Manipulation of light-absorbing particles in air with optical bottle arrays

Abstract

We demonstrate optical trapping and movement of a carbon nanoparticle agglomeration with both a single optical bottle beam and arrays of such traps. Diffractive optical elements (DOE) designed by a method based on a superposition of the Bessel beams were employed for the generation of the optical traps. Due to the structure of the generated traps, we were able to carry out a three-dimensional movement of trapped microscopic objects.

Laser Trapping Based on Photophoretic Forces Using a Spatial Light Modulator

“…These particles have a non-spherical shape, and therefore ideally suited for experiments of this kind that has been shown in previous experiments [10,16,21]. Figure 3 shows the experimental results of how the position of each of the trapped particles using a spatial light modulator can be controlled dynamically.…”

“…The velocity the trapped particle is 1.8±0.1μm/s. Thus, SLMs may be used to dynamically control the position of trapped air-borne light-absorbing micro-particles, which is analogous to the optical manipulation of dielectric micro-objects in a liquid [10]. The difference is only in the trapping mechanism: (1) in the case of dielectric particles in the liquid, gradient force and scattering force play a key role, (2) in the case of light-absorbing particles in the air, photophoretic forces dominate.…”

“…In order to solve the problem of retaining particles, optical tweezers based on photophoretic forces can be used [6][7][8]. Photophoretic forces are several orders of magnitude greater than radiation pressure, so low-power lasers can be used to trap lightabsorbing particles in gaseous media [9,10]. The holographic optical tweezers tech-nique using spatial light modulators enables simultaneous parallel manipulation of a variety of micro-objects [11].…”