LAYERTEC offers a wide range of substrates for your products. To help you to decide for the right one we offer many ways of support. Here you cen see transmission curves of selected materials. Please feel free to contact us for further information.

	YAG (undoped)	Sapphire	BaF2	CaF2	Infrasil 1)	Fused silica (UV)	N-BK7 2)	N-SF10 2)
Wavelength range free of absorption	400 nm - 4 μm	400 nm - 4 μm	400 nm - 10 μm	130 nm - 7 μm	300 nm - 3 μm	190 nm - 2 μm3)	400 nm - 1.8 μm	400 nm - 4 μm
Refractive index at
200 nm				1.49516		1.55051
300 nm				1.45403		1.48779
500 nm	1.8450	1.775	1.479	1.43648	1.46233	1.46243	1.5412	1.7432
1 μm	1.8197	1.756	1.468	1.42888	1.45042	1.45051	1.5075	1.7039
3 μm	1.7855	1.71	1.461	1.41785	1.441941
5 μm		1.624	1.451	1.39896
9 μm			1.408	1.32677
Absorbing in 3 μm region	no	no	no	no	yes	yes	yes	yes
Absorbing in 940 nm region	For higher power applications at 940 nm we recommend the fused silica SUPRASIL 300 1) and SUPRASIL 3001 / 3002 1)
Birefringence	no	yes	no	no 4)	no	no	no	no
Thermal expansion coefficient [10-6 K] 5)	7	5	19	18	0.5	0.5	7	8
Resistance against temperature gradients and thermal shock	high	high	very low	low	high	high	high	medium
LAYERTEC standard specifications for substrates with Ø 25 mm
surface roughness (rms)	< 0.2 nm	< 0.3 nm	< 0.3 nm	< 0.4 nm	< 0.2 nm	< 0.2 nm	< 0.3 nm	< 0.3 nm
Flatness (plane surface) (546 nm)	λ / 10	λ / 2	λ / 10	λ / 10	λ / 10	λ / 10	λ / 10	λ / 10
Surface figure (curved) (546 nm)	λ / 4 reg.	λ / 2 reg.		λ / 4 reg.	λ / 10 reg.	λ / 10 reg.	λ / 10 reg.
Surface quality (ISO 10110)	5 / 1 x 0.025; L2 x 0.004 Scratch-Dig 20-3	5 / 1 x 0.025; L20 x 0.0025 Scratch-Dig 20-3	5 / 3 x 0.025; L1 x 0.0025 Scratch-Dig 20-3	5 / 3 x 0.063;   Scratch-Dig 20-10	5 / 1 x 0.025; L1 x 0.004 Scratch-Dig 10-3	5 / 1 x 0.025; L1 x 0.004 Scratch-Dig 10-3	5 / 2 x 0.040; L1 x 0.001 Scratch-Dig 20-10	5 / 2 x 0.040; L1 x 0.001 Scratch-Dig 20-10

1)	Registred trademark of Heraeus Quarzglas GmbH & Co. KG
2)	Registred trademark of SCHOTT AG
3)	Absorption band within this wavelength range, please see transmission curve
4)	Measurable effects only in the VUV wavelength range
5)	The values given here are rounded, because the measurements of different authors in the literature are inconsistent. Please note that the thermal expansion coefficient of crystals depends also on the crystal orientation.