total flux density catalogs was developed to meet these requirements. A correlated flux density catalog of 274 sources, accurate to about 20 percent, was derived from more than 5000 DSN VLBI observations at 2.3 GHz (S-band) and 8.4 GHz (X-band) using 43 VLBI radio reference frame experiments during the period 1989-1992. Various consistency checks were carried out to ensure the accuracy of the correlated flux densities. All observations were made on the California-Spain and California-Australia DSN baselines using the Mark 3 wideband data acquisition system. A total flux density catalog, accurate to about 20 percent, with data on 150 sources, was also created. Together, these catalogs can be used to predict source strengths to assist in the scheduling of VLBI tracking passes. In addition, for those sources with sufficient observations, a rough estimate of source structure parameters can be made

Diffraction from deformed volume holograms: perturbation theory approach

We derive the response of a volume grating to arbitrary small deformations, using a perturbative approach. This result is of interest for two applications: (a) when a deformation is undesirable and one seeks to minimize the diffracted field's sensitivity to it and (b) when the deformation itself is the quantity of interest and the diffracted field is used as a probe into the deformed volume where the hologram was originally recorded. We show that our result is consistent with previous derivations motivated by the phenomenon of shrinkage in photopolymer holographic materials. We also present the analysis of the grating's response to deformation due to a point indenter and present experimental results consistent with theory

Phase profile analysis of transparent objects through the use of a two windows interferometer based on a one beam splitter configuration

AbstractIn this research we implemented a two windows interferometer based on polarization phase shifting and grating interferometry techniques in order to retrieve the phase data profile of the object in a single capture. The optical configuration has two optical beams with circular polarization in opposite directions, and it is coupled with a 4-f system. An amplitude grid is used as a filter which is placed at the Fourier plane to obtain replicas of each beam which can properly interfere, depending on the separation between beams. The interferometer presents the capability of changing the beam separation in order to make different orders interfere properly. The interference patterns produced can be separately modulated through the operation of linear polarizer's placed on each interference replica. In order to present the capabilities of the system we will select four interferograms result of contiguous orders interference

The nature of AFGL 2591 and its associated molecular outflow: Infrared and millimeter-wave observations

The results of infrared photometry from 2 to 160 microns of AFGL and CO(12) observations of its associated molecular cloud and high velocity molecular outflow are presented and discussed. The observed solar luminosity is 6.7 x 10(4) at a distance of 2 kpc. The spectrum of AFGL 2591 is interpreted in the context of a model in which a single embedded object is the dominant source of the infrared luminosity. This object is determined to be surrounded by a compact, optically thick dust shell with a temperature in excess of several hundred degrees kelvin. The extinction to this source is estimated to be between 26 and 50 visual magnitudes. The absolute position of the infrared sources at 10 microns was determined to an accuracy of + or in. This indicates for the first time that the IR source and H2O source are not coincident. The CO(12) observations show the high-velocity molecular flow near AFGL 2591 to be extended, bipolar and roughly centered on the infrared emission. The observations suggest that the red-shifted flow component extends beyond the boundary of the ambient cloud within which AFGL 2591 is embedded. The CO(12) observations also show that AFGL 2591 is embedded in a molecular cloud with an LSR velocity of -5 km/s

Application of digital interferogram evaluation techniques to the measurement of 3-D flow fields

A system for digitally evaluating interferograms, based on an image processing system connected to a host computer, was implemented. The system supports one- and two-dimensional interferogram evaluations. Interferograms are digitized, enhanced, and then segmented. The fringe coordinates are extracted, and the fringes are represented as polygonal data structures. Fringe numbering and fringe interpolation modules are implemented. The system supports editing and interactive features, as well as graphic visualization. An application of the system to the evaluation of double exposure interferograms from the transonic flow field around a helicopter blade and the reconstruction of the three dimensional flow field is given