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Highlighted authors are members of the University of Jena.

  1. Avoiding the tip: spiral optics for robust high power beam shaping of Bessel beams

    Year of publicationPublished in:Optics Express M. Siems, J. Thomas, H. Gross, A. Schöneberg, S. Nolte
    Bessel Gaussian beams offer unique possibilities in material processing due to their elongated high-intensity line foci. They are usually created using an axicon. Being used with high power, the most critical part of the axicon is its tip, as it is prone to laser-induced damage. Any imperfection of the tip can be the source of aberrations of the focus. Therefore, we propose to apply Laguerre Gaussian beam shaping to circumvent the tip of the axicon altogether. We introduce an optical system consisting of spiral phase plates and an axicon to combine Laguerre and Bessel Gaussian beam shaping. This system is experimentally implemented using custom-made spiral phase plates and a large angle axicon. We characterize and finally apply the system to glass cutting and demonstrate the cleaving of a 2 mm thick glass sample, which results in a high-quality breaking edge with sub-micron roughness.
    University Bibliography Jena:
    fsu_mods_00023856External link

  2. LED beam shaping with mask-free adjusted fly’s eye condenser

    Year of publication J. Fearnhead
    The field of illumination optics has clear goals, using some optical system produce an intensity pattern which matches some desired visual target. For example, the projection of light onto a stage in such a way to ensure homogenous brightness across the stage is a common problem for illumination optics in theatre. The components commonly used for modern illumination optics include reflectors, lenses, diffusers, masks and more. Components have specialised use cases, which allow for the production of a desired effect in a specific use case. Single channel systems must be large to ensure sufficient brightness in the desired intensity pattern. Large lenses and other optical elements can be bulky and expensive, which results in a design solution which is unfriendly to manufacturing. Industry has a preference for systems which occupy less volume (compact), produce high transmission and can be mass produced effectively. A current solution to these requirements are microlens arrays (MLA). Unlike single channel systems MLA systems use a multi-channel approach. Multi-channel systems are compact, possess high optical transmission and can be suitable for mass production. The fly’s eye condenser (FEC) is a multichannel system that homogenizes an extended source using Köhler illumination. This system is composed of an LED, a single-aperture collection lens, and a multi-aperture microlens array. The FEC enables homogenization with reduced optical thickness. Irregular FEC (iFEC) systems improve on FEC systems by altering the emitted irradiant/radiant light distribution. For this reason iFEC systems are considered the state of the art in the field of MLA-based arbitrary beam shaping. This work first introduces the FEC/iFEC systems and then an improvement in the form of an adjusted FEC (aFEC).
    University Bibliography Jena:
    fsu_mods_00028251External link

  4. Quantum key distribution with entangled photons in daylight

    Year of publication A. Kržič
    Quantum key distribution (QKD) offers means to transmit data with unprecedented security, ultimately promising to remove the need to trust anything or anyone involved but the laws of quantum mechanics. The use of entangled photons as quantum information carriers seems particularly well suited for this purpose. One of the main challenges for implementation over free-space channels is operation in daylight. During the day, the receiver system collects a large amount of sunlight that materializes as noise, which requires filtering in every available degree of freedom. Spatial filtering is further hindered by atmospheric turbulence. The vast majority of free-space QKD experiments to date have been thus limited to nighttime conditions. This thesis aims to provide the next stepping stone in the development of entanglement-based QKD over free-space channels in daylight. An experimental system for polarization-based QKD was developed and deployed over a 1.7-km urban free-space link. The system incorporates tip-tilt correction to mitigate the effects of atmospheric turbulence and a dedicated adjustable spatial filter to enable daytime operation. The system's daytime QKD performance is experimentally demonstrated, showcasing key rates of about 2.5 kbps in direct noon sunlight, which is an improvement of entanglement-based QKD daylight capability by an order of magnitude in both secure key rate and link range. This is followed by a more thorough investigation of the role of spatial filtering on QKD in daylight. Furthermore, it is shown that active adjustment of the system field of view to the ever-changing link conditions has the potential to substantially improve the overall secure key output of the system. The thesis concludes with a numerical simulation of a satellite-based implementation, which shows that the first daytime QKD from an orbiting satellite is within reach.
    University Bibliography Jena:
    fsu_mods_00016584External link

  5. Field curvature reduction in miniaturized high numerical aperture and large field-of-view objective lenses with sub 1 μm lateral resolution

    Year of publicationPublished in:Biomedical Optics Express S. Stark, H. Gross, K. Reglinski, B. Messerschmidt, C. Eggeling
    In this paper the development of a miniaturized endoscopic objective lens for various biophotonics applications is presented. While limiting the mechanical dimensions to 2.2 mm diameter and 13 mm total length, a numerical aperture of 0.7 in water and a field-of-view (FOV) diameter of 282 μm are achieved. To enable multimodal usage a wavelength range of 488 nm to 632 nm was considered. The performed broad design study aimed for field curvature reduction when maintaining the sub 1 μm resolution over a large FOV. Moreover, the usage of GRadient-INdex (GRIN) lenses was investigated. The resolution, field curvature improvement and chromatic performance of the novel device were validated by means of a confocal laserscanning- microscope.
    University Bibliography Jena:
    fsu_mods_00009462External link

  6. Pupil slicer at high throughput for the EXtreme Precision Spectrograph (EXPRES) at the Lowell Discovery Telescope

    Year of publicationPublished in:SPIE Astronomical Telescopes + Instrumentation; Montreal, Canada; 17 July 2022 - 22 July 2022 E. Beckert, D. Fischer, R. Blackman, C. Jurgenson, O. de Vries, H. Gross, R. Hambach, O. DeVries
    University Bibliography Jena:
    fsu_mods_00009444External link

  7. Material-specific ptychographic imaging at 13.5 nm using a high-order harmonic source

    Year of publicationPublished in:Compact EUV & X-ray Light Sources: part of High Brightness : 21-25 March 2022, Budapest, Hungary W. Eschen, L. Loetgering, V. Schuster, R. Klas, A. Kirsche, L. Berthold, M. Steinert, T. Pertsch, H. Gross, M. Krause, J. Limpert, J. Rothhardt
    University Bibliography Jena:
    fsu_mods_00001772External link

  8. Material-specific high-resolution table-top extreme ultraviolet microscopy

    Year of publicationPublished in:Light: Science and Applications W. Eschen, L. Lötgering, V. Schuster, R. Klas, A. Kirsche, L. Berthold, M. Steinert, T. Pertsch, H. Gross, M. Krause, J. Limpert, J. Rothhardt
    Microscopy with extreme ultraviolet (EUV) radiation holds promise for high-resolution imaging with excellent material contrast, due to the short wavelength and numerous element-specific absorption edges available in this spectral range. At the same time, EUV radiation has significantly larger penetration depths than electrons. It thus enables a nano-scale view into complex three-dimensional structures that are important for material science, semiconductor metrology, and next-generation nano-devices. Here, we present high-resolution and material-specific microscopy at 13.5 nm wavelength. We combine a highly stable, high photon-flux, table-top EUV source with an interferometrically stabilized ptychography setup. By utilizing structured EUV illumination, we overcome the limitations of conventional EUV focusing optics and demonstrate high-resolution microscopy at a half-pitch lateral resolution of 16 nm. Moreover, we propose mixed-state orthogonal probe relaxation ptychography, enabling robust phase-contrast imaging over wide fields of view and long acquisition times. In this way, the complex transmission of an integrated circuit is precisely reconstructed, allowing for the classification of the material composition of mesoscopic semiconductor systems.
    University Bibliography Jena:
    fsu_mods_00000362External link

  9. New Surface Contributions for Higher Order Color Aberrations and Chromatic Variations of Seidel Aberrations

    Year of publicationPublished in:International Optical Design Conference 2021: part of Optical Design and Fabrication : 27 June-1 July 2021, Washington, DC, United States A. Berner, H. Gross
    University Bibliography Jena:
    fsu_mods_00000556External link

  10. Extended aberration analysis in symmetry-free optical systems - Part I: Method of calculation

    Year of publicationPublished in:Optics Express Z. Tang, H. Gross
    The imaging performance evaluation of symmetry-free optical systems is of great importance during the correction process of optical design. However, due to the complexity and limitations of the available tools, the higher-order aberrations in the system cannot be well analyzed and are hard to control. In this paper, the theoretical background and the mathematical approach of a quantitative analysis method for surface-decomposed transverse aberration in the symmetry-free systems are introduced. With the mixed ray-tracing calculation in both real and paraxial cases, the implementations of full-order intrinsic/induced aberration, as well as the surface-additive Zernike coefficient fitting method are demonstrated. The applications of this method help assess the correction performance considering the relatively critical surfaces in an arbitrary off-axis system. The reliability and the accuracy of the method will be evaluated in part II with a test system. And as an illustration of the practical usage of the method for optical design, the corresponding applications on a group of lithographic systems will also be demonstrated.
    University Bibliography Jena:
    fsu_mods_00031516External link

  11. A benchmarked vectorial model and flexible software-tool for in-bulk laser processing

    Year of publicationPublished in:Conference proceedings from OSA Publishing Q. Li, M. Chambonneau, M. Blothe, H. Gross, S. Nolte
    University Bibliography Jena:
    fsu_mods_00006330External link

  12. Extended aberration analysis in symmetry-free optical systems - part II: Evaluation and application

    Year of publicationStatusReview pendingPublished in:Optics Express Z. Tang, H. Gross
    In part I [Opt. Express 29, 39967 (2021)] of this publication, the working principle of a mixed ray-tracing (MRT) method is introduced for surface-decomposed transverse aberration contributions, and the settings and various calculation options are discussed. Following part I, this paper is a supplement with the evaluation of the calculation results and more illustrations of practical applications, which focuses on the support of the MRT method during the symmetry-free optical system design process. The comprehensive analysis of a group of lithography systems as an application example proves that the MRT method is a powerful tool for imaging system performance assessment, as well as for relative sensitivity analysis among the surfaces in the optical system.
    University Bibliography Jena:
    fsu_mods_00031164External link
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