Optimization and evaluation of varied line spacing plane grating monochromators for third-generation synchrotron radiation sources

Grazing incidence objective Monk-Gillieson type varied line spacing plane grating monochromators with a magnification of similar to 1/10 have been designed by means of the hybrid method that takes advantages of both the ray-tracing and analytic methods. The resolving power of two monochromators thus designed was assessed experimentally at a bending magnet of the Advanced Light Source, Lawrence Berkeley National Laboratory and found to be similar to 6000 and > 10000 both at 401 eV. These values were well agreed with those estimated by ray tracing that takes into account the slope errors of the optical components. The effect of the thermal deformation of the optical components on the resolving power was simulated. Also discussed are the versatility of the designed monochromators and an improved design with a wide wavelength scanning range of 0.5-10 nm.