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Co-Authors
- T. Sivanesan
- S. Pandi
- S. Rajagopalan Nair
- P. Perraju
- J. K. Nanda
- H. Sarvothaman
- N. P. Nathan
- S. Sundara Raghavan
- R. Raman
- S. Vanitha
- M. Praba
- B. Raghavendra Prasad
- Dipankar Banerjee
- Jagdev Singh
- S. Nagabhushana
- Amit Kumar
- P. U. Kamath
- S. Kathiravan
- Suresh Venkata
- N. Rajkumar
- Madhur Juneja
- Pawan Somu
- Vaibhav Pant
- Nigar Shaji
- K. Sankarsubramanian
- Asit Patra
- R. Venkateswaran
- Abhijit Avinash Adoni
- S. Narendra
- T. R. Haridas
- Shibu K. Mathew
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Journals
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Natarajan, V.
- Non-linear Optical Properties of α-glycine Single Crystals by Z-scan Technique
Abstract Views :473 |
PDF Views:129
Authors
Affiliations
1 Dept. of Physics, Aksheya Engineering College, Puludivakkam- 603 314, Kanchipuram Dt. Tamil Nadu, IN
2 Rajalakshmi Institute of Technology, Kunthampakkam-602 107, Kanchipuram Dt., Tamil Nadu, IN
3 Dept. of Physics, Presidency College, Chennai- 600 005, IN
1 Dept. of Physics, Aksheya Engineering College, Puludivakkam- 603 314, Kanchipuram Dt. Tamil Nadu, IN
2 Rajalakshmi Institute of Technology, Kunthampakkam-602 107, Kanchipuram Dt., Tamil Nadu, IN
3 Dept. of Physics, Presidency College, Chennai- 600 005, IN
Source
Indian Journal of Science and Technology, Vol 3, No 6 (2010), Pagination: 653-655Abstract
Single crystals of α-Glycine up to the size of 4 × 4 × 1 mm3 were grown for optical characterization by the solution growth method using methanol as a solvent. The crystal structure was studied by X-ray diffraction. The UV-visual absorption spectra indicate a good transparency between 200 and 1400 nm. The non-linear refractive index n2 and susceptibility χ (3) have been measured through the Z-scan technique. α-Glycine exhibits saturation absorption and self-focusing performance. Non-linear absorption co-efficient β is determined as 2.4763 x 10 -5 cm/W. Non-linear refractive index n2 measured at the wavelength of 632.8 nm is calculated as 2.14435 x 10-8 cm2/W. The real and imaginary pars of χ (3) have been measured at 632.8 nm and found to be 7.9732 x 10-07 esu and 8.0018 x 10-07 esu, respectively. The measured 3rd order non-linear properties confirm its suitability for non-linear optical devices such as optical switching device.Keywords
Single XRD, α-Glycine, UV Spectrum, Z-scan, Crystal GrowthFull Text
References
- Fryad Z. Henari, Shane MacNamara, Orla Stevenson, Joesph Callagham, Declan Weldon, Werner J. Blau, (1993) Low power nonlinear optical response of C60 and C70 fullerene solutions Adv.Mater. 5, 930.-936.
- Gu G, Zhang W, Zen H, Du Y, Han Y, Dong F and Xia Y (1993) Large non-linear absorption in C60 thin films. J. Phys. B. 26, L451- L456.
- Gu G, Zhang W, Zen H, Du Y, Han Y, Dong F and Xia Y (1993) Large non-linear absorption in C60 thin films J. Phys. B 26 L451- L456.
- Henari FZ, MacNamara S, Stevenson O, Callagham J, Weldon D and Blau WJ (1993) Low power non-linear optical response of C60 and C70 fullerene solutions. Adv. Mater. 5, 930-936.
- Kurtz SK and Perry TT (1968) A powder technique for the evaluation of non-linear optical materials. J. Appl.Phys. 39, 3798-3812.
- Sheik–Bahe M, Said AA, Wei TH, Hagan DJ and Van Stryland EW (1990) Sensitive measurement of optical nonlinearities using a single IEEE. J. Quantum Electron. 26, 760-769.
- Wei TH, Hagan DJ, Sence MJ, Van Stryland EW, Perry JW and Coulter DR (1992) Direct measurements of non-linear absorption and refraction in solutions ofphthalocyanines. Appl. Phys. B. 54, 46-51.
- Yin M, Li HP, Tang SH and Ji W (2000) Determination of non-linear absortion and refraction by single Z-scan method. Appl. Phys. B. 70, 587-591.
- Zhao W and Palffy-Muhoray P (1994) Z-scan measurement of χ(3) using top- hat beams. Appl. Phys. Lett. 65, 673-675.
- Third Order Non-linear Optical Properties of Potassium Aluminium Sulphate Single Crystals by Z-scan Technique
Abstract Views :460 |
PDF Views:148
Authors
Affiliations
1 Department of Physics, Rajalakshmi Institute of Technology, Kuthampakkam – 602 107, Chennai, IN
2 Department of Physics Aksheyaa College of Engineering, Puludivakkam – 603 314, Kanchipuram Dt., IN
3 Head Department of Physics, Presidency College, Chennai – 600 005, IN
1 Department of Physics, Rajalakshmi Institute of Technology, Kuthampakkam – 602 107, Chennai, IN
2 Department of Physics Aksheyaa College of Engineering, Puludivakkam – 603 314, Kanchipuram Dt., IN
3 Head Department of Physics, Presidency College, Chennai – 600 005, IN
Source
Indian Journal of Science and Technology, Vol 3, No 6 (2010), Pagination: 656-658Abstract
Potassium aluminum sulphate dodeca hydrate crystals were grown from aqueous solution and studied by X-ray diffraction. The UV-Visual IR transmission spectra indicate a better transparency between 200 and 800 nm. The nonlinear refractive index n2 and susceptibility χ(3) have been measured through the Z-scan technique. The results indicate that the compound exhibits saturation absorption and self-focusing performance. Non-linear absorption Co-efficient β is determined as 7.6746 x 10 -4 cm/W. Non-linear refractive index n2 measured at the wavelength of 632.8 nm is calculated as 1.46412 x 10-8 cm2/W. The real and imaginary pars of χ(3) have been measured at 632.8 nm and found to be 7.84088 x 10-07 esu and 2.07218 x 10-08 esu, respectively. The measured 3rd order non-linear properties confirm its suitability for nonlinear optical devices such as optical limiting and switching.Keywords
Growth from Solution, Single XRD, UV Spectrum, Z-scanFull Text
References
- Fryad Z. Henari, Shane MacNamara, Orla Stevenson, Joesph Callagham, Declan Weldon and Werner J. Blau (1993) Low power nonlinear optical response of C60 and C70 fullerene solutions. Adv.Mater. 5, 930-936.
- Krauss TD and Wise FW (1994) Femtosecond measurement of nonlinear absorption and refraction in CdS, ZnSe, and ZnS. Appl. Phys. Lett. 65 1739-1741.
- Kurtz SK and Perry TT (1968) A powder technique for the evaluation of nonlinear optical materials. J. Appl. Phys. 39, 3798-3812.
- Lee W. Tutt and Thomas F. Boggess (1993) A review of optical limiting mechanisms and devices using organics, fullerenes, semiconductors and other materials. Prog. Quant. Elecr. 17, 299-306.
- Li L, Yuan HJ, Hu GH and Palffy-Muthoray P (1994) A new configurational transition in inhomogeneous nematics. Liq. Cryst. 16, 703-712.
- Ma Ma H. Gomes ASL and de Araujo GB (1992) Infrared nonlinearity of commercial Cd (S, Se) glasscomposites. Opt. Commun. 87, 19-22.
- Paparo D, Maddalena P, Abbade G, Santamato E and Jannossy (1994) Wavelength Dependence of Optical Reorientation in Dye-Doped Nematics Mol. Cryst. Liq. Cryst. 251 73-84.
- Rangel-Rojo R, Kosa T, Hajito E, Ewen PJS, Owen AE, Kar AK and Whereett BS (1994) Near-infrared optical nonlinearities in amorphous chalcogenides. Opt. Commun. 109, 145-150.
- Sheik–Bahe M, Said AA, Wei TH, Hagan DJ and Van Stryland EW (1990) Sensitive measurement of optical nonlinearities using a single. IEEE J. Quantum Electron. 26, 760-769.
- Sheik-Bahe M, Wang J and Van Stryland EW (1994) Non-degenerate optical Kerr effect in semiconductors IEEE J. Quantum Electron. 30, 249-255
- Sivanesan T, Natarajan V and Pandi S (2010) Nonlinear optical properties of α-glycine single crystals by Z-Scan technique. Indian J.Sci.Technol. 3 (6), this issue. Domain name: http://www.indjst.org.
- Wei TH , Hagan DJ, Sence MJ, Van Stryland EW, Perry JW and Coulter DR (1992) Direct measurements of nonlinear absorption and refraction in solutions of phthalocyanines, Appl. Phys. B 54, 46-51.
- Yin M, Li HP, Tang SH and Ji W (2000) Determination of nonlinear absorption and refraction by single Zscan method. Appl. Phys. B 70, 587-591.
- Zhao W and Palffy-Muhoray P (1993) Z-scan technique using top-hat beams. Appl. Phys. Lett. 63, 1613-1615.
- Zhao W and Palffy-Muhoray P (1994) Z- scan measurement of χ(3) using top- hat beams. Appl. Phys. Lett. 65, 673-675.
- Third Order Non-linear Optical Properties of L-arginine Hydrochloride Monohydrate Single Crystals by Z-scan Technique
Abstract Views :550 |
PDF Views:139
Authors
Affiliations
1 Dept. of Physics, Rajalakshmi Institute of Technology, Kunthampakkam-602124, TN, IN
2 Dept. of Physics, Aksheyaa College of Engineering, Puluthivakkam, Kanchipuram 603 314, TN, IN
3 Dept. of Physics, Presidency College, Chennai- 600 005, IN
1 Dept. of Physics, Rajalakshmi Institute of Technology, Kunthampakkam-602124, TN, IN
2 Dept. of Physics, Aksheyaa College of Engineering, Puluthivakkam, Kanchipuram 603 314, TN, IN
3 Dept. of Physics, Presidency College, Chennai- 600 005, IN
Source
Indian Journal of Science and Technology, Vol 3, No 8 (2010), Pagination: 897-899Abstract
L-arginine hydrochloride monohydrate (L-arginine hydrochloride monohydrate) was synthesized by the reaction between hydrochloric acid and the strongly basic amino acid, L-arginine taken in the ratio of 1:1. The crystal structure of the sample was studied by single X-ray diffraction. The UV transmittance spectra of the grown crystals indicate a good transparency between 200 and 1000 nm. The nonlinear refractive index η2 and susceptibility χ(3) have been measured through the Z-scan technique. The results indicate that the compound exhibits reverse saturation absorption and selfdefocusing performance. Non-linear absorption co-efficient is determined as 9.2194 x 10- 4 cm/w. The non-linear refractive index of the L-arginine hydrochloride single crystals were found to be 1.7129 x 10- 7cm 2/w. The real and imaginary pars of non-linear susceptibility χ(3) have been measured at 632.8 nm and found to be 1.1573 x 10-05 esu and 3.1382 x 10-05 esu, respectively.Keywords
Growth from Solution, Single XRD, UV Spectrum, Z-scanFull Text
References
- Fryad Z Henari, Shane MacNamara, Stevenson O, Callagham J, Weldon D and Blau WJ (1993) Low power nonlinear optical response of C60 and C70 fullerene solutions. Adv. Mater. 5, 930-936.
- Gomes MH and De Araujo GB (1992) Infrared non-linearity of commercial Cd(S, Se) glass composites. Opt. Commun. 87, 19-22.
- Kalaiselvi D, Mohan Kumar R and Jayavel R (2008) Single crystal growth and properties of semi-organic nonlinear optical L-arginine hydrochloride monohydrate crystals. Cryst. Res. Technol. 43(8), 851–856.
- Kurtz SK and Perry TT (1968) A powder technique for the evaluation of non-linear optical materials. J. Appl. Phys. 39, 3798-3812.
- Lee W Tutt and Boggess TF(1993) A review of optical limiting mechanisms and devices using organics, fullerenes, semiconductors and other materials. Prog. Quant. Elecr. 17, 299-306.
- Li L, Yuan HJ, Hu GH and Palffy- Muthoray P (1994) A new configurational transition in inhomogeneous nematics. Liq. Cryst. 16, 703-712.
- Meera K, Muralidharan R, Dhanasekaran R, Manyum P and Ramasamy P (2004) Growth of non-linear optical material: Larginine hydrochloride and its characterization. J. Crystal Growth. 263, 510–516.
- Monaco SB, Davis LE, Velso SP, Wang FT, Eimerl D and Zalkin A (1987) Synthesis and characterization of chemical analogs of L-arginine phosphate. J. Crystal Growth. 85, 252- 257.
- Natarajan V, Sivanesan T and Pandi S (2010) Third order nonlinear optical properties of potassium aluminium sulphate single crystals by Z-Scan technique. Indian J.Sci.Technol. 3 (6), 656-658.
- Paparo D, Maddalena P, Abbade G, Santamato E and Jannossy (1994) Wavelength dependence of optical reorientation in dye-doped nematics. Mol. Cryst. Liq. Cryst. 251, 73-84.
- Rangel-Rojo R, Kosa T, Hajito E, Ewen PJS, Owen AE, Kar AK and Whereett BS (1994) Near-infrared optical non-linearities in amorphous chalcogenides. Opt. Commun. 109, 145-150.
- Sivanesan T, Natarajan V and Pandi S (2010) Non-linear optical properties of a-glycine single crystals by Z-Scan technique. Indian J.Sci.Technol. 3 (6), 653-655.
- Tod D Krauss and Wise FW (1994)Femto-second measurement of non-linear absorption and refraction in CdS, ZnSe, and ZnS. Appl. Phys. Lett. 65, 1739-1741.
- Wei TH, Hagan DJ and Sence MJ, Van Stryland EW, Perry JW and Coulter DR (1992) Direct measurements of non-linear absorption and refraction in solutions of phthalocyanines. Appl. Phys. B. 54, 46-51.
- Yin M, Li HP, Tang SH and Ji W (2000) Determination of non-linear absorption and refraction by single Z-scan method. Appl. Phys. B. 70, 587-591.
- Zhang W, Zen H, Du Y, Han Y, Dong F and Xia Y (1993) Large non-linear absorption in C60 thin films. J. Phys. B. 26, L451-L456.
- Zhao W and Palffy-Muhoray P (1993) Z-scan technique using top-hat beams. Appl. Phys. Lett. 63, 1613-1615.
- Post-Kurnool Thrust and other Structural Features in the Northeast Part of the Palnad Basin, Krishna District, Andhra Pradesh
Abstract Views :171 |
PDF Views:2
Authors
Affiliations
1 Geological Survey of India, Andhra Pradesh Circle (N), Hyderabad 500029, IN
1 Geological Survey of India, Andhra Pradesh Circle (N), Hyderabad 500029, IN
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 18, No 3 (1977), Pagination: 111-116Abstract
In the northeast part of the Palnad Basin, Krishna district, Andhra Pradesh, interesting structural features are noticed in Precambrian sedimentary rocks. A prominent thrust which has brought the Cumbums over the younger Kurnools, and other primary and secondary structures in the rocks are significant and help in deciphering structural events. The thickness of the Narji limestones based on the structural studies is estimated to be 300 m and not 6400 m as suggested by Heron.
- 'Peninsular Gneiss' in the Northern Parts of Andhra Pradesh
Abstract Views :217 |
PDF Views:4
Authors
P. Perraju
1,
V. Natarajan
1
Affiliations
1 Geological Survey of India, Hyderabad, IN
1 Geological Survey of India, Hyderabad, IN
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 18, No 5 (1977), Pagination: 224-232Abstract
The' Peninsular Gneiss' in the northern parts of Andhra Pradesh can be described briefly as a group of composite gneisses, mostly banded or layered, formed as a result of migmatisation of the older meta-pelites (predominantly biotite-schists), metapsammites, and meta-basics (predominantly amphibolites and hornblende schists), by a grey quartzo-feldspathic injection. The resultant migmatitic gneisses enclose inclusions of all shapes and sizes of the older rocks and exhibit different degrees of interaction and assimilation of them. This complex was later intruded by a 'Pink Granite' the effect of which is also seen as a ' second period of migmatisation '. The two major injections appear to be fairly well separated in time.
These two granitic injections and their corresponding migmatisation effects on the older group of diverse rocks has produced a heterogeneous complex of rock types which show wide variations in composition as well as in texture over the region. Both granites have their own groups of aplite, pegmatite and quartz veins. The white quartz and pegmatite veins traversing the grey porphyroblastic biotite gneisses in Karimnagar district carry molybdenite and sulphide mineralisation. All the rocks were later injected by quartz, epidote and at places by fluorite veins. Fluorite is also found as a component mineral of the' pink granites' in Karimnagar district. Dolerite dykes which cut across all the above, mark the last phase of igneous activity.
- Laterite Cappings in Parts of Medak and Nizamabad Districts, Andhra Pradesh
Abstract Views :174 |
PDF Views:117
Authors
Affiliations
1 3-4-756 A/I, Barkatpura, Hyderabad, IN
2 10-2-317/22, Vijayanagar Colony, Hyderabad, IN
3 12-2-111/A, Muradnagar, Mehdipatnam, Hyderabad, IN
4 3-4-448,2/1, Narayanguda, Hyderabad, IN
1 3-4-756 A/I, Barkatpura, Hyderabad, IN
2 10-2-317/22, Vijayanagar Colony, Hyderabad, IN
3 12-2-111/A, Muradnagar, Mehdipatnam, Hyderabad, IN
4 3-4-448,2/1, Narayanguda, Hyderabad, IN
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 21, No 3 (1980), Pagination: 138-140Abstract
A number of laterite cappings have been demarcated over the Deccan Trap basaltic rocks in parts of Medak and Nizamabad districts of Andhra Pradesh. Favourable lithology of traps and a geomorphic surface with almost gentle unidirectional slope from south to north appear to have strongly influenced the lateritisation process in the area that resulted in thick lateritic cappings.Full Text
- Large Scale Basin and Dome Structures in the High Grade Metamorphics, Near Visakhapatnam, South India
Abstract Views :173 |
PDF Views:2
Authors
V. Natarajan
1,
J. K. Nanda
1
Affiliations
1 Geological Survey of India, Southern Region, Hyderabad 500001, IN
1 Geological Survey of India, Southern Region, Hyderabad 500001, IN
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 22, No 12 (1981), Pagination: 584-592Abstract
Large scale basin and dome structures with intense buckling in some layers are recorded in the Archaean high grade metamorphic-migmatitc complex of the Eastern Ghats near Visakhapatnam, South India. Two major phases of deformation have been deciphered. The earlier phase was regionally continuous, and resulted in nonplunging, tight and isoclinal (overturned) folds, as well as gently plunging elongate structures. The axial trends of these folds vary from NE-SW to ENE-WSW. Gneissic layering of rocks, development of axial plane schistosity and tight isoclinal angular parasitic minor folds, and large scale shearing and faulting in the axial regions, are correlated to this event.
The later phase of deformation was discontinuous and variable in nature. Southerly/southeasterly plunging, open to tight, normal, similar folds belong to this event and they were superposed on the earlier structures. They modified the pattern and plunges of the latter, and also produced intense buckling or gentle warping locally at several places. Development of warp-like open minor folds, and groove and mineral lineations are correlated to this deformation.
On the basis of critical synthesis of the available structural data, the evolution of the Balacheruvu basin and Madhuravada dome has been attributed to a single deformation of the earlier phase of folding.
- Petrography and Petrochemistry of the Cordierite Bearing Metapelites of Nartamalai Area, Pudukkottai District, Tamil Nadu
Abstract Views :188 |
PDF Views:1
Authors
Affiliations
1 Geological Survey of India, Op : Tamil Nadu & Pondicherry, Madras - 600032, IN
1 Geological Survey of India, Op : Tamil Nadu & Pondicherry, Madras - 600032, IN
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 46, No 5 (1995), Pagination: 477-483Abstract
Occurrence of cordierite bearing metapelites of Khondalitic suite of rocks is reported from Nartamalai area, Pudukkottai district for the first time. The cordierite bearing gneiss occurs in close association with chamockite and pyroxene granulite in the vicinity of the Nartamalai granites. The mineral assemblages seen in the metapelites are cordierite-almandine-sillimanite-plagioclase-K-feldspar- biotite and quartz. Zircon, magnetite and spinel are the accessory minerals. The texture of the metapelites is generally gneissose except in the eastern part of the area where it simulates a hornfels. The Nartarnalai cordierite contains 59% Mg-cordierite and 41 % Fe-cordierite. The Fe+2/Fe+2+Mg ratio of the Nartamalai cordierite is 0.414 which is strikingly higher than that of the cordierites of regional metamorphism and it is comparable with the Fe2/Fe+2+Mg ratios of the cordieritcs described from hornfels assemblage. The coexisting garnet is an almandine-pyrope with very minor andradite and spessartitc, which is comparable with the garnets of regional metamorphic assemblage. The tie-line joining the composition of the coexisting cordierite and garnet indicates a regional metamorphic environment. An overprint of thermal metamorphism, attributable to the intrusion of Nartamalai granites, on the pre-existing regional metamorphic fabric is suggested.Keywords
Petrography, Petrochemistry, Cordierite, Nartamalai, Tamil Nadu.- Utilisation of Waste Plastics as a Partial Replacement of Coarse Aggregate in Concrete Blocks
Abstract Views :146 |
PDF Views:0
Authors
Affiliations
1 Department of Civil Engineering, Sathyabama University, Chennai - 600119, Tamil Nadu, IN
2 Jeppiaar Engineering College, Chennai - 600119, Tamil Nadu, IN
1 Department of Civil Engineering, Sathyabama University, Chennai - 600119, Tamil Nadu, IN
2 Jeppiaar Engineering College, Chennai - 600119, Tamil Nadu, IN
Source
Indian Journal of Science and Technology, Vol 8, No 12 (2015), Pagination:Abstract
The rapid industrialization and urbanization in the country leads lot of infrastructure development. This process leads to several problems like shortage of construction materials, increased productivity of wastes and other products. This paper deals with the reuse of waste plastics as partial replacement of coarse aggregate in M20 concrete. Usually M20 concrete is used for most constructional works. Waste Plastics were incrementally added in 0%, 2%, 4%, 6%, 8% and 10% to replace the same amount of Aggregate. Tests were conducted on coarse aggregates, fine aggregates, cement and waste plastics to determine their physical properties. Paver Blocks and Solid Blocks of size 200 mm X 150 mm X 60 mm and 200 mm X 100 mm X 65 mm were casted and tested for 7, 14 and 28 days strength. The result shows that the compressive strength of M20 concrete with waste plastics is 4% for Paver Blocks and 2% for Solid Blocks.Keywords
Coarse Aggregate, Fine Aggregate, Paver Blocks, Solid Blocks, Waste PlasticsFull Text
- Visible Emission Line Coronagraph on Aditya-L1
Abstract Views :257 |
PDF Views:73
Authors
B. Raghavendra Prasad
1,
Dipankar Banerjee
1,
Jagdev Singh
1,
S. Nagabhushana
1,
Amit Kumar
1,
P. U. Kamath
1,
S. Kathiravan
1,
Suresh Venkata
1,
N. Rajkumar
1,
V. Natarajan
1,
Madhur Juneja
1,
Pawan Somu
1,
Vaibhav Pant
1,
Nigar Shaji
2,
K. Sankarsubramanian
2,
Asit Patra
3,
R. Venkateswaran
4,
Abhijit Avinash Adoni
2,
S. Narendra
2,
T. R. Haridas
5,
Shibu K. Mathew
6,
R. Mohan Krishna
2,
K. Amareswari
2,
Bhavesh Jaiswal
2
Affiliations
1 Indian Institute of Astrophysics, 2nd Block, Koramangala, Bengaluru 560 034, IN
2 ISRO Satellite Centre, Old Airport Road, Vimanapura Post, Bengaluru 560 017, IN
3 Space Applications Centre, Jodhpur Tekra, Ambawadi Vistar, P.O., Ahmedabad 380 015, IN
4 Laboratory for Electro-Optics Systems, First Phase, Peenya Industrial Estate, Bengaluru 560 058, IN
5 ISRO Inertial Systems Unit, Vattiyoorkavu PO, Thiruvananthapuram 695 013, IN
6 Udaipur Solar Observatory, Near Fatehpur Lake, Shilpgram, Udaipur 313 004, IN
1 Indian Institute of Astrophysics, 2nd Block, Koramangala, Bengaluru 560 034, IN
2 ISRO Satellite Centre, Old Airport Road, Vimanapura Post, Bengaluru 560 017, IN
3 Space Applications Centre, Jodhpur Tekra, Ambawadi Vistar, P.O., Ahmedabad 380 015, IN
4 Laboratory for Electro-Optics Systems, First Phase, Peenya Industrial Estate, Bengaluru 560 058, IN
5 ISRO Inertial Systems Unit, Vattiyoorkavu PO, Thiruvananthapuram 695 013, IN
6 Udaipur Solar Observatory, Near Fatehpur Lake, Shilpgram, Udaipur 313 004, IN
Source
Current Science, Vol 113, No 04 (2017), Pagination: 613-615Abstract
Solar coronagraph mimics total solar eclipse by blocking the solar disk and enabling the observation of extended coronal atmosphere of the Sun. Visible Emission Line Coronagraph (VELC), on-board Aditya-L1 space mission, is an internally occulted solar coronagraph capable of simultaneous imaging, spectroscopy and spectro-polarimetry close to the solar limb. This payload is designed to study the coronal plasma and heating of the solar corona. Studying development, dynamics and origin of coronal mass ejections and measurement of coronal magnetic fields over active regions are other important science goals. VELC is designed to image the solar corona at 500 nm with an angular resolution of 5" over a field of view (FOV) of 1.05-3 Ro. It also facilitates simultaneous multi-slit spectroscopy at three emission lines, viz. Fe XIV (530.3 nm), Fe XI (789.2 nm) and Fe XIII (1074.7 nm) with a spectral resolution of 28 , 31 and 202 mÅ/pixel respectively, over an FOV of 1.05-1.5 Ro. The payload has a dual-beam spectro-polarimetry channel for magnetic field measurements at 1074.7 nm.Keywords
Coronagraph, Coronal Mass Ejection, Payload, Solar Corona.Full Text
References
- Aditya-L1 first Indian mission to study the Sun; http://www.isro.gov.in/aditya-l1-first-indian-missiontostudy-sun (12 May 2016).
- Singh, J. et al., Proposed visible emission line space solar coronagraph. Curr. Sci., 2011, 100(2), 167–174.
- Singh, J., Bayanna, R. and Sankarasubramanian, K., Visible emission line space solar coronagraph: science and optical design. J. Opt., 2013, 42(2), 96–100.
- Sankarasubramanian, K., Solar coronal studies with Aditya-1 mission. In 31st ASI Meeting, ASI Conference Series, 2013, vol. 9, pp. 43–48.
- Venkata, S. N., Prasad, B. R., Nalla, R. K. and Singh, J., Scatter studies for visible emission line coronagraph on board ADITYAL1 mission. J. Astron. Telesc. Instrum. Syst., 2017, 3, 014002.
- Bayanna, R. A., Mathew, S. K., Sankarasubramanian, K., Venkatakrishnan, P., Singh, J. and Prasad, B. R., Issues with external occultation of a coronagraph. Exp. Astron., 2011, 29, 145–153.
- Design, Fabrication and Evaluation of an Underwater Acoustic Imaging Sensor Array
Abstract Views :203 |
PDF Views:0
Authors
Affiliations
1 Naval Physical & Oceanographic Laboratory, Kochi, IN
2 Naval Materials Research Laboratory, Mumbai, IN
1 Naval Physical & Oceanographic Laboratory, Kochi, IN
2 Naval Materials Research Laboratory, Mumbai, IN
Source
Journal of Pure and Applied Ultrasonics, Vol 35, No 2-3 (2013), Pagination: 52-55Abstract
Acoustic imaging array systems generate an image by processing the acoustic waves backscattered from an underwater object. Generally these systems operate at higher frequencies and provide shorter imaging ranges. The lateral resolution is determined by the ultrasound beam width which is a function of aperture diameter and frequency. The diffraction pattern of an array accounts for all linear effects, such as, transducer size, side and grating lobes, focusing, and beam steering. Angular resolution enhance with increase in the number of elements or the frequency. The side lobes appear as a background noise in the image. The ability and usefulness of the algorithms depend on the quality (Sensitivity, bandwidth, and dynamic range) of the original echo signal, making the transducer the most critical component of ultrasound imaging systems. The present paper presents the design of a 128 element underwater acoustic imaging sensor linear array that operates at 500 kHz and with a horizontal beam width less than 1°. There are several sound field parameters that are critical in designing an ultrasonic transducer array, which have been discussed in the paper. The array evaluated underwater at 500 kHz shows a source level of 184 dB and a receiving sensitivity of -192 dB re V/μPa @1 m. The acoustic cross-talk and other acoustical parameters are also discussed.Full Text