Optimization of single beam optical trap using nonlinear refractive index parameter of microspheres

Authors

Divine Banzon Physics Department, De La Salle University
Jeane Camelo Physics Department, De La Salle University
Romeric Pobre Physics Department, De La Salle University
Alvin Baclig National Institute of Physics, University of the Philippines Diliman
Bernardino Buenaobra National Institute of Physics, University of the Philippines Diliman
Carlo Mar Blanca National Institute of Physics, University of the Philippines Diliman
Caesar Saloma National Institute of Physics, University of the Philippines Diliman

Abstract

Optimization of single beam optical trap using nonlinear refractive index parameter of microspheres (e.g. fused silica and fused quartz) was considered using a 1064 nm Nd:YAG diode-pumped solid state (dpss) laser. Other experimental parameter (e.g. back focal power, numerical aperture, and diameter size of the microsphere) were also included in the optimization process. Near the beam focus, optical trapping force behaves linearly with microsphere displacement where trapping stiffness is the constant of proportionality. Optical trapping stiffness was determined using the drag force method which was determined from the kinematic variables of the trapped microspheres. This computation was realized when trapped particles are subjected to external oscillations driven by a piezoelectric transducer attached to a glass slide. Detection and measurement of these kinematic variables were taken from the CCD imaging system of IMAQ-National Instruments. Through MATLAB's image processing program, position, velocity, and acceleration of the microspheres were calculated. Results show that all four experimental parameters had a direct effect on the trapping stiffness of the single beam optical trap. Optimum optical trap is achieved when quartz crystal microsphere was chosen among other nonlinear microsphere with experimental parameters: N.A. = 0.5, refractive index of 1.458, back focal power of 16 mW and diameter size of 10 μm.

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Issue

2006: Proceedings of the 24th Samahang Pisika ng Pilipinas National Physics Congress

Article ID

SPP-2006-PA-12

Section

Poster Session PA

Published

2006-10-25

How to Cite

[1]

D Banzon, J Camelo, R Pobre, A Baclig, B Buenaobra, CM Blanca, and C Saloma, Optimization of single beam optical trap using nonlinear refractive index parameter of microspheres, Proceedings of the Samahang Pisika ng Pilipinas 24, SPP-2006-PA-12 (2006). URL: https://proceedings.spp-online.org/article/view/SPP-2006-PA-12.