Three grant proposals were submitted in France (INSU, Observatoire de Paris, Ministère de la Recherche) of which two were successful. Results of the OHANA kick-off meeting were presented at the SPIE conference held in Munich7 at the end of March and at a CNES/ONERA meeting on aperture synthesis held in Chatillon in June.
IRTF and SUBARU were approached by our directors and committee to extend a welcome to the project if they so wish.
A technical meeting also took place at the end of June between the authors and fiber manufacturers and users. One of the very fundamental questions, albeit one that does not need an immediate or an unequivocal decision, is what fibers to use. The choice, simple in appearance, is full of interesting considerations. On the one hand, silicate fibers are commonly available and especially polarization maintaining components with low transmission loss exist. These fibers transmit J and H bands (1,2 and 1.6 microns). However, those are the wavelengths where adaptive optics does not provide the best correction and coupling efficiency will be lower. Also, the fibers are sensitive to temperature and need to be actively controlled (the birefringence dispersion needs to be equal in both arms of the interferometer to maximize fringe contrast, and it depends on temperature, but also the fiber bending and twisting status; the use of polarization maintaining fibers helps to overcome this effect). On the other hand are fluoride glass fibers that transmit the K band (2.2 microns) and are fairly insensitive to temperature. Yet, polarization maintaining components are not as advanced yet as for silica fibers.
Independantly of the different technical challenges linked with each type of fiber, there is a scientific motivation to actually use both types, namely access to the J, H and K bands. Whatever the case may, the concerned parties (Gwenael Maze from "Le Verre Fluoré" and Francois Reynaud, from IRCOM in Limoges) were very enthusiastic, and we hope to be able to further these collaborations in the future.