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Characterisation Tools

1. The Lossmeter

A NovaWave Technologies’ LossPro™ precision reflectometer and optical lossmeter operates at 3 wavelengths: 808, 1030 and 1550 nm. It enables high performance optical components to be accurately characterized with ultra high precision. The system utilizes the proven cavity ringdown technique to determine reflectance and losses in thin films and optical substrates with unparalleled precision. Reflectance from 98 % to 99.9995 % or total optical loss ranging from 2 % to 0.0005 % can be precisely and rapidly determined with sub-ppm-level precision using proprietary, high speed data acquisition and analysis software.

The lossmeter is located at the LMU Building, Am Coulombwall 1 (Garching).

Contact: Vladimir Pervak.

2. The Spectrometer

Spectrometer Perkin Elmer Lambda – 950.  Spectral range 180-3300 nm; absolute accuracy of transmission measurements 0.1 %; maximal reflectivity which can be measured 99.9 %.

The spectrometer is located at the LMU Building, Am Coulombwall 1 (Garching)

Contact: Vladimir Pervak.


3. White-Light-Interferometry 

Dispersions measurements
We have developed a white-light interferometer (WLI) for characterization of dispersive optics. It is based on broad-band scanning Michelson interferometer and measures the group delay different spectral components suffer in the mirror under study. Our WLI currently covers the spectral range of 350 nm to 2.2 ?m and permits measurement of the group-delay dispersion with an accuracy better than 10 fs² within this spectral range. This combination of spectral coverage and accuracy is currently unique in the world.

More details ...

For details: D. Grupe. Measuring group delay dispersion in the UV-VIS-IR range by white light interferometry. Diploma work 2008

The WLI is located at the LMU Building, Am Coulombwall 1 (Garching).

Contact: Vladimir Pervak.

4. Ellipsometry

Our ellipsometer M-2000 is from J.A. Woolam Co. and fixed to the IBD-O, but can also be used to measure samples. It is equipped with a white light Xe source (240-1700nm) and an appropriate detector.
In ellipsometry, a polarizer and an analyzer is used to measure the change in polarization by reflection of the sample. Numerical fits are then be used to

  • get the optical constants in the measured range with a high accuracy and
  • to measure the film thickness with Angstrom accuracy. This allows in- situ thickness control during deposition in the IBD-O.

The ellipsometer is located at the MPQ (Garching).

Contact: Michael Hofstetter


5. Surface Profilometer

Surface characterization
Surface quality is of critical importance for minimizing the losses and/or maximizing the damage threshold of our optical components. A Zygo interferometer operated at a wavelength of 632 nm and a home-built interferometer operated at 532 and 790 nm (both having a 150-mm aperture) are used for measuring the large-scale surface quality. With a Dektak 150 Stylus (Veeco) surface profiler we can scan the surface of our optics over a range up to 200 mm and measure surface roughness, film thicknesses with a resolution of several nanometres.

Our lab is equipped with a Dektak 150 Stylus Profiler from Veeco. A cantilever scans the surface profile of a sample mechanically along one axis with few nm resolution. Measurement series allow 3-D surface profile picture and can be used as easy characterization tools to measure film thicknesses, stress and surface roughnesses over the surface up to 200 mm.

The profilometer is located at the LMU Building, Am Coulombwall 1 (Garching).

Contact: Vladimir Pervak.

6. Zygo Interferometer

150 mm aperture, operates at the wavelengths 532, 632,  and 790 nm.

This interferometer is located at the MPQ (Garching).

Contact: Stefan Karsch

7. Damage-threshold measurement

For a complete characterization of the multilayer optical devices it is mandatory to investigate their damage threshold, especially when high-power applications are considererd. For this purpose we are currently developing a setup for measuring the damage threshold of such coatings on the 30 fs timecsale at 800 nm wavelength using a modified Femtopower Compact Pro (Femtolasers GmbH) Ti:Sapphire chirped-pulse amplifier system, which can deliver pulses at a repetition rate of 1kHz and a pulse energy of up to 1.5 mJ. The fully automated damage-threshold measurement assembly will be available in the near future.