High-resolution confocal Fabry-Perot interferometer for absolute spectral parameter detection of excimer laser used in lithography applications

A spectrometeter based on a high-resolution confocal Fabry-Perot interferometer for detection of FWHM and/or 95% bandwidth of a laser beam of a narrow band tunable excimer or molecular fluorine lithography laser, comprising:

• a) reduction telescope for reducing the laser beam;
• b) a diffusor to homogenize the incident excimer or molecular fluorine lithography laser beam;
• c) a confocal Fabry-Perot interferometer between windows in a sealed and temperature-stabilized housing, the beam entering and exiting the housing and interacting with the interferometer through the windows of the housing;
• d) imaging optics for bringing the incident beam to focus at approximately a center of the interferometer;
• e) interferometer fringe imaging optics;
• f) a photoelectric detector of the interferometer fringe image.