Light rays creating caustic patterns from lensing events at the fluid surface on the surface of a Porites coral in Samoa (V. Chirayath).
Fluid Lensing & Applications (PhD Work)
Welcome to the world of my Fluid Lensing research! This page focuses on developments, research, and applications related to the Fluid Lensing technology I am developing as part of my PhD research at Stanford University's Department of Aeronautics, Aerospace Design Lab under Professor Juan Alonso.
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What is Fluid Lensing?
Fluid Lensing is a theoretical model and algorithm I am developing for fluid-optical interactions in turbulent flows as well as two-fluid surface boundaries that, when coupled with computational imaging and an unique computer vision processing pipeline, may be used to not only remove strong optical distortions along the line of sight (below right, further details of test), but also significantly enhance the angular resolution of an otherwise underpowered optical system.
Fluid Lensing in a poolRAW frame showing wave distortion (above) and Fluid Lensed resolved image (below). Test target is imaged from the bottom of a 12ft deep pool, while attached to a pole 7 feet above the surface (the inverse problem looking down is similar). (V. Chirayath)
As part of my Reactive Reefs Project, we used Fluid Lensing to map coral reefs underwater from an aerial UAV-platform at sub-cm scale for the first time and enabled 3D reconstruction, which has proved a ground-breaking tool in modern marine research and for marine environment conservation (below).
Fluid Lensing results from Quadcopter UAV Coral Mapping Mission in American Samoa (V. Chirayath)
Fluid Lensing overview
Venus Transit 2012A full solar disk panorama showing Venus transiting a dynamic Sun replete with solar features including filaments, flares, sunspots and prominences. More than 1 Terabyte of data were recorded to produce this unprecedented high-resolution result. Captured using the Fluid Lensing method with a narrowband (7nm) hydrogen alpha bandpass filter on a 90mm refractor June 5, 2012.
In addition to marine targets, Fluid-Lensing has shown applicability to imaging targets through the turbulent atmosphere at high resolution with amateur equipment, such as the Venus Transit event (below), which may also apply to imaging targets from LEO. Such a capability may enable novel Earth Science remote sensing capabilities for terrestrial and coastal regions.
More than 1 Terabyte of data were recorded to produce the image above. The quality of RAW video is shown below (along with what appears to be an errant birthday balloon) as well as the imaging setup.
Slideshow of the team taking data. Selected photographs from Stanford News Story by Linda Cicero.
Fluid Lensing Testing - Underwater imaging setup, zenith pointing, RAW frame showing wave distortion (left) and Fluid Lensed resolved image (right). Test target is imaged from the bottom of a 12ft deep pool, while attached to a pole 7 feet above the surface (the inverse problem looking down is similar). Recorded at 1280 x 960, 100 fps, broad spectrum, compressed video feed on GoPro Hero 3
<-- RAW cropped frame showing multiple lensing events and under-sampled data
Post-processed Fluid Lensing preliminary result showing corrected geometry, dithering, transient rejection and some artifacts from DWTs ->
Below are the RAW frames to show you the levels of distortion I was making. Also, we tried to move around the target (xy plane only) to try and make our lives even more difficult, but prevailed in resolving details on my resolution target. Notice the significant lensing events. You can actually make out some of the resolution target features by eye.
More to come soon from air to water testing and high definition results.