The present article describes a method for the determination of the radical photopolymerization conversion of acrylic coatings suitable for an in situ monitoring during the coating process. Acrylate based coatings are increasingly used in many kinds of industrial coating processes, because of advantages of the solvent-free application process. The applied method is based on 1620 nm light absorption of the acrylate. To overcome the disadvantages of a common NIR spectrometer, only the diffuse reflection of the relevant discrete wavelength at 1620 nm and of a reference wavelength is measured. A sophisticated sensor setup including an optical spatial filter and lock-in amplified signal processing is used to achieve a sufficient signal to noise ratio. The capability of the sensor to discriminate between polymerized and unpolymerized coatings on metal substrates down to a coating thickness of 16 lm is demonstrated. Furthermore, the information on polymerization from larger depth in TiO 2 pigmented coatings is investigated. The results can be analytically modeled in analogy to the Lambert-Beer's law, resulting in a detection limit of a maximum pigment concentration of 15 wt % with 100 lm coating thickness. The presented sensor design is suitable to be used in an industrial production environment for example in screen printing applications as a monitoring and quality control tool.

The extreme adaptive optics deformable mirror as outlined in the study of EPICS for the EELT helps to detect planets much fainter than the observed star. In doing so, excellent wavefront quality ensured by a high actuator count is mandatory. A long actuator lifetime is equally important since it reduces the number of dead actuators to a minimum, which is necessary for the coronagraphy techniques.The Fraunhofer Institute of Applied Optics in Jena and Physik Instumente GmbH teamed up to response to an ESO Call for Tender. We developed an appropriate deformable mirror (DM) concept, and are currently elaborating the breadboards to demonstrate critical technologies. The considered DM technology is based on piezoelectric stack actuators which deform a thin-shell glass substrate. As a main feature, we provide a modular solution, meaning that actuator modules may be inserted into a DM substrate. With that an exchange of actuator modules in case of actuator failure is possible that characterizes the SWAP DM for extreme adaptive optics. In order to enable a high lifetime of the DM, we will pre-stress the actuator and use a modified PICMA® actuator, which exhibits a ceramic insulation extending the lifetime. Thus, the array benefits from an improved actuator lifetime without the requirement for an additional encapsulation which would be disadvantageous for the necessity of a low actuator pitch.In this project several laboratory breadboards will be developed to demonstrate key aspects of the deformable mirrors and their TRL level. We present the current state of the preliminary design, the schematic design and the status of the breadboards.

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