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Recent developments in the Mid Wave InfraRed (MWIR) optical domain were made on materials, optical design and
manufacturing. They answer increasing demands for more compact, less temperature dependent optical systems with
increased optical performances and complexity (multi- or hyper- spectral imagery). At the same time, the
characterization of these components has become strategic and requires solutions with higher performance.
The optical quality of such devices is measured by wave front sensing techniques. PHASICS previously developed wave
front sensors based on Quadri-Wave Lateral Shearing Interferometry (QWLSI) using broadband microbolometers
cameras for infrared measurements. However they suffer from reduced light sensitivity in the MWIR domain, which
limits their use with broadband sources such as black bodies. To meet metrology demands, we developed an innovative
wave front sensor. This instrument combines the metrological qualities of QWLSI with the radiometric performances of
a last generation detection block (Infrared Detector Dewar Cooler Assembly, IDDCA) with a quantum infrared focal
plane array (IRFPA) of HgCdTe technology.
The key component of QWLSI is a specific diffractive grating placed a few millimeters from the focal plane array. This
requirement implies that this optics should be integrated inside the IDDCA. To achieve this, we take advantage of the
experience acquired from recent developments with optics integrated in IDDCA. Thanks to this approach, we developed
a high spatial resolution MWIR wave front sensor (160x128 points) with a high sensitivity for accurate measurements
under low-flux conditions.
This paper will present the instrument technological solutions, the development key steps and experimental results on
various metrology applications.
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