Automated assembly of lens barrels with active wavefront sensor guiding

Abstract

Miniaturized optics are main-components in many different areas ranging from smart devices over medical products to the area of automotive and mobility. Thus several millions if not billions of small lenses are merged into objectives. One characteristic type of objective holder is the lens barrel. The successful assembly of lenses with diameters of just a couple of millimeters into a lens barrel is an error-prone task antagonized with mass production and an optical inspection at the end of the assembly. Obviously, this process is neither time- nor cost-effective. Furthermore, the increasing imaging qualities demand for highly accurate aligned lens systems. The demand for high-quality optics in large quantities together with the small dimensions of the lenses make assembling a complex process. The Fraunhofer IPT investigates a much more elegant way inspecting the optical system during the fully automated assembly. In the assembly cell, our six-axis micromanipulator aligns the lens camera-led in the lens barrel. Next, the wavefront sensor analyses the imaging function of the lens and compares the actual status with the data from the optic model. This feedback loop between wavefront sensor and micromanipulator continues until the best position is found. We save this information as a digital twin and continue with the next lenses until the optics is completed. The observation of the optical function during the assembly process leads to high quality objectives produced in short cycle times. Moreover, our assembly cell is modular and this allows us to adopt the setup for new lens barrels easily.