Alejandro Cornejorodriguez | Instituto Nacional de Astrofisica, Optica y Electronica (original) (raw)

Papers by Alejandro Cornejorodriguez

$Research paper thumbnail of La abertura de una lente, su efecto en el espectro de difracción convolutivo, frecuencia espacial y viñeteado$

Revista Mexicana De Fisica, Dec 1, 2011

El objetivo del trabajo presentado fue determinar los modelos matemáticos de difracción de frecue... more El objetivo del trabajo presentado fue determinar los modelos matemáticos de difracción de frecuencia espacial, uno paraxial y el otro no paraxial. El estudio se realizó considerando el efecto que produce la abertura finita de una lente esférica sobre un haz de luz difractado que incide en ella, empleando conceptos de laóptica geométrica; y de laóptica física, como la propagación del espectro angular interpretado como un campo de difracción convolutivo de ondas monocromáticas. El análisis se centró en la propagación del campo eléctrico de ondas monocromáticas difractadas por un objeto extendido, desde el plano x0y0 hasta el plano de incidencia xy de la lente referida; el objeto fue iluminado con ondas planas, y se situó a una distancia finita de la lente esférica. Como resultados se obtuvieron los modelos matemáticos de espectros de difracción de frecuencia paraxial y de máxima frecuencia espacial; a partir de dicha formulación se determinaron las expresiones para las frecuencias espaciales máxima y paraxial, que debe aceptar la pupila de entrada con respecto a las dimensiones que debe poseer el objeto difractor extendido, para minimizar el efecto de viñeteado. Descriptores: Lente; espectro angular; difracción; viñeteado; pupila. We present two diffraction models considering spatial frequencies, one paraxial and the other non-paraxial, to study the effect of the finite aperture of a lens used as transformer of the diffracted light. We use concepts of both geometrical and physical optics as the propagation of the angular spectrum as a convolved diffracted field of monochromatic waves. The analysis is based on the propagation of a diffracted monochromatic electric field produced by an object, located in a perpendicular plane to the propagation path, and placed at a finite distance of a transformer lens. We obtained a set of equations for the paraxial and maximum spatial frequencies accepted by the entrance pupil, associated to the lens, with respect to the size of the diffracting object, in order to reduced the vignetting.

$Research paper thumbnail of <title>Influence of the mechanical stress and heat parameters into the transmittance function of the integrals of the diffraction phenomena</title>$

22nd Congress of the International Commission for Optics: Light for the Development of the World, 2011

For the diffraction equations for the exact and convolutions Fourier's integrals, the paramet... more For the diffraction equations for the exact and convolutions Fourier's integrals, the parameters related with mechanical stress and heat are introduced into the mathematical function of the transmittance t0(x0,y0). Taking into account the new transmittance equation, a new set of equations for the exact and convolution Fourier's integrals have been derived. The only restriction for the analysis done is that for the apertures under study, they are only on a plane. An example af an experiment where a diffraction aperture suffers of a mechanical stress is shown.

Optical and Infrared Interferometry III, 2012

ABSTRACT A method based on a variant of genetic algorithm is proposed to obtain the wavefront abe... more ABSTRACT A method based on a variant of genetic algorithm is proposed to obtain the wavefront aberrations of a real ronchigrams using only one ronchigram without using polynomial fit or trapezoidal integration. The recovery of the aberration coefficients of third order is achieved by assigning random values but controlled in the equation of the optical path difference (OPD) which is given for a lateral shear interferometer. The proposed method retrieves the coefficients of the polynomial of the analyzed Ronchigram in a reliable and accurate way.

Optical Review, 2013

ABSTRACT With the Ronchi test a technician controls the manufacturing process using the following... more ABSTRACT With the Ronchi test a technician controls the manufacturing process using the following procedure: first, a Ronchigram is simulated which is scale-printed and placed on the surface as a mask and is usually printed with a low spatial resolution. This simulated Ronchigram is compared visually with the experimental pattern observed. This way of comparison leads to systematic errors in the evaluation of the surface, because it depends largely on the experience of the technician. Therefore, the main objectives of this work are to increase the spatial resolution and eliminate the dependence on the technician’s experience. Therefore, we compare the simulated Ronchigrams obtained by lateral shear interferometry, whose profiles are cosine, with Ronchigrams obtained experimentally. We present the simulation algorithm for the Ronchigrams of spherical and aspherical surfaces based on the expressions of a lateral shear interferometer. We show the results, of the comparison between simulated Ronchigrams (ray tracing and lateral shear interferometry) and experimental Ronchigrams.

Optical Engineering, 2013

ABSTRACT We present the validation for Ronchigram recovery with the random aberrations coefficien... more ABSTRACT We present the validation for Ronchigram recovery with the random aberrations coefficients (ReRRCA) algorithm. This algorithm was proposed to obtain the wavefront aberrations of synthetic Ronchigrams, using only one Ronchigram without the need for polynomial fits or trapezoidal integrations. The validation is performed by simulating different types of Ronchigrams for on-axis and off-axis surfaces. In order to validate the proposed analysis, the polynomial aberration coefficients that were used to generate the simulated Ronchigrams were retrieved. Therefore, it was verified that the coefficients correspond to the retrieved ones by the algorithm. The results show that the ReRRCA algorithm retrieves the aberration coefficients from the analyzed Ronchigram with a maximum error of 9%.

Applied Optics, 1975

If authors will state in their covering communications whether they expect their institutions to ... more If authors will state in their covering communications whether they expect their institutions to pay the publication charge, publication time should be shortened (for those who do).

Journal of the Optical Society of America, 1978

Optical Engineering, 2014

ABSTRACT Substructured Ronchi gratings are used to sharpen and increase the number of fringes in ... more ABSTRACT Substructured Ronchi gratings are used to sharpen and increase the number of fringes in Ronchigrams, thereby increasing their spatial resolution and allowing greater accuracy in the evaluation of a surface under test. This work presents a simple method for generating substructured Ronchi gratings and for calculating the intensity pattern produced by this type of grating. For this, we propose the generation of this kind of grating from the linear combination of classical gratings; the pattern of irradiance produced by these Ronchi gratings will be a linear combination of the intensity patterns produced by each combined classical grating. A comparison between theoretical and experimental Ronchigrams was obtained by analyzing a parabolic mirror.

The Ronchi test is a well-known method for the testing of optical components and systems, and can... more The Ronchi test is a well-known method for the testing of optical components and systems, and can be studied by ray tracing and lateral shearing interferometry. In this paper, the Ronchi test is applied using an LCD, for generating gratings with different periods for the dark and light zones, in order to obtain sharpening of the fringes. Experimental and computer simulations will be presented for parabolic surfaces.

Applied Optics, Dec 1, 1999

The fabrication of a conic surface begins with the grinding of a best-fit sphere. The desired con... more The fabrication of a conic surface begins with the grinding of a best-fit sphere. The desired conic surface can then be obtained by further grinding with a subaperture tool. Finally, the surface is polished. Normally the best-fit sphere is chosen so as to minimize the second grinding step. However, this method tends to produce mid-spatial frequency errors near the edge of the surface and can cause errors in the paraxial radius of curvature. This paper presents an alternative method of calculating the initial sphere so as to avoid these errors. It requires more grinding time but far less time for polishing.

Revista Mexicana De Fisica, 2004

We report a qualitative method to detect piston errors in an optical segmented surface. The test ... more We report a qualitative method to detect piston errors in an optical segmented surface. The test consists of illuminating a segmented surface, with a spherical wavefront coming from a linearly polarized beam. The behavior of the vectors of polarization of the light in the reflected beam are analyzed doing the experimental measurement of the Stokes parameters U and Q, rotating the analyzer for four positions of 0, 45, 90 and 135 degrees. The mirror used for this test has 20 and 120 centimeters for the diameter and the paraxial radius of curvature, respectively.

Applied Optics, Oct 1, 1986

... 9.10 0.2222 B 8.40 0.2026 C 6.48 0.1621 D 5.88 0.1481 E 0.06 0.0016 F 0.01 0.0004 ... Alejand... more ... 9.10 0.2222 B 8.40 0.2026 C 6.48 0.1621 D 5.88 0.1481 E 0.06 0.0016 F 0.01 0.0004 ... Alejandro Cornejo-Rodriguez is on sabbatical leave at the Universidad Autonoma de Puebla. ... 4. J.Pedraza-Contreras, A. Cornejo-Rodriguez, and A. Cordero-Davila, "Formulas for Setting the ...

Journal of the Optical Society of America, 1979

In subaperture testing, the main problem is the best fitting of all individual measurements. This... more In subaperture testing, the main problem is the best fitting of all individual measurements. This is achieved by introducing different tilt, piston and defocus parameters to the individual images. In this work we calculate these required additional parameters when the wave front generated by the system under test is spheric or aspheric ones.

Optics Express, 2004

We present simulated results on piston detection applying the classical Ronchi test to a segmente... more We present simulated results on piston detection applying the classical Ronchi test to a segmented surface. We have found that a piston error in a test segment, induces a change in the transversal aberration, that can be analyzed by mutually comparing the fringes frequency in each segment. We propose that the piston term of the segmented surface can be recovered by geometrically relating the change in transversal aberration with the piston term. To test this, we have simulated some ronchigrams for a known piston error, and we have been able to recover this term for a dynamic range comprised among 57nm and 550 µm. For piston errors > 550µm a change in the transversal aberration can be appreciated and measured in the ronchigrams although these large pistons are now classical defocusings. Thus we have demonstrated that the Ronchi test can be an alternative method for the piston detection with a large dynamic range.