Radiation energy sensor with extended lifetime

摘要

The present invention relates to a radiation energy sensor which can be used for monitoring the energy of EUV radiation and/or soft X-rays. The energy sensor comprises a detection chamber (1) having a gas inlet (5) for supply of a detection gas and a measuring unit (13, 14, 15) for measuring effects which are caused by interaction of the radiation with the detection gas in said detection chamber (1) and which are dependent on the energy of the radiation. The energy sensor also comprises a second chamber (2) having a gas inlet (6) for supply of a filtering gas. Said second chamber (2) absorbing unwanted radiation is arranged between an entrance opening (3) for the radiation and said detection chamber (1) and is connected with said detection chamber (1) via a passage (7, 9, 11) allowing the straight pass of said radiation between the entrance opening (3) and the detection chamber (1). The radiation energy sensor is insensitive to debris and allows a spectral selective measuring of the energy of to be measured radiation.