A MULTI-CHANNEL PHOTOELECTRIC SPECTROMETER EMPLOYING A FABRY-PEROT ETALON AND AXICON G. I. KATCHEN, J. KATZENSTEIN et L. LOVISETTO J. Phys. Colloques, 28 C2 (1967) C2-230-C2-238 DOI: 10.1051/jphyscol:1967243