Low Loss Optical Components (340 – 3000 nm)

HR Mirrors

• R > 99.99 % in the VIS and NIR spectral range
• R > 99.999 % was demonstrated at several wavelengths between 1000 – 1600 nm
• Mirrors with defined transmittance (e.g. T = 0.002 %)
• For Cavity ring-down time spectroscopy, it is favorable to adjust the transmittance to the value of the scattering and absorption losses (T = S + A)
• All mirrors for CRD experiments are delivered with rear side AR coating. Wedged substrates on request
• Plane and spherically curved Fused Silica substrates
• Premium polish, RMS roughness: ≤ 0.15 nm (see Table 2 on page Standard Quality Substrates)
• Surface imperfection tolerance: 5/ 1 × 0.010 (ISO 10110) for Ø 25 mm
• Coating technique: magnetron sputtering, ion beam sputtering
• Optical parameters are stable against changes in temperature and humidity
• Attractive prices for small and medium numbers of substrates per coating run
• Very high reflectance values for complex coating designs, e.g. GTI laser mirrors with R > 99.95 % (see page Gires-Tournois-Interferometer (GTI) Mirrors (600 – 1600 nm) f.)
• Vacuum packaging or packaging under nitrogen cover gas in dust free boxes
• Designed for vacuum application

Important note for an order

The following balance equation applies:
1 = Reflectance R + Transmittance T + Losses L with
L = Absorbance A + Scattered Light S

Please specify the transmittance required for the application. LAYERTEC has dealt with the reduction of optical losses for many years and knows about the typical values of absorption and scattering in the NUV, VIS and NIR spectral range. Based on this experience LAYERTEC calculates the achievable reflectance from:

R = 1 - T - V

e.g.
Customer: T (0°, 633 nm) = 10 ppm (±5 ppm)
LAYERTEC: V (0°, 633 nm) < 25 ppm (typically < 20 ppm)
Specification: R (0°, 633 nm) > 99.996 %

Customer: T (0°, 390 nm) = 100 ppm (±20 ppm)
LAYERTEC: V (0°, 390 nm) < 50 ppm
Specification: R (0°, 390 nm) > 99.983 %

Cavity ring-down time measurements and reference data

Wavelength	Rmax	T	Loss L = 1 - R - T	Measured at
248 nm	99.87 %	0.00024 %	1300 ppm	LAYERTEC GmbH
266 nm	99.941 %	0.0031 %	560 ppm	LAYERTEC GmbH
355 nm	99.983 %	0.0105 %	65 ppm	LAYERTEC GmbH
380 nm	99.988 %	0.007 %	50 ppm	LAYERTEC GmbH
550 nm	99.9977 %	0.00039 %	19 ppm	LAYERTEC GmbH
633 nm	99.992 %	0.006 %	20 ppm	Westsächsische Hochschule Zwickau, Germany
660 nm	99.992 %	0.006 %	20 ppm	Heidelberg University, Germany
689 nm	99.9982 %	0.0005 %	13 ppm	LAYERTEC GmbH
798 nm	99.995 %	0.003 %	10 ppm	LAYERTEC GmbH
840 nm	99.9988 %	0.0002 %	10 ppm	LAYERTEC GmbH
1030 nm	99.9980 %	0.0012 %	8 ppm	LAYERTEC GmbH
1150 nm	99.9994 %	0.00035 %	2.5 ppm	LAYERTEC GmbH
1392 nm	99.9985 %	0.0007 %	8 ppm	TIGER OPTICS, USA (R measurement) LAYERTEC GmbH (T measurement)
1550 nm	99.999 %	0.0002 %	8 ppm	IPHT Jena, Germany
2350 nm	99.995 %	0.002 %	30 ppm	University of Grenoble, France
3250 nm	99.928 %	0.012 %	600 ppm	University of Grenoble, France
4000 nm	99.9 %	—	—	Bielefeld University, Germany

Notes

• Losses = absorption + scattered light; with absorption << scattered light
• Losses = f (polished surface, wavelength, coating technology, design and defects)
• E.g. scattered light of a plane or curved surface < scattered light of a concave surface combined with a plane chamfer for bonding

The development of low loss optics is highly dynamic. The tabular values are therefore guidelines for specific customer requests.