Calibration method of transmission grating diffraction efficiency with weak high-order harmonics

The accuracy of transmission grating calibration on synchrotron radiation could be worsened by high-order harmonics. In order to correct this influence, a calibration method was proposed for the light source with weak high-order harmonics. This method corrected the fundamental wave diffraction efficiency using the high-order harmonics diffraction efficiencies which were obtained in calibration too. This verifying experiment was carried out on Beijing Synchrotron Radiation Facility. The experimental results show that the corrected ratio of first-zero order diffraction efficiency to zero-order agreed well with the calculated results between 100-800 eV where high-order harmonics existed. The ratio of second-order diffraction efficiency to first-order was more closed to the calculated results though some difference still existed. This difference came from the weak two-order diffraction.