Information retrieval from holographic interferograms: Fundamentals and problems

Holographic interferograms can contain large amounts of information about flow and temperature fields. Their information content can be very high because they can be viewed from many different directions. This multidirectionality, and fringe localization add to the information contained in the fringe pattern if diffuse illumination is used. Additional information, and increased accuracy can be obtained through the use of dual reference wave holography to add reference fringes or to effect discrete phase shift or hetrodyne interferometry. Automated analysis of fringes is possible if interferograms are of simple structure and good quality. However, in practice a large number of practical problems can arise, so that a difficult image processing task results

Onset of convection due to horizontal laser beams

When a horizontal cw laser beam is suddenly turned on in a quiescent isothermal fluid there is a delay time t∗ during which thermal blooming is governed by absorption of radiation and thermal conduction. For t≳t∗, free convection becomes a significant factor. t∗ is determined by an approximate quasisteady hydrodynamic stability analysis and is compared with existing experimental data.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/71189/2/APPLAB-26-6-287-1.pd

Onset of convection near a suddenly heated horizontal wire

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/34099/1/0000381.pd

Digital interferometry for flow visualization

Digital holographic interferometry is a hybrid optical-digital technique for determining the phase of an interferogram. This technique improves the accuracy of interferometric measurement of fluid properties and enhances the utility of interferometric flow visualization. Displays of the interferometric phase produce excellent images of weakly refracting two-dimensional flows and can be used to produce integral projection images of three dimensional flows which differ from and complement schlieren and shadowgraph images. The technique is explained herein and examples of its use in both continuous wave and pulsed interferometry are presented.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/47080/1/348_2004_Article_BF00264404.pd

Measurement of three-dimensional temperature fields above heated surfaces by holographic interferometry

Optical holography can be used to record multi-directional interferometric data, which provides a basis for measuring three-dimensional, asymmetric temperature or density fields in fluids. If continuous optical pathlength data are available over a 180[deg] angle of view, the temperature or density field is shown to be equal to the inverse Radon transform of the data. A procedure for computing limited-resolution reconstructions of the field in terms of discrete data collected over a limited angle of view is presented.The technique of holographic interferometry was used to map isothermal contours in the developing convective plume above heated, horizontal, rectangular surfaces. It was found that the thermal structure of the developing plume is strongly influenced by the partitioning of the flow adjacent to the surface along lines of geometric symmetry.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/22227/1/0000661.pd

Turbulent flow visualization by interferometric integral imaging and computed tomography

An experimental system using integral interferometric imaging and computer tomography for visualizing the structure of a turbulent, vertical helium jet is described. Integral images and tomographic integral data were obtained using a pulsed phase-shifted interferometer. The integral images revealed a sinuous overall jet structure and large-scale buckling motions in the far-field. Tomographic reconstruction of jet cross-sections at numerous axial locations were made for three turbulent jets at two different Reynols numbers, 2,800 and 4,300. Tomographic images revealed unmixed ambient fluid far inside the jet boundary and a bimodal concentration distribution. Image interpretation and experimental errors are discussed.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/47084/1/348_2004_Article_BF00217195.pd

Laminar natural convection above a horizontal laser beam

The steady laminar natural convective plume above a horizontal laser beam has been studied. The plume, which is caused by absorption of thermal energy from the beam, is three-dimensional. The three-dimensionality is a consequence of mass continuity and the variation in the thermal energy absorption in the propagation direction. Flow visualizations have verified the three-dimensionality in that a significant velocity component, in a direction opposite to that of laser beam propagation, was observed.The problem is reduced by similarity analysis to a system of ordinary differential equations which are solved numerically for the Prandtl number, Pr = 1.0. Integral approximations are also presented for Pr = 0.7, 1.0, 10.0 and 100.0. The effect of Pr on the velocities, and temperature boundary layer thicknesses is discussed in detail.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/24418/1/0000689.pd

Natural convection boundary layers adjacent to pyrolyzing surfaces

The temperature, velocity, and concentration distributions were measured in boundary layers adjacent to heated vertical polymethyl methacrylate (PMMA) and wood (Southern Pine) surfaces, and next to a heated, vertical, sintered bronze plate through which propane was injected. The temperature, velocity, and concentration were measured as functions of position and time using thermocouple probes, flow visualization techniques, and heterodyne holographic interferometry, respectively. The measured distributions were compared to the results of a simple model. The agreement between the measured values and the results of the model was generally good and was within the experimental uncertainty.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/25044/1/0000471.pd

Optical measurement of profile and contact angle of liquids on transparent substrates

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/47069/1/348_2004_Article_BF00296430.pd

Case study of a performance-active changing trans* male singing voice

A professional classical singer of more than 25 years (AZ) in his early 50s requested this voice researcher’s consultation and assistance in early 2014. He was about to start living full time as a trans* man. Despite his intention to be included in the low start/gradual increase testosterone option of the Trans* Male (previously, “FTM”) Singing Voice Program, the request contained a rather unconventional aspect: AZ would continue to sing while his voice was changing. The above request was integral with his singing history. After the introduction of safeguards and his informed consent, AZ was accepted onto the Program. Due to the highly individual circumstances, his participation was recorded as a case study. The study has aimed to replicate the particulars of the slow hormonal changes and continuing singing ability found in certain cisgender male adolescent voices. Despite dealing with an adult trans* male individual, the progress has been comparable. This has been achieved by carefully monitoring AZ’s low start/gradual increase testosterone administration in communication with the medical practitioner. The participant’s vocal health remained safeguarded and promoted by carefully individualized vocal tuition. This article will discuss the collective results of the case study, including the recordings and the data analysis