Development of Novel Infrared Filters for the Next Generation of Astronomical Telescopes and Planetary Probes
PhD Thesis - The University of Reading, School of Systems Engineering (2005)
The spectral design and physical construction of interference thin-film multilayers for the Q-band region of infrared filters in the 20-40µm wavelength range has notoriously been a problematic area of research study for many years. The limiting selection of transparent and robust materials in this wavelength region, together with the various multilayer thin-film thickness constraints have prevented a suitable and sustainable solution to many of these design issues. In this thesis, I describe the current boundaries inherent to multilayer interference technology and investigate various research alternatives to provide a tangible solution to these limitations.
Novel applications of improving the adhesion of infrared multilayers deposited on CVD diamond optical substrates with amorphous hydrogenated diamond-like carbon precursor films are investigated to assess their enhanced spectral and environmental viability for use in future mid-infrared instruments.
An experimental research study into the intrinsic and composite stress properties of deposited thick multilayers is presented with a view to understanding the optical and mechanical effects resulting from bending deformations induced on optical substrates by the deposited thin-film structures. Understanding and compensating for these stress properties aided the construction of thin-film multilayers for focal plane detector array filters on the Mars Climate Radiometer.
A research investigation into the application of novel short wavelength pass blocking filters comprising metallic waveguide arrays manufactured by micro-machining technologies is described. These enable enhanced mechanical properties that are deficient in current filtering technology and contribute to spectral rejection of long wavelength radiation.