Influence of Oblique Incidence on Transmission Grating Diffraction in Soft X-Ray Region

Transmission grating diffraction of soft X-ray plays an important role in grating calibrations and soft X-ray measurements. In order to investigate the influence of oblique incidence on the applications of conventional transmission grating spectrometer in the soft X-ray area, the Kirchhoff diffraction theory with the Fraunhofer approximation is applied and detailed asymmetrical diffraction characteristics are demonstrated. The formation of the asymmetrical diffraction patterns is analyzed with the Fourier optics theory. Various grating structures are performed to explore the optimal structures to minimize the oblique incident influence and this can be a convenient means to control the oblique incident influence in future grating designs.