New types of focusing optical devices based on glass‐capillary converters (GCCs) for the extreme ultraviolet (EUV) region have been constructed and tested. The EUV spectra of He II (np‐1s) line radiation have been recorded in the spectral region from 23.0 to 30.6 nm both with and without GCC. Experimentally an enhancement of EUV radiation by a factor of 4–5 has been demonstrated for a small solid angle of the detection system. Theoretically, a computer simulation has been performed producing an enhancement coefficient of about 30–50 for optimal conditions of such experiments. ©1995 American Institute of Physics.