Mirror-based double diffraction grating system for coherence generation: additional study of periodicity error

Based on Doppler and Fourier optics analysis method, analyzed the configuration of double diffraction grating, and built its non-contact optical measurement mathematic model. And built double diffraction grating interference displacement measurement system, the design of double diffraction light path can compensate the deflection angle of grating moving, greatly improved tolerance of grating’s deflection. The compact and micro configuration of its light path, shorten optical distance, improving system’s environment anti-interference ability. Experimental resulting show, within 20nm displacement measurement, and<50mm/sec measurement speed, the system resolution is 1nm and measurement precision is less than 30nm.

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Analysis of imaging characteristics of parallax images in double diffraction grating imaging

Optik ◽

10.1016/j.ijleo.2019.163826 ◽

2020 ◽

Vol 207 ◽

pp. 163826 ◽

Cited By ~ 1

Author(s):

Hoon Yoo ◽

Jung-Un Jang ◽

Jae-Young Jang

Keyword(s):

Diffraction Grating ◽

Double Diffraction ◽

Imaging Characteristics

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Uniformity of Magnification from Different Electron Microscopes

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100060179 ◽

1967 ◽

Vol 25 ◽

pp. 32-33

Author(s):

Godfrey C. Hoskins ◽

V. Williams ◽

V. Allison

Keyword(s):

Diffraction Grating ◽

The Other ◽

Carbon Replica ◽

Electron Microscopes ◽

The Stability

The method demonstrated is an adaptation of a proven procedure for accurately determining the magnification of light photomicrographs. Because of the stability of modern electrical lenses, the method is shown to be directly applicable for providing precise reproducibility of magnification in various models of electron microscopes.A readily recognizable area of a carbon replica of a crossed-line diffraction grating is used as a standard. The same area of the standard was photographed in Phillips EM 200, Hitachi HU-11B2, and RCA EMU 3F electron microscopes at taps representative of the range of magnification of each. Negatives from one microscope were selected as guides and printed at convenient magnifications; then negatives from each of the other microscopes were projected to register with these prints. By deferring measurement to the print rather than comparing negatives, correspondence of magnification of the specimen in the three microscopes could be brought to within 2%.

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Computer Indexing of Electron Diffraction Patterns Including the Effects of Lattice Symmetry

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s042482010007775x ◽

1977 ◽

Vol 35 ◽

pp. 22-23

Author(s):

J. S. Lally ◽

R. J. Lee

Keyword(s):

Electron Diffraction ◽

Zone Axis ◽

Crystal Thickness ◽

Double Diffraction ◽

Automated Method ◽

Lattice Symmetry ◽

Intensity Calculations ◽

Unknown Structure ◽

Diffraction Patterns ◽

Orientation Parameters

In the 50 year period since the discovery of electron diffraction from crystals there has been much theoretical effort devoted to the calculation of diffracted intensities as a function of crystal thickness, orientation, and structure. However, in many applications of electron diffraction what is required is a simple identification of an unknown structure when some of the shape and orientation parameters required for intensity calculations are not known. In these circumstances an automated method is needed to solve diffraction patterns obtained near crystal zone axis directions that includes the effects of systematic absences of reflections due to lattice symmetry effects and additional reflections due to double diffraction processes.Two programs have been developed to enable relatively inexperienced microscopists to identify unknown crystals from diffraction patterns. Before indexing any given electron diffraction pattern, a set of possible crystal structures must be selected for comparison against the unknown.

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