2011 06 02 (uned) emadrid mlcalvo ucm m learning y holografia tecnicas compatibles

m-Learning and Holography: Compatible techniques?
María L. Calvo
Departamento de Óptica, Facultad de Ciencias Físicas, Universidad Complutense de Madrid (UCM)
II Jornadas eMadrid sobre e-Learning, UNED, 1-2 junio 2011

Outline
Introduction: What is m-Learning?
Objectives.
What is a hologram?
In-line Gabor hologram
The concept of diffraction: Fresnel zones
Classroom accessibility: some results
Other proposals.
References.

Introduction: m-Learning
Image sensors consists of devices that capture an image for purposes of display or storage.
Cell phones are nowadays ubiquitous.
Camera phones comprised over 80% of all shipped image sensors in 2008, with recent growth coming from the continuing penetration of dual-camera phones in the global market.
Improvement of the technical design provides in 2011 cell phones with resolution of the order of 8 Mpixels (digital camera resolution).
These facts provide unique tools for teaching and technological tools.

[Source: Wikipedia]

Objectives
Experimental methods for studying the basis of optical phenomena are needed to be extended to class room as a routine tool for students in physics and engineers.
These methods can be simplified and easily implemented by the use of the new technical assistance provided by camera phones: classroom accessibility.
In 2009, Z. Ben Lakhdar et al. introduced a procedure for studying diffraction and interference by the use of overhead projectors and camera phone image capture.
All tools accessible in the class room by the students.
This technique can be extended to other optical phenomena, such as Holography.
Some discussions arise after the analysis of the experimental results.

Antecedents: Holography
Volume holography developed by Y. Denisyuk(1962) as an extension of the pioneering experiments done by D. Gabor in 1947 (Nobel Prize, 1971) combined with the principles of color photography earlier obtained by G. Lippmann(1894).
C.V.Raman and N.S.N.Nath obtained evidence of thin grating behavior of an acoustic wave irradiated with light and studied the nature of the diffracted field in 1935.
During 20th century an important amount of work was done to introduce new techniques such as digital holography (A. Lohman, J. W. Goodman).
The 21st century is called to be the century of information photonics in which holographic techniques appear to be among the most appealing ones.
C. V. Raman in his laboratory ca. 1930.

What is a hologram?
Real image
A hologram is an interferogram in which it is encoded the amplitude and phase associated to the light wave diffracted by an object (object wave).
The encoded information can be retrieved by the light wave diffracted by the hologram (reading the hologram).
Virtual image

In-line holography: Gabor hologram
Real image plane

Example: digital in-line holographic microscopy
Holograms generated with a
green LED
Reconstructed holographic images
Images obtained with a Nikon Eclipse TE300
inverted microscope
Set-up for a lensless digital holographic microscope with LED illumination.
From: L. Repetto, E. Piano, and C. Pontiggia,Lensless digital holographic microscope with light-emitting diode illumination, Opt. Letters, Vol. 29, No. 10, 1132 (May 15, 2004)

Somehistoryondiffractionexperiments
In 1665 Francesco M. Grimaldi (an Italian Jesuit, Bolonia, 1618-1663), developed a simple experiment with a light source (a candle), a slit and a screen.
source
He was one of the earliest physicists to suggest that light was wavelike in nature. He formulated a geometrical basis for a wave theory of light in his work: “Physicomathesis de lumine, coloribus, et iride, aliisqueannexis” (Bolonia, 1665). He coined the term diffraction.
Grimaldi’s experiment was disseminated by HonoreFabri (1607-1688). His publications (1669) allowed Isaac Newton to know on these antecedents.
Slit
Screen

Scheme for the diffraction of a laser beam by a circular aperture
xm
aperture
Laser cavity
Detection plane XY (Screen)
R
Camera phone
Fresneldiffractionplane: FresnelZone

Fresnelzones: definition
Area of Fresnel zone number-n:
Generally, it is assumed that all areas of the regions are similar ones.

Fresnel lens hologram
From: S. S. Sarkar, P. K. Sahoo, H. H. Solak, C. David, J. F. van derVeen, Fresnel zone plates made by holography in the extreme ultraviolet region, Journal of Physics: Conference Series, 186 012071 (2009).

SomeResults:Operating in theclassroom

Operating in the classroom
We need a white screen.
Students carry the camera phones.
We need a metric tape.
We need two types of laser pointers. To compare data: One emitting in green light another emitting in red light.
Pictures are taken at fixed distances from the screen.
Laser pointers have to be handled with caution. Radiation can be hazardous to eyes.
Output power: From 1 to 400 mW/cm2.

Propagationdistance: 1 m. Red laser pointer (l= 632 nm)
Image as captured by the camera phone. Type: P3450 (CMOS camera)
Line profile
Intensity: 256 gray levels(8 bits)
1pixel: 29 mm.
pixels pixels

Propagationdistance: 1m. Green laser pointer (l = 532 nm.)
Image as capturedbythe camera phone.
Line profile
pixelspixels

Propagationdistance 3 m. Red laser pointer (l = 632 nm)
Image as captured by the camera.
Line profile
pixels pixels

Propagationdistance: 3m. Green laser pointer (l = 532 nm.)
Image as captured by the camera phone
Line profile
pixels pixels

1 m. propagation diffraction regimes
FFT Intensity FFT Phase FFT Intensity FFT Phase

3 m. propagation diffraction regimes
FFT Intensity FFT Phase FFT Intensity FFT Phase

Results with another camera phone model
Model: Nokia 8600 Luna
Resolution: 1200x1600
400 pixels/cm.
Original captured images:1200x1600
After image treatment for line profile obtention: 150x150 pixels.
Pixel: 25 mm

Green laser pointerpropagation distance: 242 cm
Image as captured by the camera phone
Image treated with falsh color for line profile

Digital image treatment
Image converted into grey scale and treated with colormap
Phase
Square modulus of the FFT: focus

Other proposals: lab-on-a-chip
Holographic optofluidic microscopy
Fundamentals:
Objects of interest are placed directly on the image sensor (i.e. within less than a few micrometers), and utilize either carefully fabricated sub-micron apertures , or multi-frame processing to improve resolution beyond the sensor pixel size limitation.
From: W. Bishara, H. Zhu, and A. Ozcan, Holographic opto-fluidicmicroscopy,
Opt Express. 2010 December 20; 18(26): 27499–27510.

Applications: real time observation of malaria parasites
Portable lensless on-chip microscope:
Resolution: < 1 mm.
Wide-field-of-view: 23 mm2.
Weight: 95 g.
Digital sensor array (CMOS).
W. Bishara, U. Sikora, O. Mudanyali, T. Su, O. Yaglidere, S. Luckhart and A. Ozcan, Holographic pixel super-resolution in portable lenslesson-chip microscopyusing a fiber-opticarray, Lab Chip, 2011, 11, 1276-1279.

Conclusions
Camera phones are very useful for education and technical purposes.
Over the last years, cell phones have become increasingly popular and are ubiquitous.
Cell phones are now equipped with text messaging, internet, camera features, and other facilities.
Cell phones offer many benefits. Technologues can easily use them as a technical tool.
The combination of laser sources and cell phones provides a unique tool for the experimental demonstration of diffraction phenomena in the class room.
The great advantage is that it requires a very reduced infrastructure and can be implemented as a micro-device.
Combination with digital holographic techniques provides a quite promising tool for imaging data manipulation.

OtherReferences
J. C. Wyatt, FresnelDiffraction.nb (Internet available).
Z. Ben Lakhdar, Z.Dhaouadi, H.Ghalila, S.Lahmar and Y. Majdi, “Using mobile camera for a better exploitation and understanding of interference and diffraction experiments”, Proc. The Education and Training in Optics and Photonics (ETOP) (Ed. A. Shore), Proc. SPIE (2009).
“Image sensor market set forcyclicgrowth”, NaturePhotonics, vol.3, November 2009.

GICO-UCM
The Interdisciplinary Group for Optical Computing(GICO-UCM):
María Luisa Calvo Padilla
PavelCheben, National Institute for Microstructural Science, NRC, Ottawa, Canada
Tatiana Alieva
ÓscarMartínez-Matos
José A. Rodrigo (Instituto de Óptica, CSIC)
María de la Paz Hernández-Garay
Alejandro Cámara Iglesias
AitorVillafranca Velasco
Acknowledgements:
- M. C. Fernández-Panadero (UC3M).
- David ParedesBarato (under graduate student, Statistical Optics, 2010, UCM).
http://www.ucm.es/info/giboucm

Example: some recent applications: the Gabor superlens
(a)
From: K. Stollberg, A. Brückner, J. Duparré, P. Dannberg, A. Bräuer and A. Tünnermann, “The Gabor superlens as an alternative wafer-level camera approach inspired by superposition compound eyes of nocturnal insects”, Opt. Express, Vol. 17, No. 18, 15747 (31 August 2009 ).

2011 06 02 (uned) emadrid mlcalvo ucm m learning y holografia tecnicas compatibles

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2011 06 02 (uned) emadrid mlcalvo ucm m learning y holografia tecnicas compatibles — Presentation Transcript