M.Sc.

Zontar, Daniel

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  • Publication
    Automated PM-fiber array assembly with high-precision four DOF alignment
    ( 2020)
    Berger, Marvin
    ;
    Alippi, Andrea
    ;
    Haag, Sebastian
    ;
    Hoeren, Maximilian
    ;
    Müller, Tobias
    ;
    Zontar, Daniel
    ;
    Brecher, Christian
    Polarization maintaining fibers arrays are key enablers to process high bandwidth data, representing a powerful part within the photonic integrated chip technology. The different channels increase the information density and allow to multiple singles through one fiber bulk at the same time. Due to fiber's small dimensions (ø125 mm) they can be integrated in existing infrastructure easily and are very flexible at the same time. However, the compact design together with the flexible material properties demands for new precise tools and technologies to reach the necessary precision during packing. The Fraunhofer-Institute for Production Technology IPT develops, together with their partners Phix and Aixemtec, new handling and assembly tools, as well as processes as one of the leading companies in this field. In the self-developed assembly cell, the fiber handling tool-head operations automatically to pick up, manipulate and tack single fibers to a glass plate or fiber to chip. Each fiber is moved by a portal robot within the assembly cell with micrometer accuracy but also can be rotated with a repetition accuracy less than 0.01°. Advanced illumination units observation techniques allow to package fibers arrays much quicker and more robust than before. Therefore, additional camera systems and material characteristics are used to develop smart alignment routines. As a result, the observation of the orientation of the PM-fiber core as well as the fiber layout during the assembly process leads to high quality products within fast production cycles. Due to the flexible construction of the assembly call also PIC packaging and fiber-to-chip coupling is possible.
  • Publication
    Automated sensor-guided packaging of diamond tools
    ( 2020)
    Ehret, Susanne
    ;
    Saunders, Gordon D.
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    Hillmer, Nils
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    Müller, Tobias
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    Hoeren, Maximilian
    ;
    Zontar, Daniel
    ;
    Brecher, Christian
    Automated, ultra-precise packaging strategies reduce production time and costs while increasing yield, quantity, and precision, making them one of the main research and development questions in the field of production technology. Fraunhofer IPT develops sensor-guided assembly solutions for packaging and testing of optical and non-optical components to meet the demand. In this paper, we present a prototypical process for the automated, ultra-precise passive alignment using the assembly of a diamond engraving tool as an example. The challenge is to place a diamond measuring three millimetres in its largest dimension into a groove of similar size and to position the tip of the diamond within tolerances of a few micrometres and arcminutes. This six dimensional assembly problem is tackled by feeding live camera data to an image processing algorithm and by aligning the diamond using Fraunhofer IPT's ultra-precise micromanipulator, collectively forming an automated, closed-loop assembly process. Thus, a fully automated packaging process with very high accuracy and reliability is proven to be technically possible.
  • Publication
    Offline development of active-alignment-algorithms by efficient interpolation of discrete databases
    ( 2019)
    Hoeren, Maximilian
    ;
    Zontar, Daniel
    ;
    Sauer, Sebastian
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    Schmetz, Arno
    ;
    Berger, Marvin
    ;
    Müller, Tobias
    ;
    Brecher, Christian
    Automated active alignment of optical components during the assembly process of optical systems is state of the art in todays optics-production. With the increasing demand of optical systems in smart devices and automotive technologies, new methods and strategies have to be developed to guarantee rapid and goal-oriented development of active-alignment algorithms. A key approach to this is offline development via simulations. This paper presents and evaluates an efficient approach to generate a continuous data-feedback for the offline development of active-alignment-algorithms by interpolation of a discrete database. Dependent on the system-input the described procedure generates the raw, array-like output data of a CCD-chip from the existing data of the local neighborhood.
  • Patent
    Vorrichtung und Verfahren zur Ausrichtung von polarisationserhaltenden Lichtleitfasern
    ( 2019)
    Haag, Sebastian
    ;
    Alippi, Andrea
    ;
    Dekker, Ronald
    ;
    Müller, Tobias
    ;
    Zontar, Daniel
    Bei einem Verfahren zur Ausrichtung einer polarisationserhaltenden Lichtleitfaser, bei dem die Lichtleitfaser (7a, 7b, 7c) mit einer Klemmeinrichtung (12, 19, 23) klemmend gehalten wird, eine um die Faserlängsachse gegebene Rotationslage der Lichtleitfaser (7a, 7b, 7c) detektiert wird, und die Lichtleitfaser (7a, 7b, 7c) mittels der Klemmeinrichtung (12, 19, 23) um die Faserlängsachse rotiert wird, wird vorgeschlagen, dass für die Rotation der Lichtleitfaser (7a, 7b, 7c) mindestens ein an der Lichtleitfaser (7a, 7b, 7c) anliegendes Klemmelement (13, 14, 20-22, 24-27) der Klemmeinrichtung (12, 19, 23) relativ zu mindestens einem weiteren, ebenfalls an der Lichtleitfaser (7a, 7b, 7c) anliegenden Klemmelement (13, 14, 20-22, 24-27) der Klemmeinrichtung (12, 19, 23) bewegt wird. Des Weiteren wird eine entsprechend eingerichtete Vorrichtung vorgestellt.
  • Publication
    Automated sprue removal from injection moulded micro-optics with ultrasonic cutting
    ( 2019)
    Berger, Marvin
    ;
    Hoeren, Maximilian
    ;
    Sauer, Sebastian
    ;
    Müller, Tobias
    ;
    Zontar, Daniel
    ;
    Brecher, Christian
    Injection moulding is key to fast mass production for smart devices, mobility and medical products, like micro-optics, covers and lab-on-a-discs respectively. For optics, several million 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 millimetres into a lens barrel is an error-prone task antagonized with mass production and an optical inspection at the end of the assembly. Before the assembly and after the manufacture of the individual optics, the sprue separation takes place. This is a critical moment because even optics whose dimensions are within the target tolerance after manufacturing can be damaged by improper action. Common methods here are the separation by means of a blade, hot wire, laser or saw blade. Each of these methods has its advantages and disadvantages, but all have in common the introduction of stress and/or heat into the component. The Fraunhofer IPT investigates a much more elegant way removing the sprue from injection-moulded optics in an automated environment. Based on the ultrasound technology developed by IPT back in the 1980s, we use a high frequency generator to get an AC voltage and piezo crystal for the inverse piezoelectric effect. The crystal oscillates with a high frequency and low amplitude. Next, the l/2 to l/4 sonotrode amplifies the amplitude. The sonotrode is designed with a CAD model, simulated in ANSYS and the complete experimental verified on real lenses afterwards.
  • Publication
    Characterization of individualized assembly for BFL-compensated FAC on bottom tab modules
    ( 2018)
    Zontar, Daniel
    ;
    Müller, Tobias
    ;
    Sauer, Sebastian
    ;
    Baum, Christoph
    ;
    Brecher, Christian
    Uncertain glue gaps lead to challenging assembly tasks in respect to shrinkage control. With decreasing back-focal lengths (BFL) in collimators, the tolerance window for correct alignments decreases as well and forces manufactures to find novel approaches to realize the bonding process. We present performance characteristics of an automated assembly cell for individualized FAC on bottom tab modules. BFL-compensated collimators allow minimizing the critical adhesive gap between substrate and diode laser. This provides optimal control over shrinkage, as well as thermal aspects of the bonding properties. We will focus on the active alignment, which provides the individual focus distance, as well as the relative image processing necessary to assemble both components with ±1 µm precision. Our machine concept and measurement equipment is suitable as stand-alone process for optic manufacturers, as well as integrated part in the final application assembly. In last year’s publication (SPIE 10086), we presented the general concept and can now support our approach with more details from our operating data. With minimized adhesive gaps, the robustness of the proposed concept and a precise characterization of its process window is key, as minimal variations lead to rejects and cause high costs during the final application assembly. Besides classic properties, many more characteristics, e.g. smile behavior of the optic module, are potential optimization factors to increase beam quality. Characterization data from both optic and laser allow applying tolerance matching, where alignment is physically constraint. Performance wise, we will discuss the repeatability, achievable precision and the implications on process time.
  • Publication
    Curing-in-the-loop strategy for multidimensional-shrinkage compensation in active alignment FAC assembly
    ( 2018)
    Zontar, Daniel
    ;
    Müller, Tobias
    ;
    Sauer, Sebastian
    ;
    Baum, Christoph
    ;
    Brecher, Christian
    Tight tolerances for the final position and orientation of optical components are best controlled in automated and high volume production with statistical process control. Semi-automated and low-volume scenarios on the other hand are in need for a suitable approach, capable to react resiliently on remaining uncertainties of the bonding process. Active alignment has proven to lower the tolerances for finding the optimal position regarding the overall performance. We will present a novel shrinkage-compensation strategy, which extends the active control loop to integrate the curing process. We will discuss the adhesive properties necessary for the realization of our strategy and our measurement equipment used for the characterization of such properties. Besides a predicable shrinkage curve, the critical cross-linking level, until no further manipulation is possible, is a key factor. Furthermore, the machine concept, the curing capabilities and the active evaluation needs to follow special requirements. Since the shrinkage-behavior is highly sensitive to the amount of UV, the effective power on the adhesive needs to be controlled by optimizing the orientation of the light source. We integrated the UV-light in our micromanipulator in order to always ensure an optimal illumination In order to apply regression analysis for a multidimensional shrinkage model, misalignments in the selected degrees of freedom must be observable with sufficient precision. As validation of our strategy, we examine the collimation of a diode laser bar.
  • Publication
    Robust adhesive precision bonding of laser optics II
    ( 2017)
    Müller, Tobias
    ;
    Beleke, Andreas
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    Haag, Sebastian
    ;
    Zontar, Daniel
    ;
    Sauer, Sebastian
    ;
    Baum, Christoph
    ;
    Brecher, Christian
    ;
    Wenzel, Christian
    Laser systems face massive economic challenges for cost effective, but yet ultraprecise assembly processes. Costs are mainly driven by the final assembly requirements of laser systems. Most challenging in this context is the robust process control of the UV-curing adhesive bonding process. The work presented aims for a significant reduction of the impact of shrinkage effects during curing and a resulting increase in assembly precision. Key approaches are integrated and characterized curing systems, ultraprecise dispensing processes and the automated characterization of adhesive shrinkage magnitude. These technologies allow for reproducible adhesive bonding processes in prototyping, job-shop assembly and automated assembly cells.
  • Publication
    Active alignment of DOE based structured light application in consumer electronics
    ( 2017)
    Zontar, Daniel
    ;
    Müller, Tobias
    ;
    Sauer, Sebastian
    ;
    Hettler, Nicolaus
    ;
    Brecher, Christian
    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.
  • Publication
    Individualized FAC on bottom tab subassemblies to minimize adhesive gap between emitter and optics
    ( 2017)
    Sauer, Sebastian
    ;
    Müller, Tobias
    ;
    Haag, Sebastian
    ;
    Beleke, Andreas
    ;
    Zontar, Daniel
    ;
    Baum, Christoph
    ;
    Brecher, Christian
    High Power Diode Laser (HPDL) systems with short focal length fast-axis collimators (FAC) require submicron assembly precision. Conventional FAC-Lens assembly processes require adhesive gaps of 50 microns or more in order to compensate for component tolerances (e.g. deviation of back focal length) and previous assembly steps. In order to control volumetric shrinkage of fast-curing UV-adhesives shrinkage compensation is mandatory. The novel approach described in this paper aims to minimize the impact of volumetric shrinkage due to the adhesive gap between HPDL edge emitters and FAC-Lens. Firstly, the FAC is actively aligned to the edge emitter without adhesives or bottom tab. The relative position and orientation of FAC to emitter are measured and stored. Consecutively, an individual subassembly of FAC and bottom tab is assembled on Fraunhofer IPT's mounting station with a precision of +/- 1 micron. Translational and lateral offsets can be compensated, so that a narrow and uniform glue gap for the consecutive bonding process of bottom tab to heatsink applies (Figure 4). Accordingly, FAC and bottom tab are mounted to the heatsink without major shrinkage compensation. Fraunhofer IPT's department assembly of optical systems and automation has made several publications regarding active alignment of FAC lenses [SPIE LASE 8241-12], volumetric shrinkage compensation [SPIE LASE 9730-28] and FAC on bottom tab assembly [SPIE LASE 9727-31] in automated production environments. The approach described in this paper combines these and is the logical continuation of that work towards higher quality of HPDLs.