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Pinero D.P.,Medimar International Hospital | Pinero D.P.,University of Alicante | Alcon N.,Medimar International Hospital | Alcon N.,Instituto Tecnologico Of Optica
Journal of Cataract and Refractive Surgery | Year: 2014

Interest in corneal biomechanics has increased with the development of new refractive surgery techniques aimed at modifying corneal properties and a variety of surgical options for corneal ectasia management. The human cornea behaves as soft biological material. It is a viscoelastic tissue and its response to a force applied to it depends not only on the magnitude of the force, but also on the velocity of the application. There are concerns about the limitations to measuring corneal biomechanical properties in vivo. To date, 2 systems are available for clinical use: the Ocular Response Analyzer, a dynamic bidirectional applanation device, and the Corvis ST, a dynamic Scheimpflug analyzer device. These devices are useful in clinical practice, especially for planning some surgical procedures and earlier detection of ectatic conditions, but further research is needed to connect the clinical measurements obtained with these devices to the standard mechanical properties. Financial Disclosure Neither author has a financial or proprietary interest in any material or method mentioned. © 2014 ASCRS and ESCRS. Source


Ocana R.,Instituto Tecnologico Of Optica
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2014

Laser projection devices should be designed to maximize their luminous efficacy and color gamut. This is for two main reasons. Firstly, being either stand alone devices or embedded in other products, they could be powered by battery, and lifetime is an important factor. Secondly, the increasing use of lasers to project images calls for a consideration of eye safety issues. The brightness of the projected image may be limited by the Class II accessible emission limit. There is reason to believe that current laser beam scanning projection technology is already close to the power ceiling based on eye safety limits. Consequently, it would be desirable to improve luminous efficacy to increase the output luminous flux whilst maintaining or improving color gamut for the same eye-safe optical power limit. Here we present a novel study about the combination of four laser wavelengths in order to maximize both color gamut and efficacy to produce the color white. Firstly, an analytic method to calculate efficacy as function of both four laser wavelengths and four laser powers is derived. Secondly we provide a new way to present the results by providing the diagram efficacy vs color gamut area that summarizes the performance of any wavelength combination for projection purposes. The results indicate that the maximal efficacy for the D65 white is only achievable by using a suitable combination of both laser power ratios and wavelengths. © 2014 Copyright SPIE. Source


Pinero D.P.,Medimar International Hospital | Pinero D.P.,University of Alicante | Alcon N.,Instituto Tecnologico Of Optica
Clinical and Experimental Optometry | Year: 2015

Biomechanics is often defined as 'mechanics applied to biology'. Due to the variety and complexity of the behaviour of biological structures and materials, biomechanics is better defined as the development, extension and application of mechanics for a better understanding of physiology and physiopathology and consequently for a better diagnosis and treatment of disease and injury. Different methods for the characterisation of corneal biomechanics are reviewed in detail, including those that are currently commercially available (Ocular Response Analyzer and CorVis ST). The clinical applicability of the parameters provided by these devices are discussed, especially in the fields of glaucoma, detection of ectatic disorders and orthokeratology. Likewise, other methods are also reviewed, such as Brillouin microscopy or dynamic optical coherence tomography and others with potential application to clinical practice but not validated for in vivo measurements, such as ultrasonic elastography. Advantages and disadvantages of all these techniques are described. Finally, the concept of biomechanical modelling is revised as well as the requirements for developing biomechanical models, with special emphasis on finite element modelling. © 2014 Optometry Australia. Source


Ocana R.,Instituto Tecnologico Of Optica | Molina T.,Instituto Tecnologico Of Optica
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2014

In this work we have constructed a range gated imaging LIDAR with the aim to show the potential of this technique as well as to further determine aspects such as the typical energy per pulse needed, the illumination distribution of the laser source and the safety class. For this, we built a custom frequency doubled nanosecond pulsed Nd:YAG laser as illumination source, a CCD coupled to a generation II image intensi er and a simple progressive delays set for the camera gate using a pulse delay generator. At low levels of the illumination pulse and assuming safety perimeter around the system of approx. 1.5 m, the LIDAR could be classi ed as class 2M. In these conditions, we could resolve objects as far as 690 m. © 2014 SPIE. Source


Portales C.,Instituto Tecnologico Of Optica | Portales C.,University of Valencia | Ribes-Gomez E.,Instituto Tecnologico Of Optica
Computers in Industry | Year: 2015

In this paper we present a hardware system and related computer processes to assess a preliminary quality control of grape harvest batches by automatically detecting, classifying and quantifying grape stems and other objects from images acquired on arrival at the winery, from which a quality grading is given. A non-invasive methodology based on computer vision is implemented, and the developed approach is based on the combination of a spectral and spatial analysis, where the inspection is performed in a small region of the near infrared (from 1000 to 1100 nm range). A non-expensive optical system was designed, which is composed of two high resolution CCD cameras, a long pass filter, some halogen light sources, related electronics and a standard PC. The performance of the optical system and implemented computer vision-based algorithms were tested in a laboratory setup for repeatability and overall accuracy while operating outdoors and over a whole working day, with varying illumination conditions. The system response presented small variations when estimating the occurrences of grape stems or other objects in the scene under analysis. The best results - lowest standard deviations and lowest root mean square errors - were obtained for the system working with added artificial lights and for the analysis being performed in the green channel. The system was also installed at a winery, where operators tested it for its good performance in a real scenario. The system worked as expected and the outcomes show that it is a robust and intuitive inspection system. © 2014 Elsevier B.V. All rights reserved. Source

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