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Browsing by Author "Banyal, R. K"

Browsing by Author "Banyal, R. K"

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  • High-contrast, all-optical switching in bacteriorhodopsin films 
    Banyal, R. K; Prasad, B. R (Optical Society of America, 2005-09)
    We report experiments with nonlinear-absorption-based, high-contrast, all-optical switching in photochromic bacteriorhodopsin (BR) films. The switching action is accomplished by control of the transmission of a weak probe ...
  • Holographic recording in Fe:Ce:Ti doped LiNbO3 crystal 
    Banyal, R. K; Prasad, B. R (Elsevier, 2007-06)
    High diffraction efficiency measurements in a triply doped Fe:Ce:Ti LiNbO3 crystal are reported. The crystal shows an improved recording sensitivity, weak light-induced scattering and extremely slow readout erasure which ...
  • Host star metallicity of directly imaged wide-orbit planets: implications for planet formation 
    Swastik, C; Banyal, R. K; Narang, Mayank; Manoj, P; Sivarani, T; Reddy, B. E; Rajaguru, S. P (IOP Publishing, 2021-03-01)
    Directly imaged planets (DIPs) are self-luminous companions of pre-main-sequence and young main-sequence stars. They reside in wider orbits (~tens to thousands of astronomical units) and generally are more massive compared ...
  • In defence of scientific temper 
    Banyal, R. K (Indian Academy of Sciences, 2009-07-10)
  • Innovations and advances in instrumentation at the W. M. Keck Observatory, vol. II 
    Kassis, Marc F; Allen, Steve; Alvarez, Carlos; Banyal, R. K; Bertz, Robert; Beichman, Charles; Brown, Aaron; Brown, Matthew; Cabak, Gerald; Bundy, Kevin; Cetre, Sylvain; Chin, Jason; Chun, Mark; Deich, Will; Dekany, Richard; Delorme, Jacques; Devenot, Mark; Doppmann, Greg; Fitzgerald, Michael P; Fucik, Jason R; Hill, Grant; Hinz, Philip; Holden, Bradford P; Howard, Andrew; Gao, Maodong; Gibson, Steve; Gomez, Percy; Gottschalk, Colby; Gillingham, Peter R; Jones, Tucker; Jovanovic, Nemanja; Kirby, Evan; Konopacky, Quinn; Krishnan, Shanti; Kupke, Renate; Larkin, James E.; Leife, Stephanie D; Lewis, Hilton A; Lilley, Scott; Lu, Jessica; Lyk, James E; MacDonald, Nick; Marin, Eduardo; Matuszewski, Matt; Mawet, Dimitri; McGurk, Rosalie; A Millar-Blanchaer, Maxwell; Nash, Reston B; Nance, Craig; Neill, James D; M. O'Meara, John; Peretz, Eliad; Poppett, Claire L; Mather, John C; Radovan, Matthew V; Roberts, Mitsuko K; Ragland, Sam; Rider, Kodi; Rockosi, Constance M; Sandfor, Dale; Shen, Boqiang; Steidel, Charles C; Simha, Sunil; Skemer, Andy; Stelter, Deno; Surendran, Avinash; Thorne, James; McCarney, Ben; Lanclos, Kyle; Baker, Ashley; Rubenzah, Ryan; Roy, Arpita; Halverson, Sam; Edelstein, Jerry; Martin, Christopher; Savage, Maureen; Sandford, Dale; Sallum, Stephanie; Walawender, Josh; Wizinowich, Peter; Westfall, Kyle B; Vahala, Kerry J; Wright, Shelley; Wold, Truman; Yeh, Sherry (SPIE-The International Society for Optical Engineering, 2022-08)
    Since the start of science operations in 1993, the twin 10-meter W. M. Keck Observatory (WMKO) telescopes have continued to maximize their scientific impact and to produce transformative discoveries that keep the observing ...
  • Installation of solar chromospheric telescope at the Indian Astronomical Observatory, Merak 
    Ravindra, B; Prabhu, K; Thulasidharen, K. C; Rajalingam, M; Sagayanathan, K; Kamath, P. U; Dorjey, N; Angchuk, D; Kemkar, P. M. M; Dorjai, T; Banyal, R. K (Indian Academy of Sciences, 2018-10)
    We report the observations of the solar chromosphere from a newly commissioned solar telescope at the incursion site near Pangong Tso lake in Merak (Leh/Ladakh). This new Hα telescope at the Merak site is identical to the ...
  • Intensity profile of light scattered from a rough surface 
    Chatterjee, S; Vani, V. C; Banyal, R. K (Optical Society of America, 2013-08-20)
    We present in this paper, approximate analytical expressions for the intensity of light scattered by a rough surface, whose elevation ξ x; y in the z-direction is a zero mean stationary Gaussian random variable. With ...
  • A laser-lock concept to reach cm-1s-precision in Doppler experiments with Fabry-Perot wavelength calibrators 
    Reiners, A; Banyal, R. K; Ulbrich, R. G (EDP Sciences, 2014-09)
    State-of-the-art Doppler experiments require wavelength calibration with precision at the cm s − 1 level. A low-finesse Fabry-Pérot interferometer (FPI) can provide a wavelength comb with a very large ...
  • Light-induced absorption in photorefractive BaTiO3 crystals 
    Banyal, R. K; Prasad, B. R (American Institute of Physics, 2003-06-15)
    We present the experimental results on the measurement of temporal and steady-state light-induced absorption change in undoped and rhodium-doped barium titanate (Rh:BaTiO3) crystals at different wavelengths and intensities. ...
  • Measurements of atmospheric turbulence parameters at Vainu Bappu Observatory using short-exposure CCD images 
    Sreekanth Reddy, V; Banyal, R. K; Sridharan, R; Aishwarya, S (IOP Publishing, 2019-05)
    We report atmospheric turbulence parameters, namely atmospheric seeing, tilt-anisoplanatic angle (θ0) and coherence time (τ0), measured under various sky conditions, at Vainu Bappu Observatory in Kavalur. Bursts of short ...
  • Measurements of photoinduced refractive index changes in bacteriorhodopsin films 
    Banyal, R. K; Prasad, B. R (Indian Academy of Sciences, 2007-03)
    We report the pump--probe measurements of nonlinear refractive index changes in photochromic bacteriorhodopsin films. The photoinduced absorption is caused by pump beam at 532 nm and the accompanying refractive ...
  • Method for tilt correction of calibration lines in high-resolution spectra 
    Das, Tanya; Banyal, R. K (Optical Society of America, 2021-11-01)
    Technological advancement has led to improvement in the design capabilities of astronomical spectrographs, allowing for high-precision spectroscopy, thereby expanding the realms of observational astronomy. High-resolution ...
  • Myths, Superstitions and Propaganda in Scientific Age 
    Banyal, R. K (2012-01)
    From prehistoric times, humans have evolved as pattern seeking and storytelling species. While the capacity to find patterns and infer meanings had obvious advantages for survival, the brain is not always successful in ...
  • Natural calamities and pseudoscientific menace 
    Banyal, R. K; Saigeetha, A. J (Indian Academy of Sciences, 2005-12)
  • Nonlinear response studies and corrections for a liquid crystal spatial light modulator 
    Banyal, R. K; Prasad, B. R (Indian Academy of Sciences, 2010-06)
    The nonlinear response of light transmission characteristics of a liquid crystal (LC) spatial light modulator (SLM) is studied. The results show that the device exhibits a wide range of variations with different ...
  • Observations of photospheric vortical motions during the early stage of filament eruption 
    Sajal Kumar Dhara; Ravindra, B; Banyal, R. K (Springer, 2014-12)
    Solar filaments/prominences exhibit rotational motion during different phases of their evolution from their formation to eruption. We have observed the rotational/vortical motion in the photosphere near the ends of ten ...
  • On the Resolving Power of an Echelle Grating in the Presence of a Corrugated Wavefront of Incidence 
    Chatterjee, S; Banyal, R. K; Prasad, B. R; Chandrasekharan, K (Astronomical Society of India, 2003)
  • Opto-thermal analysis of a lightweighted mirror for solar telescope 
    Banyal, R. K; Ravindra, B; Chatterjee, S (Optical Society of America, 2013-03-25)
    In this paper, an opto-thermal analysis of a moderately heated lightweighted solar telescope mirror is carried out using 3D finite element analysis (FEA). A physically realistic heat transfer model is developed to account ...
  • Phase characteristics of reflecting and transmitting type twisted nematic spatial light modulators 
    Roopashree, M. B; Vyas, A; Banyal, R. K; Prasad, B. R (Central Scientific Instruments Organisation (CSIR), 2009-11)
    The phase characteristics of reflecting and transmitting type twisted nematic liquid crystal based Spatial Light Modulators (SLMs) were measured using interferometry. Device parameters like contrast, brightness, input ...
  • Pixel size and pitch measurements of liquid crystal 
    Banyal, R. K; Prasad, B. R (Indian Academy of Sciences, 2005-08)
    We present a simple technique for the determination of pixel size and pitch of liquid crystal (LC) based spatial light modulator (SLM). The proposed method is based on optical diffraction from pixelated LC panel that has ...

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