Hemispherical curved monolithic cooled and uncooled infrared focal plane arrays for compact cameras

Abstract

International audienceInfraRed (IR) sensor systems like night vision goggles, missile approach warning systems and telescopes have an increasing interest in decreasing their size and weight. At the same time optical aberrations are always more difficult to optimize with larger Focal Plane Arrays (FPAs) and larger field of view. Both challenges can now take advantage of a new optical parameter thanks to flexible microelectronics technologies: the FPA spherical curvature. This bio-inspired approach can correct optical aberrations and reduce the number of lenses in camera conception. Firstly, a new process to curve thin monolithic devices has been applied to uncooled microbolometers FPAs. A functional 256×320 25μm pitch (roughly 1cm2) uncooled FPA has been thinned and curved. Its electrical response showed no degradation after our process (variation of less than 2.3% on the response). Then a two lenses camera with a curved FPA is designed and characterized in comparison with a two lenses camera with a flat FPA. Their Modulation Transfer Functions (MTFs) show clearly an improvement in terms of beams dispersion. Secondly, a new process to fabricate monolithic cooled flip-chip MCT-IRCMOS FPAs was developed leading to the first spherical cooled IR FPA: with a radius of 550 mm. Other radii are achieved. A standard opto-electrical characterization at 80 K of the imager shows no additional short circuit and no mean response alteration compared to a standard IRCMOS shown in reference. Noise is also studied with a black body between 20 and 30°C

Innovative focal plane design for large space telescopes

“…Indeed, the Laboratory of Astrophysics of Marseille (LAM, France) and the CEA Leti (France) works on Variable Curved Detector technology and are able to curve continuously from convex to concave VIS and IR matrix detectors [5] [6]. This technology provides an other degree of freedom for the aberration correction (especially astigmatism and field curvature aberration) and would help this design to be more compact with simpler mirror shape.…”

Curved detectors developments and characterization: application to astronomical instruments

“…Firstly, there are several developments on the nsors. For the monolithic approach, the fabrication has been demonstrated on uncooled and , for very compact high-performance camera [5], Charge Couple Device (CCD) [6], or xide Semiconductor (CMOS) [7,8]. None are in industrial production.…”

Curved detectors for astronomical applications: characterization results on different samples

“…The study of curved detectors also belongs to this framework [curved CCDs 1 and CMOS [5][6][7][8][9][10]. This technology has been gathering increasing attention as the fields of application are numerous, from low-cost commercial to high impact scientific systems, to mass-market and on board cameras [11], defense and security [12].…”