June 20, 2021
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.
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May 20, 2021
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.
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April 20, 2021
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.
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January 29, 2021
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.
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