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Optomechatronic Technologies, 2009. ISOT 2009. International Symposium on

Date 21-23 Sept. 2009

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Displaying Results 1 - 25 of 110
  • Transient properties of a liquid crystal lens with multiple divided circularly hole-patterned electrodes

    Publication Year: 2009 , Page(s): 1 - 4
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1085 KB) |  | HTML iconHTML  

    Optical phase retardation distributions and transient properties of a liquid crystal (LC) lens with multiple divided circularly hole-patterned electrodes and external electrode are experimentally measured and numerically analyzed for an LC molecular orientation in a consideration of time domain by using a three-dimensional (3D) finite-difference method. The dynamical behaviors of the reorientation in LC directors and of the phase retardation in the LC lens with positive and negative lens properties are compared. View full abstract»

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  • Enhancing blurred image by hand-motion of compact imaging system using wavefront coding and property of point spread function

    Publication Year: 2009 , Page(s): 5 - 10
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2403 KB) |  | HTML iconHTML  

    Image of mobile camera is easily blurred during the exposure time by hand motion. To reduce hand motion blur of image, optical image stabilization technologies are widely used. They need additional mechanism and fine alignment of optical components and make the size of system bulky. In the mobile devices, however, using minimum number of optical and mechanical component is important. In this paper, we propose noble image restoration algorithm using upscaled image and recalculated deconvolution filter from the point spread function of optical system not to use any additional mechanical or optical components. Upscaled and restored image represents higher image resolution than the reference image which is not upscaled. View full abstract»

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  • High-resolution high-speed spectral domain optical coherence tomography

    Publication Year: 2009 , Page(s): 11 - 15
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (972 KB) |  | HTML iconHTML  

    We have designed the spectral domain optical coherence tomography system using a broadband superluminescent diode laser source and home-built spectrometer, which acquires 2D or 3D images with high speed and high resolution. We have also introduced the N-point complex FFT algorithm, which is faster than 2N point real FFT, into the signal processing part, thus shortening signal processing time after image data acquisition. For the sake of convenient measurements, the spectral domain optical coherence tomography was manufactured in the form of a microscope. The volumetric image of a mouse anterior eye could be reconstructed from a few hundred 2D images. View full abstract»

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  • Space-frequency analysis of pseudo-periodic patterns for subpixel position control

    Publication Year: 2009 , Page(s): 16 - 21
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (959 KB) |  | HTML iconHTML  

    This paper reports on visual position measurement based on space-frequency analysis of a pseudo-periodic pattern. This approach can be seen as a two-dimensional extension of the Vernier principle as used in the Vernier caliper. The pseudoperiodic pattern fixed on the target is seen as a secondary scale that is compared to the reference scale formed by the image pixel frame. By performing space-frequency analysis and phase computations, the center of the pseudo-periodic pattern is retrieved with a subpixel accuracy and the in-plane orientation is determined as well. Several configurations allow different kinds of measurement. A single camera vision system leads to in-plane pose estimation. Stroboscopic illumination can be used to quantify vibration amplitudes down to the nanometer range. A two camera setup can be used for displacement measurements along the three spatial directions while the choice of an interference objective, sensitive to out-of-plane direction, can complement the measurement to address the six degrees of freedom. An extended pseudo-periodic pattern was also designed to locate any field of observation within a wide dimension surface. View full abstract»

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  • Position encryption of extended surfaces for subpixel localization of small-sized fields of observation

    Publication Year: 2009 , Page(s): 22 - 27
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (3435 KB) |  | HTML iconHTML  

    A vision system is used for measuring in-plane target position, displacement and orientation. An encrypted pseudo-periodic pattern fixed on the target forms a phase reference. Absolute position is determined with subpixel accuracy by phase computations from any local view of a small zone of the pattern. Method principle is presented and performances are characterized. The capability to resolve position on depth ranges larger than the lens depth of focus is demonstrated. The method is applied to position referencing of live cell culture boxes and could be used as visual control sensor in other applications. View full abstract»

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  • Numerical evaluation of an off-axis Point Spread Function reconstruction from the Woofer/Tweeter Adaptive Optics system

    Publication Year: 2009 , Page(s): 28 - 33
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (882 KB) |  | HTML iconHTML  

    This paper presents the derivation, implementation and testing of an off-axis Point Spread Function (PSF) reconstruction technique for the applied numerical model of the University of Victoria's dual Deformable Mirror (DM) Woofer-Tweeter (W/T) Adaptive Optics (AO) system. The methodology has been tested; it is based on the data saved by the AO system during the science exposure, and on the analytical expression of the anisoplanatic transfer function. This data is later used in the post-processing stage to reconstruct the off-axis PSF that degrades the AO system's performance at greater angular distances from the guide star (GS). Although the results are unique to the UVic W/T AO bench model, the proposed PSF reconstruction methodology will be applicable to other dual DM systems and to multi DM AO systems. View full abstract»

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  • Multi-wavelength single-shot interferometry

    Publication Year: 2009 , Page(s): 34 - 39
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1266 KB) |  | HTML iconHTML  

    A new surface profiling technique is proposed, which enables us fast and robust 3D measurements with interferometric resolution and extended measurement range. It is accomplished by a newly developed multi-wavelength imaging system, which is easily and economically constructed by a commercially available RGB LED illuminator and a color camera. With this imaging system, we first developed a two-wavelength single-shot technique. Then we expanded it to three wavelengths and successfully measured a step height of 1000 nm. For this purpose, we developed several algorithms including crosstalk compensation and frequency estimation. The algorithms and experimental results are presented. View full abstract»

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  • Fusion of AFM and SEM scans

    Publication Year: 2009 , Page(s): 40 - 45
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (941 KB) |  | HTML iconHTML  

    Atomic Force Microscopy (AFM) and Scanning Electron Microscopy (SEM) are commonly used technologies for high resolution surface investigations. Combined AFM and SEM studies provide a thorough view of specimen topography and material properties, due to a large number of sophisticated imaging techniques. This work aims at providing a more meaningful representation of results from combined examinations, by applying methods of image fusion and visualization. Multiple application scenarios are discussed. According to the specification of requirements, three imaging procedures are presented in detail and applied to scans from a combined AFM and SEM study. View full abstract»

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  • Real-time photogrammetric stitching of high resolution video on COTS hardware

    Publication Year: 2009 , Page(s): 46 - 51
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1559 KB) |  | HTML iconHTML  

    It is often necessary to stitch images together into a larger image; examples include generating a panoramic image, building an aerial terrain photo, and wide area surveillance. The latter is an example in which this stitching must happen in real time, i.e. less than one frame period. If further constraints are placed on the system such as operation in poor contrast conditions and multiple targets moving against a changing background in the system's field of view, yet it must still operate deterministically, then current predominant methods using image registration do not suffice. These methods typically require a large overlap between adjacent cameras in a static staring array, and involve manipulating the individual video frame images by means of rotation, translation and scaling until detected feature points optimally match. This is non-ideal because more cameras are needed due to the overlap of the adjacent cameras, the requirement to determine salient image points (which may not be evident in poor contrast conditions), the iterative manner used to align images' salient points, the frequent neglecting of lens distortion effects and the inability to align two cameras if the one between them fails. Photogrammetric methods have been used before to rectify these short comings, but have always required expensive, bulky, custom processing hardware. This paper shows that it is possible to stitch an array of minimally overlapped high resolution wide angle cameras irrespective of scene content and lighting changes in a deterministic manner via novel use of commercial graphics processing hardware and a parallelized algorithm. View full abstract»

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  • Optical distance control for a multi focus image in camera phone module assembly

    Publication Year: 2009 , Page(s): 52 - 58
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1199 KB) |  | HTML iconHTML  

    Camera phones are very popular these days and mass production is essential for manufacturing the camera modules used in the phones. This study aims at developing a focusing method for use in the camera module assembly process. The camera module is composed of small components and machine vision is necessary to align them before their assembly. The inspected images usually have multiple areas with different focal distances, due to the different thicknesses of the components. Sharpness is the evaluation of focus, calculated by determining its absolute derivative and used for determining the focal point. A dynamic focus region (DFR) is defined to find the object of interest to be focused on. The DFR is built from the edge fragments detected using several narrow ROIs across the vision screen. An assembly machine was constructed to attach lens mounts to a PCB for the experiment. The distance between the lens mount and vision camera was adjusted to find the focus position by means of the sharpness and DFR. The result shows that the desired object is brought into focus and the proposed method can be applied to the camera module assembly process. View full abstract»

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  • Displacement analysis of micromirror composed of large deflection spiral beams

    Publication Year: 2009 , Page(s): 59 - 64
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1506 KB) |  | HTML iconHTML  

    We present a new two-axis spiral-shaped micromirror manipulator developed for free space optical switching. The actuator is an electrostatic actuator, comprised of two different parts, which are fabricated using conventional surface micromachining processes and then assembled. In spite of the conventional monolithic self-assembling design approaches, these two parts are fabricated on two different chips and assembled using a spatial-mechanical approach from point of view of a simple MEMS-manufacturing process of each part. Making as one MEMS device becomes a lot of number of processes. Because a fixed place of the screw beam from the mirror device is at the position where only the height of a lower micro pyramid is low compared with the height of a central point. The design utilizes the increased flexibility of the spiral shaped electrode and zipping effect technique in order to increase the maximum tilt angle. The footprint of the assembled device is 600 mum times 600 mum and height of the micro pyramid is 200 mum.The switch was simulated using an energy concept and electromechanical coupled model. Its performance was measured statically using a reflection measurement approach. A continuous tilt actuation of 17 degree has been achieved with actuation voltage of 235 volts. View full abstract»

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  • Application of AZARASHI (seal) positioning mechanism to micromanipulation by vacuum suction

    Publication Year: 2009 , Page(s): 65 - 70
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1099 KB) |  | HTML iconHTML  

    This paper deals with an application of a small mobile device, ldquoAZARASHI (seal) Mechanismrdquo with three degrees of freedom (DOFs) to a micromanipulation device. AZARASHI mechanism has a smaller number of controlled devices than the inchworm-like device. The small device with multiple DOFs can be built by combining such mechanism. A micromanipulation device consists of an L-shaped device for the x-, y- and thetas-motions, and one-DOF device in the z-motion. By the visual feedback, a glass bead is placed automatically. In order to trap a glass bead with a diameter of 60-70 mum, the air was gently sucked through the glass capillary. Then the bead is trapped and placed after moving the stage. Finally, the bead is placed. The performance of the manipulation device was measured. Positioning accuracy of the stage was within 1 pixel. However, a process of the bead release often disturbed the total accuracy. View full abstract»

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  • Fabrication of organic light emitting display using inkjet printing technology

    Publication Year: 2009 , Page(s): 71 - 76
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1059 KB) |  | HTML iconHTML  

    In this paper, we have investigated the characteristics of polymer inkjet printing and fabricated OLED (organic light emitting diode) display using inkjet printing technology. To control the wetting condition of the droplet to the substrate, UV/ozone treatment technique is used. To make the repeated pixels on a substrate, precise vision alignment and multi-layer printing is used. With the successive printing of PEDOT/PSS as a hole injection layer and MEH-PPV as a light emitting layer, we have successfully fabricated an OLED and demonstrated basic working of OLED. View full abstract»

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  • Low cost polymer MEMS mirrors fabricated by photolithography and wet etching processes

    Publication Year: 2009 , Page(s): 77 - 82
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1247 KB) |  | HTML iconHTML  

    This paper presents two types of low cost mirror devices composed of the glass and the polymer material. These devices are new constructions composed of the inexpensive glass as the mirror substrate and the polymer as the torsion hinge. The devices can be fabricated by the photolithography and wet etching processes without deep-RIE process. The proposed one construction is the Lorentz force type mirror device made of polyimide material. And the other construction is the electromagnet force type mirror device made of SU-8 material containing the magnetic particles. In the former type mirror, the mirror device was fabricated without expensive dry etching equipment such as RIE, and the device can be fabricated only by the sputtering, photolithography and wet etching processes. Further, the inexpensive glass and polymer material are used instead of expensive Si. In the latter type mirror, the SU-8 polymer material containing the magnetic particles is used. The actuation system which attracts the mirror directly with the electromagnet is adopted. We fabricated the large-sized mirror (20 mm times 10 mm) device without expensive dry etching equipment such as deep-RIE, and evaluated the characteristics of the fabricated mirror device. The optical deflection angle of plusmn20 deg. was achieved. As the result, we confirmed the feasibility to realize the low cost polymer MEMS mirror. View full abstract»

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  • Lightweight and low cost lens for infrared sensors using a computer generated hologram

    Publication Year: 2009 , Page(s): 83 - 87
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (5327 KB) |  | HTML iconHTML  

    Infrared (IR) sensors are used for various purposes, such as human body detection. This study concerns the development of downsized, low-cost lenses for IR sensors, and it is argued that computer generated holograms (CGH) are applicable to a lens. Lenses with CGH are inexpensive and lightweight since they can be mass-produced by using stampers, similar to compact discs. This study shows that lenses with CGH can detect IR with excellent angular resolution with a viewing angle of up to plusmn60deg. View full abstract»

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  • Aerial imagery terrain classification for long-range autonomous navigation

    Publication Year: 2009 , Page(s): 88 - 91
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2298 KB) |  | HTML iconHTML  

    This article focuses on the problem of terrain classification from aerial imagery with the intention to increase unmanned ground vehicle (UGV) road and off-road performance by providing means to analyze data from unmanned aerial vehicle (UAV). View full abstract»

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  • Control of a quadrotor air vehicle by vanishing points in catadioptric images

    Publication Year: 2009 , Page(s): 92 - 97
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1426 KB) |  | HTML iconHTML  

    Nowadays, Unmanned Air Vehicles (UAVs) have become more and more important. These vehicles are employed in many applications from military operations to civilian tasks. Under situations where global positioning system (GPS) and inertial navigation system (INS) do not function, or as an additional sensor, vision systems can be used. In recent years omnidirectional camera usage has experienced a remarkable increase. In many fields innovative research has been done by this camera which captures 360deg view in a single frame. However, employment of omnidirectional cameras in UAVs is very new. In this paper, we present the use of catadioptric systems in UAVs. The parallel lines that exist on many structures in an urban environment are used by the algorithm for the estimation of the attitude of the UAV. After explanation of the algorithm, the UAV modelling and control will be presented. Various simulations have been done to present the effectiveness of the estimation algorithms as well as the UAV controllers. Finally, we will present the experiments and the results of the estimation and control algorithms on a real model helicopter. View full abstract»

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  • Improved air gap control using optimized antishock control algorithm for SIL-based near-field storage system

    Publication Year: 2009 , Page(s): 98 - 103
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (9587 KB) |  | HTML iconHTML  

    In this paper, the optimized anti-shock control algorithm is developed and implemented in an solid immersion lens (SIL)-based near-field (NF) storage systems to improve air gap control performance during dynamic conditions. Accordingly, to detect the stable gap error signal under continuous operating conditions, the air gap control performance must be increased to avoid collisions due to external shocks. In this study, we propose an anti-shock air gap control system using a double disturbance observer (DOB) and a dead-zone non-linear controller. Experimental results demonstrate that a double DOB with a dead-zone non-linear controller maintained the optical head with SIL optics for a 5.31 G@10 ms shock. Thus, the air gap control performance in the presence of external shocks was improved. View full abstract»

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  • Impact of angle ranges on thickness resolution in thin film reflectometry

    Publication Year: 2009 , Page(s): 104 - 109
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1004 KB) |  | HTML iconHTML  

    Thin film reflectometry is a common way to monitor film thicknesses in numerous processes. Semiconductor and optics producing industries, e.g., require film thickness observation. Spectral reflectometry interrogation is one of several methods, which can be assessed by various algorithms depending on resolution and measuring range demands. Incident angle is a crucial parameter to these interrogation methods. Light, under different incident angles, produces different spectral reflectivity functions. These are integrated by a detector, in this case a spectrograph. Therefore, one needs to minimize the range of incident angles onto the measured object in order to increase the resolution of film thickness. Lateral resolution may also be a crucial parameter in some processes. Lateral resolution is a function of the range of incident angle, it increases with increasing angle range. These two crucial facts result in an estimate of measuring error introduced by the angle range under a given maximal lateral resolution. A measuring setup for a range of incident angle measurements is presented, as well as an example interrogation of a thin film under different incident angles. View full abstract»

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  • Form measurement of thin cylinders using three-wavelength interferometry

    Publication Year: 2009 , Page(s): 110 - 115
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (4270 KB) |  | HTML iconHTML  

    A new interferometric measurement technique for form measurements of cylindrical objects with diameters up to 2.5 mm is presented. This technique provides a contactless and non-scanning form measurement of reflective cylinders with a resolution in the nanometre range. The specimen is placed in the centre of an inverse conic mirror and is illuminated by a diode laser. The reflected light is superposed under a slight angle with a reference beam and imaged on a CCD camera. From the recorded interferogram the surface topography of the specimen can be derived by a spatial phase shifting algorithm. The measurement range can be varied from the nanometre to the micrometre range by using three lasers with different wavelengths. Results of form measurements of different samples are presented and discussed. View full abstract»

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  • Improved MEMS based FT-IR spectrometer

    Publication Year: 2009 , Page(s): 116 - 121
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1317 KB) |  | HTML iconHTML  

    We discuss recent improvements of our MEMS-based FT-IR spectrometer. A novel MEMS actuator design of the translational mirrors features an increased mirror surface of 7 mm2 and enables larger translation amplitudes (up to plusmn250 mum), leading to improved performance of the spectrometer. Furthermore we present a new method for accurate position detection of the MEMS device, thus enabling the implementation of closed-loop control. A dedicated circuit demodulates the reference signal and generates a highly accurate control signal returning the zero-crossing position of the mirror. The implementation of a closed-loop control ensures optimally stable MEMS mirror movement and maximal mechanical amplitude, even under varying environmental conditions allowing building robust MEMS-based Fourier-transform infrared (FT-IR) spectrometers with large mechanical amplitudes and thus good spectral resolutions. View full abstract»

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  • Comparison of different peak detection algorithms with regards to spectrometic fiber Bragg grating interrogation systems

    Publication Year: 2009 , Page(s): 122 - 126
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2672 KB) |  | HTML iconHTML  

    The resolution of many optical measurement systems employing ID or 2D array sensors (e.g. CCD-cameras) is limited by the pixel-resolution of the detector. Subpixel algorithms allow to exceed this limit. This paper aims at fiber Bragg grating interrogators, which acquire the sensor signal spectrometrically. The accuracy of measurement of these systems is strongly depending on the used algorithms. Five different algorithms for peak detection are described and compared in theory and experiment. Most of these algorithms can be found both in literature and in different software-libraries (e.g. MATLAB, LabVIEW...) To compare the different algorithms, a single fiber Bragg grating sensor was used to acquire data with a spectrometric measurement system consisting of a lD-CCD-line-array, a superluminescent light source and a reflection grating. The same data was fed the five algorithms, such that the output signals are comparable. To characterize the peak-search algorithms the standard deviation of the output data has been computed for different frame rates and variable wide regions of interest around a FBG-peak. As a result we can provida a concise recommendation which of the analyzed algorithms is suitable for an application in spectrometric fiber Bragg grating interrogators. View full abstract»

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  • Fiber Bragg grating-based acceleration sensor

    Publication Year: 2009 , Page(s): 127 - 132
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (5370 KB) |  | HTML iconHTML  

    We present the design process of a fiber Bragg grating based fiber-optic single-axis acceleration sensor with minimized crosstalk. Crosscoupling of non-directional accelerations is minimized by introducing a unique double-membrane fixture of the sensor's mass of inertia leading to an almost diagonal form of the sensors stiffness-matrix. The sensor's resonance frequency, the sensor's sensitivity towards the stiffness of the spring-mass system and the mass of inertia are calculated from an analytical model and are verified by FEM simulation of the sensor. A singleaxis sensor design yielding a resonance frequency of 6.0 kHz with a sensitivity of Deltalambda = 1 pm/g at a non resonant acceleration is proposed. View full abstract»

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  • Stabilization of a forward looking bow camera using photogrammetric measurements

    Publication Year: 2009 , Page(s): 133 - 139
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1069 KB) |  | HTML iconHTML  

    Stabilization of images is required for many applications, these include target identification and tracking. Many methods of performing this stabilization exist, primarily classifiable as either software techniques or mechanical stabilization using external information such as an inertial reference system or geo-pointing system. The aim of this work is to investigate the feasibility of using only photogrammetric data obtained from a bow-mounted narrow field of view camera to mechanically stabilize the resultant image in rough sea conditions. This will allow the exclusion of inertial measurement equipment with its accuracy/expense trade off, yet still be able to stabilize the image in the presence of sea surge that places the target outside of the camera's nominal field of view. The experimental results obtained using a 3 axis ship motion simulator showed a 20 dB and 30 dB attenuation for roll and pitch respectively. View full abstract»

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  • Design of an ultra thin secondary lens for visible light communication based on a white LED

    Publication Year: 2009 , Page(s): 140 - 145
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (8659 KB) |  | HTML iconHTML  

    Light-emitting diodes (LEDs) have begun to penetrate the traditional lighting industry and have left a profound impact on the illumination of thin and portable personnel telecommunication devices. Aside from this, LEDs can also be used in the design of visible optical wireless communication systems. In lighting applications, surface mount device (SMD) LEDs play an important role; however, their low light flux brought about by the large viewing angle should be redistributed to increase luminescence and the communication range in communication applications. For this reason, the current study issue in this application is how to achieve a long data transmission range while dramatically reducing the overall system size for use in thin electronic products. This work presents a proposed design of an ultra-thin secondary lens for visible light communication based on white LEDs. The accurate physical modeling of a chip die and its package can make ray-trace simulation a powerful tool in predicting power distribution of the SMD LEDs in the near-field. To verify the proposed method, modeled ray data was compared with measured data. While relaxing several design constraints, the secondary light colliminator was carried out with a solution of a central refractive aspheric surface and an outer reflective surface. The optical performance of the modeled LEDs was very similar to the real one. The designed lens reduced the viewing angle of white SMD LEDs from 120deg to 20deg in FWHM. The proposed lens is extremely compact and efficient and is a good starting point in achieving an effective design of visible light communication between personnel telecommunication devices. View full abstract»

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