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Title: Active resonant subwavelength grating for scannerless range imaging sensors.


No abstract prepared.

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Publication Date:
Research Org.:
Sandia National Laboratories
Sponsoring Org.:
OSTI Identifier:
Report Number(s):
TRN: US200722%%809
DOE Contract Number:
Resource Type:
Resource Relation:
Conference: Proposed for presentation at the SPIE Photonics West 2007 held January 22-25, 2007 in San Jose, CA.
Country of Publication:
United States

Citation Formats

Kemme, Shanalyn A., Nellums, Robert O., Boye, Robert R., and Peters, David William. Active resonant subwavelength grating for scannerless range imaging sensors.. United States: N. p., 2007. Web.
Kemme, Shanalyn A., Nellums, Robert O., Boye, Robert R., & Peters, David William. Active resonant subwavelength grating for scannerless range imaging sensors.. United States.
Kemme, Shanalyn A., Nellums, Robert O., Boye, Robert R., and Peters, David William. Mon . "Active resonant subwavelength grating for scannerless range imaging sensors.". United States. doi:.
title = {Active resonant subwavelength grating for scannerless range imaging sensors.},
author = {Kemme, Shanalyn A. and Nellums, Robert O. and Boye, Robert R. and Peters, David William},
abstractNote = {No abstract prepared.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Mon Jan 01 00:00:00 EST 2007},
month = {Mon Jan 01 00:00:00 EST 2007}

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  • In this late-start LDRD, we will present a design for a wavelength-agile, high-speed modulator that enables a long-term vision for the THz Scannerless Range Imaging (SRI) sensor. It takes the place of the currently-utilized SRI micro-channel plate which is limited to photocathode sensitive wavelengths (primarily in the visible and near-IR regimes). Two of Sandia's successful technologies--subwavelength diffractive optics and THz sources and detectors--are poised to extend the capabilities of the SRI sensor. The goal is to drastically broaden the SRI's sensing waveband--all the way to the THz regime--so the sensor can see through image-obscuring, scattering environments like smoke and dust.more » Surface properties, such as reflectivity, emissivity, and scattering roughness, vary greatly with the illuminating wavelength. Thus, objects that are difficult to image at the SRI sensor's present near-IR wavelengths may be imaged more easily at the considerably longer THz wavelengths (0.1 to 1mm). The proposed component is an active Resonant Subwavelength Grating (RSG). Sandia invested considerable effort on a passive RSG two years ago, which resulted in a highly-efficient (reflectivity greater than gold), wavelength-specific reflector. For this late-start LDRD proposal, we will transform the passive RSG design into an active laser-line reflector.« less
  • Resonant subwavelength gratings (RSGs) may be used as narrow-band wavelength and angular reflectors. Rigorous coupled wave analysis (RCWA) predicts 100% reflectivity at the resonant frequency of an incident plane wave from an RSG of infinite extent. For devices of finite extent or for devices illuminated with a finite beam, the peak reflectivity drops, coupled with a broadening of the peak. More complex numerical methods are required to model these finite effects. We have modeled finite devices and finite beams with a two-dimensional finite difference Helmholtz equation. The effect of finite grating aperture and finite beam size are investigated. Specific casesmore » considered include Gaussian beam illumination of an infinite grating, Gaussian illumination of a finite grating, and plane wave illumination of an apertured grating. For a wide grating with a finite Gaussian beam, it is found that the reflectivity is an exponential function of the grating width. Likewise, for an apertured grating the reflectivity shows an exponential decay with narrowing aperture size. Results are compared to other methods, including plane wave decomposition of Gaussian beams using RCWA for the case of a finite input beam, and a semi-analytical techniques for the case of the apertured grating.« less
  • Scannerless range imaging (SRI) is a unique approach to three dimensional imaging without scanners. SRI does, however, allow a more powerful light source to be used as compared to conventional Laser Radar (LADAR) systems due to the speed of operation associated with this staring system. As a result, a more efficient method of operation was investigated. As originally conceived, SRI transmits a continuous intensity modulated sinusoidal signal; however, a square wave driver is more energy efficient than a sinusoidal driver. In order to take advantage of this efficiency, a square wave operational methodology was investigated. As a result, four imagemore » frames are required for the extraction of range using a square wave to unambiguously resolve all time delays within one time period compared to a minimum of three frames for the sinusoidal wave.« less
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  • No abstract prepared.