Development of a Background Oriented Schlieren-Based Wavefront Sensor for Aero-Optics

Bichal, Abhishek; Thurow, Brian S.

doi:10.2514/6.2010-4842

Cited by 15 publications

(20 citation statements)

References 17 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Resonance phenomena with periodic supercritical topography [8] will also be part of this future work. Another step could be to extend this work for laboratory experiments to three-dimensional topography with two possible approaches: (i) with synthetic Schlieren but looking at the experiment from different angles using multiple-cameras or a plenoptic camera (see for example [26]), (ii) from multi-planes 2D PIV or from 3D PIV.…”

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

Computation of Density Perturbation and Energy Flux of Internal Waves from Experimental Data

Bordois

Nycander

Paci

2020

Fluids

View full text Add to dashboard Cite

We hereby present two different spectral methods for calculating the density anomaly and the vertical energy flux from synthetic Schlieren data, for a periodic field of linear internal waves (IW) in a density-stratified fluid with a uniform buoyancy frequency. The two approaches operate under different assumptions. The first method (hereafter Mxzt) relies on the assumption of a perfectly periodic IW field in the three dimensions (x, z, t), whereas the second method (hereafter MxtUp) assumes that the IW field is periodic in x and t and composed solely of wave components with downward phase velocity. The two methods have been applied to synthetic Schlieren data collected in the CNRM large stratified water flume. Both methods succeed in reconstructing the density anomaly field. We identify and quantify the source of errors of both methods. A new method mixing the two approaches and combining their respective advantages is then proposed for the upward energy flux. The work presented in this article opens new perspectives for density and energy flux estimates from laboratory experiments data.

show abstract

Section: Discussionmentioning

confidence: 99%

“…The purpose of the final test is to test the strong hypothesis of upward energy propagation made in MxtUp. To this end, we add to the IW ideal field in (26) an IW field containing only waves with downward group velocity (referred to as IW down ):…”

Section: Analytic Iw Fieldsmentioning

confidence: 99%

Computation of Density Perturbation and Energy Flux of Internal Waves from Experimental Data

Bordois

Nycander

Paci

2020

Fluids

View full text Add to dashboard Cite

show abstract

“…where is half the angle of the TO solution of a conical shape. Thus, in the known methods [15,16], one position of the TO located in the registration zone of the photo recorder is registered and one value of the TO speed is determined. In addition, a typical schema photographic head SW [17] suggest, the presence of elements of the scheme of registration commensurate with the size TO; the use of a point light source; no external (background) illumination or the use of photographic electronic shutter.…”

Section: Application Of Background Oriented Schlieren Methodsmentioning

confidence: 99%

“…These factors narrow the scope of the known methods. To eliminate these shortcomings, methods have been developed [15,16]. they are based on video recording of an OI moving at supersonic speed against a background that is a surface with a structure of many small details with high optical contrast (artificial background screen, forest, grass, sand, brick wall...).…”

Section: Application Of Background Oriented Schlieren Methodsmentioning

confidence: 99%

On the development of aeroballistic experiment techniques for flow visualization

Герасимов¹,

Ерофеев²,

Kikeev³

et al. 2021

View full text Add to dashboard Cite

The schemes of shadow rendering, supplementing the methodology of aeroballistic experiment, consisting in the ejection model, mounted in a special separable pallet, ballistic installation; the separation and capture of the pallet by the clipper; the span of the model with given initial conditions of motion speed and angle of attack on the measuring site aeroballistic tracks; contactless external trajectory registration model of the synchronous photographing models of digital cameras stereophotos, operating in standby mode on the background of reference marks of the coordinate reference system. Photographing takes place at the moment when pulsed light sources are triggered synchronously with the model's movement. Under these conditions, shadow visualization schemes are functional, which represent an upgraded method of a luminous point using a protective lens, a combined method that includes registration in passing light using a camera with an electron-optical shutter, and a shadow background method. Typical registration patterns are given.

show abstract

“…The size of this region is dependent on three camera parameters: the object plane distance S o , determined by Equation 3; the magnification of the camera M , determined by Equation 4; and the diameter of the main lens d, given by the f /# of the lens. 9 The front distance L 1 and back distance L 2 of the depth of field can be found by the equations where C is the circle of confusion. This is the uncertainty caused by the spatial resolution of the camera, and the value is given by…”

Section: Prediction Of S Imentioning

confidence: 99%

Calibration of a Microlens Array for a Plenoptic Camera

Thomason

Thurow

Fahringer

2014

52nd Aerospace Sciences Meeting

View full text Add to dashboard Cite

This paper describes current calibration methods for plenoptic cameras and introduces a new method of calibration that seeks to estimate the position and orientation of the microlens array based on the camera geometry and on a calibration image. A geometrical model was formulated to relate the position of a microlens to the location on the image sensor where the lens was focused. The location of the focal points were determined by stopping down the aperture of the main camera lens such that only a small beam of light was incident on each microlens. The position and orientation of the microlens array was assumed, and the predicted focal points were compared with the known points determined from the calibration data. This process was repeated until the root-mean-square difference between the expected and predicted results was minimal. The geometrical method was shown to provide a reasonable estimate for the orientation of the microlens array, as each translational parameter converged to less than one pixel and each rotational parameter converged to within 0.00034 radians. Preliminary results show that the best estimate for the image distance is obtained from a measurement of the magnification by imaging a ruler.

show abstract

Development of a Background Oriented Schlieren-Based Wavefront Sensor for Aero-Optics

Cited by 15 publications

References 17 publications

Computation of Density Perturbation and Energy Flux of Internal Waves from Experimental Data

Computation of Density Perturbation and Energy Flux of Internal Waves from Experimental Data

On the development of aeroballistic experiment techniques for flow visualization

Calibration of a Microlens Array for a Plenoptic Camera

Contact Info

Product

Resources

About