Research On Imaging Properties Of Bending Gratings Related Metrology Technology

The technical innovation becomes vigorously forging ahead in the beamline with the rapid development of the synchrotron radiation (SR) facility and its applications. Monochromator, acting as the core component in SR beamline, mainly consists of the entrance slit, exit slit, dispersion unit and reflection mirror. Wherein, the dispersion unit, diffraction gratings, is the important element, which mostly determines the performance in monochromatizing SR. So it is necessary and imperative to develop the theory of SR monochromator related metrology technology for diffraction gratings.On the other hand, the development of SR puts greater demands on surface quality, figure and shape parameters of the optical elements used in beamline. Meanwhile, the unique characteristics of these optical elements are generally narrow but long shapes. Therefore, novel surface measurement method and measuring system should accordingly enhance to cope with the increasing requirements in SR.This article locates the research content in SR technology, and pays attention to the SR monochromator theory related metrology technique. In the constant deviation angle spherical grating (Dragon) monochromator, the exit distance usually moves seriously and changes the value of SR at the sample position uncertainly. More recently, to minimize the far movements of the exit distance during scanning process, bending of gratings into weak cylindrical or polynomial surfaces has been analyzed or designed. Whereas it is still the primary time to research on a bending-grating-based monochromator, it is meaningful and significant to derive the imaging properties of a bending grating, furthermore for its practical application in SR beamline. The long trace profiler (LTP) is a useful and absolute optical metrology instrument capable of measuring surface profile of very long dimension, especially for SR optical elements. The development of the long trace profiler is supported by project 211 from the Ministry of State Education and the author participated some related constructions. Affording to detecting the slope error and groove density of a diffraction grating, the long trace profiler takes advantage in optical metrology for these kinds of optical elements, As a sequence, it is necessary to establish a LTP method to measure the groove density of diffraction gratings. The main research content divides to several aspects as follow:1. Research on imaging properties of bending gratingBending-grating-based monochromator is a mostly novel concept in SR beamline, superiority in a fixed exit slit with an adjustable curvature or changeable surface profile to satisfy the focusing condition during scanning. This kind of grating whose surface can be controlled and bent to desirable figures, named as bending grating, appears lately. Therefore, research on imaging properties of bending gratings...