New Technique for Single-Beam Gradient-Force Laser Trapping in Air

Abstract

Laser trapping is becoming an important technique for microsystem technologies. To apply it to industrial uses, it should be developed to function in air. However, there is not much research about laser trapping in air. One of the reasons is the difficulty of trapping micro-objects. Therefore, we have proposed a new technique to trap micro-objects in air. In particular, we focused our attention on the substrate where the micro-object is set. By applying a textured surface and employing tungsten carbide as the substrate material, the trapping probability was improved by a remarkable amount. Although a certain degree of improvement was attained, the trapping was still not perfect. To ascertain the forces working on the micro-object, an analytical calculation of the adhesion forces and an electromagnetic simulation of the optical forces were implemented. Based on these calculations, we discuss what the most important factor is for successful laser trapping in air.

Surface-Sensing Principle of Microprobe System for Micro-Scale Coordinate Metrology: A Review

“…The surface forces become increasingly more prominent than gravity when the size of the microprobe tip is less than a few millimeters. Surface forces are several orders of magnitude greater than gravity at scales of several tens to several hundred micrometers in diameter [31][32][33][34]. Therefore, surface forces attract the probe tip to the surface when the probe tip is close to the measurement surface [35].…”

“…Therefore, surface forces attract the probe tip to the surface when the probe tip is close to the measurement surface [35]. Although surface forces can be reduced via chemical treatment, surface texture, and environmental control [32,33], it is difficult to ignore the effect of these surface forces in micro-CMM probes. Surface forces significantly degrade measurement repeatability and reproducibility.…”

“…Surface forces working on the microprobe tip with dependence on the tip diameter. The calculation equations for each force are based on [32]. The probe tip and measurement surface material were assumed to be tungsten carbide and silicon, respectively.…”

“…High-sphericity microspheres are commercially available; thus, they can be processed by gluing them to the probe tip [45][46][47][48]. Although this is possible at a laboratory scale, it is difficult [32]. The probe tip and measurement surface material were assumed to be tungsten carbide and silicon, respectively.…”

Surface Imaging Technique by an Optically Trapped Microsphere in Air Condition

“…First, a microsphere was trapped optically. The details of the procedure were reported previously [17]. A sample surface was structured as a blazed diffraction grating with a grating pitch of 417 nm and a depth of 50 nm.…”