The past decades have witnessed the development of new X-ray beam sources with brightness growing at a rate surpassing Moore’s law.Current and upcoming diffraction limited and fully coherent X-ray beam sources,includ...The past decades have witnessed the development of new X-ray beam sources with brightness growing at a rate surpassing Moore’s law.Current and upcoming diffraction limited and fully coherent X-ray beam sources,including multi-bend achromat based synchrotron sources and high repetition rate X-ray free electron lasers,puts increasingly stringent requirements on stability and accuracy of X-ray optics systems.Parasitic motion errors at sub-micro radian scale in beam transport and beam conditioning optics can lead to significant loss of coherence and brightness delivered from source to experiment.To address this challenge,we incorporated optical metrology based on interferometric length and angle sensing and real-time correction as part of the X-ray optics motion control system.A prototype X-ray optics system was constructed following the optical layout of a tunable X-ray cavity.On-line interferometric metrology enabled dynamical feedback to a motion control system to track and compensate for motion errors.The system achieved sub-microradian scale performance,as multiple optical elements are synchronously and continuously adjusted.This first proof of principle measurement demonstrated both the potential and necessity of incorporating optical metrology as part of the motion control architecture for large scale X-ray optical systems such as monochromators,delay lines,and in particular,X-ray cavity systems to enable the next generation cavity-based X-ray free electron lasers.展开更多
Osmotic conditions play an important role in the cell properties of human red blood cells(RBCs),which are crucial for the pathological analysis of some blood diseases such as malaria.Over the past decades,numerous eff...Osmotic conditions play an important role in the cell properties of human red blood cells(RBCs),which are crucial for the pathological analysis of some blood diseases such as malaria.Over the past decades,numerous efforts have mainly focused on the study of the RBC biomechanical properties that arise from the unique deformability of erythrocytes.Here,we demonstrate nonlinear optical effects from human RBCs suspended in different osmotic solutions.Specifically,we observe self-trapping and scattering-resistant nonlinear propagation of a laser beam through RBC suspensions under all three osmotic conditions,where the strength of the optical nonlinearity increases with osmotic pressure on the cells.This tunable nonlinearity is attributed to optical forces,particularly the forward-scattering and gradient forces.Interestingly,in aged blood samples(with lysed cells),a notably different nonlinear behavior is observed due to the presence of free hemoglobin.We use a theoretical model with an optical force-mediated nonlocal nonlinearity to explain the experimental observations.Our work on light self-guiding through scattering biosoft-matter may introduce new photonic tools for noninvasive biomedical imaging and medical diagnosis.展开更多
基金support from the Laboratory Directed Research and Development program at the SLAC National Accelerator Laboratorythe National Science Foundation under Grant No.NSF-2011786Use of the Linac Coherent Light Source(LCLS),SLAC National Accelerator Laboratory,is supported by the U.S.Department of Energy,Office of Science,Office of Basic Energy Sciences under Contract No.DE-AC02-76SF00515.
文摘The past decades have witnessed the development of new X-ray beam sources with brightness growing at a rate surpassing Moore’s law.Current and upcoming diffraction limited and fully coherent X-ray beam sources,including multi-bend achromat based synchrotron sources and high repetition rate X-ray free electron lasers,puts increasingly stringent requirements on stability and accuracy of X-ray optics systems.Parasitic motion errors at sub-micro radian scale in beam transport and beam conditioning optics can lead to significant loss of coherence and brightness delivered from source to experiment.To address this challenge,we incorporated optical metrology based on interferometric length and angle sensing and real-time correction as part of the X-ray optics motion control system.A prototype X-ray optics system was constructed following the optical layout of a tunable X-ray cavity.On-line interferometric metrology enabled dynamical feedback to a motion control system to track and compensate for motion errors.The system achieved sub-microradian scale performance,as multiple optical elements are synchronously and continuously adjusted.This first proof of principle measurement demonstrated both the potential and necessity of incorporating optical metrology as part of the motion control architecture for large scale X-ray optical systems such as monochromators,delay lines,and in particular,X-ray cavity systems to enable the next generation cavity-based X-ray free electron lasers.
基金the National Key R&D Program of China(2017YFA0303800)the National Natural Science Foundation of China(91750204,11504184,11604058)+3 种基金the NSERC through the Steacie,Strategic,Discovery and Acceleration Grants Schemesthe Canada Research Chair Program(Canada)additional support by the Government of the Russian Federation through the ITMO Fellowship and Professorship Program(grant 074-U 01)the 1000 Talents Sichuan Program in China.
文摘Osmotic conditions play an important role in the cell properties of human red blood cells(RBCs),which are crucial for the pathological analysis of some blood diseases such as malaria.Over the past decades,numerous efforts have mainly focused on the study of the RBC biomechanical properties that arise from the unique deformability of erythrocytes.Here,we demonstrate nonlinear optical effects from human RBCs suspended in different osmotic solutions.Specifically,we observe self-trapping and scattering-resistant nonlinear propagation of a laser beam through RBC suspensions under all three osmotic conditions,where the strength of the optical nonlinearity increases with osmotic pressure on the cells.This tunable nonlinearity is attributed to optical forces,particularly the forward-scattering and gradient forces.Interestingly,in aged blood samples(with lysed cells),a notably different nonlinear behavior is observed due to the presence of free hemoglobin.We use a theoretical model with an optical force-mediated nonlocal nonlinearity to explain the experimental observations.Our work on light self-guiding through scattering biosoft-matter may introduce new photonic tools for noninvasive biomedical imaging and medical diagnosis.
