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Title: Gated frequency-resolved optical imaging with an optical parametric amplifier

Abstract

A system for detecting objects in a turbid media utilizes an optical parametric amplifier as an amplifying gate for received light from the media. An optical gating pulse from a second parametric amplifier permits the system to respond to and amplify only ballistic photons from the object in the media. 13 figs.

Inventors:
; ; ;
Publication Date:
Research Org.:
Sandia Corporation
Sponsoring Org.:
USDOE, Washington, DC (United States)
OSTI Identifier:
678605
Patent Number(s):
US 5,936,739/A/
Application Number:
PAN: 8-791,037
Assignee:
Sandia Corp., Albuquerque, NM (United States) SNL; SCA: 440600; PA: EDB-99:085768; SN: 99002124519
DOE Contract Number:
AC04-94AL85000
Resource Type:
Patent
Resource Relation:
Other Information: PBD: 10 Aug 1999
Country of Publication:
United States
Language:
English
Subject:
44 INSTRUMENTATION, INCLUDING NUCLEAR AND PARTICLE DETECTORS; OPTICAL SYSTEMS; DETECTION; VISIBLE RADIATION; PARAMETRIC AMPLIFIERS; AMPLIFICATION

Citation Formats

Cameron, S.M., Bliss, D.E., Kimmel, M.W., and Neal, D.R. Gated frequency-resolved optical imaging with an optical parametric amplifier. United States: N. p., 1999. Web.
Cameron, S.M., Bliss, D.E., Kimmel, M.W., & Neal, D.R. Gated frequency-resolved optical imaging with an optical parametric amplifier. United States.
Cameron, S.M., Bliss, D.E., Kimmel, M.W., and Neal, D.R. 1999. "Gated frequency-resolved optical imaging with an optical parametric amplifier". United States. doi:.
@article{osti_678605,
title = {Gated frequency-resolved optical imaging with an optical parametric amplifier},
author = {Cameron, S.M. and Bliss, D.E. and Kimmel, M.W. and Neal, D.R.},
abstractNote = {A system for detecting objects in a turbid media utilizes an optical parametric amplifier as an amplifying gate for received light from the media. An optical gating pulse from a second parametric amplifier permits the system to respond to and amplify only ballistic photons from the object in the media. 13 figs.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = 1999,
month = 8
}
  • A system for detecting objects in a turbid media utilizes an optical parametric amplifier as an amplifying gate for received light from the media. An optical gating pulse from a second parametric amplifier permits the system to respond to and amplify only ballistic photons from the object in the media.
  • Implementation of optical imagery in a diffuse inhomogeneous medium such as biological tissue requires an understanding of photon migration and multiple scattering processes which act to randomize pathlength and degrade image quality. The nature of transmitted light from soft tissue ranges from the quasi-coherent properties of the minimally scattered component to the random incoherent light of the diffuse component. Recent experimental approaches have emphasized dynamic path-sensitive imaging measurements with either ultrashort laser pulses (ballistic photons) or amplitude modulated laser light launched into tissue (photon density waves) to increase image resolution and transmissive penetration depth. Ballistic imaging seeks to compensate formore » these {open_quotes}fog-like{close_quotes} effects by temporally isolating the weak early-arriving image-bearing component from the diffusely scattered background using a subpicosecond optical gate superimposed on the transmitted photon time-of-flight distribution. The authors have developed a broadly wavelength tunable (470 nm -2.4 {mu}m), ultrashort amplifying optical gate for transillumination spectral imaging based on optical parametric amplification in a nonlinear crystal. The time-gated image amplification process exhibits low noise and high sensitivity, with gains greater than 104 achievable for low light levels. We report preliminary benchmark experiments in which this system was used to reconstruct, spectrally upcovert, and enhance near-infrared two-dimensional images with feature sizes of 65 {mu}m/mm{sup 2} in background optical attenuations exceeding 10{sup 12}. Phase images of test objects exhibiting both absorptive contrast and diffuse scatter were acquired using a self-referencing Shack-Hartmann wavefront sensor in combination with short-pulse quasi-ballistic gating. The sensor employed a lenslet array based on binary optics technology and was sensitive to optical path distortions approaching {lambda}/100.« less
  • A system provides an input pump pulse and a signal pulse. A first dichroic beamsplitter is highly reflective for the input signal pulse and highly transmissive for the input pump pulse. A first optical parametric amplifier nonlinear crystal transfers part of the energy from the input pump pulse to the input signal pulse resulting in a first amplified signal pulse and a first depleted pump pulse. A second dichroic beamsplitter is highly reflective for the first amplified signal pulse and highly transmissive for the first depleted pump pulse. A second optical parametric amplifier nonlinear crystal transfers part of the energymore » from the first depleted pump pulse to the first amplified signal pulse resulting in a second amplified signal pulse and a second depleted pump pulse. A third dichroic beamsplitter receives the second amplified signal pulse and the second depleted pump pulse. The second depleted pump pulse is discarded.« less
  • We demonstrate depth-resolved imaging in a ballistic imaging system, in which a heterodyned femtosecond optical Kerr gate is introduced to extract useful imaging photons for detecting an object hidden in turbid media and a compound lens is proposed to ensure both the depth-resolved imaging capability and the long working distance. Two objects of about 15-μm widths hidden in a polystyrene-sphere suspension have been successfully imaged with approximately 600-μm depth resolution. Modulation-transfer-function curves with the object in and away from the object plane have also been measured to confirm the depth-resolved imaging capability of the low-depth-of-field (low-DOF) ballistic imaging system. Thismore » imaging approach shows potential for application in research of the internal structure of highly scattering fuel spray.« less
  • Laboratory experiments utilizing different near-infrared (NIR) sensitive imaging techniques for LADAR range gated imaging at eye-safe wavelengths are presented. An OPO/OPA configuration incorporating a nonlinear crystal for wavelength conversion of 1.56 micron probe or broadcast laser light to 807 nm light by utilizing a second pump laser at 532 nm for gating and gain, was evaluated for sensitivity, resolution, and general image quality. These data are presented with similar test results obtained from an image intensifier based upon a transferred electron (TE) photocathode with high quantum efficiency (QE) in the 1-2 micron range, with a P-20 phosphor output screen. Datamore » presented include range-gated imaging performance in a cloud chamber with varying optical attenuation of laser reflectance images.« less