Mr. Dan Slater Profile

Dan Slater

Retired

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Publications (6)

Proceedings Article | 15 May 2017 Presentation + Paper

Photo-acoustic and video-acoustic methods for sensing distant sound sources

Dan Slater, Stephen Kozacik, Eric Kelmelis

Proceedings Volume 10204, 1020408 (2017) https://doi.org/10.1117/12.2263889

KEYWORDS: Acoustics, Video, Remote sensing, Video processing, Sensors, Cameras, Photodiodes, Modulation, Video acceleration

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Long range telescopic video imagery of distant terrestrial scenes, aircraft, rockets and other aerospace vehicles can be a powerful observational tool. But what about the associated acoustic activity? A new technology, Remote Acoustic Sensing (RAS), may provide a method to remotely listen to the acoustic activity near these distant objects. Local acoustic activity sometimes weakly modulates the ambient illumination in a way that can be remotely sensed. RAS is a new type of microphone that separates an acoustic transducer into two spatially separated components: 1) a naturally formed in situ acousto-optic modulator (AOM) located within the distant scene and 2) a remote sensing readout device that recovers the distant audio. These two elements are passively coupled over long distances at the speed of light by naturally occurring ambient light energy or other electromagnetic fields. Stereophonic, multichannel and acoustic beam forming are all possible using RAS techniques and when combined with high-definition video imagery it can help to provide a more cinema like immersive viewing experience. A practical implementation of a remote acousto-optic readout device can be a challenging engineering problem. The acoustic influence on the optical signal is generally weak and often with a strong bias term. The optical signal is further degraded by atmospheric seeing turbulence. In this paper, we consider two fundamentally different optical readout approaches: 1) a low pixel count photodiode based RAS photoreceiver and 2) audio extraction directly from a video stream. Most of our RAS experiments to date have used the first method for reasons of performance and simplicity. But there are potential advantages to extracting audio directly from a video stream. These advantages include the straight forward ability to work with multiple AOMs (useful for acoustic beam forming), simpler optical configurations, and a potential ability to use certain preexisting video recordings. However, doing so requires overcoming significant limitations typically including much lower sample rates, reduced sensitivity and dynamic range, more expensive video hardware, and the need for sophisticated video processing. The ATCOM real time image processing software environment provides many of the needed capabilities for researching video-acoustic signal extraction. ATCOM currently is a powerful tool for the visual enhancement of atmospheric turbulence distorted telescopic views. In order to explore the potential of acoustic signal recovery from video imagery we modified ATCOM to extract audio waveforms from the same telescopic video sources. In this paper, we demonstrate and compare both readout techniques for several aerospace test scenarios to better show where each has advantages.

Proceedings Article | 25 September 2014 Paper

Afocal viewport optics for underwater imaging

Dan Slater

Proceedings Volume 9192, 91920P (2014) https://doi.org/10.1117/12.2061445

KEYWORDS: Cameras, Water, Ocean optics, Lens design, Glasses, Video, Photography, Contact lenses, Zoom lenses, Distortion

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Proceedings Article | 18 September 2014 Paper

A telescopic cinema sound camera for observing high altitude aerospace vehicles

Dan Slater

Proceedings Volume 9227, 92270A (2014) https://doi.org/10.1117/12.2061399

KEYWORDS: Modulation, Radar, Rockets, Bragg cells, Acoustics, Cameras, Sensors, Remote sensing, Aerospace engineering, Receivers

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Proceedings Article | 25 September 2007 Paper

Remote sensing with passive specular probes

Dan Slater, Sandy Shaw

Proceedings Volume 6709, 67090W (2007) https://doi.org/10.1117/12.734838

KEYWORDS: Telescopes, Modulation, Sensors, Atmospheric optics, Eye, Reflectivity, Cameras, Receivers, Remote sensing, Acoustics

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Proceedings Article | 1 September 2006 Paper

Passive long range acousto-optic sensor

Dan Slater

Proceedings Volume 6304, 63040E (2006) https://doi.org/10.1117/12.681389

KEYWORDS: Bragg cells, Acoustics, Sensors, Atmospheric optics, Scintillation, Modulation, Receivers, Telescopes, Atmospheric scintillation, Turbulence

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Proceedings Article | 30 August 2005 Paper

High resolution long range terrestrial imaging

Dan Slater

Proceedings Volume 5896, 58960B (2005) https://doi.org/10.1117/12.614165

KEYWORDS: Image resolution, Atmospheric optics, Image fusion, Cameras, Image processing, Video, Telescopes, Imaging systems, Speckle, Antennas

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Showing 5 of 6 publications

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