Paper and Progress Report Artoni Kevin R. Ang July 1, 2009

Progress Report Changed substrate holder Added a new pair of electrodes and boat holder

Progress Report Coated Cr-Cu-Cr mirror (4 designs) Measured transmission of the Cr-Cu-Cr coatings using the Ocean Optics Spectrophotometer

Slide 1 Exp (nm)Theo (nm)Error (%) Air Cr Cu Cr8560 Glass Slide

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Slide 2 Exp (nm)Theo (nm)Error (%) Air Cr Cu Cr Glass Slide

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Slide 4 Exp (nm)Theo (nm)Error (%) Air Cr Cu Cr Glass Slide

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Slide 5 Exp (nm)Theo (nm)Error (%) Air Cr Cu Cr Glass Slide

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Things to do: Get micrograph of Cr-Cu-Cr mirrors Schedule FTIR analysis for mirrors Perform adhesion tests on Cr-Cu-Cr mirrors Finalize anti-reflection design Modify evaporation set-up to allow evaporation of new film materials.

Paper Report Multilayer antireflection coatings for the visible and near-infrared regions –H. Ganesha Shanbhogue, C. L. Nagendra, M. N. Annapurna, S. Ajith Kumar, and G. K. M. Thutupalli –1 September 1997 Vol. 36, No. 25 APPLIED OPTICS

Introduction Current research involves improving: –optical performance over a wider spectral range –transmission efficiency –spectral coverage –angle-of-incidence stability –durability –efficiency (residual reflection loss)

Introduction Problems: –AR coatings on a variety of glass substrates Different indices, chemical compositions, hardness, environmental stability, etc. –Different uses Residual reflection loss, transmission efficiency, angle of incidence stablity, etc.

Optical material combinations MgF 2 and medium or high index materials MgF 2 and ZrTi0 4 and Zr0 2 (sub2) MgF 2 and Si0 2, Al 2 O 3, oxides of tantalum, titanium zirconium, and niobium Sub1 and Ta2O 5 +SiO2,TiO2+Ta2O5 and SiO 2 +TiO 2

Optical Material Preparation and Characterization Sub2 –E-beam evaporation –Base pressure: mbar –Added high purity dry oxygen: mbar

Optical Material Preparation and Characterization Hitachi double-beam spectrophotometer, Model U 3400

Optical Material Preparation and Characterization

MgF 2 –Same fabrication set-up –Substrate temperature: 200°C –2x10 -5 mbar

Optical Material Preparation and Characterization T peak : transmission peak A: Cauchy dispersion constant

Optical Material Preparation and Characterization MgF 2 index of 1.35±0.01 Literature value of

Design optimization Seven layer system of MgF 2 and Sub2 coatings in alternate layers –Wideband (WB) AR coatings –Limited band (LB) AR coatings OPTOSOFT- software to optimize design

Design optimization

Experimental investigation Leybold Hereaus vacuum evaporation plant Model 560L –Optically polished and cleaned glass substrates –Substrate temperature: 200 ±5° –Rate: nm/s for MgF 2 and nm/s for Sub2

Experimental investigation Optical transmittance and reflectance Durability tests –High-temp. humidity –Thermal shock/ cycling –hot-cold soak.

Experimental investigation

Conclusions 1.IRL R*, R av, ripple R max are interlinked to spectral bandwidth. The higher the bandwidth, the higher R*/R av and the R max. 2.Higher-ripple designs can also have global optical properties (R*/R av and T av ) that are comparable with those of lower-ripple designs but they have higher spectral instability.

Conclusions 3. Sub2 high-index material in combination withMgF2 allows the production of efficient AR coatings with the electron-beam evaporation technique, in terms of both optical properties and durability of the coatings.