purcell and koomen have shown [ j. d. purcell and m. j. koomen , coronagraph with improved scattered-light properties , report of nrl progress , 1962 ( u.s. gpo , washington , d.c. , 1962 ) ] that a toothed occulting disk greatly reduces diffraction problems in coronagraphy .
C0041703
u.s
C0043038
washington