06-11-2023 # PIAA prototype Manufacture # We have ordered a PIAA optics, made of CaF2. It is being manufactured in a single piece, by diamond turning. Overall wavefront error seems very promizing. It will be tested on a nulling test bench that is under construction.
21-09-2023 # Spectrograph Tank Delivery # The spectrograph manufacturing is in course. Today we received the Vacuum tank. It looks pretty “RISTRETTO” compared to its predecessors. We immediately pumped it to check vacuum tightness: After some trial and error the pressure reached 1.5 10-5 mBar
30-06-2023 # Nulling experiments with 3d printed IFU # The IFU has been put to te test. First cheching its properties, and then we could test the coupling properties and the nulling with our ring coronagraph. A lot has been learned, and we are devloping a new test bench for improving upon the test that have been performed.
20-12-2022 # Spectrograph Design Review # We had a successful spectrograph Design review. In order to validate the spectrograph hardware design and start fabrication. We also presented the status of the design of the Front end. Thanks to all the reviewer!
29-06-2022 # PIAA Coronagraph # A new Coronagraph has been studied for RISTRETTO and shows very promizing characteristics. It is a PIAA, based coronagraph, that using distortion change the illumination of the pupil of the instrument from a top-hat (minus obstruction and spiders) to a truncated gaussian. The gaussian profile allow to increase significantly the coupling into the fibers for the planetary signal, the truncation allow for the nulling of the stellar signals. ...
01-01-2022 # 3d printed IFU prototype # We have manufactured a an IFU prototype, using 3d printing technology. It was one of the few available solution to achieve the extremely tight requirement we have in the relative alignment of the micolenses to the fibers. The procurement has been done in 2 steps : The manufacture of a bundle of 7 fibres assembled in an hexagonal pattern The printing on top of the bundle, with the possibility to center as well as possible each micro lens to the actual fiber core position. ...
20-06-2021 # First Nulling Results with simple ring cornagraph # Thanks to our Intern Yoann Leclerc, we have a first test bench to test at the same time the injection into the IFU with MLA and a fiber, and we have the first nulling results. It is very promising. The test bench allowed us to test a grid of ring coronagraphs developped by Jonas Kühn. The test bench after a painstaking alignement of the fiber to the MLA and to the bench allow to scan the image of the MLA with high resolution (better than 0. ...
20-05-2021 # A Ring Nulling Coronagraph # A first coronagraph, easy to implement has been studied, it is a simple pupil mask with a ring. The idea of this mask is to change the shape of the PSF in order to have a null where the fiber are located. An important feature of this system is to be circularly symetric. It alows to produce a relatively broad band null with good enough nulling performances. ...
20-04-2021 # Playing with hexagonal MLA # We have procured a hexagonal MLA with characteristics that are near to what we need for the instrument. The plan is to gain experience with it. We set-up a new test bench to simulate the light injection at the level of the telescope. It produces a ~ F/200 beam so that a 250 microns pitch MLA can map the ring at 2λ/d. ...
29-01-2021 # First Nulling Trials # In order to Validate some of our ideas on the coronagraph approach for RISTRETTO, we have first set-up a test bench trying to achieve good nulling contrast levels using a S-630-HP fiber, the one we have selected for the instrument. A PSF, has been produced, by a fiber test set-up with an F/4 beam (the optical quality was far from perfect). This allowed us to test some precise translation system and map the coupling of a fiber when wandering around the PSf. ...