Quality inspection of high-performance laser optics

© Fraunhofer IPM
Typical PCI measurement of a fused silica sample with double-sided antireflection coating

Highly sensitive photothermal spectroscopy for the determination of residual absorption

When components for nonlinear optics and laser technology are exposed to high (laser) light intensities, already very low absorptions, such as those still occurring in high-purity materials, can cause local heating. This results in malfunctions or even permanent damage of the components. Therefore, even low absorptions in the range of a few parts-per-million need to be detected before the components are used.

Fraunhofer IPM uses photothermal spectroscopy as a highly sensitive measurement method to determine residual absorption. With this method, both volume materials and dielectric coatings can be analized with ppm sensitivity.

© Fraunhofer IPM
PCI spectrum of a fused silica sample (Corning 7980), measured using the C-WAVE OPO pump source developed at Fraunhofer IPM

Service measurements and setup of measurement stations

We provide service measurements as well as measurement stations for the highly accurate determination of residual absorption, supporting your technology development in material production and your quality control of optical components – especially for use in high-power lasers. Depending on the material and wavelength, our measurement stations can detect residual absorptions in the range of a few ppm/cm in volume materials and below 1 ppm in coatings.

© Fraunhofer IPM
Wavelength ranges of available pump light sources for absorption measurements on optical materials

Measurement range from VIS to MIR

For the first time, Fraunhofer IPM is using tunable optical parametric oscillators as pump light sources for the determination of residual absorption. This facilitates the recording of absorption spectra from the visible spectral range to the mid infrared, i.e. at customer-specific wavelengths beyond those of standard lasers.

The tunability of the pump sources is also used for the calibration of the absorption data – making it possible to access absorption measurements on »new« materials.


Measurement over large wavelength ranges

By using tunable optical parametric oscillators as pump light sources, we are able to record absorption spectra from the visible to the mid infrared even beyond standard laser wavelengths.

Service and equipment

We have extensive experience in the field of highly sensitive absorption measurement technology. Via our service lab you can order individual measurements. Furthermore, we support you in setting up measurement stations for your specific applications.

Easy absolute calibration

Thanks to the tunable pump lasers, absorption features present in the material can also be scanned. The comparison with data from transmission measurements allows calibration without the need for specially prepared samples, resulting in more reliable data.