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Papers by Fernando Vargas-martín

Multiactuators Acoustical Panels are flat geometry loudspeakers that generate acoustic waves by m... more Multiactuators Acoustical Panels are flat geometry loudspeakers that generate acoustic waves by mechanical actuators transferring acoustics energy to the environment. They are capable of generating a wide range of frequencies over directions of propagation. The surface of these panels could act as a projection screen properly treating it. It must ensure that its reflective properties are appropriate and check that the vibration of the surface itself does not affect the image quality. In this paper we have experimentally evaluated its suitability as audiovisual playback screen. Los Paneles Multiactuadores Acústicos son altavoces de geometría plana que generan ondas acústicas mediante actuadores mecánicos que transfieren al ambiente. Son capaces de generarlas con un amplio margen de direcciones de propagación y frecuencias. La superficie de los mismos podría actuar como pantalla de proyección tratándola adecuadamente. Se debe lograr que sus propiedades de reflexión sean adecuadas y ha...

Page 59. HARTMANN-SHACK WAVEFRONT SENSOR IN THE EYE: ACCURACY AND PERFORMANCE LIMITS PABLO ARTAL,... more Page 59. HARTMANN-SHACK WAVEFRONT SENSOR IN THE EYE: ACCURACY AND PERFORMANCE LIMITS PABLO ARTAL, JUAN L. ARAGON, PEDRO M. PRETO, FERNANDO VARGAS-MARTIN AND ESTHER BERRIO ...

ABSTRACT Las aberraciones ópticas determinan la formación de imágenes en el ojo, tanto en el proc... more ABSTRACT Las aberraciones ópticas determinan la formación de imágenes en el ojo, tanto en el proceso de la visión como en las observaciones oftalmoscópicas del fondo de ojo. La corrección total de estas aberraciones permitiría una resolución limitada sólo por la difracción en las pupilas utilizadas. Las aberraciones del ojo difieren de un sujeto a otro y no responden a modelos sencillos. En este trabajo se propone el uso de técnicas de Óptica Adaptativa para el desarrollo de un sistema experimental para la medida y corrección de las aberraciones estáticas del ojo. Estas técnicas pueden ser igualmente útiles para obtener imágenes de alta resolución de la retina, utilizarse en el diseño de lentes oftálmicas, etc. Para la medida de la función aberración de onda, se han utilizado dos métodos no invasivos aplicables al ojo humano: La Recuperación de Fase a partir de dos imágenes de Doble Paso, y el Sensor de Hartmann-Shack. Para la corrección de la aberración se ha utilizado un Modulador Espacial de Cristal Líquido. Se han desarrollado los procedimientos de control y de calibrado de estos métodos, y se estudia la viabilidad de aplicación para el ojo. Finalmente, se han realizado medidas de la aberración, mediante ambos métodos, y su posterior corrección mediante el modulador espacial de cristal líquido, en un ojo artificial y en sujetos reales. Abstract: The image formation properties of the eye are determined by the aberrations of the optics. The complete correction of the aberrations would allow diffraction-limited resolution. The aberrations of the eye are not easily modeled and are different for each subject. This thesis proposes the use of adaptive optics techniques to measure and correct the static aberrations of the eye. The principles and methods developed are useful in specific applications, i.e., high-resolution retinal imaging, ophthalmic lens design, etc. Two non-invasive methods have been used to measure the wave aberration function: Phase Retrieval Techniques from two double-pass retinal images; and the Hartmann-Shack sensor. A Liquid Crystal Spatial Light Modulator was used to adaptively correct the wave front aberration of the eye. This thesis also includes guidelines to calibrate and control the proposed techniques. Finally, experimental explorations of these methods are reported. Several results are presented, including the measure and the subsequent compensation of the wave aberration for artificial and human eyes.

SID Symposium Digest of Technical Papers, 2001

... [1] Hoeft, WW, Feinbloom, W., Brilliant R., Gordon R., Hollander C., Newman J., Novak E., Ros... more ... [1] Hoeft, WW, Feinbloom, W., Brilliant R., Gordon R., Hollander C., Newman J., Novak E., Rosenthal B ... [5] Spitzer, MB, Aquilino, PD and other authors (1998) Optical approaches to incorporation of displays within glasses. Journal of the SID 6: 211-212. [6] URL of Peli Lab. ...

Investigative ophthalmology & visual science, 2006

To determine how severe peripheral field loss (PFL) affects the dispersion of eye movements relat... more To determine how severe peripheral field loss (PFL) affects the dispersion of eye movements relative to the head in patients walking in real environments. This information should help to define the visual field and clearance requirements for head-mounted mobility visual aids. Eye positions relative to the head were recorded in five patients with retinitis pigmentosa who had less than 15 degrees of visual field and in three normally sighted people, each walking in varied environments for more than 30 minutes. The eye-position recorder was made portable by modifying a head-mounted system (ISCAN, Burlington, MA). Custom data processing was implemented, to reject unreliable data. Sample standard deviations of eye position (dispersion) were compared across subject groups and environments. The patients with PFL exhibited narrower horizontal eye-position dispersions than did the normally sighted subjects (9.4 degrees vs. 14.2 degrees , P < 0.0001), and the vertical dispersions of patien...

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In this study we evaluated the immediate effectiveness of an optoelectronic visual field expander... more In this study we evaluated the immediate effectiveness of an optoelectronic visual field expander in a sample of subjects with retinitis pigmentosa suffering from a severe peripheral visual field restriction. The aid uses the augmented view concept and provides subjects with visual information from outside their visual field. The tests were carried out in daylight conditions. The optoelectronic aid comprises

Most of disposable cameras have an optical viewfinder. The usual configuration is a reversed Gali... more Most of disposable cameras have an optical viewfinder. The usual configuration is a reversed Galilean telescope with reduction of the image size. After easy removal, this viewfinder can be used as a central or bioptic field expander. After comparing several commercial cameras, optical features are described and the best cameras are selected. Description of the procedure of obtaining and mounting are described. D

Binocular head-mounted displays (HMDs) that could be used non-immersively produced substantial in... more Binocular head-mounted displays (HMDs) that could be used non-immersively produced substantial interruption of the visual field. Monocular HMDs designed to be used non-immersively created minimal interruption of the visual fields. The scotomata are small enough to allow the HMD to be worn in mobile situations, but inattention associated with use of the HMD may cause safety concerns for some mobile situations. A small opaque display can be positioned to provide a seethrough functionality.

Spectacle mounted telescopic systems have been prescribed for visual impairment, providing magnif... more Spectacle mounted telescopic systems have been prescribed for visual impairment, providing magnified images of objects at farther distances. Typically, bioptic telescopes are mounted toward the top of spectacle lenses or above the frame with the telescope eyepiece positioned above the eye's pupil. This allows the wearer to alternate between the magnified narrow field of view available through the eyepiece and

SID Symposium Digest of Technical Papers, 2001

Investigative ophthalmology & visual science, 2006

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