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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 7.2 5 44
Cu 199 200 0.5
Cr 8 5 60
Glass Slide
Slide 1
Experimental Transmission
-5
0
5
10
15
20
0 200 400 600 800 1000
Wavelength (nm)
Tra
ns
mis
sio
n (
%)
14-May
19-May
20-May
Slide 1
Theoretical Transmission
0
0.00001
0.00002
0.00003
0.00004
0.00005
0.00006
0 200 400 600 800 1000
Wavelength (nm)
Tra
ns
mis
sio
n (
%)
TheoreticalTransmission
Slide 2
Exp (nm) Theo (nm) Error (%)
Air
Cr 6.8 5 36
Cu 98 100 2
Cr 7.1 5 42
Glass Slide
Slide 2
Experimental Transmission
01020304050607080
0 200 400 600 800 1000
Wavelength (nm)
Tra
nsm
issi
on
(%
)
14-May
19-May
20-May
Slide 2
Theoretical Transmission
0
0.01
0.02
0.03
0.04
0.05
0 200 400 600 800 1000
Wavelength (nm)
Tra
ns
mis
sio
n (
%)
Series1
Slide 4
Exp (nm) Theo (nm) Error (%)
Air
Cr 6.1 5 22
Cu 144.7 150 3.533333
Cr 5.6 5 12
Glass Slide
Slide 4
Experimental Transmission
0
10
20
30
40
50
60
70
0 200 400 600 800 1000
Wavelength (nm)
Tra
ns
mis
sio
n (
%)
19-May
20-May
Slide 4
Theoretical Transmission
-0.005
0
0.005
0.01
0.015
0.02
0.025
0.03
0.035
0 200 400 600 800 1000
Wavelength (nm)
Tra
ns
mis
sio
n (
%)
Series1
Slide 5
Exp (nm) Theo (nm) Error (%)
Air
Cr 6.8 5 36
Cu 50.5 50 1
Cr 6.3 5 26
Glass Slide
Slide 5
Experimental Transmission
0
5
10
15
20
25
30
0 200 400 600 800 1000
Wavelength (nm)
Tra
ns
mis
sio
n (
%)
19-May
Slide 5
Theoretical Transmission
-0.2
0
0.2
0.4
0.6
0.8
1
0 200 400 600 800 1000
Wavelength (nm)
Tra
ns
mis
sio
n (
%)
Series1
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
• MgF2 and medium or high index materials
• MgF2 and ZrTi04 and Zr02 (sub2)
• MgF2 and Si02, Al2O3, oxides of tantalum, titanium zirconium, and niobium
• Sub1 and Ta2O5+SiO2,TiO2+Ta2O5 and SiO2+TiO2
Optical Material Preparation and Characterization
• Sub2– E-beam evaporation– Base pressure: 10-5 mbar– Added high purity dry oxygen: 10-4 mbar
Optical Material Preparation and Characterization
• Hitachi double-beam spectrophotometer, Model U 3400
Optical Material Preparation and Characterization
Optical Material Preparation and Characterization
• MgF2
– Same fabrication set-up– Substrate temperature: 200°C– 2x10-5 mbar
Optical Material Preparation and Characterization
• Tpeak: transmission peak
• A: Cauchy dispersion constant
Optical Material Preparation and Characterization
• MgF2 index of 1.35±0.01
• Literature value of 1.38-1.37
Design optimization
• Seven layer system of MgF2 and Sub2 coatings in alternate layers– Wideband (WB) AR coatings– Limited band (LB) AR coatings
• OPTOSOFT- software to optimize design
Design optimization
Design optimization
Experimental investigation
• Leybold Hereaus vacuum evaporation plant Model 560L– Optically polished and cleaned glass
substrates– Substrate temperature: 200 ±5°
– Rate: 0.3-0.5 nm/s for MgF2 and 0.05-0.1 nm/s for Sub2
Experimental investigation
• Optical transmittance and reflectance
• Durability tests– High-temp. humidity– Thermal shock/ cycling– hot-cold soak.
Experimental investigation
Experimental investigation
Experimental investigation
Experimental investigation
Conclusions
1. IRL R*, Rav, ripple Rmax are interlinked to spectral bandwidth. The higher the bandwidth, the higher R*/Rav and the Rmax.
2.Higher-ripple designs can also have global optical properties (R*/Rav and Tav) 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.