# Twin-beam real-time position estimation of micro-objects in 3D

## TL;DR

This paper introduces a simple, real-time 3D micro-object position estimation method using twin-beam illumination and a standard image sensor, enabling feedback control in micro-manipulation tasks.

## Contribution

The paper presents a novel, hardware-efficient method for real-time 3D micro-object positioning using twin-beam illumination and a lensless image sensor setup.

## Key findings

- Achieves ~3 um lateral and ~7 um axial accuracy
- Operates at 10 Hz refresh rate
- Effective in micro-manipulation feedback control

## Abstract

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.