Physical Properties and Mathematical Simulation
Bulk diagnostics of optical properties
High-quality results are achieved using state-of-the-art analytical equipment in the field of bulk and real structure analysis. The analytical methods are adapted to future demands by sustained further development in accordance with our accreditation according to DIN EN ISO/IEC 17025:2005-08.
Focal points are:
- Scattering diagnostics (Rayleigh R90, Mie, Forward, TIS).
- Analysis of light conversion (fluorescence, phosphorescence, quantum yield).
- Characterization of fluorescence, transmission, remission, reflexion and refractive index/dispersion at room temperature and temperature dependent optical properties between 10 and 450 K.
- Investigation of vibrations in microstructures and the composition of glass and glass-ceramics (Raman, FT-IR).
Example 1: Glass Defects
Raman analysis of gaseous, fluid and solid inclusions in glass. Inclusions and bubbles well below 50 microns can be identified and quantified. Moreover, the structural properties of solids can be characterized.
Example 2: UV Solarization
UV solarization test equipment for staining tests in the solar and optical industries. The accessible power density exceeds the solar power of the sun by more than an order of magnitude. Accelerated testing can be applied for several 100 cm² of sample surface.
Example 3: Stress in Glass
Stress-optic diagnostics are used to determine residual and mechanical stress in glass and glass-ceramic products in order to predict their reliability. The integral tension profile is visualized on the basis of the polarisation-dependent light distribution. For special geometries, e.g. bottles used for pharmaceutical packaging, even rotational stress components are characterized.
Development of new optical methods
New methods are needed in order to characterize innovative materials and composites. The design and development of precise and efficient optical metrology or other physical testing methods are based on the long experience of our scientists and engineers. Solutions are tailored to customer needs.
Glass-based reference materials
Over the last couple of years, demands on standard and reference materials have risen strongly. For prominent optical properties, e.g. fluorescence intensity, transmittance and reflectance, we offer glass-based reference materials.
Intense cooperation with federal metrology institutions, e.g. BAM and PTB, guarantee the reliability and accuracy of the desired reference materials and characterization procedures.
Certificates for transmittance, reflectance and fluorescence are available on request.
Our quality policy is to offer our customers in this field technical advice or consultation and customer-oriented services. Our three core competencies are thermal characterization, process analysis and process optimization even up to thermo-mechanical simulation. The strong interaction guarantees a classification of the analysis order to the specific area, the application of the best possible state-of-the-art analysis/characterization technology, and implementationand, if necessary, support on site.
Example 1: Thermal Expansion
The coefficient of thermal expansion of a sample of ZERODUR®-mirror substrates for earthbound and orbital telescopes is determined by dilatometry using an interferometric measurement equipment.
Example 2: Viscosity
Knowing the exact viscosity of a specific glass composition over the relevant temperature range is important to ensuring a robust molding process. To determine the lowest viscosity values, a rotating viscosimeter is used with temperatures of up to 1600 °C.
Example 3: Simulation
Result of a thermo-mechanical simulation of temperature distribution in a specific furnace used in production.
Based on these types of simulation calculations, layout designs of the aggregates are possible. The result is an optimized design of the aggregate.
Methods for optical properties
- Transmission, reflexion, remission, absorption in UV-VIS-IR range
- Thermal emission and temperature dependent transmission
- Refractive index and dispersion UV-VIS-NIR
- Stress-optical coefficient and stress-induced birefringence
- Spectral and temporal resolved fluorescence, phosphorescence
- Raman spectroscopy
- Light Scattering UV-VIS-NIR (Total Integrated Scattering TIS, Rayleigh R90, Forward scattering)
- Solarization tests (DUV, UV, Solar)
- also: E-modulus, Poisson ratio
- Thermal Expansion (CTE) from -180°C up to 1400°C
- Viscosity from 300°C up to 1650°C
- Electrical Volume Resistivity tk100
- Stress due to CTE-mismatch of glass-to-glass sealing
- Simultaneous Thermal Analysis up to 1500°C
- Differential Scanning Calorimetry, specific heat up to 1400°C
- Fusibility of glass (detection of crystallization)
- Thermal conductivity
- Long-term thermal stability
- Thermo-mechanical simulation, model and process development
- Optimization of processes and specific product properties
Dr. Axel Engel