Optical force model based on sequential ray tracing.

Area of Science:

• Optics
• Computational Physics
• Nanotechnology

Background:

• Optical forces and torques are crucial for manipulating microscopic particles.
• Ray-tracing methods offer a potential avenue for calculating these optical interactions.
• Accurate prediction is essential for advancing optical trapping applications.

Purpose of the Study:

• To demonstrate the utility of ray-tracing techniques for calculating optical forces and torques.
• To validate the augmented ray-tracing code against experimental results.
• To explore the application of this method to complex trapping scenarios.

Main Methods:

• Augmenting a general ray-trace computer code with illumination polarization, irradiance distributions, and Fresnel surface coefficients.
• Calculating optical forces and torques on particles, particularly large ones off-axis.
• Comparing computational predictions of trapping location under non-uniform illumination with experimental data.

Main Results:

• The augmented ray-tracing code provides reasonably accurate predictions of particle interaction.
• Experimental validation confirmed the accuracy of the computational method for trapping location.
• Successful calculations were performed for trapping a hemispherical lens and a two-particle system.

Conclusions:

• Ray-tracing is a viable and accurate method for calculating optical forces and torques.
• The developed computational approach enhances the prediction of optical trapping.
• This technique has broad applicability in optical manipulation research.