The Investigation Of The Self-accelerating Beams And Array Beams And Their Applications In Optical Manipulation

Optical tweezers(OTs)are based on optical mechanical effect which could trap and manipulate microparticles.The pramary OTs were invented by Ashkin that are formed with highly focused Gassian beam and own the three-dimensional optical potential structure.The scale of OTs acting force and operating distance range are in the orders of pN and micron,which makes the OTs rather adaptable to apply in the reasearches of soft matter,disperse system or single molecule regions etc.However,as the newly emerging fields rising or additinal requirements for the optical manipulation proposing,the traditional Gassian beam OTs suffer limitation,such as in the fields of simultaneous trapping or selective transportation of uniform particles,the viscoelasticity measurement for the heterogeneous,absorbing particles trapping and also the cell trapping in the deep biological tissue.All these problems' solutions are dependent on the development of the advanced optical trapping technology,and their solving may also promote the research progress of soft matter and biophysics regions.The self-accelerating beams and array beams are the current research hotspot in the diffractive optics,and applying them in OTs system may overcome the trapping dilemma of the traditional Gassian beam.The accelerating beams are the generic terms for a series of caustics beam,and the typical ones include Airy beam and circular Airy beam etc.Generally,they are all the solotions of helmholtz equation and could be experimentally generated by the diffractive optical elements.While the array Gassian beams are the typical case of array beams,which could be generated by the phase modulation with the spatial light modulators.So far,many algorithms were proposed to design the phase diagram of the Array Gassian beam.And the array optical tweezers are rather adaptable to study the issues of self-assembly or measure the viscoelasticity of heterogeneous.My doctoral dossertation focuses on the research of the propagation properties of the self-accelerating beams and array beams as well as their multifunctional applications in the optical trapping or the viscoelasticity measurement of soft matter.The main content of this thesis includes:1.We summarized the theoretical basis and development of the self-accelerating beams and array beams,as well as the complex fields modulation of the liqiud-crastal spatial light modulator(LC-SLM).2.Based on the angular spectrum theory,we proposed two kinds of amplitude masks and investigated their amplitude modulation of symmetric Airy beam in the angular spectrum plane.The first one is the exponential amplitude mask which can enhance one side angular spectral components of the symmetric Airy beam but restrain the other side's.Hereby,a new kind of compensating self-accelerating beam was proposed.By setting appropriate mask parameter,the beam can not only keep its main-lobe intensity invariant in different absorbing media,but also inherit the beam structure from the symmetric Airy beam with damped oscillating property.The proposed accelearating beam is expected to benefit the optical manipulation in deep biological tissue.The second one is a symmetric amplitude mask,we theoretically and experimentally studied its amplitude modulation for the symmetric Airy beam.The mask can modulate the beam's high frequency spectrum compenents and it's found that the antofocusing property and axial gradient force of the symmetric Airy beam can be enhanced by the mask.The newly amplitude modulated symmetric Airy beam can improve the Ots' trapping performance for large amounts of particles.3.We proposed a new kind of symmetric self-bending beams by symmetrization of the triple-cusp beams' angular spectrum.The propagation properties of this new symmetric beam was investigated theoretically and experimentally,and it was found that the beam not only owns the autofocusing property but also gets a needle-like central lobe and mutilchannel beam structure.Through the beam's apodization experiment,it's also found the beam possess the strong self-healing property.Furthermore,we coupled the beam into the OT system and realized the optical multi-functional manipulation that selective transportation or trapping the particles in separate spatial positions.The beam was believed to get special application in opofludic regions etc.4.We utilized a controllable optical bottle to realize controllable trapping absorbing particles in the aqueous solutions.The optical bottle was generated by the superposition of modified bessel functions.And its darkess size and degree can be controlled continuously by adjusting the geometry parameter.Based on the complex field modulation technology of the LC-SLM,the optical bottle was generated in experiment and was applied in optical trapping.We analyzed the photophoresis force functioning on the absorbing particles from the optical bottle with different darkess degree,and through adjusting the geometry parameter we realized the controlable trapping of the aborbing particles by the optical bottle.The optical bottle can help the OT solve the absorbing particles trapping issue.5.We constructed an abberation-eliminated array holographic optical tweezers set-up which was used to conduct the mutil-localization area viscoelasticity measurement of soft matter.We first conducted abberation correction for the array holographic optical tweezers with phase compensation technique of the zemike polynomials,which enhances the stiffness of array optical trapps by 40%.Based on these abberations correction results,we improved the equipment by eliminating its abberations.And the high-quality array optical traps were designed by the GS algorithm and were applied to measure the mutil-localized areas viscoelasticity of the soft matter.The experimental results illustrate that the the parallel detection of array optical traps can improve the measurement accuracy,meanwhile its capability of mutil-localization measurement was also verified.Our work formed a good foundation for the viscoelasticity measurement of the heterogeneous by the array holographic optical traps.In conclusion,we have built the theoretical and experimental methods to investigate the novel beams' trapping and their application.Aiming at trapping dilemma of traditional OT,we studied or optimized the propagation property of the self-accelerating beams and array beams.We also proposed some newly self-accelerating beam and explored their multifunctional applications in optical manipulation.Our work was believed to benefit the OT to get better applications in soft matter or biomedicine regions etc.