33 research outputs found

    A continuum robotic platform for endoscopic non-contact laser surgery: design, control, and preclinical evaluation

    Get PDF
    The application of laser technologies in surgical interventions has been accepted in the clinical domain due to their atraumatic properties. In addition to manual application of fibre-guided lasers with tissue contact, non-contact transoral laser microsurgery (TLM) of laryngeal tumours has been prevailed in ENT surgery. However, TLM requires many years of surgical training for tumour resection in order to preserve the function of adjacent organs and thus preserve the patient’s quality of life. The positioning of the microscopic laser applicator outside the patient can also impede a direct line-of-sight to the target area due to anatomical variability and limit the working space. Further clinical challenges include positioning the laser focus on the tissue surface, imaging, planning and performing laser ablation, and motion of the target area during surgery. This dissertation aims to address the limitations of TLM through robotic approaches and intraoperative assistance. Although a trend towards minimally invasive surgery is apparent, no highly integrated platform for endoscopic delivery of focused laser radiation is available to date. Likewise, there are no known devices that incorporate scene information from endoscopic imaging into ablation planning and execution. For focusing of the laser beam close to the target tissue, this work first presents miniaturised focusing optics that can be integrated into endoscopic systems. Experimental trials characterise the optical properties and the ablation performance. A robotic platform is realised for manipulation of the focusing optics. This is based on a variable-length continuum manipulator. The latter enables movements of the endoscopic end effector in five degrees of freedom with a mechatronic actuation unit. The kinematic modelling and control of the robot are integrated into a modular framework that is evaluated experimentally. The manipulation of focused laser radiation also requires precise adjustment of the focal position on the tissue. For this purpose, visual, haptic and visual-haptic assistance functions are presented. These support the operator during teleoperation to set an optimal working distance. Advantages of visual-haptic assistance are demonstrated in a user study. The system performance and usability of the overall robotic system are assessed in an additional user study. Analogous to a clinical scenario, the subjects follow predefined target patterns with a laser spot. The mean positioning accuracy of the spot is 0.5 mm. Finally, methods of image-guided robot control are introduced to automate laser ablation. Experiments confirm a positive effect of proposed automation concepts on non-contact laser surgery.Die Anwendung von Lasertechnologien in chirurgischen Interventionen hat sich aufgrund der atraumatischen Eigenschaften in der Klinik etabliert. Neben manueller Applikation von fasergefĂŒhrten Lasern mit Gewebekontakt hat sich die kontaktfreie transorale Lasermikrochirurgie (TLM) von Tumoren des Larynx in der HNO-Chirurgie durchgesetzt. Die TLM erfordert zur Tumorresektion jedoch ein langjĂ€hriges chirurgisches Training, um die Funktion der angrenzenden Organe zu sichern und damit die LebensqualitĂ€t der Patienten zu erhalten. Die Positionierung des mikroskopis chen Laserapplikators außerhalb des Patienten kann zudem die direkte Sicht auf das Zielgebiet durch anatomische VariabilitĂ€t erschweren und den Arbeitsraum einschrĂ€nken. Weitere klinische Herausforderungen betreffen die Positionierung des Laserfokus auf der GewebeoberflĂ€che, die Bildgebung, die Planung und AusfĂŒhrung der Laserablation sowie intraoperative Bewegungen des Zielgebietes. Die vorliegende Dissertation zielt darauf ab, die Limitierungen der TLM durch robotische AnsĂ€tze und intraoperative Assistenz zu adressieren. Obwohl ein Trend zur minimal invasiven Chirurgie besteht, sind bislang keine hochintegrierten Plattformen fĂŒr die endoskopische Applikation fokussierter Laserstrahlung verfĂŒgbar. Ebenfalls sind keine Systeme bekannt, die Szeneninformationen aus der endoskopischen Bildgebung in die Ablationsplanung und -ausfĂŒhrung einbeziehen. FĂŒr eine situsnahe Fokussierung des Laserstrahls wird in dieser Arbeit zunĂ€chst eine miniaturisierte Fokussieroptik zur Integration in endoskopische Systeme vorgestellt. Experimentelle Versuche charakterisieren die optischen Eigenschaften und das Ablationsverhalten. Zur Manipulation der Fokussieroptik wird eine robotische Plattform realisiert. Diese basiert auf einem lĂ€ngenverĂ€nderlichen Kontinuumsmanipulator. Letzterer ermöglicht in Kombination mit einer mechatronischen Aktuierungseinheit Bewegungen des Endoskopkopfes in fĂŒnf Freiheitsgraden. Die kinematische Modellierung und Regelung des Systems werden in ein modulares Framework eingebunden und evaluiert. Die Manipulation fokussierter Laserstrahlung erfordert zudem eine prĂ€zise Anpassung der Fokuslage auf das Gewebe. DafĂŒr werden visuelle, haptische und visuell haptische Assistenzfunktionen eingefĂŒhrt. Diese unterstĂŒtzen den Anwender bei Teleoperation zur Einstellung eines optimalen Arbeitsabstandes. In einer Anwenderstudie werden Vorteile der visuell-haptischen Assistenz nachgewiesen. Die Systemperformanz und Gebrauchstauglichkeit des robotischen Gesamtsystems werden in einer weiteren Anwenderstudie untersucht. Analog zu einem klinischen Einsatz verfolgen die Probanden mit einem Laserspot vorgegebene Sollpfade. Die mittlere Positioniergenauigkeit des Spots betrĂ€gt dabei 0,5 mm. Zur Automatisierung der Ablation werden abschließend Methoden der bildgestĂŒtzten Regelung vorgestellt. Experimente bestĂ€tigen einen positiven Effekt der Automationskonzepte fĂŒr die kontaktfreie Laserchirurgie

    Survey on Photo-Voltaic Powered Interleaved Converter System

    Get PDF
    Renewable energy is the best solution to meet the growing demand for energy in the country. The solar energy is considered as the most promising energy by the researchers due to its abundant availability, eco-friendly nature, long lasting nature, wide range of application and above all it is a maintenance free system. The energy absorbed by the earth can satisfy 15000 times of today’s total energy demand and its hundred times more than that our conventional energy like coal and other fossil fuels. Though, there are overwhelming advantages in solar energy, It has few drawbacks as well such as its low conversion ratio, inconsistent supply of energy due to variation in the sun light, less efficiency due to ripples in the converter, time dependent and, above all, high capitation cost. These aforementioned flaws have been addressed by the researchers in order to extract maximum energy and attain hundred percentage benefits of this heavenly resource. So, this chapter presents a comprehensive investigation based on photo voltaic (PV) system requirements with the following constraints such as system efficiency, system gain, dynamic response, switching losses are investigated. The overview exhibits and identifies the requirements of a best PV power generation system

    Handbook of Optical and Laser Scanning

    Get PDF
    From its initial publication titled Laser Beam Scanning in 1985 to Handbook of Optical and Laser Scanning, now in its second edition, this reference has kept professionals and students at the forefront of optical scanning technology. Carefully and meticulously updated in each iteration, the book continues to be the most comprehensive scanning resource on the market. It examines the breadth and depth of subtopics in the field from a variety of perspectives. The Second Edition covers: Technologies such as piezoelectric devices Applications of laser scanning such as Ladar (laser radar) Underwater scanning and laser scanning in CTP As laser costs come down, and power and availability increase, the potential applications for laser scanning continue to increase. Bringing together the knowledge and experience of 26 authors from England, Japan and the United States, the book provides an excellent resource for understanding the principles of laser scanning. It illustrates the significance of scanning in society today and would help the user get started in developing system concepts using scanning. It can be used as an introduction to the field and as a reference for persons involved in any aspect of optical and laser beam scanning

    Applications of Power Electronics:Volume 2

    Get PDF

    Applications of Power Electronics:Volume 1

    Get PDF

    ISOTOPE SHIFT SPECTROSCOPY OF ULTRACOLD STRONTIUM

    Get PDF
    We describe the design, construction, and performance of a laser system to probe the ultra-narrow (Γ/2π ≈ mHz) clock transition 1S0 → 3P0 in strontium. We present the first reported spectroscopy of this transition in two of the bosonic isotopes, 84Sr and 86Sr. Furthermore, we measure the complete set of isotope shifts between all four stable isotopes on the clock line and the narrow intercombination line 1S0 → 3P1, permitting a King plot analysis of the isotope shifts. Complications arising from the unambiguous determination of a line center in 87Sr 3P1 prevent us from making claims about the King linearity, but we provide a statistical boot- strap analysis of the isotope shifts 88−84Sr and 88−86Sr to compute a field shift ratio F698/F689 = 0.9979, with a 95% confidence interval [0.9952,1.0008]. The intercept term K698 − (F698/F689) K689 is similarly determined to be -2.0 GHz-amu, with a 95% confidence interval [−3.9, −0.3] GHz-amu. Finally, we describe the design of a next-generation apparatus that will enable improvements on the results described here, as well as other studies that involve coherent manipulation of strontium atoms on the clock line

    Reliability-Oriented Design and Optimization of Photovoltaic Microinverters

    Get PDF

    Vibration, Control and Stability of Dynamical Systems

    Get PDF
    From Preface: This is the fourteenth time when the conference “Dynamical Systems: Theory and Applications” gathers a numerous group of outstanding scientists and engineers, who deal with widely understood problems of theoretical and applied dynamics. Organization of the conference would not have been possible without a great effort of the staff of the Department of Automation, Biomechanics and Mechatronics. The patronage over the conference has been taken by the Committee of Mechanics of the Polish Academy of Sciences and Ministry of Science and Higher Education of Poland. It is a great pleasure that our invitation has been accepted by recording in the history of our conference number of people, including good colleagues and friends as well as a large group of researchers and scientists, who decided to participate in the conference for the first time. With proud and satisfaction we welcomed over 180 persons from 31 countries all over the world. They decided to share the results of their research and many years experiences in a discipline of dynamical systems by submitting many very interesting papers. This year, the DSTA Conference Proceedings were split into three volumes entitled “Dynamical Systems” with respective subtitles: Vibration, Control and Stability of Dynamical Systems; Mathematical and Numerical Aspects of Dynamical System Analysis and Engineering Dynamics and Life Sciences. Additionally, there will be also published two volumes of Springer Proceedings in Mathematics and Statistics entitled “Dynamical Systems in Theoretical Perspective” and “Dynamical Systems in Applications”

    HIGH-SPEED ENDOSCOPIC OPTICAL COHERENCE TOMOGRAPHY AND ITS APPLICATIONS

    Get PDF
    Optical coherence tomography (OCT) is a real-time high-resolution imaging technology providing cross-sectional images of biological structures at a resolution of <1 to 20 ”m and a penetration depth of 1 to 3 mm in most highly scattering tissues. OCT is in general non-invasive and can perform real-time ‘optical biopsy’ with a resolution approaching standard low magnification histopathology but without tissue removal. Conventional OCT requires a bulky imaging probe, which limits most of the in vivo applications to ophthalmology and dermatology. The development of miniature OCT imaging probe has greatly expanded the scope of the applications (e.g., cardiology, gastroenterology, etc.). Recent technical advances in OCT has extended the imaging speed from a few kHz to a few hundreds kHz, enabling in vivo three-dimensional (3D) imaging. This dissertation describes the development of a high-speed endoscopic OCT imaging system. The system employs the Fourier domain mode locking laser technology at a wavelength range of 1300 nm to reach an axial resolution of 9.7 ”m and an A-scan rate of 220 kHz. A Mach-Zehnder interferometer setup is used to achieve shot-noise limited detection. A generic OCT software platform is developed for data acquisition, processing, display, storage, and 3D visualization. Miniature OCT imaging probes are designed and fabricated for in vivo 3D OCT imaging. The utility of the high-speed endoscopic OCT system is demonstrated for clinical and basic researches in pulmonology and gastroenterology. In addition, an ultrahigh-resolution endoscopic OCT system is developed at a wavelength range of 800 nm to reach an axial resolution of 3.0 ”m and an A-scan rate of up to 20 kHz. Furthermore, a novel type of OCT contrast agents, scattering dominant gold nanocages, is developed with the aid of a cross-reference OCT imaging method. Finally, a multimodal endoscopic imaging system combines 1300 nm en face OCT and 1550 nm two photon fluorescence is developed. Compared with most of other imaging modalities, high-speed endoscopic OCT has unmatched advantages including high spatial resolution, imaging speed, and non-invasiveness / minimal invasiveness. The results in this dissertation suggest that high-speed endoscopic OCT may has a great impact on healthcare as well as basic research
    corecore