Active alignment of DOE based structured light application in consumer electronics
New applications with 3D sensing technologies are entering the market every day. Based on diffractive optical elements, structured light is a key factor to realize computer vision based sensing solutions. Tight quality requirements and fast ramp up times lead to new approaches during packaging. Active alignment can compensate uncertain tolerances during early stages of the product development, which eases prototyping and ramp up of production. Additionally, challenges of high volume markets, like consumer electronics, have to be addressed too. Low variance in cycle time with high throughput and reliability are necessary factors for production. In this paper, we will present an active alignment solution for random dot pattern applications. Based on an industrial gantry and control system, a specialized part handling system has been designed. Built upon a customizable micromanipulator design, measurement and UV curing capabilities have been integrated additionally. The measurement system consists of four cameras installed in a dome construction to collect projected light from the package during alignment. These images are processed by our alignment algorithm, which derives suitable quality metrics, which further can be transformed into movements of the micromanipulator. We will discuss general quality metrics and our approach to fuse the image data streams before examination. We will further present our algorithm design, which directly connects to the industrial control environment. Finally, the curing process is initiated by integrated UV illumination on the gripper. A shrinkage compensation strategy is necessary to preserve the obtained optimum beyond the bonding process.