For mechanically ruled gratings, a ‘test’ ruling can quickly be checked with this approach, whereas a complete ruling sometimes requires several days or even weeks of continuous use of expensive ruling machines. This is much more effective in compare to the earlier approaches, wherein: (1) a master grating is fabricated, whether by mechanical burnishing with a ruling engine, or holographic writing (interferometry), or direct laser recording (DWL), or various newer writing techniques, like as electron-beam lithography (EBL) and Si-etching, or their combinations then, (2) it is replicated or/and coated, and, finally, (3) tested for the diffraction efficiency and scattering light intensity. The main purpose of such modern approach is rejecting unusable samples on earlier stages and decreasing expenses for their production and research. The advantage of using direct and exact groove metrology to predict efficiency and polarization characteristics of gratings now is well-known and widely used. Several widely used direct (or semi-direct – ‘imaging’) methods and respective instruments applicable for this purpose are compared. Here the author briefly compares various standard techniques for exact determining the digital profile and 3D topography of a surface relief grating. These gratings were chosen because high quality efficiency data exists, in particular, for flight gratings or/and X-ray gratings characterized by synchrotron radiation sources and their groove profiles, together with random nanoroughness, were measured by AFM or STM to be included in rigorous efficiency and scattered light intensity calculus. The author demonstrates examples of AFM & STM data and comparisons with other widely-used metrology techniques for bulk, coated, and multilayer-coated ruled, or holographic, or laser-lithographic, or electron-lithographic gratings having lamellar, or sinusoidal, or blazed, or other realistic groove profiles. The following problems are discussed here: the tip deconvolution, geometry, and radius groove shapes and abrupt groove slopes roughness PSD functions other. However, a wide analysis of the use of the STM and AFM methods for surface relief grating groove metrology has not really been undertaken in details. STM images of holographic relief grating surfaces (Au-coated) obtained by (a) organic and (b) non-organic photoresists (after ). In the present chapter, both the earlier published results and the recent, non-published yet results are described and discussed. These gratings were chosen because high quality efficiency data exists, in particular, for space gratings or/and X-ray gratings characterized by synchrotron radiation sources and their groove profiles, together with random nanoroughness, were measured by AFM or STM to be included in rigorous efficiency and scattered light intensity calculus. Also, the author demonstrates comparisons with other widely-used metrology techniques and examples of AFM & STM data of bulk, coated, and multilayer-coated ruled, or holographic, or lithographic gratings having realistic groove profiles. The following problems are discussed in this chapter: the cantilever tip deconvolution, geometry, and radius groove shapes and abrupt groove slopes roughness PSD functions etc. However, a wide review of the results of the use of AFM & STM methods for groove metrology of various surface relief gratings has not really been undertaken. Since then, many AFM & STM groove profile measurements on surface relief diffraction gratings have been presented. AFM & STM metrology has been around for a long time, and especially intense since it has been awarded by the Nobel Prize in Physics in 1986.
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