Many applications in the field of aerospace require the use of high-end materials. They should endure a hostile environment, need to be shock resistant, low weight and most importantly reliable with a long lifetime.
Many aircrafts and spacecrafts are equipped with numerous sensors that use optics to detect, track or identify countless things. In general, many applications are a smaller remote version of a laboratory setup on the ground. Many of these applications include remote sensing. From the larger distance, light is analyzed using a spectrometer. This light may need to be diffused to achieve a homogenized illumination or remove any angular dependence. Many materials can serve as a diffusor; these include plastic, ground glass or opaque glass.
The sensors may need a simple transparent cover that allows UV to NIR radiation to pass through, or require some optical components (e.g. lenses or prisms). Here it is important to understand what grade of fused silica offers what transmission performance for a specific wavelength region. However, not only is the absolute value of transmission important, it may also be of interest to know what to expect in terms of bubble or inclusion size and density. This is important to judge if any scattering defects or obscurations will be in the clear aperture of the optic.
More information on transmission performance
Because the sensors are in the air (or in space), it is difficult or impractical for a technician to perform maintenance during flight. Therefore, it is paramount to use materials that can sustain the working conditions for at least the duration of the flight. For space applications, this may be several years or more than a decade. Particularly in space, the materials have to sustain a dose of ionizing radiation without significant aging or degeneration of properties. Knowing how high intensity light and radiation can damage fused silica is very valuable to select the optimum materials.
More information on fused silica properties
Fused silica can be surprisingly shock resistant, if it is handled correctly and some general design rules are observed.
Heraeus materials have been involved in several Aerospace projects over the years:
- Gravity Probe B:
measure spacetime curvature near Earth, and thereby the stress–energy tensor in and near Earth
space telescope with the primary goal to analyze the distribution of dark matter and to study the properties of dark energy
- Civa camera system on Philae, Rosetta mission:
camera system for panorama view on comet Churyumov-Gerasimenko
mission is to make the largest, most precise three-dimensional map of our Galaxy
monitoring and characterising the Earth’s environment on a global scale
global navigation satellite system
…. And several others where high performance optics are required.