This PDF file contains the front matter associated with SPIE Proceedings Volume 12274 including the Title Page, Copyright information, Table of Contents, and Conference Committee Page.

Long range 3D imaging is a key technology for future target acquisition and ID. Dstl have demonstrated high resolution 3D image acquisition of representative vehicle targets at a range of 1.4 km in daylight, using currently available visible band technology. With modern GPS timing capabilities, it should also be possible to separate laser and camera by some considerable distance, enabling long baseline bistatic lidar or distributed sensing to be achieved. Preliminary results from an exploration of this concept will also be shown.

Time-correlated single-photon counting (TCSPC) has been established as the preferred choice of detection for high resolution depth profiling due to its excellent surface to surface resolution and high optical sensitivity. This presentation will describe an underwater transceiver system based on a planar CMOS silicon single photon avalanche diode (Si-SPAD) detector array, and interfaced with a graphics processing unit (GPU) for real time processing capabilities with video rates up to 25 Hz. Depth and intensity profiles of stationary and moving targets were acquired with the transceiver fully submerged in scattering water, equivalent up to 7.5 attenuation lengths.

Sub-pixel micro-scanning is a relatively simple way of utilizing a low pixel count sensor to better realise the resolution capabilities of a given objective lens. This technique accomplishes this by shifting the sensor array in the image plane through distances less than the pixel dimensions, gathering multiple images from different viewpoints that can be combined into a single, more detailed image. Applying this technique to a single-photon counting light detection and ranging (LiDAR) system allows for improved depth and intensity image reconstruction. Time-correlated single-photon counting (TCSPC) allowed for time-of-flight data to be measured, and the high-sensitivity and picosecond timing resolution this provided enabled us to create high-resolution intensity images and depth maps from distant targets whilst maintaining low average optical output power levels. The LiDAR system operated at a wavelength of 1550 nm, and used a pulsed fiber laser source for flood-illumination of the target scene. The detector was a 32 × 32 InGaAs/InP single-photon avalanche diode detector array mounted on precision translation stages. Operating in the short-wave infrared meant that the system could work at long range in daylight conditions, as the effect of solar background is reduced compared to shorter wavelengths and atmospheric transmission was relatively high. This paper presents depth and intensity profiles taken at a target range of approximately 325 m from the system location. The transceiver system operated at eye-safe, low average optical output power levels, typically below 5 mW.

The recent development of single-photon avalanche diode (SPADs) arrays as imaging sensors with both picosecond binning capabilities and single photon sensitivity has led to the rapid development of time-of-flight imaging systems however, simulations of SPAD systems outside of the Poisson regime remain rare. Here we present a model for SPAD systems which combines single photon counting statistics with computational parallelization which together enable the efficient generation of photo-realistic SPAD data. We confirm the accuracy of out model by experimental verification. Further, we apply this simulator to the problem of drone identification, orientation, and, segmentation. The proliferation of semi-autonomous aerial multi-copters i.e. drones, has raised concerns over the ability of existing aerial detection systems to accurately characterize such vehicles. Here, we fuse the 3D imaging of SPAD sensors with the classification capabilities of a bespoke convolutional neural network (CNN) into a system capable of determining drone pose in flight. To overcome the lack of publicly available training data we generate a photo-realistic dataset to enable the training of our network. After training, we are able to predict the roll, pitch, and yaw of the several different drone types with an accuracy greater than 90%.

Fog is a difficult medium to image through using Single-Photon Avalanche Diode (SPAD) based Light Detection and Ranging (LiDAR) systems because of its light scattering properties. Scattering significantly decreases the signal-to-noise ratio of photon returns, making it difficult to reconstruct meaningful images for target detection. In this paper, an image feature-based approach for reconstructing SPAD LiDAR images of a single target is proposed. Geometric characteristics of the target are used in the algorithm to differentiate between target and background photon returns. Combinations of different features such as Fourier shape descriptors and apparent target size are used to improve performance. To validate the algorithm, a 32×32 silicon SPAD array Flash LiDAR system operating at 532nm is used for collecting images through fog. Simple geometric shapes are placed indoors in a dark tunnel 44.6m from the sensor with fog decreasing the visibility in steps down to 12m. The proof-of-concept algorithm achieves good localization performance at a fog level of 1.4 attenuation lengths.

Classical electro-optical (EO) sensing focuses on detecting light intensity and displaying it in grayscale images. Therefore, the development of EO systems was mainly concerned with the trade-off between resolution, signal-to- noise ratio, and image or data rate. In recent years, the development of silicon based single photon-counting avalanche diode (SPAD) detectors has initiated an almost unnoticed revolutionary development and paradigm shift in sensor technology. In contrast to intensity imaging, SPAD sensors are capable to sense a single photon event as a binary and noise free intensity. Furthermore, the occurrence of these photon events can be determined very precisely in time, allowing access to the sub-nanosecond or even picosecond time scale and application in precise distance measurement. Combined with computational imaging, i.e. linking the acquisition process to a strong mathematical model, it is possible to obtain information that was previously inaccessible and extend the perceptual range of EO sensors. In this paper, we provide an overview of various active and passive SPAD imaging techniques that are coupled with laser illumination or use ambient light. We focus on applications with relevance to military use. In detail, we summarize results in the areas of passive imaging, range finding and vision through scattering media, and advanced acquisition methods such as non-line-of-sight imaging.

Accurate object tracking or target identification are key requirements in the automotive, consumer, and defence industries. These tasks require hardware to provide good quality images and accurate analysis routines to interpret the data. Here we will report on the use of next-generation single-photon avalanche detector (SPAD) array sensors combined with neural networks for high-speed three-dimensional imaging and object tracking. Such detectors enable three-dimensional imaging at high speeds and low light levels, and they can operate in a wide range of conditions and at large standoff distances. We will discuss the use of such detectors for tracking and monitoring airborne objects, such as drones. We will also discuss our recent work on human pose estimation, achieved from a low-cost SPAD time-of-flight sensor with only 4x4 pixels. Here we use neural networks to first increase the resolution of the data and then reconstruct the skeletal form of multiple humans in three dimensions. It is clear that the next generation of technology for object tracking and identification will use a combination of advanced imaging hardware and data fusion approaches. We will discuss our group's recent research in this area.

The recent development of single-photon avalanche diode (SPAD) based sensors has completely revolutionized the field of advanced imaging and contributed to the rapid increase of "computational imaging". In this paper, we show that it is possible to visualize the transient propagation wave when a laser pulse is entering into a cavity (e.g. an integrating sphere) though an opening, a skylight or any hole. The photon time-signature at the opening of the cavity depends on the volume or diameter of the cavity and on its spectral reflectance. By using ultra-short laser pulses, we demonstrated that the temporal observation of the reflected waves at such cavities can give a very fast information on the cavity volume and would allow to make a first evaluation before a more detailed analysis, for example with the NLOS technique. Our method of rapid cavity perimeter determination could be used in cavity assessment for disaster and damage scenarios and assistance for first responders, as well as for cavity exploration during geological/archaeological excavations or extraterrestrial missions to the Moon or Mars.

Avalanche photodiodes (APDs) capable of operating at telecommunication wavelengths usually utilize an InGaAs absorber and a multiplication region of InP or InAlAs. Since the electron and hole ionization coefficients (α and β respectively) in these multiplication regions are very similar they suffer from high excess noise, limiting their sensitivity. In recent years, there have been a number of reports of Sb containing III-V semiconductor alloys that appear to show very low excess noise characteristics, similar to or better than that obtained in silicon. These reports show that AlInAsSb grown on GaSb appears to show a β/α ratio of ~0.015. Both AlAsSb and Al_0.85Ga_0.15As_0.56Sb_0.44 grown lattice matched on InP also show β/α values that vary from 0.005-0.01. The exception to this appears to be AlGaAsSb grown lattice matched on GaSb where a β/α ratio of ~2.5 has been seen. This paper reviews the published results in this area.

Semiconductor based single-photon avalanche diode (SPAD) detectors are widely used in quantum technology applications, which focus on the arrival time of single photons. Using germanium as the absorption region in a Separate Absorption and Multiplication design solves the operating limitation beyond the spectrum range of silicon, i.e. typically at a wavelength of ~ 1000 nm. Our first-generation planar geometry Ge-on-Si single-photon avalanche diodes utilised a 1000 nm Germanium absorption region and showed extremely low noise-equivalent-power of 7.7 × 10−17 WHz−½ at a wavelength of 1310 nm. We demonstrate new structures designed to achieve high single-photon detection efficiency at a wavelength of 1550 nm.

Single Photon Avalanche Diodes (SPADs) are the enabling device for different kind of applications in which low noise, high photon detection efficiency, and compactness are required. They are capable of providing high photon count rate and picosecond timing precision. Furthermore, they can be fabricated in arrays, unlocking very high-count rates and the possibility to retrieve also incident photon’s spatial information. For these reasons, SPADs are the sensors of choice in many applications such as Light detection and ranging (LiDAR), Time Correlated Single Photon counting (TCSPC) and quantum key distribution (QKD). Whether the SPAD is implemented in a custom technology, allowing detector tailoring on specific application constraints, or in a CMOS process, with great benefits in terms of large-scale integration and compactness, a quenching circuit is always required, and it sets the ultimate performance that can be extracted from this sensor. The custom approach for SPAD fabrication poses a challenge in the design of the external quenching circuit mainly due to the parasitics (capacitance, wire-bonding inductance, etc.) that intrinsically come with having the detector and the circuit on two separate silicon dies, which is potentially a limiting factor for speed and timing precision. In this work, we present a fully-integrated active quenching circuit capable of driving external custom SPADs up to 250 Mcps. The circuit has been fabricated exploiting a 150nm high voltage technology and extensively tested with a custom SPAD.

Time-Correlated Single Photon Counting (TCSPC) represents a fundamental tool for the investigation of biological light signals. Unfortunately, due to pile-up distortion the photon acquisition rate must be kept below few percents of the laser rate, thus increasing the acquisition time. Recently, we proposed a single-channel TCSPC system allowing us to overcome pile-up by matching the detector dead time to the laser period. In this work, we perform on-field fluorescence measurements with this system showing that an acquisition speed of 32 Mcps can be reached without significant distortion. Thanks to the promising results, we are now developing a multi-channel module based on the same acquisition technique.

In this work, we present the configurable Fast-Time-to-Amplitude Converter (FTAC), a versatile and completely integrated multichannel timing device constituted by 8 high-performance Time-to-Amplitude Converters (TACs) and a smart front-end logic. The designed converter can not only provide state-of-the-art performance in terms of conversion frequency (up to 100Mcps) and timing precision (down to 1.1ps rms, i.e. 2.6 ps Full Width at Half Maximum), but also a unique flexibility to the end user, who can select the most suitable configuration for its specific requirements. Above all, this chip gives the possibility of using the 8 channels separately, as a building block of a multichannel system, or combining the internal converters to reach picosecond precision, that could open the way to on-field exploitation of Super Conducting Nanowire Single Photon Detectors (SNSPDs). The chip provides 11 different configurations among which select the best option in terms of a combination of parallel channels, speed and timing precision.

High performance imaging sensors are a fundamental requirement for many defense and security applications. The usually high cost of such sensors, however, prevents their broad deployment. Modern Computational Imaging approaches like Compressed Sensing (CS) promise cost efficient sensor architectures that might enable a wider usage of some sensor technologies. However, the technological potential for military applications still has to be verified. In order to test the capabilities of a CS-system for threat detection, a software framework for automated testing was implemented. The code contains different methods for scene modulation and image reconstruction. In our previous work, we studied the classic iterative optimization methods for image reconstruction with promising, but not completely satisfactory results. Therefore, we implemented another method. This CS video method is the ‘Fourier domain regularized inversion’ (FDRI) which promises real time single pixel video imaging. In the study presented here, we compare the rather new method with the already implemented optimization approaches regarding runtime, conventional image quality metrics and suitability for threat detection applications in different spectral bands.

We exploit micro-nano structuration to achieve multifunctional windows offering outstanding optical and fluidic properties to enhance the operation of surveillance or detection devices under rainy conditions. These windows are based on synthesis of an artificial index gradient for antireflection properties and improvement of their water repellency property thanks to their structuration at a subwavelength scale with controlled conical geometries. We demonstrate the realization of multifunctional germanium windows for LWIR camera, using two approaches: nanoimprint lithography, well-known for its very high resolution enabling applications from visible to thermal infrared domain, followed by etching techniques, and 3D direct laser writing based on Two-Photon Polymerization (TPP), which is of interest thanks to its ability to manufacture complex 3D structuration directly. Optical characterization shows the ability of such windows to improve optical transmission within 8-14μm spectral range, as compared to non-structured window. In terms of water repellency, the structured windows enable an increase of the contact angle up to 160° with a very low hysteresis. To evaluate the advantage of the multifunctional windows for imaging devices, the windows are integrated in front of a thermal infrared camera and images analysis shows that the camera sensitivity is increased for the nanoimprint window thanks to the multifunctional window and high water repellency in presence of water.

Compared to frame-based visual streams, event-driven visual streams offer very low bandwidth needs and high temporal resolution, making them an interesting choice for embedded object recognition. Such visual systems are seen to overcome standard cameras performances but have not yet been studied in the frame of Homing Guidance for projectiles, with drastic navigation constraints. This work starts from a first interaction model between a standard camera and an event camera, validated in the context of unattended ground sensors and situational awareness applications from a static position. In this paper we propose to extend this first interaction model by bringing a higher-level activity analysis and object recognition from a moving position. The proposed event-based terminal guidance system is studied firstly through a target laser designation scenario and the optical flow computation to validate guidance parameters. Real-time embedded processing techniques are evaluated, preparing the design of a future demonstrator of a very fast navigation system. The first results have been obtained using embedded Linux architectures with multi-threaded features extractions. This paper shows and comments these first results.

This paper introduces the field of metamaterials, details various optical uses of metasurfaces and demonstrates their suitability for imaging with single-photon avalanche diode (SPAD) detector arrays as an integrated optical component. A design for a metasurface-based color filter array (CFA) is presented, the fabrication methodology detailed, and a sample is integrated with a SPAD array. Examples of imaging applications using the integrated assembly are demonstrated, including passive and fluorescence imaging microscopy. The limitations of current metasurface color filtering techniques are highlighted and directions for future advances and applications discussed.

Finite-difference time-domain simulations have been made of a security screening polarimetric radar over the band 18 GHz to 26 GHz, comparing the results with a proof-of-concept system operating over the same band. The proof-of-concept radar is presented together with its calibration and measurement set-up. Measurements indicate the cross-polarisation returns from a human subject are approximately 10 % to 25 % of the co-polarisation returns. A simulation model has been built using the openEMS software to simulate the body of a human, using realistic primitive shapes and electrical properties appropriate for these frequencies, indicating cross-polar returns are in the region of 15 % of the co-polar responses, with the duration of the reflections lasting around 2 ns. The comparisons between the measurements and simulations are good and provide a qualitative understanding of what happens when security screening radar radiation impinges on the human body. The simulation is extended to two simple enclosures, a cubic box and a short cylinder having dimensions of 300 mm and wall thicknesses of 5 mm, which could be made of wood, cardboard, paper or plastic. Results indicate the cross-polar reflection ranges from 3% to 75 % of the co-polar and bursts of reflections are commensurate with reflections from the front and back surfaces, these being separated in time by 2 ns.

The next generation of sUAS (small Unmanned Aircraft Systems) for automated navigation will have to perform in challenging conditions, bad weather, high and low temperature and from dusk-to-dawn. The paper presents experimental results from a new wide-angle vision camera module specially optimized for low-light. We present the optical characteristics of this system as well as experimental results obtained for different sense and avoid functionalities. We also show preliminary results using our camera module images on neural networks for different scene understanding tasks.

We present work on versatile, compact optical components for waveguided atom interferometry with rotation sensing in mind. These diffractive optical elements: static Fresnel zone plates (FZPs), paired with a dynamic spatial light modulator, expand on the previous design and construction in our group of FZPs for smooth, red-detuned optical waveguides, allowing a wider range of functionality such as dark trapping with blue-detuned light and the generation of multiple, distinct waveguides from single FZPs. Our experiment utilises Bose-Einstein condensates of Rb-87 for interferometry, currently in a free-space configuration, by introducing such waveguides we can reduce the scale of this apparatus while increasing sensitivity to rotation.

We describe simple quantum lidar and show it provides the best, most rapid identification of high reflectivity nearby targets. For lower reflectivities or more distant targets quantum lidar is impractical so we describe a protocol that mimics the relevant feature of quantum lidar via random intensity modulation of a classical beam. This provides a degree of covertness together with many of the other useful properties of a quantum lidar without the complication of producing quantum states and crucially, without the limit on mean photon number. Hence it is useful for identifying much lower reflectivity targets than is practical with quantum states.

Quantum technologies containing key GaN laser components will enable a new generation of precision sensors, optical atomic clocks and secure communication systems for many applications such as next generation navigation, gravity mapping and timing since the AlGaInN material system allows for laser diodes to be fabricated over a wide range of wavelengths from the U.V. to the visible. We report our latest results on a range of AlGaInN diode-lasers targeted to meet the linewidth, wavelength and power requirements suitable for quantum sensors such as optical clocks and cold-atom interferometry systems. This includes the [5s²S_1/2-5p²P_1/2] cooling transition in strontium+ ion optical clocks at 422 nm, the [5s₂¹S₀-5p¹P¹] cooling transition in neutral strontium clocks at 461 nm and the [5s²s_1/2 – 6p²P_3/2] transition in rubidium at 420 nm. Several approaches are taken to achieve the required linewidth, wavelength and power, including an extended cavity laser diode (ECLD) system and an on-chip grating, distributed feedback (DFB) GaN laser diode.

We give an overview of our research programme on the use of atomic magnetometers to detect and image concealed conductive objects via electromagnetic induction. The extreme sensitivity of atomic magnetometers at low frequency, several orders of magnitude higher than a coil-based system of similar size, allows for their operation in such a frequency range, thus permitting deep penetration through different barriers. This overcomes the limitations usually associated with electromagnetic detection. Applications in security and surveillance are discussed.

We present the polarization effect on surface plasmonic polariton (SPP) modes in plasmonic waveguides under high-intensity radiation via the Floquet engineering methods. First, we analyze the strong light coupling to the metallic system using a nonperturbative procedure. Then, we describe the behavior of dressed metal fermion system using the Floquet state solutions. Furthermore, we examine the impurity scattering effects on electron transport in disordered plasmonic metals using the generalized Floquet-Fermi golden rule. We also show that we can reduce the SPP propagation losses in plasmonic metals by applying a dressing field. We introduce a new figure of merit to compare the performance of popular plasmonic metals, assessing their performance enhancements under two different polarization types of dressing fields. Our study can be applied to accurately interpret the usage of strong external radiation as a tool in quantum plasmonic circuits and devices.

Encoding of key bits in the quadratures of the electromagnetic light field is an essential part of any continuousvariable quantum key distribution system. However, flaws of practical implementation can make such systems susceptible to leakage of secret information. We verify a side channel presence in an optical in-phase and quadrature modulator which is caused by limited suppression of a quantum information-carrying sideband. We investigate various strategies an unauthorized third party can exploit the vulnerability in a proof-of-concept experiment and theoretically assess the modulation leakage effect on a security of the Gaussian coherent-state continuous-variable quantum key distribution protocol and show that the leakage reduces the range of conditions which support secure key generation. Without the control of sideband modulation in practical in-phase and quadrature modulator-based systems the security can be compromised.

Continuous Variables Quantum Key Distribution (CV-QKD) tackles the problem of the generation and distribution of cryptographic keys without assuming any computational limitations while employing standard telecom equipment. Gaussian Modulation (GM) theoretically maximizes the information a CV-QKD system is capable of transmitting while exhibiting a higher resistance to excess channel noise. However, GM-CV-QKD protocols put an extreme burden on the transmitter’s random number source and tend to be more susceptible to imperfect state preparation. Due to these difficulties, most experimental implementations of CV-QKD have used Discrete Modulation (DM). The closer the DM constellation approaches a GM one, the closer the theoretical performance of the associated system will be to the optimum value. To achieve this, high-cardinality constellations, coupled with probabilistic shaping, can be explored. However, choosing a too complex constellation will cause the modulation stage imperfections to again become apparent. Thus, the choice of the constellation format is not direct and is of high importance. In this work we present a methodology to determine the optimum constellation for a given DM-CV-QKD system, taking into account the limitations of the modulation stage, choosing from a variety of M-QAM and M-APSK constellations coupled with probabilistic shaping. Our obtained methodology will allow for the optimum modulation format for each specific system to be selected.

This paper presents the demonstrator of a fully polarimetric ultra-wideband (UWB) multistatic imaging system for screening of groups of walking people in public areas. The system is working in the FCC UWB frequency band from 3.6 GHz to 10.6 GHz. The low frequency range is chosen to reduce the influence and clutter of clothes to a minimum. This is important for the screening in public places because the scanner needs to identify threats even under thick and heavy jackets with a low false alarm rate. Furthermore, the effect of motion blurring in the reconstructed radar images is enormously reduced. To further improve the detection of threats a fully polarimetric radar frontend was chosen for the imaging system. Radar polarimetry is a well-established technique in remote sensing to characterize di erent scattering mechanisms like single and double bounce or volumetric scattering. This offers the opportunity to classify different terrain properties or manmade objects in remote sensing. The investigated antenna arrangement is a roof-like geometry which can be installed on ceilings or archways in public areas. This approach doesn't disturb the flow of walking persons and even could enable a hidden installation of the screening device. Furthermore, this arrangement reduces shadowing risks, i.e. that a terrorist hides himself between closely walking neighbors. The paper discusses the applied signal processing and the polarimetric evaluation. Results are demonstrated for static and dynamic scenarios.

With regards to composite materials, the need for noninvasive evaluation of their structures, components, or systems they form continues to rise. It relates to the fact that composites, due to their two-phased (at least) composition, are vulnerable to different damages arising during their manufacturing or their use. Thus, there is a need to non-destructively monitor such materials especially when they are used in safety applications such as e.g., bulletproof vests and their damage may pose a real threat. In the frame of this work, the use of the newly developed non-destructive testing (NDT) method based on the application of Terahertz (THz) radiation was presented. For this purpose, the series of samples without defects and with a defect in their interior was investigated. The samples were prepared as the soft insert of a bulletproof vest and one of them had intentionally introduced defect in the form of aramid fibers textile soaked in salty water. The results obtained using the THz imaging method were compared to the ones obtained using the conventional X-ray method. Overall, the potential of THz transmission measurements was demonstrated and a selected application using THz-based system was presented.

Improving the security screening requires good knowledge and understanding of human skin signatures. Our previous publications indicate that the signature of the human skin varies from person to person under a dry and wet state. Human skin is a very sensitive organ and not all material can be applied or attached directly to the skin. Therefore, it is an essential requirement to find a close surrogate i.e. (animal tissue) and characterise similarities in signature between human and animal skin. The importance of this is that it will allow us to investigate more easily signatures of the human skin under different materials and conditions. This paper investigates signatures for the human skin and ex-vivo porcine skin samples using the 90 GHz calibrated radiometer. The paper aims to compare and show similarities and differences in the signature between human and ex-vivo porcine skin samples for the first time using millimetric wave radiometry. To this end, water and different types of cream were applied to the palm of the hand and porcine skin samples namely: skin with water jel, skin with silver sulfadiazine cream, and skin with betadine cream. The reflectance of the skin was measured before and after the application, with and without the presence of a clothing layer. Reflectance measurements on human skin were applied on six participants in the palm of the hand region for comparison with reflectance measurements of porcine skin from six samples taken from the back region of different animals. Reflectance measurements for the palm of the hand skin show that the mean reflectance values for all six participants are: 0.458, 0.618, 0.578, 0.548, and 0.488 for normal skin, skin with water, skin with water jel, skin with silver sulfadiazine cream, and skin with betadine cream respectively. For porcine skin samples, the mean reflectance values for all six samples are: 0.438, 0.608, 0.598, 0.558, and 0.508 for normal skin, skin with water, skin with water jel, skin with silver sulfadiazine cream, and skin with betadine cream respectively. These measurements indicate the similarities between the palm of the human hand and the back region of swine. The measurements also show that the difference in the mean reflectance values between the palm of the hand region and porcine skin for all cases is ~0.02. After adding a clothing layer made of textiles on the palm of the hand skin and porcine skin samples; the reflectance measurements for the palm of the hand skin become 0.408, 0.545, 0.498, 0.488, and 0.458 for normal skin, skin with water, skin with water jel, skin with silver sulfadiazine cream, and skin with betadine cream respectively. For porcine skin samples the mean reflectance values are: 0.388, 0.518, 0.488,0.488, and 0.478 respectively. These measurements indicate that textiles are relatively transparent over the frequency band (80-100) GHz and the signature of the skin can be observed through clothing. The increased understanding of these measurements brings means research into the medical applications of millimetre wave imaging to assess wounds under dressings. More specifically, subjects bearing bandaged wounds could be screened more reliably using imagers. In addition to the security screening applications and anomalies detection.

Nanofibers based on polymers are widely used in different fields, including cosmetics, electronics, sensing, medicine, phtonics, energy and filtration. These materials have a 1D character and exhibit tailorable physico-chemical properties which enables their use in multifunctional devices. They are characterized by properties such as, high surface to volume ratio, large area coverage and low-cost manufacturing which makes their use already widespread in industry. Here I report on our research on nanofibers made by spinning technologies assisted by electric fields, which exhibits photonic functions and energy harvesting/sensing capabilities1. An additional exploited application relies on their use as photoprogrammable material, based on an epoxy-based negative photoresist. Intelligent, flexible, paper-based labels, capable to operate by visual contrast and indicate inappropriate time-temperature exposure of perishable food and drugs are demonstrated2. The research leading to these results has received funding from the European Research Council under the European Union’s Horizon 2020 Research and Innovation Programme (Grant Agreement no. 682157, “xPRINT”) and the Italian Minister of University and Research PRIN 2017PHRM8X and 20173L7W8K projects. References 1 L. Persano et al., Advanced Materials 2017, 29, 1701031, 10.1002/adma.201701031. 2 L. Romano et al. Nature Communications 2020, 11, 5991, https://doi.org/10.1038/s41467-020-19676-y.

This conference presentation was prepared for the Emerging Imaging and Sensing Technologies for Security and Defence VII conference at SPIE Security + Defence, 2022.

We report on nanoimprint and plasma etching technologies development for high-density sub-wavelength surface structuration at a scale from 1.5μm to 200nm or below, to get multifunctional windows (of size ~2”-3”) offering both outstanding optical and fluidic properties. Such windows are of interest for outdoor surveillance systems, which need to operate whatever the environmental conditions. We demonstrate the realization of multifunctional surfaces enabling antireflection and water repellency properties on different optical materials, i.e. glass/silica, silicon and germanium, for applications from visible to longwave infrared domains. Illustration of such multifunctional window advantages for imaging is provided thanks to its integration in front of a MWIR camera and image analysis in presence of water droplet.

Recently the authors proposed a new angle measurement technology based on the use of the two-dimensional scales. The rotation angle measurement is based on measuring the rotation of the pattern image on the sensor of a digital camera. The report presents the results of generalization of the developed earlier technology of angular measurements using a two-dimensional scale to measurements of linear displacements. It is shown that using a simple optical-digital system with a physical resolution, for example, of the order of several micrometers, it is possible to measure angles with an error of one thousandth of an arc second and linear displacements with an error of a fraction of a nanometer.

Brain modulation achieved with biophysical approaches has a huge potential in order to enhance, rescue and modulate cognitive functions. On this regards, the brain modulation approaches has been always focused on neurons. However, studies over the past four decades have lighten-up the attention of neuroscientist towards the role of astrocytes in brain functions at multiple spatio-temporal scales and raised questions on the limits of the classical Neurocentric vision of the brain function. Accordingly, the role of ions, water and structural dynamics of astrocytes is assuming relevance for brain communication processes, typically univocally assigned to neurons. A major obstacle in studying astrocytes is that most of the technologies used to probe and sense them are derived from those developed to study neurons. In this presentation, I will review the results from my laboratory for Glial Interfaces and Engineering obtained by highly collaborative, truly multidisciplinary, international EU and non-EU countries research effort enabled by the support of AFOSR-Biophysics Program, and more recently, leveraging funding from EU-MSCA. I will overview insight on mechanism underpinning the ability of astrocytes to sense, transduce and respond to chemo-physical stimuli and to communicate with neurons, achieved by pioneered use of materials interface, technologies and approaches ad hoc tailored to stimulate, monitor and modulate the structure and function of astrocytes.

We report on a series of novel experimental results based on new electrically conductive nanoparticle-electrically insulating, guest-host, electromagnetic interference shielding (EMIS) composites. An EMIS effectiveness in excess of -10dB was achieved over a frequency range of 8 to 12 GHz. Film thicknesses were ~150 μm. Material processing, thin film fabrication and EMIS effectiveness are presented.

This conference presentation was prepared for the Emerging Imaging and Sensing Technologies for Security and Defence VII conference at SPIE Security + Defence, 2022.

Tunability is an important aspect of lasers. Nowadays there are many possible ways to achieve this advantageous property; however, dynamic tuning is limited. Red to InfraRed emissive dyes allow a direct visualization of molecular interactions, through deep tissue penetration, along with minimal tissue damage. In our studies we use simple systems based on a single dye-doped polymeric thin films for distributed feedback (DFB) and random lasing (RL) investigations. As active compounds we have applyed novel push-pull luminescent diphenylaminofluorene and tiophene derivatives, with different acceptor groups. Integration of such luminescent dyes with transparent polymeric medium allows fabricating real-time lasing tunability in the visible region and first biological window (650-950 nm). The observed spectral tuning of 150 nm is a groundbreaking value obtained in a single-dye system. Also Excited-State Intramolecular Proton Transfer (ESIPT) compounds, have attracted our considerable attention, due to their unique optical properties. In this contribution we show a novel bis-trimethylsilyl substituted 2-(2’hydroxyphenyl)benzothiazole (HBT) derivatives functionalized with a trifluoromethyl - a strong electron-withdrawing group. Such structure enabled real-time red-green-blue (RGB) switching of emission, both in solution and solid-state, providing white laser light emission. We show strong dependence on environment polarity, as well as Aggregation-Induced Emission Enhancement (AIEE) properties, and successful implementation of ESIPT molecules in DFB lasing, both in solution and solid-state.

A new type of optical resonator gyroscopes based on systems with parity-time-symmetry properties is considered. A system with parity-time-symmetry properties is composed of two direct coupled waveguides, one of which is characterized by losses, and the second one – by amplification, and a passive ring resonator connected to them. The influence of the characteristics of the parity-time-symmetry system on the optical resonator gyroscope parameters is investigated. Attention is paid to the influence of the gain, losses and coupling coefficients of the waveguides that make up the system with the parity-time-symmetry properties. The influence of the gain coefficient instability caused by a change in the pumping power on the angular velocity measurement results is also considered. The advantages and disadvantages of this approach are compared with a conventional optical resonator gyroscope. The main advantage of using systems with parity-timesymmetry properties is the increase of accuracy of registration of passive ring resonator eigenfrequencies by several orders of magnitude and, as a result, the maximum sensitivity to angular velocity.

A sample of a ring confocal resonator designed to operate as a sensitive element of an optical resonator gyroscope is studied. The sample has a monoblock design - the resonator is a single block (prism) with reflective surfaces operating on the effect of total internal reflection. The optical contour of the resonator has the shape of a square with a side length of 10 mm and is formed by four reflective surfaces. Three reflecting surfaces are flat, and one is toroidal with curvature radii in the meridional and sagittal planes that satisfy the confocality condition. The resonator is designed to operate at wavelengths of about 1.55 μm. The advantages of using a of a ring confocal resonator as a sensitive element of an optical resonator gyroscope are analyzed. In particular, it is shown that the reduction of the angular velocity measurement error caused by the optical Kerr effect becomes possible (compared to the use of a waveguide cavity and a whispering gallery mode cavity). The resistance of the system to external influences also improves.

The geometric parameters of sharpening the rake surface are very important for the efficient use of the drill. Therefore, it is important to know the correct sharpening angle of the drill in the radial direction. This is especially important at the stage of regrinding the drill, due to the incorrect installation of the drill into the fixture. In this paper, a new image processing algorithm is proposed that allows you to set indicators and factors that determine the correct choice of the angular position of the drill after regrinding. This algorithm can be of great industrial use due to the simplicity of implementation and minimization of the necessary equipment for setting up the measuring station. The presented model has an important application value and differs from the existing ones in that it can be applied for regrinding of drills with curvilinear cutting edges. This advantage is achieved by using a simpler construction of the drill’s flank surfaces. The proposed design ensures a rational distribution of the clearance angle value along the cutting part regardless of the original shape of the flank surface before the regrinding. Taking into account the limitations of the image processing algorithm and the theoretical model of the cutting part of a tri-flute drill, a rational ratio of the rake and clearance angles obtained by simulating the edge movement in cutting process. This approach allows a radical revision of the traditional recommendations for regrinding process of tri-flute drills. This is becomes possible to solve problems associated with regrinding drills with involute and multi-level flat flank surface. However, the validity of our work still needs to be carefully checked.

Modern methods of control geometry parameters of cutting tools often incorporate measuring operations performed using high-precision CCD cameras which work on the contrast-detection method. The key advantages of this method are the high speed of measurements, the simplicity of using general method on modern CNC measuring systems and a wide range of possibilities for controlling profile locations of surfaces. However, using this method largely depends on the resolution of the camera's ability and the size of the controlled area, which in turn imposes significant restrictions on the measurement of surface areas which are less than 10% of the frame area. This paper proposes a new way to measure the area of profile section of microtool surfaces, based on the identifying of a focused area throughout the entire frame area. This method makes it possible to recognize the nature of the focus distribution at different camera positions, which in turn makes it possible to measure the area of profile section of microtool surfaces when the size of the controlled area is less than 10% of the frame size to use the contrast autofocus method to incomparably increase.

The article proposes a fusion technique and an algorithm for combining images recorded in the IR and visible spectrum in relation to the problem of processing products by robotic complexes in dust and fog. Primary data processing is based on the use of a multi-criteria processing criterion with complex data analysis and cross-change of the filtration coefficient for different types of data. The search for base points is based on the application of the technique of reducing the range of clusters (image simplification) and searching for transition boundaries using the approach of determining the slope of the function in local areas. As test data used to evaluate the effectiveness, pairs of test images obtained by sensors with a resolution of 1024x768 (8-bit, color image, visible range) and 1024x768 (8 bit, color, IR image) are used. Images of simple shapes are used as analyzed objects.

This article describes the fiber-optic Bragg grating sensor which is encapsulated by using 3D print and polylactic acid material. This FBG sensor is designed for heart rate monitoring of the human body. In this article, we describe the complete process consisting of creating, encapsulating, and experimental verification of the sensor. This sensor we compared with the conventional ECG monitoring system. Measurement was performed with a group of 5 volunteers in the laboratory conditions. The measured data were compared by the Bland-Altman method.

Wave Front Phase Imaging (WFPI) is a new wafer shape measurement technique that acquires millions of data points in just seconds or less, on a full 300mm silicon wafer. This provides lateral resolution well below 100μm with the possibility of reaching the lens’ optical resolution limitation between 3-4μm. The system has high repeatability with root-mean-square (RMS) standard deviation (σ_RMS) in the single digit nm for the global wafer shape geometry and for nanotopography it reaches in the sub ångström (Å = 10^-10 m) range. WFPI can collect data on the entire wafer to within a single pixel away from the wafer edge roll off¹. The flatness of the silicon wafers used to manufacture integrated circuits (IC) is controlled to tight tolerances to help ensure that the full wafer is sufficiently flat for lithographic processing. Advanced lithographic patterning processes require a detailed map of the wafer shape to avoid overlay errors caused by depth-of-focus issues². In this paper we go deep into the theoretical explanation as to how the wave front phase sensor works.