INVERSE PROBLEM OF BRAGG'S SCATTERING FOR MEASURING THE SPECTRUM SURFACE ROUGHNESS IN THE OPTICAL GRADIENT WAVEGUIDE Статья Grishaeva N., Osovitsky A., Espinosa N., Cadena L., Vega C., Alvarez J. Proceedings of SPIE - The International Society for Optical Engineering. Society of Photo-Optical Instrumentation Engineers, Bellingham, WA, United States. Том 10372. 2017.