Sobre la propuesta de una nueva definición del metro

Una vez revisados los antecedentes sobre las sugerencias para definir el metro según la longitud de onda de alguna radiación, los que se remontan a la propuesta que Babbset formuló en 1827, se pasa a analizar la sucesión de trabajos y de resultados que permitió concluir en la necesidad de cambiar la definición de 1960 basada en la radiación anaranjada del criptón 86. Se describen los fundamentos y algunos detalles que han llevado al Comité Consultivo para la Definición del Metro a proponer una nueva definición basada en la instancia de la velocidad de la luz, así como las formas experimentales con que podrá implentársela en los laboratorios metrológicos

Hidden grids, moiré patterns and optoelectronically measurement of distances

Hidden grids from the photocopy process are used to produce moiré patterns. The method of production of moiré patterns is extended to hidden grids generated in the optoelectronical CCD observations. An application of this moiré is proposed to measure distances

Compact device for interferometric holography

The diffraction phenomenon produced by a Fabry-Perot interference pattern record is analized. As a result of this analysis, a compact device for interferometric holography has been developed. It is presented as example an application of this device to the interferometric determination of deformations in a loaded metallic cantilever

Optical image subtraction through speckle modulated by young fringes

A new method for subtracting images is proposed. It is based on assigning complementary Young's fringes to the speckles of the common parts of two images. In this way, carrier frequency is cancelled, and “a-posteriori” spatial filtering shows only noncommon parts. Suggestions on applications of the method are briefly commented

Pseudocoloring method for 3-D contouring

The interference properties of white light speckle pattern obtained with an optical system not corrected for chromatic aberration are applied to pseudocolor encode the depth level contours of a 3-D diffusing object. At a first step, a recording of the different encoded images of depth levels is done. In a second step, a reconstructed pseudocolored image is obtained, where different color assignements can be tuned by changing the position of a spatial filter slit. Also, a quantitative contouring can be made scanning the pseudocolored image plane with a spectroscopic device

A speckle method of gray level pseudocoloring

A simple method of pseudocoloring gray level images is proposed. It is based on Young’s fringes modulated speckle encoding of images. Reconstruction from a photographic register is obtained using two light beams with different wavelengths at the same time. Pseudocoloring is produced by the superposition of a (diffracted) direct image in one color and a (directly transmitted) contrast reversed image in another color

New spectroscopic results in Xe II, Xe III, and Xe IV

New results obtained in spontaneous xenon spectrum employing a conventional pulsed gaseous laser tube as light source, are presented in this work. A total of 626 spectral lines has been ionically assigned as follows: 50 to Xe II spectrum, 103 to Xe III spectrum, arid 222 to Xe IV spectrum. 30 Lines previously assigned to Xe II were reassigned as belonging to Xe III, 94 lines were assigned with some doubts to Xe II-III spectrum and 84 lines to Xe Ill-IV spectrum. Also there were classified 43 lines of Xe II.Nuevos resultados obtenidos en el espectro del xenon espontaneo logrado mediante la utilizacion de un tuba de laser gaseoso pulsarlo convencional coma fuente de luz son presentados en este trabajo. Han sido estudiadas en total 626 I ineas espectrales las que fueron asignadas ionicamente de la siguiente manera: 50 al espectro del Xe II, 103 al de Xe Ill y 222 al de Xe IV. 30 Lineas asignadas anteriormente al Xe II fueron reasignadas como pertenecientes al Xe Ill. 94 Lineas fueron asignarlas con cierta duda al espectro del Xe II-III y 84 Iíneas al de Xe III-IV. Fueron clasificadas ademas 43 lineas del Xe II

Interference profiles with multiple spherical waves: general case

Characteristics of multiple-beam interference fringes, as in a Fabry–Perot interferometer with monochromatic light, are analyzed. The optical path and the optical-path difference between interfering beams are calculated for the most general case. Different refractive indices in the inner and outer media, and arbitrary locations of the light source and the point of observation, are taken into account. An expression for the impulse response of the system is given. The results obtained from experimental tests confirm the theoretical predictions

Color storage and image processing through Young's fringes modulated speckle

Young's fringes modulated speckle (YFMS) can be used for storing several pictures in a single photographic plate. In this Letter we present a simple application of this technique for color storage on black and white film, which allows information processing in different colors in an independent way

In-plane motion measurements with Fourier lensless holography

A holographic and moire technique for measuring inplane motions of a holographic plate attached to an object is described. This one seems easier to implement than a similar approach given by Roychoudhuri and Machorro. It is well known that when spherical and plane coherent wave fronts interfere, they give rise to a Fresnel-zonelike interference pattern. This is so when a lensless Fourier hologram of an empty pupil is recorded.If between two such exposures the holographic plate is rotated or translated inplane, the two overlapping interference patterns will produce low-frequency moire patterns. If the displacement involved is small (less than the innermost Fresnel ring), the moire pattern consists of equally spaced straight lines perpendicular to the direction of the displacement.a and the interfringe spacing is inversely proportional to the magnitude of the displacement