RMS roughness: < 1.5Å on plane surfaces and about 2Å on smoothly bended spherical surfaces

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1 HIGH QUALITY CAF 2 COMPONENTS LOWEST STRAYLIGHT LOSSES IN THE UV Our special polishing technique for calcium fluoride guarantees: RMS roughness: < 1.5Å on plane surfaces and about 2Å on smoothly bended spherical surfaces Figure1: 3D AFM measurement of a high quality polished CaF 2 substrate (performed at FhG IOF Jena) rms roughness.12nm Lowest scattering losses: 2 x 1 5 at 248nm (total backscattering) 5.6 x 1 4 (total backscattering) and 7.5 x 1 4 (total forward scattering) at 193nm Surface quality: 1 5 scratch digs, 5/1 x.25 (according to DIN 111) Flatness: λ/1 on diameters up to 25nm, λ/4 on Ø38.1nm and Ø5mm Substrate dimensions: maximum diameter investigated: 5 mm thickness: about 1/4 of substrate diameter for flatness of λ/1 All fluoride HR coatings for 193nm show improved laser damage thresholds (A. Duparré et al., Proc. SPIE Vol p.148) Improved adhesion of HR coatings for the IR on super polished substrates

2 HIGH QUALITY CAF 2 COMPONENTS 41 1 µm Figure 2: Interference microscope image of standard polished CaF 2 * Calcium fluoride is a non birefringent material showing high transmission in the wavelength range between 13nm and 8µm. Because of its unique optical and mechanical properties CaF 2 is the favourite material for transmissive components in the deep UV, especially for ArF and F 2 excimer laser applications. Moreover, it is widely used as substrate material for excimer laser mirrors and for many spectroscopic applications in the wavelength range from the DUV to the NIR/IR. 1 µm Figure 3: Interference microscope image of specially polished CaF 2 * Especially in the UV scattering losses become a serious problem. Thus, it is essential to have substrates with extremely smooth surfaces. Figure 2 and 3 show interference microscope images of standard polished and special polished CaF 2, respectively. The special polishing technique developed at LAYERTEC enables the production of CaF 2 substrates with rms roughnesses as low as 1.5Å which are completely free of the typical scratch marks of conventionally polished substrates shown in figure 2. * Measured with differential interference contrast microscope (area 3 x µm) by Jenoptik LOS GmbH Ernst - Abbe - Weg 1, D Mellingen, Germany, info@layertec.de Phone 49 () /7 44 -, Fax 49 () /7 44 -,

3 42 YAG Sapphire BaF 2 CaF 2 Infrasil * Fused silica BK7 ** SF1 ** (undoped) (UV) wavelength range free nm nm nm 13nm 3nm 19nm nm nm of absorption 4 µm 4 µm 1 µm 7 µm 3 µm 2. µm*** 1.8 µm 2. µm Refractive index at nm nm nm µm µm µm µm SUBSTRATE MATERIALS Absorbing in the 3 µm region no no no no yes yes yes yes Birefringence no yes no no no no no no Resistance against temperature high high very low low high high high medium gradients and thermal shock LAYERTEC specifications Surface roughness (rms).5 nm.5 nm 1nm.15 nm.2 nm.2 nm.5 nm.5 nm Flatness (plane surfaces) (546 nm) λ/4 λ/4 λ/2 λ/4 λ/1 λ/1 λ/1 λ/1 Surface figure (curved) (546 nm) λ/4 λ/2 λ/2 λ/4 λ/4 λ/4 λ/4 λ/4 Surface quality (DIN 111) 5/1x.63 5/5x.1 5/1x.1 5/1x.25 5/1x.25 5/1x.25 5/3x.25 5/3x.25 * Registred trademark of Heraeus Quarzglas GmbH & Co. KG ** Registred trademark of SCHOTT Glaswerke, Mainz *** Absorption band within this wavelength range, please see transmission curve

4 SUBSTRATE MATERIALS 43 TRANSMISSION CURVES YAG undoped (3mm thick) Sapphire (3mm thick) Calcium fluoride (3mm thick) Barium fluoride (3mm thick) Fused Silica IR (Infrasil ) (3mm thick) Standard fused silica UV (Corning 978 ) (3mm thick) BK7 (3mm thick) SF1 (4mm thick) Ernst - Abbe - Weg 1, D Mellingen, Germany, info@layertec.de Phone 49 () /7 44 -, Fax 49 () /7 44 -,

5 44 STANDARD SUBSTRATES The precision optics facility of LAYERTEC produces plane and sherically curved mirror substrates, lenses and prisms of fused silica, optical glasses like BK7 and SF1 and some crystalline materials, e. g. calcium fluoride. In the following you can find information on the specifications and prices of our standard substrates. Please do not hesitate to contact us also for other sizes, shapes, radii and materials or for special components like prisms, etalons or meniskus lenses. SPECIFICATIONS Common specifications Tolerances: Diameter: +mm,.1mm Thickness: ±.1mm Clear aperture: central 85% of dimension Chamfer:.2.4mm at 45 Materials: Fused silica: Corning 798, prices for fluorescence free material as SQ1 (SICO) on request Fused silica IR: Infrasil 32, Heraeus BK7 : optical glass, SCHOTT CaF 2 : transparent from UV to IR, prices for excimer grade qualities on request Sapphire: random oriented, single crystalline YAG: random oriented, single crystalline Surface quality: A: Fused silica: MIL: scratch dig 1 5, equivalent to 5/1x.25 (DIN 111) BK7: MIL: scratch dig 1 5, equivalent to 5/3x.25 (DIN 111) CaF2: MIL: scratch dig 1, equivalent to 5/3x.63 (DIN 111) B: Sapphire: MIL: scratch dig, equivalent to 5/5x.1 (DIN 111) YAG: MIL: scratch dig, equivalent to 5/1x.63 (DIN 111) Plane substrates, parallels and wedges Ø: diameter [mm] t: thickness [mm] Surface figure: Fused silica, BK7: λ/1 (633nm) CaF 2 : Ø6.35mm 25.4mm: λ/1 (633nm), Ø mm: λ/4 (633nm) Sapphire, YAG: λ/4 (633nm) Wedge: Standard plane substrates: wedge < 5min Standard parallels: wedge < 1min or wedge < 1sec Standard wedges; wedge = 3min or wedge = 1deg Plano concave and plano convex substrates Surface figure of curved side: λ/4 (633nm) Standard radii of curvature (ROC): Group R1: 1, 15,, 25, 3, 5, 75, 1,, 3, 5mm Group R2: 5, 75mm Other standard radii: 25, 3, 38mm Wedge: CaF 2 : wedge < 15min, all other materials: wedge < 5min Ø: diameter [mm] te: edge thickness [mm] tc: centre thickness [mm]