Twin-beam real-time position estimation of micro-objects in 3D
This provides a simple, low-cost solution for real-time 3D position sensing in micro-manipulation, though it is incremental as it combines existing twin-beam and lensless imaging concepts.
The authors present a twin-beam illumination method for real-time 3D position estimation of micro-objects using a lensless image sensor, achieving ~3 μm lateral and ~7 μm axial accuracy at 10 Hz refresh rate during micro-manipulation feedback control.
Various optical methods for measuring positions of micro-objects in 3D have been reported in the literature. Nevertheless, majority of them are not suitable for real-time operation, which is needed, for example, for feedback position control. In this paper, we present a method for real-time estimation of the position of micro-objects in 3D; the method is based on twin-beam illumination and it requires only a very simple hardware setup whose essential part is a standard image sensor without any lens. Performance of the proposed method is tested during a micro-manipulation task in which the estimated position served as a feedback for the controller. The experiments show that the estimate is accurate to within ~3 um in the lateral position and ~7 um in the axial distance with the refresh rate of 10 Hz. Although the experiments are done using spherical objects, the presented method could be modified to handle non-spherical objects as well.