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We report on the isomerization dynamics of an amphiphilic azobenzene that dwells within the plasma membrane. We found that in aggregates formed in water, the isomerization reaction is hindered, while radiative deactivation is favoured. However, once in the membrane, the molecule reacquires its isomerisation capacity. These data fully account for the recently reported experiments in neurons, showing that the amphiphilic azobenzenes are effective light actuators for the modification of the electrical state of the membrane. [ABSTRACT FROM AUTHOR]

Electromagnetic scattering is the main phenomenon behind all optical measurement methods where one aims to retrieve the shape or physical properties of an unknown object by measuring how it scatters an incident optical field. Such an inverse problem is often approached by solving, several times, the corresponding direct scattering problem and trying to find the best estimate of the object which is compatible with a set of measurements. In the direct scattering problem, two regimes can be distinguished depending on the size of the object and the permittivity contrast: the weak-scattering regime and the strong-scattering regime. Generally, the presence of the scatterer alters the form of the incident field inside the scatterer. If that effect is neglected in the physical model, then one speaks of the so-called single-scattering regime or, more often, the Born approximation. The regime in which this approximation is valid is the weak-scattering regime. The corresponding inverse problem, that aims to retrieve the object from scattering data, becomes linear in this case. Linearizing the problem simplifies the method to solve it, but also introduces limitations to the maximum spatial resolution achievable in the reconstruction of the object. In the strong-scattering regime, multiple-scattering effects are not neglected and the inverse problem is treated in its full non-linear nature, which makes finding its solution a far more challenging task. Despite the existence of numerical methods, a powerful way to solve those direct problems would be to use a perturbation approach where the field is expressed as a series, known as the Born series. The advantage of a perturbation approach stems from the fact that each term of the series has a clear physical meaning and can unveil much more about the scattering process than a purely numerical approach can offer. Unfortunately, the series solution turns out to be strongly divergent in the strong-scattering regime, making it an unpractical approach for problems under these strong-scattering conditions. Thus, despite the fact that multiple scattering could, in principle, allow resolving sub-wavelength details of the unknown object, this possibility is in practice hampered by the divergent nature of the higher-order terms of the Born series. In this work, we show how to solve this problem by employing Padé approximants and how to treat electromagnetic problems well beyond the weak-scattering regime and provide an accurate evaluation of the scattered field even under strong-scattering conditions. Padé approximants are rational functions that can offer improvements in two ways, namely series acceleration of converging series and analytic continuation of a series outside its region of convergence. In the case of a symmetric approximant of order N, the approximant is calculated from 2N + 1 terms in the Born series, therefore incorporating multiple-scattering effects to which these higher-order corrections in the Born series correspond. We apply the method to two scalar scattering problems: that of a one-dimensional slab and that of an infinitely long cylinder, which reduces to a two-dimensional problem under normal incidence. In particular, we treat cases in the strong-scattering regime where the Born series diverges, but where Padé approximation retrieves a valuable result. In Fig. 1 the case of a cylinder is shown which is well beyond the weak-scattering regime, but where the most accurate Padé approximant gives a good result for the field. The presented approach incorporates multiple-scattering effects and can therefore represent an important building block to the application of the Born series to direct and inverse problems, with potential applications in superresolution, optical metrology, and phase retrieval. [ABSTRACT FROM AUTHOR]

In this paper we present the theory and the experimental setup used to transfer a standard frequency, to synchronize two clocks linked by an optical fiber. In order to verify the accuracy on frequency transfer over fiber link, we prepared an experiment that allows testing the performance of the setup for a variable set of environmental conditions, namely associated to temperature and vibration variations. The experimental setup shows the fiber optic link between one laboratory, where the standard frequency is generated, and another laboratory, where the equipment for simulating temperatures and vibrations are installed. The standard frequency, traceable to UTC(IPQ), is used to modulate two lasers with different wavelength,, injected in the optical fiber. At the end of the optical fiber the signals will be out of phase due to the inherent chromatic dispersion, which is also dependent on the temperature of the propagation media. Measuring the phase variations, caused by temperature gradients in the fiber, we can compensate the frequency transfer and synchronize the clocks. Evaluating all uncertainty components in this model, allows the metrological characterization of the synchronization and obtain the associated uncertainty of this quantity. [ABSTRACT FROM AUTHOR]

We present a new concept for a fully integrated nano-optical snapshot imaging polarimeter. It consists of a nano-optical retarder and polarizer array with various orientations combined with a microlens array and crosstalk module. That facilitates a fast, robust, and compact stokes imaging polarimeter without moving parts for applications at 450 nm wavelength. [ABSTRACT FROM AUTHOR]

We are developing a form measurement system for the surfaces of freeform optics and large conventional optics. The specifications of the optics are diameters up to 1.5 m and radii of curvature down to 10 m. This includes optics like telescope mirror segments and synchrotron optics. Using a Fizeau interferometer, we propose a subaperture stitching method that involves vertically aligning the interferometer's optical axis to the local surface gradient and measuring the absolute distance from the interferometer's reference flat to the specimen. Experimental results for the absolute distance measurement are shown. [ABSTRACT FROM AUTHOR]

In this paper, we show picometer-order mechnical displacmment measurements using a heterodyne interferometer with a phase-locked loop (PLL). A heterodyne light source for the interferometer is implemented with a frequency stabilized HeNe laser and two acousto-optic modulators. A real time phase measurement is performed by the PLL, whose software is programmed in a field-programmable gate array (FPGA). A stiff parallel spring stage combined with a high-voltage piezoelectric actuator is used to generate picometer-order mechanical motion. With the above implementations, mechanical displacement of 10 picometer or less can be measured. [ABSTRACT FROM AUTHOR]

The analysis of 2D scattering maps generated in scatterometry experiments for detection and classification of nanoparticle on surfaces is a cumbersome and slow process. Recently, deep learning techniques have been adopted to avoid manual feature extraction and classification in many research and application areas, including optics. In the present work, we collected experimental dataset of nanoparticles deposited on wafers for four different classes of polystyrene particles (with diameters of 40, 50, 60, 80 nm) plus background (no particles) class. We trained a convolutional neural network, including its architecture optimization, and achieved 95% accurate results. We compared the performance of this network to a existing method based on line-by-line search and thresholding, demonstrating up to a twofold enhanced performance in particle classification. The network is extended by a supervisor layer that can reject up to 80% of the fooling images at the cost of only rejecting 10% of original data. [ABSTRACT FROM AUTHOR]

A phase shift time of flight technique determines a position by comparing the phase angle of a continuously modulated signal in the source and its reflection on a target. However, due to its cyclical properties, the position information is contained within an ambiguity interval. For an absolute measurement, this interval is repeated N times plus a residual part given by the phase shift. In this work we propose an application of the Vernier method to determine N and a setup for mid-range applications (10-20) m with a 3 GHz amplitude modulated source to allow accuracies ≤ 100 μm. [ABSTRACT FROM AUTHOR]

This paper presents an overview of the design of a voice coil based white light intensity stabilization tool. A system is created capable of mechanically stabilizing the fluctuations in a beam of light. This is achieved with a use of a voice coil and simple PID based feedback loop, controlled using a LabVIEW interface. Stability results are shown using Allan deviations curves. [ABSTRACT FROM AUTHOR]

Quantum estimation theory provides bounds for the precision in the estimation of a set of parameters that characterize a system. Two questions naturally arise: Is any of these bounds tight? And if this is the case, what type of measurements can attain such a limit? In this work we show that for phase objects, it is possible to find a tight resolution bound. Moreover one can find a set of spatial modes whose detection provides an optimal estimation of the complete set of parameters for which we propose a homodyne detection scheme. We call this method spatial spectroscopy since it mimics in the spatial domain what conventional spectroscopy methods do in the frequency domain employing many frequencies (hyperspectral imaging). [ABSTRACT FROM AUTHOR]

In this contribution, we emphasize the need for a sophisticated characterization of measurement devices in particular for optical bidirectional measurements. As an example, the ongoing characterization of the UV-microscope at PTB's linescale comparator is presented. First results of spectroscopic measurements of the employed UV-LED are presented and the impact of deviations in the center wavelength of the LED on the measurements are illustrated by rigorous simulations. [ABSTRACT FROM AUTHOR]

We report on a method for the characterization of optical absorption in semiconductors at photon energies below the bandgap energy. We use intensity dependent deflection spectroscopy to measure spatially resolved the optical absorption and to separate the occurring absorption mechanisms. To this end, we take advantage of the different intensity scaling of these mechanisms and extract the material parameters by fitting the intensity dependent absorption to a physical model. Our method enables a simple but sufficient determination of crucial optical loss properties (e.g. impurity related absorption and two-photon absorption) in various semiconductor systems, e.g. substrates for optical components or solar cells. [ABSTRACT FROM AUTHOR]

Ultra narrow-band absorbing surfaces answer a growing demand of precise control of absorption spectra. Starting from a design of guided mode resonator (GMR), we present here a versatile architecture presenting resonances of very high quality factors (up to 10 000) and spectrally adjustable. This design uses multiple slices of dielectrics to focus resonating field in the middle of a metallic waveguide, diminishing its extension in the metal and thus the loss rate of the propagating mode. [ABSTRACT FROM AUTHOR]

Fringe visibility and noise removal, are key success factors in interferometric techniques, where novel deep learning techniques can be applied. We test the use U-Net deep convolutional network applied to the obtained interference images, trained with an ad-hoc generated image dataset with complex fringe patterns, computed using high order Zernike polynomials. [ABSTRACT FROM AUTHOR]

We present an approach for measuring the shape of transparent glasses, which enables us to significantly reduce the comparatively long measurement time while increasing the measurement accuracy. Instead of using area-like patterns, we irradiate the object to be measured successively in a locally strongly restricted area with considerably higher irradiance. [ABSTRACT FROM AUTHOR]

Composite materials are used for high-performance rotating blades, e.g. in turbines and wind power plants. Here, optical coherence tomography was used to visualize large areas of fibre-reinforcedpolymer discs at rotation speeds of up to 1200 rpm. These measurements allowed to visualize the fibre structure over large areas of the disc. By recording the front and back reflex, the wobble of the disc was measured precisely. Additionally, the recorded structure was used to detect even small deviations from a uniform rotation. [ABSTRACT FROM AUTHOR]

We designed, realized, and characterised an imaging Mueller matrix ellipsometry setup for the pixelwise measurement of the Mueller matrices in microscope images. Our setup is capable of performing measurements in reflection as well as in transmission in a broad range of angles of incidence for wavelengths between 400 nm and 700 nm. We compared measurements of specially designed nanostructured samples with AFM and SEM measurements as well as with numerical simulations using the finite element method. [ABSTRACT FROM AUTHOR]

Microsphere-assisted microscopy is a new imaging technique which allows the diffraction limit to be overcome using transparent microspheres. It makes it possible to reach a resolution of up to 100 nm in air while being label-free and full-field. An overview of the imaging technique is presented showing the influence of the photonic jet on the image nature and the unconventional behaviour of the magnification factor. Moreover, interferometry through microspheres is demonstrated for the 3D reconstruction of nanoelements. [ABSTRACT FROM AUTHOR]

Many nanophotonic devices rely on the excitation of photonic resonances to enhance light-matter interaction. The understanding of the resonances is therefore of a key importance to facilitate the design of such devices. These resonances may be analyzed by use of the quasi-normal mode (QNM) theory. Here, we illustrate how QNM analysis may help study and design resonant nanophotonic devices. We will in particular use the QNM expansion of far-field quantities based on Riesz projection to design optical antennas. [ABSTRACT FROM AUTHOR]

We discuss an approach for modal expansion of optical far-field quantities based on quasinormal modes (QNMs). The issue of the exponential divergence of QNMs is circumvented by contour integration of the far-field quantities involving resonance poles with negative and positive imaginary parts. A numerical realization of the approach is demonstrated by convergence studies for a nanophotonic system. [ABSTRACT FROM AUTHOR]

Two disruptive space telescope concepts are being designed and developed at the University of Arizona; these are the 20-meter OASIS (Orbiting Astronomical Satellite for Investigating Stellar Systems) and 8.5-meter Nautilus. OASIS combines break-through inflatable aperture and adaptive optics techniques to realize the dream of a 20+ meter class spaceborne terahertz/far-infrared telescope. In the Nautilus visible/near-infrared telescope concept, conventional primary mirrors are replaced by an ~8.5-meter MODE (Multi-order diffractive engineered) lens with 10 times lower areal density and up to 100 times lower mis-alignment sensitivity over traditional systems, enabling large-diameter optical space telescopes. The OASIS and Nautilus concepts have the potential to greatly reduce mission costs and risks compared to the current state of the art. [ABSTRACT FROM AUTHOR]

Subwavelength-structures with different fill factors in the lateral dimensions result in unique phase shifts for the different polarization states of transmitted light. By using this additional degree of freedom for diffractive optical elements, we yield additional functionalities for compact optical systems with DOEs. As a fully operable example we present a binary subwavelength-grating which acts as a polarizing beamsplitter for TE- and TM-polarization over a wide range of incidence angles. We show our design approach, the manufacturing process with Soft-UV-Nanoimprint-Technology, as well as experimental results. We will also lay out possibilities for the design and application of multilevel polarization-functionalized gratings. [ABSTRACT FROM AUTHOR]

Plasmonics plays a vital role in realizing nanophotonic devices for integrated optics due to its strong light localization into subwavelength dimensions beyond the diffraction limit. Therefore, plasmonics has a wide range of applications such as sensing, solar cells, microscopy, etc. Plasmonics modelling techniques are necessary for understanding the underlying physics of plasmonic devices. However, correct modelling of these devices is still an obstacle facing some of existing modeling techniques. In this paper, we discuss the shortcomings of the existing tools for analysing plasmonic devices, highlight their main features and suggest some powerful remedies. [ABSTRACT FROM AUTHOR]

We present the design and fabrication advances on active lithium niobate metasurfaces. We determine by numerical calculations a metasurface design with electro-magnetic resonances in the visible and near-infrared, by taking into account the constraints for fabrication on thin films of lithium niobate. We suggest that the optical properties of the metasurface can be switched using the electro-optical properties of lithium niobate. [ABSTRACT FROM AUTHOR]

Ion-exchange in glass is a well-known technique to fabricate phase optical elements. For elements with reduced dimensions, the side diffusion, intrinsic to ion-exchange processes, can affect the performance of these elements if it is not taken into account. Here we present a procedure to optimise the zero-order suppression of ion-exchanged phase gratings. [ABSTRACT FROM AUTHOR]

This study proposes a plasmonic band-stop filter with surface plasmon resonance in a doublelayer wire grid structure targeting short-wavelength visible and near-ultraviolet regions for applications in ultraviolet photography. Using Ag and Al, the rigorous coupling wave of analysis method revealed that the maximum absorption was approximately 90% at 450 nm and 375 nm. The experiments using Ag produced similar results in a simulation. These results demonstrate that plasmonic band-stop filters in the visible and near-UV region can be realized at 450 nm and 375 nm using Ag or Al. [ABSTRACT FROM AUTHOR]

We demonstrate the strong coupling between excitons in organic molecules and all-dielectric metasurfaces formed by arrays of silicon nanoparticles supporting Mie surface lattice resonances (MSLRs). Compared to Mie resonances in individual nanoparticles, MSLRs have extended mode volumes and much larger quality factors, which enables to achieve collective strong coupling with very large coupling strengths and Rabi energies. Moreover, due to the electric and magnetic character of the MSLR given by the Mie resonance, we show that the hybridization of the exciton with the MSLR results in exciton-polaritons that inherit this character as well. Our results demonstrate the potential of all-dielectric metasurfaces as novel platform to investigate and manipulate exciton-polaritons in low-loss polaritonic devices. [ABSTRACT FROM AUTHOR]

Frequency conversion plays an important role in both fundamental and applied nano-optics. Doubling the frequency of light by second harmonic generation (SHG) is a vital process e.g. in laser optics or high-resolution microscopy. SHG can be created through symmetry breaking at plasmonic nanostructures, or the local high electric near-fields of plasmonic nanoantennas can be utilized to further enhance the SHG e.g. from nonlinear crystals. Examples of SHG microscopy using cylindrical vector beams in combination with tilted nanocones and radially symmetric oligomers are shown as well as enhancement studies of the SHG from nonlinear crystals decorated with polarization-matched nanostructures. [ABSTRACT FROM AUTHOR]

Compact cross-grating spectrometers are inspired by classical high-end Echelle spectrometers and allow to acquire a large spectrum with a high spectral resolution in a single shot. To decrease the size of an Echelle spectrometer substantially, a cross grating was employed combining both required dispersive functionalities. First, an Echelle grating diffracts light in several higher diffraction orders, while a superposed, perpendicularly oriented cross-disperser is used in first diffraction order. In this contribution, we report on the realization of a cross-grating spectrometer employing a folded reflective beam path. A toric-convex mirror was introduced allowing aberration compensation. We present the basic concept and optical design of the system and discuss the mechanical implementation and the adjustment process. Here, different laser sources and gas emission lamps are used to realize the system and derive the optical performance. In particular, the spectral resolution in the different diffraction orders is determined for the realized device. [ABSTRACT FROM AUTHOR]

Assessing the stage and progression of enamel demineralization non-invasively is of high interest in conservative dentistry. By examining tooth samples with suspected occlusal lesions, we show the potential of depolarization imaging based on polarization-sensitive optical coherence tomography for the assessment of carious lesions and validate the results by co-registered X-ray micro-computed tomography volumes. [ABSTRACT FROM AUTHOR]

Acousto-mechanical properties of the human tympanic membrane mainly depend on the connective tissue in its layered structure. Using polarization-sensitive optical coherence tomography, a depth-resolved imaging technique which provides additional tissue specific contrast, polarization changes of the birefringent layers in the human tympanic membrane were detected. By depicting estimated local retardances, distinguishing different tissue types was possible. This suggests the ability to image pathological alterations of the connective tissue with PSOCT, which extends the conventional diagnostic methods in middle ear surgery. [ABSTRACT FROM AUTHOR]

In recent years, great advances have been made in developing minimal footprint micro-endoscopes using multimode optical fibres (MMF) [1]. By employing wavefront shaping methods the seemingly random speckle pattern resulting from the guiding of coherent light through an MMF can be formed into a diffraction limited spot. This enables the implementation of multiple laser scanning techniques. In this work we show that this approach can be employed to realize label-free non-linear microscopy techniques such as coherent anti-Stokes Raman scattering (CARS) and second harmonic generation (SHG). Backscattered light makes epi-detection possible even though these processes preferably emit light in the direction of beam propagation [2]. [ABSTRACT FROM AUTHOR]

A VIPA based Brillouin spectrometer consisting of commercially available components has been combined with a standard Raman spectrometer and a confocal microscope allowing simultaneous and co-localized measurements of biological samples and tissues. [ABSTRACT FROM AUTHOR]

In the digital age it has become a fundamental issue to monitor and control process parameters continuously and automatically. The monitoring of critical process parameters enables better quality at lower production costs and higher yields. In order to investigate the interactions between production quality and polishing parameters, we have developed a solution for automatic and reliable measurement of critical parameters. With this paper we first document the resolution and accuracy of the system compared to manual measuring methods currently in use. [ABSTRACT FROM AUTHOR]

We present a light sheet fluorescence microscope dedicated to image "Organ-on-chip"-like biostructures in microfluidic chip. Based on a simple design, the setup is built around the chip and its environment to allow 3D imaging inside the chip in a microfluidic laboratory. The experimental setup, its optical characterization and first volumetric images are reported. [ABSTRACT FROM AUTHOR]

Crystalline lenses of mice were imaged in vivo with a custom-made swept-source optical coherence tomography system. The use of the attenuation coefficient as a quantitative parameter for investigating the lens opacities magnitude is proposed, demonstrating a significant difference between the values retrieved from cataractous and normal mouse lenses. [ABSTRACT FROM AUTHOR]

Polarization sensitive optical coherence tomography (PS-OCT) has been used to visualize the orientation of the nerves in the retinal nerve fiber layer (RNFL) and to visualize the orientation of the collagen fibers in peripapillary sclera in retinas of healthy volunteers. Optic axis orientation images clearly visualize the nerve fibers leaving the optic nerve head (ONH) in all radial directions. Sclera orientation images show that the sclera consist of two layers, an inner layer with an orientation parallel to the RNFL orientation, and a deeper layer where the collagen is circularly oriented. [ABSTRACT FROM AUTHOR]

We demonstrate the use of a motorized distal scanning endoscope to acquire in vivo data in lungs of severe-asthma patients before and after an asthma treatment procedure called bronchial thermoplasty. Conventional optical coherence tomography (OCT) intensity images and polarisation sensitive OCT images were extracted from the acquired data. PS-OCT endoscopy allowing the visualization and segmentation of airway smooth muscle layer - which plays a key role in bronchoconstriction during asthma attacks - showed its potential as means to evaluate the effectiveness of bronchial thermoplasty. [ABSTRACT FROM AUTHOR]

Surface Enhanced Raman Spectroscopy (SERS) allows sensitive and selective detection of protease activity by monitoring the cleavage of specific peptide substrates. Furthermore, it offers the possibility for multiplexing, during which the activity of two (or more) proteases with different specificities is detected simultaneously. To distinguish between the contributions of different proteases, different aromatic amino acids with non-overlapping SERS peaks need to be used as Raman reporters. As the three natural aromatic amino acids only offer limited possibilities for multiplexing, we examined several non-natural aromatic amino acids with the aim of expanding multiplexing possibilities. We recorded their SERS spectra for the Raman shifts of 300-1700 cm–1 and identified their characteristic SERS peaks. Of the examined nonnatural aromatic amino acids, 3-nitro-tyrosine and two phenylalanines containing stable heavy isotopes seem particularly promising for multiplexing applications. Besides exhibiting characteristic SERS peaks in the spectral region of interest, these non-natural aromatics provide strong SERS peaks compared to natural aromatic amino acids, consequently improving detection sensitivity. [ABSTRACT FROM AUTHOR]

Polishing is according to the current state of the art, one of the key processes in precision optics. Many specialists deal with the most diverse applications of these technologies and develop stable, reproducible techniques. In this article we present results for the investigation of different effects in the initial polishing phase in combination with different materials. [ABSTRACT FROM AUTHOR]

Manufacturing of optical coatings is about the precise deposition of material and its control on the nanometer scale. This has to be achieved for a stack of multiple layers with a total thickness that can reach several micrometer. In addition, this has to be maintained for the complete functional area. In this contribution we demonstrate a process capable of delivering these accuracies not only to flat but also to curved surfaces. [ABSTRACT FROM AUTHOR]

Conventional production methods for high precision lens alignment typically rely on lens rotation. In the case of rotationally non-symmetric optics and mounts, this is problematic. Here, we report a new concept for alignment bonding without lens rotation, based on a high precision linear bearing as position reference and a hexapod actuator for lens manipulation. For the optical axis of two test lenses after bonding, <1 arcmin element tilt and <10 μm decentre was achieved. This is confirmed by an independent measurement. Our alignment device and process can be applied for any lens and mount geometry. This will be especially useful for high-end products with small size and for rotationally non-symmetric systems. [ABSTRACT FROM AUTHOR]

Ultra-fine grinding is a technology, which can be used to process inorganic non-metallic materials. High quality surfaces with a low roughness, and high flatness are achievable in a low processing time. The experimental setup which is described shall compare face grinding with lateral grinding in a single processing step using various materials, bonds and processing parameters. The results are supposed to deepen the knowledge about this grinding technology to further improve the properties of fabricated components. [ABSTRACT FROM AUTHOR]

The material fused silica, as well as other brittle-hard materials such as glass ceramics, have great potential for use in a wide range of applications due to their special material properties. The technical advantages of these materials require sophisticated processing technologies, including polishing steps, in order to be able to use these interesting materials advantageously. In addition, a current trend in modern optical manufacturing is the use of free-form surfaces and monolithic components that combine several optical and mechanical functions in one part. Novel or improved processes are needed in order to meet future requirements for resource-saving and effective production methods at the same time. [ABSTRACT FROM AUTHOR]

Simultaneous spatio-temporal focusing of few-cycle pulses is usually performed by stretcher-compressor configurations causing pulse-front tilt. By shaping and superimposing two reciprocal sub-beams, opposite tilts can compensate each other. Pulse propagation for asymmetric and symmetric focusing of near infrared 5-fs-pulses is studied by numerical simulations and proof-of-principle experiments. [ABSTRACT FROM AUTHOR]

Our goal is to evaluate the efficiency of a specialist in the field of optical design. The classification of specialists is given depending on their level of education and work experience in the field of optical design. The analysis of factors that determine the efficiency of the specialist is performed, on the basis of which the equation for calculating efficiency is derived. As an example, we present empirical data for calculating the efficiency of some specialists. [ABSTRACT FROM AUTHOR]

An investigation of extended depth-of-field camera with optimized phase mask and digital restoration is presented. The goal of this paper is to implement the wavefront coding technique without affecting much of the original design, and the design has taken the complexity of imaging system into consideration. The optimized strength of cubic phase mask (CPM) is based on the analytical optimal solution for the task-based imaging system [J. Opt. Soc. Am. A 25, 1064 (2008)]. The noisy intermediate images of CPM system with highest spatial frequency of interest can be effectively restored by vector-based Richardson-Lucy algorithm. Restoration from the system with generalized CPM produces precise image position than the system with CPM does. In general, the CPM system procures modulation transfer function higher than 0.195 in the whole depth-of-field, and the mean squared error of the restored images are less than 5 %. [ABSTRACT FROM AUTHOR]

Many optical applications require splitting or deflection of light beams. This usually is achieved by usage of standard plane optical elements such as mirror systems or prismatic elements. However, these components are usually limited to one certain function and the manufacturing process for achieving precise functionality is very demanding. The presented research topic shows the development of new optical multifunctional components that introduce certain advantages compared to existing plane optical components. The basic roof-element configuration is based on glass cuboids joined together under a certain angle that can be fine adjusted during the manufacturing process. The components are therefore rather simply built and robust, and can fulfil different optical functions simultaneously by modifications of the glass cuboids. A process chain was developed for efficient and flexible manufacturing of such plane optical elements. Technical investigations were made on novel manufacturing processes such as ultrasonic assisted grinding and ultrafine grinding for fabrication of the cuboid parts, as well as diffusion joining being one possibility to create the basic roof-element shape. [ABSTRACT FROM AUTHOR]

Multimode fibres (MMF) used in endoscopy have advantage of small diameter and flexibility, thus causing less damage to living animals. However, the imaging requires wavefront shaping techniques to obtain a sharp image despite the mode dispersion in the waveguide. We suggest version of transmission matrix calibration which uses internal modes of the waveguide and, thus, lessens requirements on the endoscopy apparatus removing the external reference path. [ABSTRACT FROM AUTHOR]

In previous publications the inhomogeneous pressure transfer through the polishing tool onto a glass surface could be shown. This experiment shows polishing trials with different polishing materials and the differences in the homogeneity of the pressure transfer through them. Only the properties of the material will be discussed explicitly, the change of the tool constitution through the process will be part of further publications. [ABSTRACT FROM AUTHOR]