I screen-grabbed the abstract, figures, and tables of your SPP 2011 papers and posted them in Google+.  This would make the job of those who want to showcase departmental research this Sunday for the students who made it to the Director’s List .  I’ll take three projects representative of the department’s laboratories for the SOSE presentation slides of Dr. Dayrit on Sunday.  We can use these pictures also for the preparation of posters for Interlinks.  Those who do not wish to have their pictures posted in Google please inform me.  These is one of the pictures:

https://plus.google.com/b/106776611692288920134/photos/106776611692288920134/albums/5707114060024938001

To simplify web administration, I shall upload in Facebook only those pictures that concern Faces.  In Google+, I shall upload only pictures that are research results or teaching materials.  In this way, these two social networking sites have their own specific functions.

Abstract

In this paper, we use geometric algebra to describe the polarization ellipse and Stokes parameters. We show that a solution to Maxwell’s equation is a product of a complex basis vector in Jackson and a linear combination of plane wave functions. We convert both the amplitudes and the wave function arguments from complex scalars to complex vectors. This conversion allows us to separate the electric field vector and the imaginary magnetic field vector, because exponentials of imaginary scalars convert vectors to imaginary vectors and vice versa, while exponentials of imaginary vectors only rotate the vector or imaginary vector they are multiplied to. We convert this expression for polarized light into two other representations: the Cartesian representation and the rotated ellipse representation. We compute the conversion relations among the representation parameters and their corresponding Stokes parameters. And finally, we propose a set of geometric relations between the electric and magnetic fields that satisfy an equation similar to the Poincaré sphere equation.

© 2012 Optical Society of America

» View Full Text: Acrobat PDF (367 KB)

Here is a link to the slides of my talk at Manila Observatory yesterday, 24 November 2011, for Geology and Geodesy students of UP Diliman. The talk was entitled: “Global Positioning Systems: Physical principles, data formats, and research applications.”

Correlation of TRMM, GPCC and ground-based measurements of monthly rainfall rate in the Manila Observatory

1 National Institute of Physics, University of the Philippines
2 Department of Physics, Ateneo de Manila University, Philippines

Abstract

The problem of pollsters is addressed which is to forecast accurately the final answers of the undecided respondents to the primary question in a public opinion poll. The task is viewed as a pattern-recognition problem of correlating the answers of the respondents to the peripheral questions in the survey with their primary answers. The underlying pattern is determined with a supervised artificial neural network that is trained using the peripheral answers of the decided respondents whose primary answers are also known. With peripheral answers as inputs, the trained network outputs the most probable primary response of an undecided respondent. For a poll conducted to determine the approval rating of the (former) Philippine president, J. E. Estrada in December 1999 and March 2000, the trained network predicted with a 95% success rate the direct responses of a test population that consists of 24.57% of the decided population who were excluded in the network training set. For the undecided population (22.67% of December respondents; 23.67% of March respondents), the network predicted a final response distribution that is consistent with the approval/disapproval ratio of the decided population.

Copyright  2002 John Wiley & Sons, Ltd

Raphael A. Guerrero 1 and Rutsy B. Arangcon 2

1 Dept. of Physics, Ateneo de Manila University, Loyola Heights, Quezoo City, Philippines
2 National Institute of Physics, University of the Philippines
Diliman, Quezon City Philippines

Abstract

We show thut the recall strength of 4 holographic associative memory demonstrates scaling behavior. Scale invariance of the associated recall with fractional content of the data input is observed. Experimental results using photorefractive volume holography are presented.

National Institute of Physics, University of the Philippines, Diliman, Quezon City, Philippines

Received 7 January 2004; revised 13 April 2004; Accepted 4 June 2004. Available online 19 July 2004.

Also at: Department of Physics, Ateneo de Manila University, Loyola Heights, Quezon City, Philippines. Tel./fax: +6324261043

Abstract

The response of a volume holographic pattern recognition system to partial versions of a reference image is investigated. Reference images used are arrays of circular apertures under uniform illumination. The arrays consist of three periodic grids, with different aperture diameters and spacing, and two arbitrary images. Partial versions of an image are generated by blocking apertures, resulting in fractional content R, where R is the ratio of remaining apertures to the total number of apertures. Recognition strength, in terms of reconstructed intensity, for five different images shows power law dependence on R. Exponents of the scaling functions depend on the nature of the reference image. The response of the holographic system is variable with respect to which apertures are present in the partial image, demonstrating a feature-specific recognition capability. Scale invariance is still observed even when a Gaussian beam is used for recording and recognition.

Copyright © 2004 Elsevier B.V. All rights reserved.

Ateneo de Manila University, Loyola School of Science and Engineering, Physics Department, Loyola Heights, Quezon City, Philippines

Abstract

We present a tutorial on the Clifford (geometric) algebra Cl3,0 and use it to reformulate the laws of geometric optics. This algebra is essentially a Pauli algebra, with the Pauli sigma matrices interpreted as unit rays or vectors. In this algebra, the exponentials of imaginary vectors act as vector rotation operators. This property lets us rewrite the laws of reflection and refraction of light in geometric optics in exponential form. The reformulated laws allow easy translation of symbols to words and to diagrams. They also are shown to be equivalent to standard vector formulations. These coordinate-free laws can be shown to simplify the analysis of geometric optics problems such as the tracing of meridional and skew rays in lenses and optical fibers.

© 2004 American Association of Physics Teachers

National Institute of Physics, University of the Philippines, Diliman, Quezon City, Philippines

Received 27 December 2005; revised 25 September 2006; Accepted 5 October 2006. Available online 24 October 2006.

Corresponding author. Also with: Department of Physics, Ateneo de Manila University, Loyola Heights, Quezon City, Philippines.

Abstract

We examine the phase structures of Helico-Conical (HC) Optical Beams produced via computer-generated holograms (CGH). The CGHs of these beams are made such that the reconstruction will have a phase which is a product of a helical and a conical phase. Interference-based phase measurement technique reveals very distinct differences between the phases of the two types of HC Beams (K = 0 and K = 1). Most obvious is the presence of screw dislocations at the center of the beam for K = 1 while no screw dislocations are found at the center for K = 0. We also compare the experimental interference patterns with numerical interference patterns calculated by superimposing a field containing vortices at different positions and a plane wave. A remarkable similarity is seen between the interferograms, which is a good indication of the phase of these beams. Contour plots are drawn to show the phases of these beams. We observe a string of vortices with equal charge in contrast to the assumption that a string of alternating charges should be seen.

Department of Physics, Ateneo de Manila University, Loyola Heights, Quezon City, 1108 PHILIPPINES

Abstract

Bessel beams are non-diffracting beams with the ability to self-reconstruct after encountering an obstacle. We report the storage of such beams in a photorefractive LiNbO3 crystal via volume holography. A Bessel beam reconstructed from volume hologram exhibits non-diffraction up to a distance of 65.9 cm.

© 2008 Samahang Pisika ng Pilipina