Higher Order Harmonics Contribution In Metrology Beamline And The Design Of Suppression Mirror

Synchrotron radiation has been well accepted as a continuous light in EUV and soft X-ray spectral (XUV).It has been proved to be an invaluable research tool especially in VUV and soft X-ray. Most of the VUV and soft X-ray monochromator are using grating splitting beam. However, according to the grating formula d sinβ= mλ/n, higher order harmonics diffract in the same direction, so higher order harmonics can't be avoided in the monochromatic synchrotron beams and how to suppress higher order harmonics in a simple way is vital.On the other hand, polarization is another feature of synchrotron radiation. Many researches can take advantage of polarization of synchrotron radiation, such as biology, physics and materials. So how to improve the polarization of light is particularly important also.The innovations of this article are describled as follow:First of all, Using the house-made transmission grating (3300 l/mm) and IRDAXUV100G (USA) photodiode detector, higher order harmonics contributions have been measured in the spectral radiation standard and metrology beamline at NSRL and the contributions of the different orders have been analyzed. In order to accurately calibrate the performance of optical elements, higher order harmonics must be efficiently suppressed. Selecting the suitable filter in different wavelength, the higher order contributions can be efficiently suppressed.Second, based on a concept of triple reflection mirrors, a polarizer integrates with suppression of higher order harmonics together is presented. The effect of suppression higher order harmonics are calculated and the performance of triple-reflecting mirrors. Au_Si_Au,Au_SiC_Au,Au_Be_Au are compared. As result, triple-reflecting mirrors Au_Si_Au can suppress higher order harmonics effectively than others and the polarization is improved also, it's up to 99% in wavelength of 20evLast the mechanics of triple mirrors suppression is designed.