Synthetic Wavelength Holography

Imaging through scattering media or around corners at high resolution

Synthetic Wavelength Holography introduces a novel solution to image through scattering media, or around the corner at the physical space bandwidth limit. Current state-of-the-art approaches are either technically limited by the low spatial and temporal resolution of time-of-flight detectors, or by a very narrow viewing angle in which the hidden scene can be reconstructed. In our approach, we beat together light at two closely spaced optical frequencies to produce a low frequency ‘synthetic wave’ (beat wave), largely immune to the unknown scattering processes between hidden scene and detector. A ‘synthetic hologram’ of the hidden scene can be acquired within milliseconds. Since the ‘synthetic wavelength’ is freely tunable, the captured hologram provides a window to fully reconstruct the three-dimensional light field of the hidden scene at the best possible resolution.

The general concept of ‘synthetic waves’ has potential applications at many different scales and wavebands, including radar, ultrasound, or X-ray. In the optical waveband the ability to look around corners or through scattering media has many potential applications in medicine, naval sciences, earth, and planetary sciences as well as automotive sensing and material sciences. Looking deeper through tissue, novel endoscopic imaging methods, or imaging through dense fog or atmospheric turbulences are just a few potential applications.

Jump to: [Publications], [News and Press], [Related Talk Recordings]

Related Talk Recordings

	F. Willomitzer Single-shot synthetic wavelength holography: a flexible approach for high-resolution imaging through scattering media OPTICA Frontiers in Optics (FiO) Health Symposium, Tacoma, 2023 [Full Video]
	F. Willomitzer Utilizing Nature’s Limits for Better Computational 3D Imaging Center For Robotics and Biosystems Seminar, Northwestern University, USA, 2022 [Full Video] , [Jump to Project (38:40)]
	F. Willomitzer A holographic camera that can see the unseen TEDx Nuremberg, Germany, July 2022 [Full Video]
	F. Willomitzer Synthetic Wavelength Holography – Imaging around Corners and through Scattering Media at the Physical Space-Bandwidth Limit Physics Colloquium Talk Series, University Erlangen-Nuremberg, Germany, 2021 [Full Video]
	F. Willomitzer Fundamental Limits in Computational 3D Imaging – From Novel 3D Cameras to Looking around Corners Beyond the Patterns Talk Series, University Erlangen-Nuremberg, Germany, 2021 [Full Video] , [Jump to Project (23:42)]

Publications

Fast Non-Line-of-Sight Imaging with High-Resolution and Wide Field of View using Synthetic Wavelength Holography
F. Willomitzer, P. Rangarajan, F. Li, M. Balaji, M. Christensen, O. Cossairt.
Nature Communications 12, 6647, 2021

Synthetic Wavelength Imaging - Utilizing Spectral Correlations for High-Precision Time-of-Flight Sensing
F. Willomitzer
Computational Imaging for Scene Understanding - Transient, Spectral, and Polarimetric Analysis, T. Funatomi, T. Okabe, Eds., ISTE Sciences, 2024
Download Preprint

Synthetic Light-in-Flight
P. Cornwall, M. Ballester, S. Forschner, MM Balaji, A. Katsaggelos, F. Willomitzer
ArXiv Preprint, 2024

Synthetic Wavelength Holography: An Extension of Gabor’s Holographic Principle to Imaging with Scattered Wavefronts
F. Willomitzer, P. Rangarajan, F. Li, M. Balaji, M. Christensen, O. Cossairt.
arXiv Preprint, 2019

Single-shot synthetic wavelength imaging: Sub-mm precision ToF sensing with conventional CMOS sensors
M. Ballester, H. Wang, J. Li, O. Cossairt, F. Willomitzer (* joint first authors)
Optics and Lasers in Engineering 178, 2024

Towards Synthetic Light-in-Flight
P. Cornwall, M.Ballester, H. Wang, F.Willomitzer
Optica Open, 2023

Towards Synthetic Wavelength Imaging through Multi-Mode Fibers
S. Forschner, P. Cornwall, M. Ballester, MM. Balaji, J. Czarske, F. Willomitzer
14th International Conference on Optics-Photonics Design and Fabrication (ODF)

Spatially resolved Indirect Imaging of objects beyond the line of sight
P. Rangarajan, F. Willomitzer, O. Cossairt, MP. Christensen
Proc. SPIE 11135, Unconventional and Indirect Imaging, Image Reconstruction, and Wavefront Sensing, 2019

Non-Line-of-Sight Imaging with Superheterodyne Remote Digital Holography
F. Willomitzer, F. Li, M.M. Balaji, P. Rangarajan, O. Cossairt
OSA Computational Optical Sensing and Imaging, CM2A. 2, 2019

Non-Line-of-Sight Imaging using Superheterodyne Interferometry
F. Willomitzer, F. Li, M.M. Balaji, P. Rangarajan, O. Cossairt.
OSA Computational Optical Sensing and Imaging, CM2E. 1, 2018

Synthetic Wavelength Holography in the News

Synthetic Wavelength Holography was Northwestern’s #3 media story in the week of Nov. 18-24, 2021 with a total reach of 3.2 million people within this week.

Official Northwestern research news release:
“New holographic camera sees the unseen with high precision” (Northwestern Now Research News, Nov. 17, 2021)
For Journalists: News release for media contacts and assets.

Research news featured on Northwestern websites:
[Northwestern McCormick School of Engineering (retrieved Nov. 18, 2021)]
[Northwestern Electrical and Computer Engineering (retrieved Nov. 18, 2021)]
[Northwestern Computer Science (retrieved Nov. 18, 2021)]

Research news featured on external websites (selection):

Newsweek: “This Holographic Camera Can See Around Corners, Under Human Skin” (Nov. 19, 2021)

NSF.gov: “High-resolution camera can see around corners and through scattering media” (Dec. 7, 2021)

SCIENTIFIC AMERICAN: “Holographic Camera Instantly Peeks around Obstacles” (Jan. 19, 2022)

Optics.org: “Northwestern University camera sees around corners” (Nov. 18, 2021)

Phys.org: “New holographic camera sees the unseen with high precision” (Nov. 17, 2021)

Daily Mail: “Powerful holographic camera is developed that can see through …” (Nov. 19, 2021)

Photonics.com: “Holographic Camera Peers Through Fog, Around Corners” (Dec., 2021)

AI in Healthcare: “Novel camera images objects around corners, behind barriers” (Nov. 19, 2021)

Science X: “Best of Last Week – Camera sees around corners, ….” (Nov. 22, 2021)

New Atlas: “Holographic camera reconstructs objects around corners in milliseconds” (Nov. 17, 2021)

IFL Science: “New Holographic Camera Can See Around Corners – Or Inside Your Skull” (Nov. 19, 2021)

Mashable: “Researchers Develop Camera That Can See Through Skin And Around Corners” (Nov. 18, 2021)

Universal-Sci: “Scientists developed a remarkable camera that can see around corners” (Nov. 17, 2021)

ZME Science: “Holographic camera can see around corners or even through the skin” (Nov. 18, 2021)

International news coverage (selection):

Report on German TV
Short report about our work on Synthetic Wavelength Holography and portrait about Florian was aired on German (Bavarian) TV on 03/20/2022.
[German language only].
Click here to watch video.