AJP	ISSN : 0971 – 3093 Vol 24, No. 10, October 2015

 

Editorial

Investigation and study of the properties of light has given birth to numerous applications of light encompassing various aspects of our lives and our environment. Study with light in last 50 years, after the first laser light sources became available to the scientists, the field of optics has seen tremendous progress. Light based technologies have contributed immensely in the service of the mankind. Recognizing this, UNESCO has declared the year 2015 as the International Year of Light and Light Based technologies (IYOL 2015). Asian Journal of Physics has taken an initiative to bring out special issues to celebrate IYOL 2015. We are glad to be associated with this effort as Guest Editors of this special issue on Optical Metrology and Sensing which is dedicated to Prof R S Sirohi, an internationally recognised name in the area of this special issue.

Metrology with light has always played an important role in Science and Engineering. Light based techniques/ technologies have some inherent advantages such as being noncontact, non-invasive, full field and very precise. Metrology of a standard meter by Michelson and ‘sensing’ of ‘aether’ by Michelson and Morley using the famous Michelson’s interferometer are examples of classic experiments of great precision achievable by light based techniques in the 19^th century. Use of lasers as a light source in classical experiments has increased the scope, range and sensitivity of optical metrology and sensing. Laser based technologies are expected to play significant role in measurement of time, gravitational waves, bio-medical imaging and measurements and many other associated technologies.

This special issue includes papers from different optical technologies of interest for the issue such as: Interference metrology and phase measurement, Shearography, Talbot interferometry, Holography and speckle techniques, Optical coherence tomography, Photonics crystal fibres, Photopolymer lithography, Computer generated holograms, Optical processing, Nanoparticle imaging, Non linear optical properties of nanoparticles, and Fibre sensors.

 

M P KOTHIYAL         CHANDRA SAKHER          N KRISHNA MOHAN

 

Asian Journal of Physics

Volume 24, No 10,2015

Foreword

                When I received a request from Professor Vinod Rastogi to write the foreword to the special issue at hand, it did not take me a second to give my reply in the affirmative. My reaction was instantaneous because I felt that this was an opportunity to express my appreciation for not only the seminal contributions in optics that Prof. Rajpal Singh Sirohi has made but also to some of the personal traits of his life which are largely unknown to many. I have known him for the past 53 years and it is impossible to detail my impressions of him in a few sentences. At best I can give only some glimpses within the framework and the space that a write-up of the present nature can accommodate.

For recollecting some of the facts, I allowed my memory to go back in time to our student days first in Meerut College Meerut (U.P.) then affiliated with the Agra university, and then to our stay in IIT Delhi. During our Masters program (1962-64) in Meerut, Rajpal was a unique personality in that he unlike most classmates, stayed aloof, always engrossed in his thoughts. We used to call him a ‘philosopher’ because he would often discuss with the teachers some intricate problems in physics. Also, he led an extremely simple life so that he could concentrate fully on his studies. If we could identify one person in the class who spent the maximum time in the laboratory, it was Rajpal. I can not claim that I was his friend during our Masters program because he always maintained certain distance from the classmates except one whom he had known since his school days. A part of the reason was also the fact that I used to stay in the college hostel while he stayed in the city, thus minimizing our interaction. I was a close competitor of his but he scored over me when the final result was declared. He came out as the topper in the class while I came a close second !

Our intimacy grew only when we came to IIT Delhi in 1965 for our Post-M.Sc. program in Applied Optics. Since we were only five students in the class and four of us were residents of the same floor in a hostel, the interaction was quite intense. It was here that I came to know more about his personal traits as also his dedication towards his studies. Being an early riser, I used to go to the washroom early and for that I had to walk past his room in which I used see the lights switched on even at as early as 4.00 AM or so. Lo and behold, he used to be at his study table in the ‘Brahm Muhurt’ ! Sometimes on Sundays or holidays, we used to trek to Qutub Minar through the rocky region that the place was way back in 1964. We also came somewhat closer and could share with each other our moments of disappointment as also those of elation. A more detailed account of our student days at IITD is given in articles elsewhere [1,2].

Even after he left to join IISc Bangalore as a Scientific Officer and I stayed back at IITD, we kept in touch with each other through letters. After he settled down at IIT Madras as a faculty member, our interaction increased considerably because our interests in optics had considerable overlap. Whenever I visited Madras, I had opportunity to stay at his residence where Mrs Vijaya Laxmi Sirohi played a generous and wonderful host. Likewise when he came to Delhi, he stayed with us and would always call my wife as Bhabhijee with much respect. Due to the nature of our professional careers, we kept in close touch with each other through participation in conferences and other meetings. We remained friendly competitors throughout our careers.  

I would restrain myself from enumerating his outstanding professional achievements because these can not be capsuled in a ‘Foreword’ which can provide only a limited space. During Professor Sirohi’s tenure (2000-2005) as Director of IIT Delhi, his acumen as an administrator came to the fore. He dedicated himself wholeheartedly to affect several reforms to make the IITD campus a better place to live in. This and several other aspects of his career are described in detail in an article [2] elsewhere. During my tenure as Dean Postgraduate Studies and Research, I had to attend many meetings where I observed closely his ability to lead meaningful discussions to arrive at just and logical solutions to the problems. He is a firm believer in the theory that it is only through the character building and practice of ethical practices that the country can move forward in the field of education as also in other spheres of life.

Professor Vinod Rastogi deserves our heart-felt gratitude for having taken initiative to bring out the present special issue of the Asian J.Physics in the year 2015 which is being celebrated the world over as the UNESCO sponsored ‘International Year of Light and Light based Technologies’. Through this issue some of the admirers, former students and former colleagues have got an opportunity to express their admiration for Prof. Sirohi by dedicating their articles in his honor. I may add that many special issues of the journal brought out due to the hard work and dedication of Prof. Rastogi have been very well received by the optics community in India and abroad. It is due to his sheer determination that so many prominent authors from India and abroad have contributed articles to these special issues.

                Some of the guest edited issues have been on Optical Pattern Recognition ( Kehar Singh and Joby Joseph), Nonlinear Dynamics in Optics ( M. Belic), Raman Spectroscopy ( W.Kiefer), Speckles in Medicine and Biology ( Sergey S.Ulyanov), Biomedical Spectroscopy & Optical Imaging ( V. Tuchin and A. Priezzhev) Optical and Solid State Sensors ( B.D.Gupta), Optics in Medicine and Biology ( Anil Kishen and A Asundi), Engineering Optics ( Kehar Singh and Rupert C.D.Young), Raman Spectroscopy (T Ilescu and S Simon), Optical Information Security (Kehar Singh), Recent Progress on Photonics (F.T. S. Yu and S. Jutamulia), special issue in honour of Prof Kehar Singh ( Joseph Shamir and V K Rastogi), and special issues in honor of Dr. A K Gupta ex-director IRDE Dehradun, and Prof. G D Barua, Dibrugargh University, India. Special issue in honour Prof Joseph Shamir ( F T S Yu and S Fainman), and Terahertz Optics (S S Negi and N Dixit) are in the pipeline.

                Professor Sirohi has mentored and inspired three generations of students, and still continues to be active in spreading the knowledge of optics. He has been a role model for many researchers and it is only in the fitness of things that the present issue on ‘Optical Metrology and Sensing Techniques’ guest edited by Prof. M P Kothiyal, Prof. Chandra Shakher, and Dr.N Krishna Mohan, has been dedicated in his honor. May Prof Sirohi be blessed by the Almighty so that he continues to enjoy good health and carry on with his passionate pursuit of knowledge!

                I also wish to thank Prof. Rastogi for having invited me to write the ‘Foreword’ to this special issue. I wish him many more years of dedicated service to the cause of physics in general and optics in particular, by way of dissemination of information. May the Almighty keep him in good health and best of spirits!

Kehar Singh

Formerly Professor Physics Department, IIT Delhi

[1] Kehar Singh, Optics and Photonics at IIT Delhi ; Past and Present, in ‘FOP-11: XXXVI OSI Symp.on Frontiers in Optics and

   Photonics, Dec.3-5, 2011. IIT Delhi. Also see ‘Optics and Photonics News India’ (OSA) Vol.1 issue 1.

[2] R S Sirohi, Nostalgia, Chapter.2 in  Kehar Singh (Editor) Those Were the Days: Golden Jubilee Memoirs of Former Faculty

   Members of IIT Delhi (Viva Books 2015, Published for the Golden Jubilee Committee IIT Delhi)

Vol. 24, No 10 (2015) 1301-1315

 Photorefractive speckle techniques for displacement and vibration measurement

 

Renu Tripathi¹ and Kehar Singh²

¹Physics and Engineering Department, Delaware State University, Dover, DE 19901 (USA)

²ITM University, Sector 23-A, Gurgaon-122 017, India

When fairly coherent light is diffusely reflected from, or transmitted through a randomly rough surface, the scattered components with random phase fluctuations interfere with one another, giving rise to a pattern in which there appears a random distribution of bright and dark regions of intensity. Such a salt and pepper appearance has come to be known as the speckle pattern. Considered undesirable in certain situations, the speckle phenomenon has been put to many useful applications because the speckles are carriers of information pertaining to the scattering surface. In the early phases of development of the subject, photographic plates were used to record speckles. However, due to the time-consuming nature of the photographic processing, the spatial light modulators, photorefractive materials, and the CCDs began to be used for quasi real-time recording of the intensity patterns. In this paper, we present an overview of the research conducted on photorefractive speckle techniques as engineering tool for various types of displacement and vibration measurements, with special reference to the work carried out at IIT Delhi. We begin with a brief review of the speckle photography technique and photorefractive effect followed by a discussion of our research leading to progressive development of photorefractive-based speckle techniques for three-dimensional displacement and vibration measurements. We have also included our work on speckle correlation technique in some detail as it provides a simple and convenient tool for accurately measuring and assessing object displacements in real-time. © Anita Publications. All rights reserved.

Keywords: Speckle metrology, Motion measurement, Optical correlator, Photorefractive crystals.

Total Refs: 105

References

1. J C, (Ed) Laser Speckle and Related Phenomena, (Springer, Berlin 1975, 2nd edn),1984.
2. Francon M , Laser Speckles and Applications in Optics, (Academic Press, New York), 1979): English translation by H HArsenault.
3. Erf R K (Ed), Speckle Metrology, (Academic Press, New York), 1978 .
4. Jones R, Wykes C, Holographic and Speckle Interferometry, (Cambridge Univ Press, Cambr, UK ), 1989.
5. Sirohi R S, (Ed) Speckle Metrology, (Marcel Dekker, New York), 1993.
6. Sirohi R S, (Ed), Selected Papers on Speckle Metrolog, SPIE MS-35 (SPIE Press, Bellingham, WA),1995.
7. Zel’dowich B Y, Mamaev A V, Shkunov V V, Speckle-Wave Interactions in Applications to Holography and Nonlinear Optics, (CRC Press, Boca Raton Florida, USA), 1995.
8. Meinlschmidt P, Hinsch K D, Sirohi R S, (Eds), Electronic Speckle Interferometry: Theory and Practice, SPIE- MS 132, (SPIE Press Bellingham,WA), 1996.
9. Fomin N A, Speckle Photography for Fluid Mechanics Measurements, (Springer-Verlag, Heidelberg), 1998.
10. Jacquot P, Fournier J-M, (Eds), Interferometry in Speckle Light, (Springer, Berlin), 2000

Photorefractive speckle techniques for displacement and vibration measurement.pdf.

---

Vol. 24, No 10 (2015) 1317-1338

Single-shot interferometry techniques for optical testing

 

Paul Kumar Upputuri^1*, Krishna Mohan Nandigana², and Mahendra Prasad Kothiyal²

¹School of Chemical and Biomedical Engineering, Nanyang Technological University, Singapore 637459

²Superannuated from the Applied Optics Laboratory, Department of Physics, Indian Institute of Technology Madras, Chennai-600 036, India

Interferometry is a well-established whole-filed non-contact highly sensitive measurement tool for optical metrology and testing. Phase shifting techniques have been widely used for quantitative interference fringe analysis. These techniques can provide accurate phase measurement, but not suitable for measurements in dynamic environment. The single shot procedures allow measurements in out-of-lab environment and makes the measurement simpler, faster, and less expensive for industrial applications. In recent years, much progress has been made in the field of quantitative analysis of single interferogram or multiple interferograms recorded in one shot. This article reviews the currently used single shot techniques. The procedures are presented with the help of measurement examples. © Anita Publications. All rights reserved.

Vol. 24, No 10 (2015) 1339-1354

Interferometry with broadband light: Applications in metrology

 

Mahendra Prasad Kothiyal¹ and Paul Kumar Upputuri²

¹Superannuated from the Applied Optics Laboratory,Department of Physics, Indian Institute of Technology Madras- 600 036, India

²School of Chemical and Biomedical Engineering, Nanyang Technological University, Singapore 637459

A broadband light interference pattern provides phase information corresponding to a range of wavelengths simultaneously.  In the recent times a variety of applications such as 3D surface profiling, film thickness measurement, dispersion measurement, optical coherence tomography, long length metrology have been developed by extracting the phase information from the interferogram. Some of these procedures have been reviewed here. © Anita Publications. All rights reserved.

Keywords: Interferometry, Broadband light, Interferogram, Fourier transform, Super Luminescent Diode (SLD).

Total Refs: 39

  Vol. 24, No 10 (2015) 1355-1361

Whole-field non-scanning white-light interferometry for surface metrology

 

Basanta Bhaduri¹ and Gabriel Popescu²

¹Department of Applied Physics, Indian School of Mines, Dhanbad, Jharkhand- 826 004, India

²Department of Electrical and Computer Engineering,University of Illinois at Urbana Champaign Urbana, Illinois-61801, USA

Rapid, noncontact surface metrology is essential in many applications.Though optical interferometric techniques are non-invasive, they are either slow or noise-prone. Here we present two different whole-field non-scanning white-light interferometry techniques which are useful for rapid surface metrology with reduced noise. Experimental data for both the techniques are presented. © Anita Publications. All rights reserved.

Keywords: Atomic force microscope, Scanning electron microscope, Optoelectronics, White light interferometer

Total Refs: 18

Vol. 24, No 10 (2015) 1363-1372

Design and fabrication of holographic optical elements for the generation of tilted and accelerating Airy beams

 

Raghu Dharmavarapu, A Vijayakumar and Shanti Bhattacharya

Center for NEMS and Nanophotonics, Department of Electrical Engineering,

Indian Institute of Technology Madras, Chennai, India

A modified perspective for the generation of tilted and acceleratingAiry beams using computer generated holography is presented. The optical system simulated in computer for the generation of such beams consists of an axicon and a Beam Path Steering Element (BPSE). The axicon generates the zeroth order Bessel-like beam propagating along the optics axis while the BPSE converts the zeroth order Bessel-like beam into an accelerating beam. The beam path profile of the accelerating beam can be precisely engineered by accurate selection of the phase profile of the BPSE. The diffraction patterns of the element were simulated in the far field using Fraunhofer diffraction formula. The computer generated holographic optical elements were fabricated using electron beam direct writing. The evaluation results matched well with the simulation results. © Anita Publications. All rights reserved.

Keywords: Accelerating Airy beams, Bessel beam, Computer generated holography

Total Refs:26

Vol. 24, No 10 (2015) 1373-1379

Photothermal techniques for nanoparticle imaging

 

Anita R Warrier¹, Voma Udaykumar², C Vijayan², K P Vijayakumar³ and C Sudha Kartha⁴

¹Amet University, Kanathur, Chennai, India

²Indian Institute of Technology Madras, Chennai-India

³Cochin University of Science and Technology, Cochin, India

In this article we summarize various imaging techniques based on the principle of ‘photothermal effect’. Photothermal techniques for imaging of nanoparticles, thin films and biological specimens have recently been gaining wide attention and topical importance. These include techniques such as photoacoustics, photothermal radiometry, photothermal beam deflection technique, photothermal microscopy and photothermal heterodyne techniques, which are non-destructive analytical techniques that allow three dimensional high resolution imaging and depth profiling. In this article we give a brief review report on the basic principle and experimental technique of photothermal techniques for imaging of thin films and nanoparticles. © Anita Publications. All rights reserved.   

Vol. 24, No 10 (2015) 1381-1389

Optical, structural and third order nonlinear optical properties of Ge nanoparticles prepared by laser ablation in acetone

 

V Sreeramulu, V Saikiran and D Narayana Rao

School of Physics, University of Hyderabad, Hyderabad-500 046, India

Here, we report on the synthesis of germanium (Ge) nanoaprticles (NPs) using pulsed laser ablation and their third order nonlinear optical properties using Z-scan and degenerate fourwave mixing (DFWM) techniques with 532 nm, picosecond laser pulses. Transmission electron microscopy (TEM) and UV-Vis absorption measurements reveal the formation of nanosized particles of Ge in acetone solution. Mircro Raman scattering experiments reveal the formation of crystalline Ge NPs and the photoluminiscence spectra show the blue emission from the Ge NPs. On the basis of TEM measurements, we estimated the average size of the Ge NPs as ~ 12nm. The nonlinear absorption coefficient (β) and the nonlinear refraction (n₂) were measured using Z-scan technique and found to be 1.75×10^-10 cm/W and 6.8×0^-15 cm²/W, respectively. The third order nonlinear susceptability and temporal response of Ge NPs were measured through DFWM technique using 532 nm, picosecond laser pulses.© Anita Publications. All rights reserved.

Keywords: Pulsed laser ablation, Germanium, nonlinear absorption, nonlinear refraction, Z-scan, degenearate fourwave mixing.

Total Refs: 29

 Vol. 24, No 10 (2015) 1391-1400

Improvement of phase map quality for Michelson interferometer based spatial phase-shift digital shearography

 

Xin Xie1, Junrui Li¹, Bin Zhang^1,4, Liping Yan^1,3, and Lianxiang Yang^1,2

¹Optical Laboratory, Department of Mechanical Engineering, Oakland University, Rochester, Michigan, 48309, USA

²School of Instrument Science and Opto-electronics Engineering, Beijing Information Science and Technology Beijing, 100192, China

³Nanometer Measurement Laboratory, Zhejiang Sci-Tech University, Hangzhou, 310018, China

⁴Department of Physics, Beijing Jiaotong University, Beijing, 100044, China

The recently fast developed spatial phase-shift digital shearography technique suits well for non-destructive testing and strain measurement under continuous/dynamic loading condition which greatly extended the application range of digital shearography. However, the phase map quality of the spatial phase shift digital shearography is usually relatively low comparing to conventional temporal phase-shift based digital shearography. This paper introduces a series of new developments on improving the phase map quality for Michelson Interferometer based spatial phase-shift digital shearography including using innovated optical path design, aperture design and directional enhanced smoothing algorithm. The theory, optical analysis, experimental setup and data comparison are shown in detail in this article. © Anita Publications. All rights reserved.

Keywords: Digital shearography, Michelson Interferometer, Temporal phase-shift

Total Refs : 11

Vol. 24, No 10 (2015) 1403-1418

Swept source based optical coherence tomography system at 1320nm-A comprehensive analysis of the opto-mechatronic instrumentation scheme

 

Ratheesh Kumar Meleppat, Murukeshan Vadakke Matham, and Seah Leong Keey

Center for Optical & Laser Engineering, School of Mechanical & Aerospace Engineering, Nanyang Technological University,

50 Nanyang Avenue, Singapore 639798

In this paper, we demonstrate an in-house developed swept source based optical coherence tomography system with detailed analysis of the instrumentation schemes from opto-mechatronic perspectives and measuring challenges for the system development. A novel numerical wavenumber calibration scheme, which can accomplish highly precise and stable measurement on a real time basis, was also demonstrated. The instrumentation scheme, involving both the optoelectronic hardware design and the signal processing schemes for the image construction, has been illustrated by discussing their technical relevance. A brief review and a comparative analysis of the major signal processing schemes were also presented. The developed imaging system is based on a rapidly sweeping wavelength source operating at 16 kHz with a central wavelength of 1320nm and bandwidth 100nm.An axial resolution of 8.5µm (in air) was obtained after the spectral apodization and spectral phase based wavenumber linearization of the fringes. An excellent peak sensitivity attractive for bio imaging applications was achieved. The developed system has a temporal resolution of 0.04s that can generate 512×1024 pixel images. It has been demonstrated that the experimentally determined values of the imaging parameters such as the axial resolution, depth and sensitivity are in good agreement with the theoretically predicated values. The feasibility of the system for in-vivo biomedical imaging has been demonstrated by acquiring the images of human finger nail and anterior chamber of a pig’s eye as test samples.© Anita Publications. All rights reserved.

Keywords: Optical coherence tomography, optical frequency domain imaging, low coherence imaging.

Vol. 24, No 10 (2015) 1419-1424

Transmission properties of nematic liquid crystal infiltrated photonic crystal fibers

 

Ranjini Radhakrishnan, V K  Shinoj and Murukeshan Vadakke Matham

School of Mechanical and Aerospace Engineering,

Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798, Singapore

This paper demonstrates the guidance properties of nematic liquid crystal infiltrated photonic crystal fibers. The transmission intensity distribution through liquid crystal infiltrated photonic crystal fibers are studied for hollow-core and solid-core photonic crystal fibers. It is found that the infiltration of liquid crystal into the fiber holes causes significant change in the guidance properties of such fibers. The switchable guidance property of photonic crystal fibers along with the tunable properties of liquid-crystal can play a vital role in lab-on-a-chip device applications.© Anita Publications. All rights reserved.

Keywords: Photonic crystal fiber, Liquid crystal, Hollow-core photonic fiber, Solid-core photonic fiber.

Vol. 24, No 10 (2015) 1425-1429

Watermarking of phase-only Fresnel hologram using symmetrical 3D modified Gerchberg-Saxton algorithm

 

Dhirendra Kumar and Naveen K Nishchal

Department of Physics, Indian Institute of Technology Patna, Patna-801 118, India

A watermarking technique for phase-only Fresnel hologram using symmetrical three-dimensional (3D) modified Gerchberg-Saxton (GS) algorithm has been proposed. The phase-only Fresnel hologram (POFH) of multi-plane object is synthesized using symmetrical 3D modified GS algorithm. Reconstruction from the POFH and the watermarked POFH has been demonstrated through simulation results. © Anita Publications. All rights reserved.

Keywords: Digital holography; Fresnel diffraction; Phase retrieval; Watermarking

Total  Refs :16

 Vol. 24, No 10 (2015) 1431-1435

Shearograms and optical currents

 

P Senthilkumaran

Department of Physics, Indian Institute of Technology Delhi, New Delhi- 110 016, India

Shearogram reveals components of the transverse phase gradient of a wave front. This is in contrast to Fizeau interferograms where the phase is visualized. The time averaged energy flow in optical beams in isotropic linear medium, namely the Poynting vector points in the direction of phase gradient in scalar optical beams. Hence there is a possibility of extracting information about the optical currents from shearograms. This article presents how one can approach this problem of finding optical currents from shearograms. © Anita Publications. All rights reserved.

Keywords: Shear, Electromagnetic fields, Poynting vector, Interferograms, Shearogram

Vol. 24, No 10 (2015) 1437-1441

Investigation of phase objects using holographic optical element

based digital speckle pattern interferometry

 

Manoj Kumar and Chandra Shakher

Laser Applications and Holography Laboratory, Instrument Design Development Centre,

Indian Institute of Technology Delhi, New Delhi – 110 016, India

Digital speckle pattern shearing interferometry based on volume phase holographic grating combined with ground glass for the measurement of refractive index and temperature distribution in gaseous flames is presented. © Anita Publications. All rights reserved.

Keywords: Refractive index, Temperature distribution; Volume phase holographic grating, Digital Speckle Pattern Shearing Interferometry.

Total  Refs12

  Vol. 24, No 10 (2015) 1443-1447

Magnetic promotion of combustion temperature in candle flame
by using Talbot interferometry

 

Shilpi Agarwal and Chandra Shakher

Laser Applications and Holography Laboratory, Instrument Design Development Centre,

Indian Institute of Technology Delhi, New Delhi – 110 016, India

This paper presents the experimental investigation of the effect of magnetic field on temperature inside the candle flame using circular gratings Talbot interferometer. The Experimental results reveal that the flame temperature is affected in the presence of gradient magnetic field. © Anita Publications. All rights reserved.

Keywords: Talbot Interferometer, Magnetic Gradient field, Combustion, Circular gratings, Magnetic field.

 Vol. 24, No 10 (2015) 1449-1465

Photopolymer Holography : Review and investigations

 

Sanjay Kumar, V Padmanapan Rao and Joby Joseph

Department of Physics, Indian Institute of Technology Delhi

Hauz Khas, New Delhi – 110 016, India

Photopolymers are preferred in holography due to their additional advantage of being self-developing along with high resolution. In the present paper, an attempt has been made to review the work relating to the holograms recorded and reconstructed in different types of photopolymers using single/multiple wavelengths. In addition, results of experiments performed on a customized photopolymer with optimized acrylamide concentration and dye concentration for achieving higher diffraction efficiency, are also presented. The results obtained are comparable to the results reported in the literature. A maximum diffraction efficiency of about 88% has been achieved using acrylamide-based photopolymer with Erythrosin B dye.© Anita Publications. All rights reserved.
Keywords: Holograms, Photopolymers, Photosensitive Materials, Diffraction Efficiency, Holographic Diffraction Gratings, Diffractive Optical Elements, Holographic Optical elements, Chain Transfer Agent.

Total Refs : 97

 Vol. 24, No 10 (2015) 1467-1471

Multidimensional measurement by hybrid digital holographic
microscopy for biological applications

 

Osamu Matoba¹, Xiangyu Quan¹, Peng Xia¹, and  Yasuhiro Awatsuji²

¹ Graduate School of System Informatics, Kobe University, Rokkodai 1-1, Nada-ku, Kobe 657-8501, Japan

² Graduate School of Science and Technology, Kyoto Institute of Technology, Matsugasaki, Sakyo-ku, Kyoto 606-8585, Japan

Photopolymers are preferred in holography due to their additional advantage of being self-developing along with high resolution. In the present paper, an attempt has been made to review the work relating to the holograms recorded and reconstructed in different types of photopolymers using single/multiple wavelengths. In addition, results of experiments performed on a customized photopolymer with optimized acrylamide concentration and dye concentration for achieving higher diffraction efficiency, are also presented. The results obtained are comparable to the results reported in the literature. A maximum diffraction efficiency of about 88% has been achieved using acrylamide-based photopolymer with Erythrosin B dye © Anita Publications. All rights reserved.

Keywords: Holograms, Photopolymers, Photosensitive Materials, Diffraction Efficiency, Holographic Diffraction Gratings, Diffractive Optical Elements, Holographic Optical elements, Chain Transfer Agent.

Total Refs : 15

 Vol. 24, No 10 (2015) 1473-1496

Curved computer generated holograms for dynamic 3D displays

 

Boaz Jessie Jackin and Toyohiko Yatagai

Center for Optical Research and Education, Utsunomiya University

Yoto, Utsunomiya, Tochigi, Japan, 321-8585

Holography is considered as the best candidate for realizing dynamic 3D displays for which the techniques of computer generated holography (CGH) is used. But practical realization of such a display device is being delayed due to i) the unavailability of a light modulating device with pixel pitch less than 1µm and ii) the need to process very large data using a machine that fits on a desk. This article focuses on both the problems by adoption of curved displays as a solution to the first problem and development of efficient fast computation methods as the solution to the second problem. We discuss how the constraint on the pixel pitch (sub-micron sized pixel) gets removed, when we move from the conventional flat holographic displays to curved displays. We also present the current status of curved holographic displays through a short review, and analyses the challenges to be addressed and the solutions. Among those solutions, this article explains in detail the fast computation algorithms for cylindrical and spherical CGH’s, which are our original contribution in this research area. The fast computation methods are demonstrated and verified using simulation results. Future research direction and technology developments needed to fully realize a dynamic 3D holographic display is presented at the end. © Anita Publications. All rights reserved.

Keywords: 3D display, Curved display, Holography, Diffraction theory, Fast computation method.

 Vol. 24, No 10 (2015) 1499-1504

 Measurement of high and low currents using single Bragg
grating for industrial applications

 

I V Anudeep Kumar Reddy¹, P Saidi Reddy¹, G R C Reddy¹, R L N Sai Prasad², and U K Tiwari³

¹National Institute of Technology Goa, Farmagudi, Ponda, Goa-403 401, India

²National Institute of Technology Warangal, Telangana-506 004, India

³CSIR-Central Scientific Instruments Organisation, Sector 30, Chandigarh-160 030, India

This paper presents a novel structure of current sensor that has been designed and developed. This proposed sensor makes use of a solenoid and fiber Bragg grating for the measurement of current. When a current is allowed to pass through a solenoid the magnetic field produced attracts the soft-iron bar kept at the end of hallow space, towards its center. If a Bragg grating is attached in between soft-iron bar and a fixed end, as current passes through the solenoid, the soft-iron bar stimulates strain in fiber Bragg grating resulting in a Bragg wavelength shift by which one can measure the current. Theoretical and experimental results are simulated using MATLAB. It is observed that the sensor exhibits good linearity and sensitivity. © Anita Publications. All rights reserved.

Keywords:  Fiber Bragg grating, Optical fiber sensors, Torsion angle, Solenoid.

Total Refs : 11