Progress in Hybrid difractive/refractive solutions for compact space infrared imager

This research contribution analyses the potential of an innovative optical component
called multilayer diffractive optical element (MLDOE) for infrared dual-band systems.
The present manuscript intends to develop a comprehensive background centred around
Earth infrared remote sensing. Infrared applications and detectors constrain the optical
designer, who must also account for the intrinsic thermal and chromatic optical aberrations.
The radiometric budget allows for understanding the available levers to build a
high-resolution infrared dual-band imager and to estimate the resulting SNR. The innovative
MLDOE ideally has a near-diffraction performance in the whole thermal infrared
waveband, with a suitable chromatic aberration. This manuscript deeply explores MLDOE
modelling using ray-tracing and an exact electromagnetic approach. An MLDOE
optical performance is impacted by the material choice and the layer design, and is largely
overestimated in the literature. One MLDOE design arose, resulting from various optimisation
studies.