1. Fused Silica for Infrared Applications Operation @946nm @1064nm @ 1319nm Dr. Mark Altwein, Pisa, 21.10.2011 Heraeus Quarzglas Home of Quarz Solutions

2. Fused Silica for Infrared Applications Overview Heraeus Group What influences absorption in the IR?  OH- Content  Metallic Purity Simulation: Absorption can lead to heating Material Synopsis Seite 2

3. Who we are | Page 2 The Group We are a globally active precious metals and technology Group with firm roots in Germany. The company has been family-owned for 160 years. We operate in global niche markets characterized by lasting growth and attractive returns.

4. The Group As of December 31, 2010 Product revenue (in € million) 4,079 Precious metals trading revenue (in € million)17,946 Employees at year-end12,931 Heraeus Group Product revenues (in € million)Human resources Precious metals 1,4472,489 Materials and technologies1,5012,980 Sensors3753,144 Dental products3061,397 Biomaterials and medical products67183 Quartz glass2791,419 Specialty light sources99689 Business Groups Facts and Figures 2010 | Page 5

5. Heraeus Quarzglas: IR Material Grades Increasing demand for: Infrared Optics for high power laser applications Material inherent properties determine „behaviour“ under irradiation Seite 5

6. 1319 nm 946 nm 1064 nm Seite 6 Heraeus Quarzglas: IR Material Grades - Attenuation OH – molecular vibrational or rotational excitation Blue: laser wavelengths Red: OH absorption @ 940nm. 940nm Source: O.Humbach et al., J. Non Crystalline Solids, 203 (1996) Low-OH material: Preferred choice! Bulk absorption can be calculated: x dB/km => x * 2.3 ppm /cmBulk Example: The attenuation @ 940nm = 2dB/km => Absorption ~ 4.6 ppm / cm

7. Seite 7 Heraeus Quarzglas: IR Material Grades Absorption @ 946nm: OH-Content dominating property

8. Seite 8 Heraeus Quarzglas: IR Material Grades Absorption @ 1064nm: Metallic purity dominating property

9. Seite 9 Heraeus Quarzglas: IR Material Grades Absorption @ 1319nm: OH-Content dominating

10. Seite 10 Heraeus Quarzglas: IR Material Grades Simulation for 946nm and 1064nm excitation based on Steady-state diffusion equation with volume and surface heat sources  Absorption can lead to heating

11. Heraeus Quarzglas: IR Material Grades Seite 11 Temperature Laser Beam Radius Laser Beam Power Excitation @ 946nm: Suprasil 300x series => neglible heating

12. Heraeus Quarzglas: IR Material Grades Seite 12 Excitation @ 946nm: High OH content can lead to very strong heating!

13. Heraeus Quarzglas: IR Material Grades Seite 13 Excitation @ ~1µ: metallic purity most important!

14. Heraeus Quarzglas: IR Material Grades 2 main contributions:  OH-Content  Metallic impurity @ 1064nm: Metallic impurites dominating!  Less metallic impurites => lower absorption  Same purity level: Lower OH content => lower absorption @ 946nm: OH-Content dominating!  Lower OH content => lower absorption  Metallic impurites are only secondary! Seite 14

15. Heraeus Quarzglas: IR Material Grades MaterialWavelengthRemarkApplicationDescription Suprasil 3001200nm – 3500nmLowest absorptionHighest Quality 3D OpticsHigh purity Synthetic Fused Silica, low OH Suprasil 3002200nm – 3500nmLowest absorptionHighest Quality 2D OpticsHigh purity Synthetic Fused Silica, low OH Suprasil 300200nm – 3500nmLowest absorptionWindows, lenses with medium need for homogeneity High purity Synthetic Fused Silica, low OH Suprasil 311190nm – 1100nmVery low absorption @ 1064nm 3D applications, e.g. high grade prisms High purity Synthetic Fused Silica, medium OH Suprasil 312190nm – 1100nmVery low absorption @ 1064nm 2D applications, e.g. lenses, windows High purity Synthetic Fused Silica, medium OH Infrasil 301270nm – 3500nmVery good cost- efficency 3D applications, e.g. high grade prisms Natural fused quartz Infrasil 302270nm – 3500nmVery good cost- efficency 2D Applications,e.g. lenses or windows Natural fused quartz Seite 15

16. Seite 16 Summary OH-absorption bands strongly influence performance. Low-OH synthetic fused silica grades show a better absorption. Absorption may lead to lens heating and changes the homogeneity. Suprasil 3001, 3002, 300 is the best choice for infrared applications, especially for excellent performance. Infrasil 301, 302 is a suitable alternative for normal IR applications.

17. Heraeus Quarzglas: IR Material Grades Thank You For Your Attention! Seite 17