Design and integration of the lens of the DRAGO-2 infrared camera
ASE Optics Europe has been contracted by the IACTEC-Space team (of the Instituto de Astrofísica de Canarias, IAC) for the design, development, manufacture, and integration of the lens for the DRAGO-2 infrared camera, which will be placed in orbit on board a microsatellite ready to be launched into space at the end of 2022. Once validated in space, the same camera will be put into orbit on board the IAC’s ALISIO-1 mission, whose objective is to carry out environmental studies, thanks to its infrared observation capabilities.
DRAGO-2 is the long-focal variant of the DRAGO (Demonstrator of Remote Analysis of Ground Observations) series, developed by IACTEC-Space. The first camera in this series, DRAGO-1, was launched into orbit in January 2021 on a Space X Falcon 9 rocket.
It is an infrared camera that will monitor the Earth from space by taking images in two bands of the SWIR range (1.1 and 1.6 µm). Its main objective is to monitor and characterize phenomena derived from climate change and other phenomena such as forest fires since this spectral range allows observing through the smoke.
Development and manufacture of the SWIR lens
ASE Optics has carried out the optical design of DRAGO-2 lens and its integration of the optics in our facilities.
After evaluating different configurations, a refractive design was selected to cover the entire observation spectrum between 1.1 and 1.6 µm. Both the design and manufacture of this lens were carried out in close coordination with the mechanical and systems engineers at IACTEC-Space, who provided support in the finite element mechanical analysis and the definition of the interfaces required for the integration of the lens in the DRAGO-2 camera.
Project challenges
One of the biggest challenges encountered by ASE Optics was the absence of accurate values in typical optical design software for lens materials in the wavelength range of DRAGO-2. Interactions with manufacturers were required for ASE Optics to implement a correction to the dispersion models that resulted in the final dual design in the two SWIR bands.
Moreover, the strict environmental requirements of the project, which will operate under vacuum conditions in space, implied a re-evaluation of our assembly processes as well as the selection of materials in order, for example, to avoid outgassing phenomena.
Results obtained
The first images taken on Earth show the correct focusing of the camera in the two selected spectral bands of the SWIR range.
Figure 1: Images were taken with DRAGO-2 at a distance of 1.5 m from the same eye in different spectral bands (left), a glass diffuser also at 1.5 m (in the middle) and a mountain far enough away to be considered at infinity (right).
