When structured illumination is used in digital holographic microscopy(DHM),each direction of the illumination fringe is required to be shifted at least three times to perform the phase-shifting reconstruction.In this...When structured illumination is used in digital holographic microscopy(DHM),each direction of the illumination fringe is required to be shifted at least three times to perform the phase-shifting reconstruction.In this paper,we propose a scheme for spatial resolution enhancement of DHM by using the structured illumination but without phase shifting.The structured illuminations of different directions,which are generated by a spatial light modulator,illuminate the sample sequentially in the object plane.The formed object waves interfere with a reference wave in an off-axis configuration,and a CCD camera records the generated hologram.After the object waves are reconstructed numerically,a synthetic aperture is performed by an iterative algorithm to enhance the spatial resolution.The resolution improvement of the proposed method is proved and demonstrated by both simulation and experiment.展开更多
Optical manipulation of metallic microparticles remains a significant challenge because of the strong scattering forces arising from the high extinction coefficient of the particles.This paper reports a new mechanism ...Optical manipulation of metallic microparticles remains a significant challenge because of the strong scattering forces arising from the high extinction coefficient of the particles.This paper reports a new mechanism for stable confinement of metallic microparticles using a tightly focused linearly polarized Gaussian beam.Theoretical and experimental results demonstrate that metallic microparticles can be captured off the optical axis in such a beam.Meanwhile,the three-dimensionally confined particles are observed spinning transversely as a response to the asymmetric force field.The off-axis levitation and transverse spinning of metallic microparticles may provide a new way for effective manipulation of metallic microparticles.展开更多
Perfect optical vortex(POV)beams offer a phase-gradient route to convey small particles along a tunable circular path or belt.The prevailing generalized POV method can be used to reshape the conveyor belt,but it usual...Perfect optical vortex(POV)beams offer a phase-gradient route to convey small particles along a tunable circular path or belt.The prevailing generalized POV method can be used to reshape the conveyor belt,but it usually deteriorates the orbital energy flow of field,leading to unstable conveying speed or even creating unwanted optical traps that prevent transportation.Here,we demonstrate optical conveyor belts with customized profiles and a uniform orbital flow over the whole transporting region by integrating isometric uniform sampling and random phases into the generalized POV generation algorithm.Smooth delivery of metallic particles,inaccessible to conventional generalized POV methods,is achieved at an almost even speed.We also demonstrate a dual-belt conveyor for delivering large metal microparticles,which experience repulsive intensity-gradient forces and thus are unable to be manipulated by a single belt.Our results present a unique addition to the toolbox of optical manipulation and would facilitate the development of small-scale drug delivery microsystems.展开更多
Owing to the ability to parallel manipulate micro-objects,dynamic holographic optical tweezers(HOTs)are widely used for assembly and patterning of particles or cells.However,for simultaneous control of large-scale tar...Owing to the ability to parallel manipulate micro-objects,dynamic holographic optical tweezers(HOTs)are widely used for assembly and patterning of particles or cells.However,for simultaneous control of large-scale targets,potential collisions could lead to defects in the formed patterns.Herein we introduce the artificial potential field(APF)to develop dynamic HOTs that enable collision-avoidance micro-manipulation.By eliminating collision risks among particles,this method can maximize the degree of parallelism in multi-particle transport,and it permits the implementation of the Hungarian algorithm for matching the particles with their target sites in a minimal pathway.In proof-of-concept experiments,we employ APF-empowered dynamic HOTs to achieve direct assembly of a defect-free 8×8 array of microbeads,which starts from random initial positions.We further demonstrate successive flexible transformations of a 7×7 microbead array,by regulating its tilt angle and inter-particle spacing distances with a minimalist path.We anticipate that the proposed method will become a versatile tool to open up new possibilities for parallel optical micromanipulation tasks in a variety of fields.展开更多
Owing to the ubiquity and easy-to-shape property of optical intensity,the intensity gradient force of light has been most spectacularly exploited in optical manipulation.Manifesting the intensity gradient as an optica...Owing to the ubiquity and easy-to-shape property of optical intensity,the intensity gradient force of light has been most spectacularly exploited in optical manipulation.Manifesting the intensity gradient as an optical torque to spin particles is of great fascination on both fundamental and practical sides but remains elusive.Here,we theoretically predict the existence of the optical intensity-gradient torque in the interaction of light with chiral particles.Such a new type of torque derives from the interplay between chirality-induced multipoles,which switches its direction for particles with opposite chirality.We show that this torque can be directly detected by a simple standing wave field,created with the interference of two counterpropagating plane-like waves.Our work offers a unique route to achieve rotational control of matter by tailoring the field intensity of Maxwell waves,demonstrated through three-dimensional spinning of a trapped chiral particle.It also establishes a framework that maps a remarkable connection between the optical forces and torques,across chiral to non-chiral.展开更多
基金This work is supported by the National Basic Research Program(973 Program)of China under Grant No.2012CB921900the National Natural Science Foundation of China(NSFC)under Grant Nos.61377008,61107003,and 61275191.
文摘When structured illumination is used in digital holographic microscopy(DHM),each direction of the illumination fringe is required to be shifted at least three times to perform the phase-shifting reconstruction.In this paper,we propose a scheme for spatial resolution enhancement of DHM by using the structured illumination but without phase shifting.The structured illuminations of different directions,which are generated by a spatial light modulator,illuminate the sample sequentially in the object plane.The formed object waves interfere with a reference wave in an off-axis configuration,and a CCD camera records the generated hologram.After the object waves are reconstructed numerically,a synthetic aperture is performed by an iterative algorithm to enhance the spatial resolution.The resolution improvement of the proposed method is proved and demonstrated by both simulation and experiment.
基金Innovation Capability Support Program of Shaanxi(2021TD-57)National Natural Science Foundation of China(NSFC)(61905189,62005208,11974417)China Postdoctoral Science Foundation(2019M663656,2020M673365)。
文摘Optical manipulation of metallic microparticles remains a significant challenge because of the strong scattering forces arising from the high extinction coefficient of the particles.This paper reports a new mechanism for stable confinement of metallic microparticles using a tightly focused linearly polarized Gaussian beam.Theoretical and experimental results demonstrate that metallic microparticles can be captured off the optical axis in such a beam.Meanwhile,the three-dimensionally confined particles are observed spinning transversely as a response to the asymmetric force field.The off-axis levitation and transverse spinning of metallic microparticles may provide a new way for effective manipulation of metallic microparticles.
基金National Natural Science Foundation of China(11974417,12127805,12274181,62135005,62335018)Key Research Program of Frontier Science,Chinese Academy of Sciences(ZDBS-LY-JSC035).
文摘Perfect optical vortex(POV)beams offer a phase-gradient route to convey small particles along a tunable circular path or belt.The prevailing generalized POV method can be used to reshape the conveyor belt,but it usually deteriorates the orbital energy flow of field,leading to unstable conveying speed or even creating unwanted optical traps that prevent transportation.Here,we demonstrate optical conveyor belts with customized profiles and a uniform orbital flow over the whole transporting region by integrating isometric uniform sampling and random phases into the generalized POV generation algorithm.Smooth delivery of metallic particles,inaccessible to conventional generalized POV methods,is achieved at an almost even speed.We also demonstrate a dual-belt conveyor for delivering large metal microparticles,which experience repulsive intensity-gradient forces and thus are unable to be manipulated by a single belt.Our results present a unique addition to the toolbox of optical manipulation and would facilitate the development of small-scale drug delivery microsystems.
基金supported by the National Natural Science Foundation of China(12274181,12127805,62135005)the National Key Research and Development Program of China(2021YFF0700303,2023YFF0613700)Guangdong Basic and Applied Basic Research Foundation(2023A1515030143).
文摘Owing to the ability to parallel manipulate micro-objects,dynamic holographic optical tweezers(HOTs)are widely used for assembly and patterning of particles or cells.However,for simultaneous control of large-scale targets,potential collisions could lead to defects in the formed patterns.Herein we introduce the artificial potential field(APF)to develop dynamic HOTs that enable collision-avoidance micro-manipulation.By eliminating collision risks among particles,this method can maximize the degree of parallelism in multi-particle transport,and it permits the implementation of the Hungarian algorithm for matching the particles with their target sites in a minimal pathway.In proof-of-concept experiments,we employ APF-empowered dynamic HOTs to achieve direct assembly of a defect-free 8×8 array of microbeads,which starts from random initial positions.We further demonstrate successive flexible transformations of a 7×7 microbead array,by regulating its tilt angle and inter-particle spacing distances with a minimalist path.We anticipate that the proposed method will become a versatile tool to open up new possibilities for parallel optical micromanipulation tasks in a variety of fields.
基金National Natural Science Foundation of China(12174076,12204117,12274181)National Key Research and Development Program of China(2023YFF0613700)+1 种基金Guangxi Science and Technology Project(2023GXNSFFA026002,2024GXNSFBA010261,2021GXNSFDA196001,AD23026117)Open Project of State Key Laboratory of Surface Physics at Fudan University(KF2022_15).
文摘Owing to the ubiquity and easy-to-shape property of optical intensity,the intensity gradient force of light has been most spectacularly exploited in optical manipulation.Manifesting the intensity gradient as an optical torque to spin particles is of great fascination on both fundamental and practical sides but remains elusive.Here,we theoretically predict the existence of the optical intensity-gradient torque in the interaction of light with chiral particles.Such a new type of torque derives from the interplay between chirality-induced multipoles,which switches its direction for particles with opposite chirality.We show that this torque can be directly detected by a simple standing wave field,created with the interference of two counterpropagating plane-like waves.Our work offers a unique route to achieve rotational control of matter by tailoring the field intensity of Maxwell waves,demonstrated through three-dimensional spinning of a trapped chiral particle.It also establishes a framework that maps a remarkable connection between the optical forces and torques,across chiral to non-chiral.
