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Author (up) Cruz, J.J.; Escudero, F.; Alvarez, E.; da Silva, L.F.F.; Carvajal, G.; Thomsen, M.; Fuentes, A. doi  openurl
  Title Three-wavelength broadband soot pyrometry technique for axisymmetric flames Type
  Year 2021 Publication Optics Letters Abbreviated Journal Opt. Lett.  
  Volume 46 Issue 11 Pages 2654-2657  
  Keywords VOLUME FRACTION; DIFFUSION FLAMES; TEMPERATURE; ABSORPTION; ETHYLENE  
  Abstract Soot temperature measurements in laminar flames are often performed through two-color broadband emission pyrometry (BEMI) or modulated absorption/emission (BMAE) techniques, using models to relate the ratio between flame intensities at two different wavelengths with soot temperature. To benefit from wider spectral range and increase the accuracy of experimental estimation of soot temperature, this work proposes a new approach that uses three-color broadband images captured with a basic color camera. The methodology is first validated through simulations using numerically generated flames from the CoFlame code and then used to retrieve soot temperature in an experimental campaign. The experimental results show that using three-color and BEMI provides smoother reconstruction of soot temperature than two-color and BMAE when small disturbances exist in the measured signals due to a reduced experimental noise effect. A sensitivity analysis shows that the retrieved temperature from three-color BEMI is more resilient to variations on the ratio of measured signals than BMAE, which is confirmed by an error propagation analysis based on a Monte Carlo approach.  
  Address  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0146-9592 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000658132700025 Approved  
  Call Number UAI @ alexi.delcanto @ Serial 1413  
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Author (up) Pinto, J.; Aylwin, R.; Silva-Oelker, G.; Jerez-Hanckes, C. doi  openurl
  Title Diffraction efficiency optimization for multilayered parametric holographic gratings Type
  Year 2021 Publication Optics Letters Abbreviated Journal Opt. Lett.  
  Volume 46 Issue 16 Pages 3929-3932  
  Keywords MULTICORE FIBER; REFRACTIVE-INDEX; TEMPERATURE; SENSOR; STRAIN  
  Abstract Multilayered diffraction gratings are an essential component in many optical devices due to their ability to engineer light. We propose a first-order optimization strategy to maximize diffraction efficiencies of such structures by a fast approximation of the underlying boundary integral equations for polarized electromagnetic fields. A parametric representation of the structure interfaces via trigonometric functions enables the problem to be set as a parametric optimization one while efficiently representing complex structures. Derivatives of the efficiencies with respect to geometrical parameters are computed using shape calculus, allowing a straightforward implementation of gradient descent methods. Examples of the proposed strategy in chirped pulse amplification show its efficacy in designing multilayered gratings to maximize their diffraction efficiency.  
  Address  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0146-9592 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000685553000028 Approved  
  Call Number UAI @ alexi.delcanto @ Serial 1444  
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