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Photonic Doppler velocimetry probe used to measure grain boundaries of dynamic shocked materials

Conference · · SPIE Proceedings, Optical System Alignment, Tolerancing, and Verification XI, 1037704
DOI:https://doi.org/10.1117/12.2276436· OSTI ID:1374064
 [1];  [1];  [1];  [2];  [3];  [3];  [3]
  1. National Security Technologies, LLC. (NSTec), Mercury, NV (United States), Los Alamos Office
  2. National Security Technologies, LLC. (NSTec), Mercury, NV (United States)
  3. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
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Material scientists have developed computational modeling to predict the dynamic response of materials undergoing stress, but there is still a need to make precision measurements of surfaces undergoing shock compression. Miniature photonic Doppler velocimetry (PDV) probes have been developed to measure the velocity distribution from a moving surface traveling tens of kilometers per second. These probes use hundreds of optical fibers imaged by optical relays onto different regions of this moving surface. While previous work examined large surface areas, we have now developed a PDV microscope that can interrogate 37 different spots within a field of view of <1 mm, with a standoff distance of 17 mm, to analyze the motion differences across grain boundaries of the material undergoing dynamic stress. Each PDV fiber interrogates a 10 μm spot size on the moving surface. A separate imaging system using a coherent bundle records the location of the PDV spots relative to the grain boundaries prior to the dynamic event. Designing the mounting structures for the lenses, fibers, and coherent bundle was a challenge. To minimize back reflections, the fibers are index matched onto the first relay lens, which is made of fused silica. The PDV fibers are aligned normal to the moving surface. The imaging probe views the surface at an 18° angle. The coherent bundle is tilted 11° to its optical relay. All components are assembled into a single probe head assembly. The coherent bundle is removed from the probe head to be used for the next dynamic event. Alignment issues will also be discussed.
Research Organization:
Nevada Test Site/National Security Technologies, LLC (United States)
Sponsoring Organization:
USDOE National Nuclear Security Administration (NNSA), Office of Defense Programs (DP) (NA-10)
DOE Contract Number:
AC52-06NA25946
OSTI ID:
1374064
Report Number(s):
DOE/NV/25946--3292
Conference Information:
Journal Name: SPIE Proceedings, Optical System Alignment, Tolerancing, and Verification XI, 1037704 Journal Volume: 10377
Country of Publication:
United States
Language:
English

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Related Subjects

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY
Photonic Doppler velocimetry
PDV
optical metrology
velocimetry
optical alignment