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Leuven, Belgium

Trita A.,Ghent University | Trita A.,Rockley Photonics Inc. | Voet E.,Ghent University | Vermeiren J.,Xenics Nv | And 4 more authors.
IEEE Photonics Journal | Year: 2015

A novel fiber Bragg grating (FBG) interrogator is demonstrated based on an optimized arrayed waveguide grating (AWG) filter. The AWG response is optimized to achieve large crosstalk between the output channels, which allows simultaneous detection of multiple FBG peaks, using centroid signal processing techniques, without constraints on the minimum FBG peak spectral width. The measured interrogator resolution is 2.5 pm, and the total measurement range is 50 nm. The device is fabricated in a silicon-on-insulator platform and has a footprint of only 2.2 x 1.5 mm. A novel approach to minimize the polarization dependence of the device is proposed and experimentally demonstrated. © 2009-2012 IEEE. Source


Verstockt S.,Ghent University | Verstockt S.,West-Flanders College | Van Hoecke S.,West-Flanders College | Beji T.,Ghent University | And 5 more authors.
Fire Safety Journal | Year: 2013

In this paper a novel multi-modal flame and smoke detector is proposed for the detection of fire in large open spaces such as car parks. The flame detector is based on the visual and amplitude image of a time-of-flight camera. Using this multi-modal information, flames can be detected very accurately by visual flame feature analysis and amplitude disorder detection. In order to detect the low-cost flame related features, moving objects in visual images are analyzed over time. If an object possesses high probability for each of the flame characteristics, it is labeled as candidate flame region. Simultaneously, the amplitude disorder is also investigated. Also labeled as candidate flame regions are regions with high accumulative amplitude differences and high values in all detail images of the amplitude image's discrete wavelet transform. Finally, when there is overlap of at least one of the visual and amplitude candidate flame regions, fire alarm is raised. The smoke detector, on the other hand, focuses on global changes in the depth images of the time-of-flight camera, which do not have significant impact on the amplitude images. It was found that this behavior is unique for smoke. Experiments show that the proposed detectors improve the accuracy of fire detection in car parks. The flame detector has an average flame detection rate of 93%, with hardly any false positive detection, and the smoke detection rate of the TOF based smoke detector is 88%. © 2012 Elsevier Ltd. Source


Trita A.,Ghent University | Vickers G.,Optocap | Mayordomo I.,Fraunhofer Institute for Integrated Circuits | Van Thourhout D.,Ghent University | Vermeiren J.,Xenics Nv
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2014

Fiber Bragg Grating or FBG sensors are gaining more and more interest in structural health monitoring of composite materials. Often, the weakest point in such a system is the ingress point of the fiber sensing chain into the composite material. For this reason we have developed a strongly miniaturized FBG interrogator unit with wireless power and data transmission, which can be incorporated in the composite structure. The interrogator is based on an arrayed waveguide grating (AWG) filter fabricated in a SOI technology, which is tailored in such a way to give large cross-talk between neighboring channels. The AWG signals are read by a linear 128 pixel InGaAs array flip-chipped on top of the Photonic Circuit (PIC). The spectrometer unit is completed with a ROIC mounted on the same substrate. The SLED and remaining electronics are integrated on a small and thin substrate and surrounded by the wireless antenna. The interrogator has an overall dimension of 100 mm diameter by max 7 mm height. The power dissipation of the electronics unit is limited to 1.5 W. The unit is capable of measuring strain values as low as 5 micro-strain. © 2014 SPIE. Source


Van Riel P.,Xenics Nv
Advanced Imaging | Year: 2010

Xenics, Leuven, Belgium has developed a new system, called Pumair for aerial surveillance and inspection. The new system is based on a modular and customizable combination of a long-wave thermal infrared (LWIR) camera with an optional thermography capability, along with a visible-spectrum camera. The two cameras are encased in a four-axis and gyro-stabilized gimbal that can be nose- or side-mounted on a helicopter or a small and slow-flying sports plane, depending on the given payload condition. Some of the key features of the new system include affordability, robust design, ease of operation, local maintainability, and simplicity. The Pumair provides a sensitive and uncooled microbolometer camera suited for long-range temperature measurements in the LWIR range or a cooled MWIR camera when thermal imaging is required. Source


Vereecken W.,Xenics Nv | Bogget U.V.,Xenics Nv | Colin T.,Xenics Nv | Vinella R.-M.,Xenics Nv | And 2 more authors.
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2013

Xenics has designed and manufactured a 1280*1024 pixel, 17 μm pitch InGaAs array for SWIR imaging in the [0.9 - 1.7 μm] range. It will report on the first characterization results of the device. As usual for this type of room temperature operated SWIR image sensors, the detector interface is based on a CTIA stage, yielding excellent linearity, a low detector bias and hence a low and stable dark current combined with low image lag. The charge to voltage conversion factor is 40 μV/e-. The pixel interface scheme contains a CDS circuit in order to reduce the kTC noise and common mode effects. The noise is expected to be below 30 erms in linear mode, resulting in a dynamic range > 60 dB. Additionally the linear dynamic range is complemented with a high dynamic range logarithmic response with a saturation level > 5 nA/pixel. The information in the pixel matrix can be read via 2, 4 or 8 outputs, yielding a maximum full frame rate between 50 and 200 Hz. Each output is operating at 40 MHz pixel rate. The outputs are differential with a common mode voltage of 0.9 V and an adjustable output swing of 2 Vptp. Nevertheless the power dissipation shall be below 330 mW. © 2013 SPIE. Source

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