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Start Over Author "Thomas, Ian" Journal applied optics
10 results on '"Thomas, Ian"'

1. Method for the preparation of porous silica antireflection coatings varying in refractive index from 1.22 to 1.44

Author

Thomas, Ian M.

Subjects
Optical coatings -- Research, Silica -- Research, Refractive index -- Research, Thin films -- Research, Colloids -- Research, Polymer solutions -- Research, Astronomy, Physics
Abstract

Coatings of refractive index that vary between 1.22 and 1.44 were prepared from combinations of a colloidal silica suspension and a polysiloxane solution. The polysiloxane acted both as a binder and a filler for the colloidal silica particles. Increasing ratios gave coatings of lower porosity, hence higher refractive index, and better abrasion resistance. This variation in refractive index allowed high-efficiency quarter-wave antireflection coatings to be prepared on substrates whose index varied from 1.45 to 2.1. The laser damage thresholds of all the coatings were > 50 J/cm squared at a wavelength of 1.06 Micrometer with a 10-ns pulse length.

Published
1992

2. NOMAD spectrometer on the ExoMars trace gas orbiter mission: part 2—design, manufacturing, and testing of the ultraviolet and visible channel

Author

Patel, Manish R., primary, Antoine, Philippe, additional, Mason, Jonathon, additional, Leese, Mark, additional, Hathi, Brijen, additional, Stevens, Adam H., additional, Dawson, Daniel, additional, Gow, Jason, additional, Ringrose, Timothy, additional, Holmes, James, additional, Lewis, Stephen R., additional, Beghuin, Didier, additional, van Donink, Philip, additional, Ligot, Renaud, additional, Dewandel, Jean-Luc, additional, Hu, Daohua, additional, Bates, Doug, additional, Cole, Richard, additional, Drummond, Rachel, additional, Thomas, Ian R., additional, Depiesse, Cédric, additional, Neefs, Eddy, additional, Equeter, Eddy, additional, Ristic, Bojan, additional, Berkenbosch, Sophie, additional, Bolsée, David, additional, Willame, Yannick, additional, Vandaele, Ann Carine, additional, Lesschaeve, Stefan, additional, De Vos, Lieve, additional, Van Vooren, Nico, additional, Thibert, Tanguy, additional, Mazy, Emmanuel, additional, Rodriguez-Gomez, Julio, additional, Morales, Rafael, additional, Candini, Gian Paolo, additional, Pastor-Morales, M. Carmen, additional, Sanz, Rosario, additional, Aparicio del Moral, Beatriz, additional, Jeronimo-Zafra, José-Maria, additional, Gómez-López, Juan Manuel, additional, Alonso-Rodrigo, Gustavo, additional, Pérez-Grande, Isabel, additional, Cubas, Javier, additional, Gomez-Sanjuan, Alejandro M., additional, Navarro-Medina, Fermín, additional, BenMoussa, Ali, additional, Giordanengo, Boris, additional, Gissot, Samuel, additional, Bellucci, Giancarlo, additional, and Lopez-Moreno, Jose Juan, additional

Published
2017
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3. Fabrication of large-aperture lightweight diffractive lenses for use in space

Author

Barton, Ian M., Britten, Jerald A., Dixit, Shamasundar N., Summers, Leslie J., Thomas, Ian M., Rushford, Michael C., Lu, Katy, Hyde, Roderick A., and Perry, Michael D.

Subjects
Lenses -- Design and construction, Telescope -- Description and travel, Outer space -- Equipment and supplies, Optical instruments -- Design and construction, Astronomy, Physics
Abstract

We describe the advantages of using diffractive (Fresnel) lenses on thin membranes over conventional optics for, among others, future space telescope projects. Fabrication methods are presented for lenses on two types of freestanding membrane up to 50 cm in size. The first is a Fresnel lens etched into a thin (380-[Mu]m) glass sheet, and the second is an ~50-[Mu]m-thick polymer membrane containing a Fresnel lens made by replication process from a specially made fused-silica master. We show optical performance analysis of all the lenses that are fabricated, including a diffraction-limited Airy spot from a 20-m-focal-length membrane lens in a diffractive telescope system. [C] 2001 Optical Society of America OCIS codes: 050.1970, 110.5220, 160.4670, 220.4000.

Published
2001

5. NOMAD spectrometer on the ExoMars trace gas orbiter mission: part 1—design, manufacturing and testing of the infrared channels

Author

Neefs, Eddy, primary, Vandaele, Ann Carine, additional, Drummond, Rachel, additional, Thomas, Ian R., additional, Berkenbosch, Sophie, additional, Clairquin, Roland, additional, Delanoye, Sofie, additional, Ristic, Bojan, additional, Maes, Jeroen, additional, Bonnewijn, Sabrina, additional, Pieck, Gerry, additional, Equeter, Eddy, additional, Depiesse, Cédric, additional, Daerden, Frank, additional, Ransbeeck, Emiel Van, additional, Nevejans, Dennis, additional, Rodriguez-Gómez, Julio, additional, López-Moreno, José-Juan, additional, Sanz, Rosario, additional, Morales, Rafael, additional, Candini, Gian Paolo, additional, Pastor-Morales, M. Carmen, additional, Aparicio del Moral, Beatriz, additional, Jeronimo-Zafra, José-Maria, additional, Gómez-López, Juan Manuel, additional, Alonso-Rodrigo, Gustavo, additional, Pérez-Grande, Isabel, additional, Cubas, Javier, additional, Gomez-Sanjuan, Alejandro M., additional, Navarro-Medina, Fermín, additional, Thibert, Tanguy, additional, Patel, Manish R., additional, Bellucci, Giancarlo, additional, De Vos, Lieve, additional, Lesschaeve, Stefan, additional, Vooren, Nico Van, additional, Moelans, Wouter, additional, Aballea, Ludovic, additional, Glorieux, Stijn, additional, Baeke, Ann, additional, Kendall, Dave, additional, De Neef, Jurgen, additional, Soenen, Alexander, additional, Puech, Pierre-Yves, additional, Ward, Jon, additional, Jamoye, Jean-François, additional, Diez, David, additional, Vicario-Arroyo, Ana, additional, and Jankowski, Michel, additional

Published
2015
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6. Single layer Al_2O_3·H_2O and multilayer Al_2O_3·H_2O–SiO_2 optical coatings prepared from colloidal suspensions

Author

Thomas, Ian M.

Abstract

Single layer coatings of Al_2O_3·H_2O have been prepared on fused silica and BK-7 substrates from aqueous colloidal suspensions of hydrated alumina at room temperature. These coatings were porous and had a refractive index of ∼1.44. Multilayer, high reflectivity, dielectric coatings were also prepared by laying down quarterwave-thick, alternating coats of this alumina with silica, also prepared from colloidal suspension, and having a refractive index of 1.22. To achieve 99% reflectivity, 30–35 layers were required. Single shot, laser damage threshold measurements at 1064 nm wavelength with a pulse length of 10 ns were carried out on both the single layer and multilayer system. The thresholds averaged 21 and 12 J/cm^2, respectively.

Published
1989

7. Single-layer TiO_2 and multilayer TiO_2–SiO_2 optical coatings prepared from colloidal suspensions

Author

Thomas, Ian M.

Abstract

Single-layer coatings on fused silica substrates have been prepared from aqueous colloidal suspensions of titania at room temperature. These coatings were porous and had a refractive index of 1.9. Multilayer high reflectivity dielectric coatings were also prepared by laying down quarterwave thick alternating coats at room temperature of this titania with silica, prepared from a colloidal suspension of silica. Single-shot laser damage threshold measurements at 1064-nm wavelength with a pulse length of 1 ns were carried out for both the titania and titania-silica systems. These averaged 7.5 and 6.2 J/cm^2, respectively.

Published
1987

10. NOMAD spectrometer on the ExoMars trace gas orbiter mission: part 2—design, manufacturing, and testing of the ultraviolet and visible channel

Author

Patel, Manish R., Antoine, Philippe, Mason, Jonathon, Leese, Mark, Hathi, Brijen, Stevens, Adam H., Dawson, Daniel, Gow, Jason, Ringrose, Timothy, Holmes, James, Lewis, Stephen R., Beghuin, Didier, van Donink, Philip, Ligot, Renaud, Dewandel, Jean-Luc, Hu, Daohua, Bates, Doug, Cole, Richard, Drummond, Rachel, Thomas, Ian R., Depiesse, Cédric, Neefs, Eddy, Equeter, Eddy, Ristic, Bojan, Berkenbosch, Sophie, Bolsée, David, Willame, Yannick, Vandaele, Ann Carine, Lesschaeve, Stefan, De Vos, Lieve, Van Vooren, Nico, Thibert, Tanguy, Mazy, Emmanuel, Rodriguez-Gomez, Julio, Morales, Rafael, Candini, Gian Paolo, Pastor-Morales, M. Carmen, Sanz, Rosario, Aparicio del Moral, Beatriz, Jeronimo-Zafra, José-Maria, Gómez-López, Juan Manuel, Alonso-Rodrigo, Gustavo, Pérez-Grande, Isabel, Cubas, Javier, Gomez-Sanjuan, Alejandro M., Navarro-Medina, Fermín, BenMoussa, Ali, Giordanengo, Boris, Gissot, Samuel, Bellucci, Giancarlo, and Lopez-Moreno, Jose Juan

Abstract

NOMAD is a spectrometer suite on board the ESA/Roscosmos ExoMars Trace Gas Orbiter, which launched in March 2016. NOMAD consists of two infrared channels and one ultraviolet and visible channel, allowing the instrument to perform observations quasi-constantly, by taking nadir measurements at the day- and night-side, and during solar occultations. Here, in part 2 of a linked study, we describe the design, manufacturing, and testing of the ultraviolet and visible spectrometer channel called UVIS. We focus upon the optical design and working principle where two telescopes are coupled to a single grating spectrometer using a selector mechanism.

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