Assertion: terrestrial planet's type | /r/HasProperty | based on the principle of a phase mask
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text: We describe a new type of coronagraph, based on the principle of a phase mask as proposed by Roddier and Roddier a few years ago but using an original mask design found by one of us (D. R.), a four-quadrant binary phase mask (0, pi) covering the full field of view at the focal plane.