Dr. Rajeev Paramel Pattathil Profile

Dr. Rajeev Paramel Pattathil

Gemini Group Leader at Rutherford Appleton Lab

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Author

Publications (10)

Proceedings Article | 3 December 2022 Poster + Presentation

Damage resilience testing of broadband thin film coatings for use in a high-energy Ti:Sa amplifier system

Agnieszka Wojtusiak, Paul Mason, Nicolas Bourgeois, Rajeev Pattathil, Cristina Hernandez-Gomez

Proceedings Volume PC12300, PC1230015 (2022) https://doi.org/10.1117/12.2642519

KEYWORDS: Optical amplifiers, Thin films, Thin film coatings, Sputter deposition, Silica, Optical coatings, Laser applications, Antireflective coatings, Pulsed laser operation, Photonics

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Proceedings Article | 13 May 2019 Presentation

Quantitatively evaluating impact of large optics in the stretcher on compressed pulse contrast (Conference Presentation)

Yunxin Tang, David Egan, Chris Hooker, Chris Gregory, Oleg Chekhlov, Cristina Hernandez-Gomez, John Collier, Rajeev Pattathil

Proceedings Volume 11034, 110340E (2019) https://doi.org/10.1117/12.2523003

KEYWORDS: Mirrors, Surface roughness, Laser systems engineering, Gold, Spatial resolution, Pulsed laser operation, Sapphire lasers, Gemini Observatory, High power lasers

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We are currently focusing on the improvement of contrast pedestal (CP) in the compressed laser pulse of PW Ti:Sapphire lasers. In our previous studies, we have identified the stretcher in our laser system as the source of CP. In order to underpin the true origins of CP, we have quantitatively characterised the surface quality of large optics used in the Gemini laser stretcher, where the laser beam is spatially dispersed and the spectral phase noise is induced by the optical surface roughness. We have measured the surface profiles of 2 different gold gratings, the new and old grating, and back mirror to a very high precision (~ a fraction of nm) by using ZYGO Dynafiz, with a spatial resolution of ~50µm over a width up to ~320mm, an unprecedented combination of very high spatial resolution with a very wide field of view. The surface roughness of the large curved mirror was determined experimentally. We have developed a simple physical model to deal with the influence of the surface roughness on the contrast pedestal. Based on the measured surface profiles and by taking the actual laser beam size into account, we are able to determine the spectral phase noise induced by the optical surface roughness in the stretcher. Consequently, we are able to accurately evaluate the impact of individual large optics in the stretcher and an overall impact of the stretcher on the contrast pedestal. The calculated contrast induced by both stretches with the new and old gratings are in an excellent agreement with the experimental results measured by the Sequoia scan. For the stretcher with the old grating, the grating is the dominant impact factor on the contrast. However, for the stretcher with the new gold grating of higher quality, the impact of the curved mirror on the contrast is comparable to that of grating. This implies that the influence of curved mirror on the contrast pedestal becomes more significant when the surface quality of grating is further improved. It is clearly observed that the impact of back mirror on the contrast is more than one order of magnitude lower than that of gratings and also much lower than that of curved mirror. In conclusion, we have demonstrated a novel method to evaluate the impact of large optics in the stretcher on the contrast pedestal by precisely quantitative characterization of optical surface quality. It is possible to accurately predict the contrast pedestal based on the stretcher configuration and precise characterisation of the optical surface in the stretcher prior to the construction of actual CPA high power laser system.

Proceedings Article | 24 April 2019 Paper

Generation of electron high energy beams with a ring-like structure by a dual stage laser wakefield accelerator

R. Spesyvtsev, E. Brunetti, G. Vieux, M. Shahzad, A. Maitrallain, S. Yoffe, B. Ersfeld, A. Kornaszewski, M. J. Streeter, O. Finlay, Y. Ma, B. Kettle, S. J. Dann, F. Albert, N. Bourgeois, S. Cipiccia, J. Cole, E. Gerstmayr, I. Gonzáles, A. Higginbotham, A. Hussein, K. Falk, K. Krushelnick, N. Lemos, N. Lopes, C. Lumsdon, O. Lundh, S. P. Mangles, Z. Najmudin, P. Rajeev, M. Smid, D. Symes, A. G. Thomas, D. Jaroszynski

Proceedings Volume 11036, 110360F (2019) https://doi.org/10.1117/12.2522781

KEYWORDS: Plasma, Electron beams, X-rays, Physics, Pulsed laser operation, CCD cameras, Laser beam propagation, Calibration

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Proceedings Article | 12 May 2015 Paper

Gamma-ray production from resonant betatron oscillations of accelerated electrons in a plasma wakes

S. Cipiccia, M. Islam, B. Ersfeld, G. Welsh, E. Brunetti, G. Vieux, X. Yang, S. M. Wiggins, P. Grant, D. Reboredo Gil, David Grant, R. Shanks, R. Issac, M. P. Anania, D. Maneuski, R. Montgomery, G. Smith, M. Hoek, D. Hamilton, D. Symes, P. Rajeev, Val O'Shea, J. Dias, N. Lemos, Dino Jaroszynski

Proceedings Volume 9512, 95121A (2015) https://doi.org/10.1117/12.2181566

KEYWORDS: Electrons, Plasma, Photons, Pulsed laser operation, X-rays, Gamma radiation, Doppler effect, Electron beams, Ions, Sensors

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Proceedings Article | 10 September 2014 Paper

High-rep rate target development for ultra-intense interaction science at the Central Laser Facility

N. Booth, R. Clarke, R. Heathcote, D. Neely, R. Pattathil, D. Rusby, C. Spindloe, D. Symes, M. Tolley, S. Tomlinson

Proceedings Volume 9211, 921107 (2014) https://doi.org/10.1117/12.2061803

KEYWORDS: Gemini Observatory, Interferometers, Diagnostics, Manufacturing, Semiconducting wafers, Laser applications, Tolerancing, Physics, Motion controllers, Solids

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Proceedings Article | 26 September 2013 Paper

Target positioning and alignment on the Astra-Gemini facility

N. Booth, O. Ettlinger, D. Neely, R. Pattathil, A. Sellers, D. Symes

Proceedings Volume 8850, 885002 (2013) https://doi.org/10.1117/12.2023965

KEYWORDS: Imaging systems, Gemini Observatory, Cameras, Mirrors, Near field optics, Reflectivity, Geometrical optics, Interferometers, Microscopes, Interferometry

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Proceedings Article | 9 June 2011 Paper

High resolution X-ray spectroscopy in fast electron transport studies

Petra Koester, Nicola Booth, Carlo Cecchetti, Hui Chen, Roger Evans, Gianluca Gregori, Luca Labate, Tadzio Levato, Bin Li, Mikako Makita, James Mithen, Chris Murphy, Margaret Notley, Rajeev Pattathil, David Riley, Nigel Woolsey, Leonida Gizzi

Proceedings Volume 8080, 80802E (2011) https://doi.org/10.1117/12.891250

KEYWORDS: X-rays, Electron beams, Electron transport, Picosecond phenomena, Spectroscopy, Ionization, Ions, Diagnostics, Crystals, Physical phenomena

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Proceedings Article | 26 May 2011 Paper

Scintillator-based ion beam profiler for diagnosing laser-accelerated ion beams

J. Green, M. Borghesi, C. Brenner, D. Carroll, N. Dover, P. Foster, P. Gallegos, S. Green, D. Kirby, K. J. Kirkby, P. McKenna, M. Merchant, Z. Najmudin, C. A. Palmer, D. Parker, R. Prasad, K. Quinn, P. P. Rajeev, M. Read, L. Romagnani, J. Schreiber, M. Streeter, O. Tresca, C.-G. Wahlström, M. Zepf, David Neely

Proceedings Volume 8079, 807919 (2011) https://doi.org/10.1117/12.888967

KEYWORDS: Scintillators, Ions, Ion beams, Diagnostics, Charge-coupled devices, Pulsed laser operation, Ion lasers, Sensors, Physics, Ionizing radiation

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Proceedings Article | 4 October 2005 Paper

Femtosecond laser induced nanostructures in fused silica

Rajeev Pattathil, Cyril Hnatovsky, Ravi-Bhardwaj Vedula, Eli Simova, Rod Taylor, David Rayner, Paul Corkum

Proceedings Volume 5971, 59711D (2005) https://doi.org/10.1117/12.629965

KEYWORDS: Plasma, Nanostructures, Silica, Femtosecond phenomena, Ionization, Waveguides, Glasses, Polarization, Dielectrics, Chromium

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Proceedings Article | 11 January 2000 Paper

X-ray emission from solid plasmas generated by femtosecond high-intensity laser pulses

Sudeep Banerjee, Riju Issac, P. Rajeev, L. Tribedi, G. Ravindra Kumar

Proceedings Volume 3886, (2000) https://doi.org/10.1117/12.375158

KEYWORDS: Plasmas, X-rays, Pulsed laser operation, Femtosecond phenomena, Polarization, Picosecond phenomena, Magnesium, Sensors, Solids, X-ray detectors

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Showing 5 of 10 publications

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