We experimentally study the generation of a partially coherent non-diffractive beam by focusing a partially coherent vortex beam with an axieon. The investigation results show that when the partially coherent vortex b...We experimentally study the generation of a partially coherent non-diffractive beam by focusing a partially coherent vortex beam with an axieon. The investigation results show that when the partially coherent vortex beam is focused by the axicon, the beam is transferred into a partially coherent higher-order non-diffractive beam. In the non-diffractive zone, the transverse intensity distribution of the partially coherent higher-order non-diffractive beam is invariant during propagation. In addition, the range of the non-diffractive zone is related to the coherence of the partially coherent vortex beam. The poorer the coherence of the partially coherent vortex beam, the shorter the range of the non-diffractive zone.展开更多
In this work,we introduce a kind of new structured radial grating,which is named the even-type sinusoidal amplitude radial(ETASR)grating.Based on diffraction theory and the principle of stationary phase,a comprehensiv...In this work,we introduce a kind of new structured radial grating,which is named the even-type sinusoidal amplitude radial(ETASR)grating.Based on diffraction theory and the principle of stationary phase,a comprehensive theoretical investigation on the diffraction patterns of ETASR gratings is conducted.Theoretical results show that novel carpet beams with beautiful optical structures and distinctive characteristics have been constructed on the basics of the ETASR grating.Their diffraction patterns are independent of propagation distance,that is,the new carpet beams have diffraction-free propagating characteristics.The non-diffracting carpet beams are divided into two types by beam characteristics:non-diffracting integer-order and half-integer-order carpet beams.Subsequently,we experimentally generate these carpet beams using the ETASR grating.Finally,their particularly interesting optical morphology and features are explored through numerical simulations and experiments.展开更多
发生火灾时因过火时间、最高温度和受火形式不同,导致混凝土构件表面酥松开裂深度、变形损伤程度差异较大。论文以六层混凝土框架主控楼电缆层发生火灾为例,通过对火灾后现场勘察确定过火时间;对火灾现场混凝土取样,采用 X 射线衍射、...发生火灾时因过火时间、最高温度和受火形式不同,导致混凝土构件表面酥松开裂深度、变形损伤程度差异较大。论文以六层混凝土框架主控楼电缆层发生火灾为例,通过对火灾后现场勘察确定过火时间;对火灾现场混凝土取样,采用 X 射线衍射、热重分析及扫描电镜推定火场不同区域温度;采用 ABAQUS 有限元软件进行了火灾温度场下结构性能数值分析。在非均匀火灾温度场中,温度附加应力和材料性能劣化相耦合是导致混凝土结构丧失承载能力、发生突然垮塌的主要原因。展开更多
基金Project supported by the National Natural Science Foundation of China (Grant No.60977068)the Foundations of the State Key Laboratory for Transient Optical and Photonic Technology of Chinese Academy of Sciences (Grant No.SKL ST200912)
文摘We experimentally study the generation of a partially coherent non-diffractive beam by focusing a partially coherent vortex beam with an axieon. The investigation results show that when the partially coherent vortex beam is focused by the axicon, the beam is transferred into a partially coherent higher-order non-diffractive beam. In the non-diffractive zone, the transverse intensity distribution of the partially coherent higher-order non-diffractive beam is invariant during propagation. In addition, the range of the non-diffractive zone is related to the coherence of the partially coherent vortex beam. The poorer the coherence of the partially coherent vortex beam, the shorter the range of the non-diffractive zone.
基金supported by the National Natural Science Foundation of China(Nos.11974314 and 11674288).
文摘In this work,we introduce a kind of new structured radial grating,which is named the even-type sinusoidal amplitude radial(ETASR)grating.Based on diffraction theory and the principle of stationary phase,a comprehensive theoretical investigation on the diffraction patterns of ETASR gratings is conducted.Theoretical results show that novel carpet beams with beautiful optical structures and distinctive characteristics have been constructed on the basics of the ETASR grating.Their diffraction patterns are independent of propagation distance,that is,the new carpet beams have diffraction-free propagating characteristics.The non-diffracting carpet beams are divided into two types by beam characteristics:non-diffracting integer-order and half-integer-order carpet beams.Subsequently,we experimentally generate these carpet beams using the ETASR grating.Finally,their particularly interesting optical morphology and features are explored through numerical simulations and experiments.
文摘发生火灾时因过火时间、最高温度和受火形式不同,导致混凝土构件表面酥松开裂深度、变形损伤程度差异较大。论文以六层混凝土框架主控楼电缆层发生火灾为例,通过对火灾后现场勘察确定过火时间;对火灾现场混凝土取样,采用 X 射线衍射、热重分析及扫描电镜推定火场不同区域温度;采用 ABAQUS 有限元软件进行了火灾温度场下结构性能数值分析。在非均匀火灾温度场中,温度附加应力和材料性能劣化相耦合是导致混凝土结构丧失承载能力、发生突然垮塌的主要原因。
