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Browsing by Author "Banyal, R. K"

Browsing by Author "Banyal, R. K"

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  • 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 ...
  • Properties and Occurrence Rates for Kepler Exoplanet Candidates as a Function of Host Star Metallicity from the DR25 Catalog 
    Narang, Mayank; Manoj, P; Furlan, E; Mordasini, C; Henning, Thomas; Mathew, Blesson; Banyal, R. K; Sivarani, T (IOP Publishing, 2018-11)
    Correlations between the occurrence rate of exoplanets and their host star properties provide important clues about the planet formation process. We studied the dependence of the observed properties of exoplanets (radius, ...
  • Radio-loud Exoplanet-exomoon Survey: GMRT Search for Electron Cyclotron Maser Emission 
    Narang, Mayank; Oza, Apurva V; Hakim, Kaustubh; Manoj, P; Banyal, R. K; Thorngren, Daniel P (American Astronomical Society, 2023-01-01)
    We conducted the first dedicated search for signatures of exoplanet–exomoon interactions using the Giant Metrewave Radio Telescope (GMRT) as part of the radio-loud exoplanet-exomoon survey. Due to stellar tidal heating, ...
  • Recovering simulated planet and disk signals using SCALES aperture masking 
    Lacha, Mackenzie R; Sallum, Steph; Banyal, R. K; Batalha, Natalie; Blake, Geoff; Brandt, Tim; Briesemeister, Zackery; Desai, Aditi; Eisner, Josh; Fong, Wen-fai; Greene, Tom; Honda, Mitsuhiko; Kain, Isabel; Kilpatrick, Charlie; Kleer, Katherine de; Liu, Michael; Macintosh, Bruce; Martinez, Raquel; Mawet, Dimitri; Miles, Brittany; Morley, Caroline; Pater, Imke de; Powell, Diana; Sheehan, Patrick; Skemer, Andrew; Spilker, Justin; Stelter, Deno; Stone, Jordan; Surya, Arun; Sivarani, T; Wagner, Kevin; Zhou, Yifan (SPIE - The International Society for Optical Engineering, 2023-10)
    The Slicer Combined with Array of Lenslets for Exoplanet Spectroscopy (SCALES) instrument is a lenslet-based integral field spectrograph that will operate at 2 to 5 microns, imaging and characterizing colder (and thus ...
  • Scattering of light by rough surfaces: high and low roughness approximations 
    Chatterjee, S; Banyal, R. K (Department of Applied Optics and photonics, University of Calcutta, 2009)
    Scattering of light by rough surface is considered in the Kirchoff approximation. Analytical expressions are presented for the scattered intensity by considering the elevations in the z-direction. «(x, y) at any point (x,y) ...
  • Simulating medium-spectral-resolution exoplanet characterization with SCALES angular/reference differential imaging 
    Desai, Aditi; Sallum, Stephanie E; Banyal, R. K; Batalha, Natalie; Batalha, Natasha; Blake, Geoff; Brandt, Tim; Briesemeister, Zack; Kleer, Katherine de; Pater, Imke de; Eisner, Josh; Fong, Wen-fai; Greene, Tom; Honda, Mitsuhiko; Kain, Isabel; Kilpatrick, Charlie; Lach, Mackenzie; Liu, Mike; Macintosh, Bruce; Martinez, Raquel A; Mawet, Dimitri; Miles, Brittany; Morley, Caroline; Powell, Diana; Sheehan, Patrick; Skemer, Andrew J; Spilker, Justin; Stelter, R. Deno; Stone, Jordan; Surya, Arun; Sivarani, T; Wagner, Kevin; Zhou, Yifan (SPIE-The International Society for Optical Engineering, 2023-10)
    SCALES (Slicer Combined with Array of Lenslets for Exoplanet Spectroscopy) is a 2 - 5 micron high-contrast lenslet-based integral field spectrograph (IFS) designed to characterize exoplanets and their atmospheres. The SCALES ...
  • The slicer combined with array of lenslets for exoplanet spectroscopy (SCALES): driving science cases and expected outcomes 
    Sallum, Steph; Skemer, Andrew; Stelter, Deno; Banyal, R. K; Batalha, Natalie; Batalha, Natasha; Blake, Geoff; Brandt, Tim; Briesemeister, Zack; Kleer, Katherine de; Pater, Imke de; Desai, Aditi; Eisner, Josh; Fong, Wen-fai; Greene, Tom; Honda, Mitsuhiko; Jensen-Clem, Rebecca; Kain, Isabel; Kilpatrick, Charlie; Kupke, Renate; Lach, Mackenzie; Liu, Michael C; Macintosh, Bruce; Martinez, Raquel A; Mawet, Dimitri; Miles, Brittany; Morley, Caroline; Powell, Diana; Sethuram, Ramya; Sheehan, Patrick; Spilker, Justin; Stone, Jordan; Surya, Arun; Sivarani, T; Unni, Athira; Wagner, Kevin; Zhou, Yifan (SPIE-The International Society for Optical Engineering, 2023-10)
    The Slicer Combined with Array of Lenslets for Exoplanet Spectroscopy (SCALES) is a 2 − 5 µm, high-contrast integral field spectrograph (IFS) currently being built for Keck Observatory. With both low (R ≲ 250) and medium ...
  • Spatial light modulator for wave-front correction 
    Vyas, A; Roopashree, M. B; Banyal, R. K; Prasad, B. R (Department of Applied Optics and photonics, University of Calcutta, 2009)
    We present a liquid crystal method of correcting the phase of an aberrated wave-front using a spatial light modulator. A simple and efficient lab model has been demonstrated for wave-front correction. The crux of a wave-front ...

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