Prof. Soyoung Stephen Cha Profile

Prof. Soyoung Stephen Cha

Associate Professor at Univ of Illinois at Chicago

SPIE Involvement:

Track Chair | Author

Publications (24)

SPIE Journal Paper | 1 October 2006

Hybrid calibration of imaging sensors by neural networks and comparison with physical models

David Lee, Soyoung Cha

OE, Vol. 45, Issue 10, 107202, (October 2006) https://doi.org/10.1117/12.10.1117/1.2360938

KEYWORDS: Calibration, Cameras, Neural networks, Neurons, Optical sensors, 3D modeling, Artificial neural networks, Sensor calibration, Imaging systems, 3D image processing

Read Abstract +

Proceedings Article | 10 November 2003 Paper

Stereoscopic vision calibration for 3D tracking velocimetry based on artificial neural networks

David Lee, Soyoung Cha, Jong-Ho Park

Proceedings Volume 5191, (2003) https://doi.org/10.1117/12.502759

KEYWORDS: Calibration, Mathematical modeling, Cameras, Particles, Artificial neural networks, Neurons, Neural networks, 3D modeling, Velocimetry, Systems modeling

Read Abstract +

Proceedings Article | 29 April 2003 Paper

Three-dimensional measurement of fluid flow by stereoscopic tracking velocimetry

David Lee, Soyoung Cha

Proceedings Volume 5058, (2003) https://doi.org/10.1117/12.509499

Read Abstract +

Proceedings Article | 29 April 2003 Paper

Phase-stepping interferometric system for capturing instantaneous flow field under harsh environments

Alpheus Burner, Enxi Yu, Soyoung Cha

Proceedings Volume 5058, (2003) https://doi.org/10.1117/12.509888

Read Abstract +

Interferometric reconstruction of a flow field usually consists of three steps. The first is to record interferograms, the second is to extract phase information from interferograms and the final is for numerical inversion of the phase data. In interferometric flow recording, test section enclosures and opaque models are frequently present, blocking a portion of the probing rays or restricting the view angle of the field to produce a partial data set especially for interferometric tomography. It also involves very harsh environments with external vibrations and disturbances of the ambient air. The ill-posed problem is susceptible to experimental noise and can produce serious distortions in reconstruction. Interferometric reconstruction of flow fields thus needs accurate phase information extraction. The major problem encountered in interferometry is that it is extremely sensitive to external disturbances including the vibration of the optical setup. This is true especially for aerodynamic wind tunnel testing. For successful application of interferometry to experimental fluid mechancis and heat/mass transfer, efficient mechanisms for accurate flow-field recording and information extraction are thus very necessary. In interferometric recording, use of the phase stepping techniques is desirable whenever possible, since they provide the most accuracy. However, they are not applicable under disturbing conditions; that is, under harsh environments. In an effort to provide accurate interferometric data, we device interferogram recording and reduction techniques. They are based on a phase-stepping method: however, applicable to harsh environments including wind tunnel testing. Here we present the governing concepts, investigation results, and application demonstration of our approaches for practical flow measurements. The developed approaches are tested through phoase extraction and 3D reconstruction of an experimental flow field, which is designed for future wind tunnel testing. The test conditions are very harsh, involving building vibrations and ambient air disturbances especially during the interferometric data acquisition in the phase stepping process. The results of the thermocouple readings agree fairly well with those from the experiment when compared. The acceptable error in the entire interferometric reconstruction process is believed to be mainly due to the ill-posed nature of the tomographic reconstruction but not from the phase extraction of the employed phase-stepping technique.

Proceedings Article | 26 November 2001 Paper

Simple approach to CCD camera calibration for optical diagnostics instrumentation

Soyoung Cha, Fred Leslie, Narayanan Ramachandran

Proceedings Volume 4448, (2001) https://doi.org/10.1117/12.449381

KEYWORDS: Calibration, Optical diagnostics, CCD cameras, Sensors, Optical calibration, Solids, Combustion, Solid state electronics, Optical engineering, Interferometry

Read Abstract +

Proceedings Article | 26 November 2001 Paper

Stereoscopic tracking velocimetry based on neural networks for particle tracking

Yi Ge, David Lee, Soyoung Cha, Dong-Jin Cha

Proceedings Volume 4448, (2001) https://doi.org/10.1117/12.449377

KEYWORDS: Particles, Neural networks, Detection and tracking algorithms, Convection, Velocimetry, Solids, Algorithm development, Data processing, Neurons, Interfaces

Read Abstract +

Proceedings Article | 13 October 1999 Paper

Intelligent regional phase unwrapping by an integrated expert system

Wonjong Joo, Soyoung Cha

Proceedings Volume 3783, (1999) https://doi.org/10.1117/12.365750

KEYWORDS: System integration, Phase shifting, Algorithm development, Fringe analysis, Image processing, Fourier transforms, Visualization, Human-machine interfaces, Edge detection, Image segmentation

Read Abstract +

Proceedings Article | 13 October 1999 Paper

New tracking algorithm for stereoscopic imaging velocimetry

Yi Ge, Soyoung Cha

Proceedings Volume 3783, (1999) https://doi.org/10.1117/12.365731

KEYWORDS: Particles, Neural networks, Detection and tracking algorithms, Velocimetry, Stereoscopy, Stochastic processes, Data processing, Neurons, CCD cameras, Cameras

Read Abstract +

Proceedings Article | 13 October 1999 Paper

Interferometric tomography for reconstructing three-dimensional transient flow

Tiejun Zhao, Soyoung Cha

Proceedings Volume 3783, (1999) https://doi.org/10.1117/12.365770

KEYWORDS: Opacity, Reconstruction algorithms, Tomography, Holograms, Interferometry, Computer simulations, Holography, Algorithm development, Imaging systems, Spatial resolution

Read Abstract +

Proceedings Article | 6 July 1999 Paper

Stereoscopic imaging velocimetry for space material processing experiments

Yi Ge, Soyoung Cha

Proceedings Volume 3792, (1999) https://doi.org/10.1117/12.351287

KEYWORDS: Particles, Neural networks, Stochastic processes, Velocimetry, Stereoscopy, Evolutionary algorithms, Detection and tracking algorithms, Neurons, Materials processing, Imaging systems

Read Abstract +

Proceedings Article | 21 November 1997 Paper

Automated regional phase unwrapping by an integrated expert system

Wonjong Joo, Soyoung Cha

Proceedings Volume 3172, (1997) https://doi.org/10.1117/12.293391

KEYWORDS: Fourier transforms, System integration, Phase shifts, Image processing, Phase shift keying, Phase shifting, Fringe analysis, Binary data, Intelligence systems, Opacity

Read Abstract +

Proceedings Article | 21 November 1997 Paper

Three-dimensional flow diagnostics by holographic diffraction image velocimetry

James Slepicka, Soyoung Cha

Proceedings Volume 3172, (1997) https://doi.org/10.1117/12.293397

KEYWORDS: Particles, Holography, Velocimetry, Diagnostics, Holograms, Diffraction, 3D image processing, Imaging systems, Optical spheres, 3D metrology

Read Abstract +

Proceedings Article | 21 November 1997 Paper

Reconstruction of a flow field by holographic interferometric tomography

Tiejun Zhao, Soyoung Cha

Proceedings Volume 3172, (1997) https://doi.org/10.1117/12.293394

KEYWORDS: Opacity, Reconstruction algorithms, Tomography, Holographic interferometry, Numerical simulations, Optical design, 3D modeling, Interferometry, Imaging systems, Holograms

Read Abstract +

Proceedings Article | 29 September 1995 Paper

Natural pixel decomposition for computational tomographic reconstruction from interferometric projection: algorithms and comparison

Don Cha, Soyoung Cha

Proceedings Volume 2546, (1995) https://doi.org/10.1117/12.221527

KEYWORDS: Reconstruction algorithms, Curium, Interferometry, Opacity, Tomography, Computer simulations, Algorithm development, Spatial resolution, Chemical elements, Distortion

Read Abstract +

Proceedings Article | 29 September 1995 Paper

Two-dimensional nonlinear regression for interferogram analysis

Enxi Yu, Soyoung Cha

Proceedings Volume 2546, (1995) https://doi.org/10.1117/12.221534

KEYWORDS: Interferometry, Data modeling, Computer simulations, Fourier transforms, Fringe analysis, Phase shifts, Modulation, Image processing, Edge detection, Nonlinear image processing

Read Abstract +

Proceedings Article | 29 September 1995 Paper

Interfermometric tomographic measurement of an instantaneous flow field under adverse environments

Enxi Yu, Soyoung Cha, Alpheus Burner

Proceedings Volume 2546, (1995) https://doi.org/10.1117/12.221565

KEYWORDS: Tomography, Interferometry, Holography, Holograms, Environmental sensing, Fringe analysis, Opacity, Phase shift keying, Integral transforms, Diffusers

Read Abstract +

Proceedings Article | 29 September 1995 Paper

Effective low-level processing for interferometric image enhancement

Wonjong Joo, Soyoung Cha

Proceedings Volume 2546, (1995) https://doi.org/10.1117/12.221540

KEYWORDS: Image processing, Image filtering, Fringe analysis, Image segmentation, Interferometry, Smoothing, Image enhancement, Aerodynamics, Visualization, Interference (communication)

Read Abstract +

SPIE Journal Paper | 1 January 1995

Use of interferometric directionality for noise reduction [also Letter 34(7)2168(Jul1995)]

Enxi Yu, Soyoung Cha, Wonjong Joo

OE, Vol. 34, Issue 01, (January 1995) https://doi.org/10.1117/12.10.1117/12.183990

KEYWORDS: Interferometry, Denoising, Digital filtering, Image processing, Edge detection, Image filtering, Computer simulations, Aerodynamics, Fringe analysis, Optical engineering

Read Abstract +

Proceedings Article | 2 December 1993 Paper

Directional smoothing for interferogram reduction

Enxi Yu, Wonjong Joo, Soyoung Cha

Proceedings Volume 2005, (1993) https://doi.org/10.1117/12.163740

KEYWORDS: Edge detection, Denoising, Digital filtering, Computer simulations, Interferometry, Image processing, Algorithm development, Fringe analysis, Moire patterns, Binary data

Read Abstract +

Proceedings Article | 2 December 1993 Paper

Expert system for noise-ridden interferometric data analysis

Wonjong Joo, Soyoung Cha

Proceedings Volume 2005, (1993) https://doi.org/10.1117/12.163724

KEYWORDS: Interferometry, Fringe analysis, Image processing, Feature extraction, Aerodynamics, Denoising, Data analysis, Image segmentation, Data processing, Phase shifts

Read Abstract +

Proceedings Article | 2 December 1993 Paper

Cross-correlation of three-dimensional images for three-dimensional three-component fluid velocity measurements

Kejian Huang, James Slepicka, Soyoung Cha

Proceedings Volume 2005, (1993) https://doi.org/10.1117/12.163748

KEYWORDS: Particles, Holography, 3D image processing, Diffraction, Scattering, Speckle, Laser scattering, Velocity measurements, Holograms, Velocimetry

Read Abstract +

SPIE Journal Paper | 1 July 1993

Improvement of a series expansion approach to interferometric tomography via natural pixel decomposition

Don Cha, Soyoung Cha

OE, Vol. 32, Issue 07, (July 1993) https://doi.org/10.1117/12.10.1117/12.138720

KEYWORDS: Interferometry, Curium, Tomography, Reconstruction algorithms, Computer simulations, Chemical elements, Spatial resolution, Opacity, Data acquisition, Diagnostics

Read Abstract +

Proceedings Article | 1 December 1991 Paper

Natural pixel decomposition for interferometric tomography

Don Cha, Soyoung Cha

Proceedings Volume 1554, (1991) https://doi.org/10.1117/12.57446

KEYWORDS: Interferometry, Curium, Tomography, Reconstruction algorithms, Computer simulations, Holographic interferometry, Chemical elements, Opacity, Spatial resolution, Mechanics

Read Abstract +

Proceedings Article | 1 December 1991 Paper

Stabilization of ill-posed nonlinear regression model and its application to interferogram reduction

James Slepicka, Soyoung Cha

Proceedings Volume 1554, (1991) https://doi.org/10.1117/12.57442

KEYWORDS: Fourier transforms, Fringe analysis, Data modeling, Interferometry, Holographic interferometry, Mechanics, Modulation, Phase measurement, Holography, Moire patterns

Read Abstract +