Improved Laser Velocimeter
Self-alining laser velocimeter uses simple lenses and Dopplerfrequency shift by scattering disk to monitor fluid motion in three dimensions.
Heflinger, L. O.↗
Engineering topics
Heflinger, L. O.
Publications and source records attributed to Heflinger, L. O..
Recording fluid currents by holography
Convection in fluids can be studied with aid of holographic apparatus that reveals three-dimensional motion of liquid. Apparatus eliminates images of fixed particles such as dust on windows and lenses, which might mask behavior of moving fluid particles. Holographic apparatus was developed for experiments on fluid convection cells under zero gravity. Principle is adaptable to study of fluid processes-for example, electrochemical plating and combustion in automotive engines.
Heflinger, L. O.↗
Holography on the NASA Space Shuttle
The SL-3 flight on the Space Shuttle will carry a 25 mW He-Ne laser holographic recorder for recording the solution growth of triglycine sulfate (TGS) crystals under low-zero gravity conditions. Three hundred holograms (two orthogonal views) will be taken (on SO-253 film) of each growth experiment. Processing and analysis (i.e., reconstructed imagery, holographic schlieren, reverse reference beam microscopy, and stored beam interferometry) of the holographic records will be done at NASA/MSFC. Other uses of the recorder on the Shuttle have been proposed.
Wuerker, R. F.↗
Spatial filter for Q-switched lasers
A spatial filtered Q-switched laser system is reported that prevents ionization of air in close proximity to the aperture of the spatial filter. A compound lens system having an astigmatic focus is positioned between the laser and the spatial filter for defocusing the light beam emanating from the laser in the vicinity of the aperture of the spatial filter to an intensity below that which produces ionization of air. The preferred construction of the compound lens system as viewed from the laser comprises a cylindrical lens and a pair of positive lenses.
Wuerker, R. F.↗
Spatial filter for Q-switched laser
Set of compound lenses reduces ionization and sparks that frequently occur around pinhole aperture in spatial filter. Lens system produces astigmatic focus near pinhole, reducing energy level there below ionization theshold.
Heflinger, L. O.↗
Dual-purpose holocamera
Camera utilizes same basic structure to record bright-field holograms (single and double exposure interferograms) or, with minor adjustments, record forward scattered light holograms. Components that must be interchanged to convert camera can be mounted on sliding plate.
Heflinger, L. O.↗
Application of holography to flow visualization within rotating compressor blade row
Two holographic interblade row flow visualization systems were designed to determine the three-dimensional shock patterns and velocity distributions within the rotating blade row of a transonic fan rotor, utilizing the techniques of pulsed laser transmission holography. Both single- and double-exposure bright field holograms and dark field scattered-light holograms were successfully recorded. Two plastic windows were installed in the rotor tip casing and outer casing forward of the rotor to view the rotor blade passage. The viewing angle allowed detailed investigation of the leading edge shocks and shocks in the midspan damper area; limited details of the trailing edge shocks also were visible. A technique was devised for interpreting the reconstructed holograms by constructing three dimensional models that allowed identification of the major shock systems. The models compared favorably with theoretical predictions and results of the overall and blade element data. Most of the holograms were made using the rapid double-pulse technique.
Wuerker, R. F.↗
Sensitive holographic detection of small aerodynamic perturbations
Phase modulations enhance the sensitivity of holographic techniques for detecting disturbances which are caused by variations in gas density of the order of 1/10 wavelength or less. In the readout, subject perturbations show up as brightenings on a dark background.
Heflinger, L. O.↗
Improving laser beam coherence - A concept
Laser frequencies may be reduced to single frequency or selected frequencies. For single frequency performance, spacing of frequencies falls in natural line width. For two or more frequencies, thicker spacing is used. Configuration adapts to operation with Kerr or Pockel cell for Q switching.
Heflinger, L. O.↗
Multifrequency laser beams for holographic contouring
Pulsed ruby laser emits two optical frequencies simultaneously so holographic recordings of test object give images showing desired range contours. Process enables generation of contour maps for practical applications such as gaging size and shape of mechanical parts and other structures.
Heflinger, L. O.↗
Multipass holographic interferometer improves image resolution
Multipass holographic interferometer forms a hologram of high diffraction efficiency, and hence provides a bright and high contrast interferogram. It is used to study any effect which changes the index of refraction and to study surface deformations of a flat reflecting surface.
Brooks, R. E.↗
Pulsed laser holography
Pulsed laser holography, discussing illumination source and holocameras for high contrast recording with Q switched ruby lasers
Heflinger, L. O.↗
Holographic instrumentation studies
Holographic interferometry, improved coherence of ruby lasers, and instrumentation techniques
Brooks, R. E.↗
Finite fringe hologram
In holographic interferometry a small movement of apparatus between exposures causes the background of the reconstructed scene to be covered with interference fringes approximately parallel to each other. The three-dimensional quality of the holographic image is allowable since a mathematical model will give the location of the fringes.
Heflinger, L. O.↗
Microbalance
A reed is vibrated by the minute vibrations of a base frame which, in turn, is vibrated by a driver mechanism. The vibration of the reed is picked off and fed back to the driver means, causing the base frame to be vibrated at the resonant frequency of the reed. A counter is connected to the feedback loop to measure the frequency of the reed oscillations. By adding the mass to be weighed to the reed, the resonant frequency of the reed will be changed, which will in turn change the reading at the counter by an amount which is proportional to the added mass.
Heflinger, L. O.↗
Pulsed laser holography
High speed pulsed ruby laser holography, discussing transmission-reflection holocameras and applications
Heflinger, L. O.↗
Two-color holography
Two holograms, made simultaneously, one with a red light component and one with the harmonic UV component to give two fringes in the UV construction due to shortened wavelength. The reconstruction, obtained with a He-Ne laser, could be photographed separately, giving quality interferograms.
Heflinger, L. O.↗
Fine-line sensitivity for holographic interferograms
Improvement in sensitivity of holography, the technique of lensless interferometry, is obtained by enhancing the higher-order structure in the interferogram. By using the light diffracted into higher orders than the first, phase sensitivity is increased over the first order sensitivity by a factor equal to the order number used.
Heflinger, L. O.↗