Abstract
It is generally considered that gratings used in vacuum spectrometers have to be replaced after certain service period because by the adherance of oil vapor on the grating surface.
To prolong the life of gratings, much efforts have been made;some of them include replacement of a vacuum pump and setting an oil vapor adsorber between the spectrometer and the evacuating system.These are not the perfect means for prevention of grating deterioration.
On the other hand, attaching an air filter at the outer side of the leak valve of the spectrometer shows much superior result.For the last 20 months, the grating has proved to be free from any remarkable deterioration.The filter consists of soda lime and molecular sieve as an adsorbers of water vapor and air impurities.The filter at the leak value is also effective for prolongation of life 'of vacuum pump oil and reduction of evacuation time of the spectrometer.
