High quality fused silica and calcium fluoride components

Premium Quality Substrates

Premium quality substrates for special laser applications as Cavity Ring Down Time Spectroscopy or EUVmirrors are characterized by:

  • Exact geometry and shape:
    • For tolerances of geometrical properties such as diameter, thickness, wegde or radius of curvature please see page 12 of our catalog
  • Surface roughness
  • Surface form tolerance
  • Number of defects on the polished surfaces.

LAYERTEC has optimized the polishing procedures for all of these parameters. In the following we show some outstanding results which were achieved with fused silica and calcium fluoride.

Specifications

plane Substrate Specs
Power spectral density (PSD) curve of a high quality polished fused silica substrate (measurement performed at FhG IOF Jena)
AFM measurement of a hq CaF2 substrate
3D AFM measurement of a high quality polished CaF2 substrate (performed at FhG IOF Jena), rms roughness 0.12 nm

Surface Roughness

  • RMS - roughness <1.5Å achieved for plane substrates of fused silica and calcium fluoride
  • Similar results on smoothly bent spherical fused silica surfaces (depending on the ratio of diameter and radius of curvature)
  • Very low scattering losses of the substrates even in the UV- range:
    • TS = 2 x 10 – 5 at 248 nm (total backscattering)
    • TS = 5.6 x 10 – 4 (total backscattering) and 7.5 x 10 – 4 (forward scattering) at 193 nm
  • Applicable for low loss optics even in the DUV / VUV wavelength range

Surface Form Tolerance

Fused silicaPlaneλ/20 (633 nm) for diameters of 6.35 mm to 101.6 mm
Sphericalλ/10 (633 nm) for diameters of 6.35 mm to 38.1 mm
CaF2Planeλ/10 (633 nm) for diameters of 12.7 mm to 25.4 mm
λ/4 (633 nm) for diameters of 38.1 mm to 50.8 mm
Sphericalλ/4 (633 nm) for diameters of 12.7 mm to 50.8 mm

Surface Quality

MaterialISO 10110 (∅25mm)Approximately equivalent to MIL-O-13830
Fused Silica5/1x 0.010 L1x 0.0005Scratch - Dig 5 - 1
CaF25/1x 0.016 L1x 0.0010Scratch - Dig 10 - 2