3-D Robotic Positioning Utilizing Holographic Interferometry

We propose a new technique for robotic positioning and calibration which utilizes holographic imaging and interferometry to avoid the disadvantages associated with conventional techniques. This technique allows both gross and fine positioning of robotic devices in space and is useful in situations where it is necessary to repeatably position a moving device to a specific location. Gross positioning is accomplished by matching the robotic device to a holographic virtual image, using a computer vision system to overlap key features of the robotic device on their holographically imaged counterparts. The use of holographic images is an advantage because the robot cannot obscure them from view or collide with them. Fine positioning is achieved to better than one-micron accuracy by utilizing the interference fringes that result when the robotic device and the holographic image are aligned to within about 50 microns of each other. Elimination of the fringes indicates exact coincidence between the robot and its holographic counterpart. A computer vision system was utilized to automate the entire positioning procedure. Theory, algorithms, and experimental implementation are described.