Optical trapping particles

Eujiwara, H., Takasaki, H., Hotta, J. and Sasaki, K. (2004) Observation of the discrete transition of optically trapped particle position in the vicinity of an interface. Appl. Phys. Lett., 84, 13-15. 

Petrov DV (2007) Raman spectroscopy of optically trapped particles. J Opt A-Pure Appl Opt 9(8) S139-S156... 

Figure 7.3 shows the two-beam photon-force measurement system using a coaxial illumination photon force measurement system. Two microparticles dispersed in a liquid are optically trapped by two focused near-infrared beams ( 1 pm spot size) of a CW Nd YAG laser under an optical microscope (1064 nm, 1.2 MWcm , lOOX oil-immersion objective, NA = 1.4). The particles are positioned sufficiently far from the surface of a glass slide in order to neglect the interaction between the particles and the substrate. Green and red beams from a green LD laser (532 nm, 21 kWcm ) and a He-Ne laser (632.8 nm, 21 kW cm ) are introduced coaxially into the microscope and slightly focused onto each microparticle as an illumination light (the irradiated area was about 3 pm in diameter). The sizes of the illumination areas for the green and red beams are almost the same as the diameter of the microparticles (see Figure 7.4). The back scattered light from the surface of each microparticle is...

J. E. and Chu, S. (1986) Observation of a single-beam gradient force optical trap for dielectric particles. Opt. Lett., 11, 288-290. 

Ashkrn, A. (2000) History of optical trapping and manipulation of small-neutral particle, atoms, and molecules. IEEE J. Select. Topics Quantum Electron., 6, 841-856. 

Ion traps have been used in a number of studies of optical properties of microdroplet lasers14,15 and the ion trap itself can be used as a useful mass spectrometer for fundamental studies of trapped particles and micrometer to nanoscale aerosols16. 

In optical tweezer experiments, the optical scattering force is used to trap particles, but the force can also be used to control the shape of liquid droplets26. An infrared laser with 43-mW power focused onto a microdroplet on a superhydrophobic surface enabled up to 40% reversible tuning of the equatorial diameter of the droplet26. Such effects must naturally also be taken into account when exciting laser modes in droplets in experiments with levitated drops. 

Ashkin, A., Optical trapping and manipulation of neutral particles using lasers, Proc. Natl Acad. Sci. USA 1997, 94, 4853 4860... 

In another application, an optical trap was used to manipulate cell-surface proteins (29). First, colloidal gold particles conjugated to monoclonal antibod-... 

Malmqvist, L., and Hertz, H. M., 1995. Second-harmonic generation in optically trapped nonlinear particles with pulsed lasers. Appl. Opt. 34 3392-97. 

D. M. Carbeny, J. C. Reid, G. M. Wang, E. M. Sevick, D. J. Searles, and D. J. Evans, Fluctuations and irreversibility an experimental demonstration of a second-law-hke theorem using a colloidal particle held in an optical trap. Phys. Rev. Lett. 92, 140601 (2004). 

The LS theory was applied to the localization of a Brownian particle in a three-dimensional optical trap [89] a transparent dielectric spherical silica particle of diameter 0.6 pm suspended in a liquid [88]. The particle moves at random within the potential well created with a gradient three-dimensional optical trap—a technique widely used in biophysical studies. The potential was modulated by a biharmonic force. By changing the phase shift between the two harmonics it was possible to localize the particle in one of the wells in very good quantitative agreement with the predictions based on the LS. 

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