Optical design of photometric techniques for specular reflection

1970 ◽

Vol 28 ◽

pp. 360-361

Author(s):

John W. Coleman

Keyword(s):

Boundary Conditions ◽

High Performance ◽

Force Fields ◽

Optical Design ◽

Direct Conversion ◽

Design Engineering ◽

Design Data ◽

Scalar Potentials ◽

Geometric Elements ◽

At Will

In the design engineering of high performance electromagnetic lenses, the direct conversion of electron optical design data into drawings for reliable hardware is oftentimes difficult, especially in terms of how to mount parts to each other, how to tolerance dimensions, and how to specify finishes. An answer to this is in the use of magnetostatic analytics, corresponding to boundary conditions for the optical design. With such models, the magnetostatic force on a test pole along the axis may be examined, and in this way one may obtain priority listings for holding dimensions, relieving stresses, etc..The development of magnetostatic models most easily proceeds from the derivation of scalar potentials of separate geometric elements. These potentials can then be conbined at will because of the superposition characteristic of conservative force fields.

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Forensic applications of IR infrared microscopic internal reflection spectroscopy

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100132273 ◽

1992 ◽

Vol 50 (2) ◽

pp. 1528-1529

Author(s):

Edward G. Bartick ◽

John A. Reffner

Keyword(s):

Specular Reflection ◽

Forensic Analysis ◽

Attenuated Total Reflection ◽

Internal Reflection ◽

Standard Size ◽

Ir Microscopy ◽

Ir Analysis ◽

Plastic Explosives ◽

Internal Reflection Spectroscopy ◽

Reflectance Measurements

Since the introduction of commercial Fourier transform infrared (FTIR) microscopic systems in 1983, IR microscopy has developed as an important analytical tool in research, industry and forensic analysis. Because of the frequent encounter of small quantities of physical evidence found at crime scenes, spectroscopic IR microscopes have proven particularly valuable for forensic applications. Transmittance and reflectance measurements have proven very useful. Reflection-absorption, specular reflection, and diffuse reflection have all been applied. However, it has been only very recently that an internal reflection (IRS) objective has been commercially introduced.The IRS method, also known as attenuated total reflection (ATR), has proven very useful for IR analysis of standard size samples. The method has been applied to adhesive tapes, plastic explosives, and general applications in the analysis of opaque materials found as evidence. The small quantities or uncontaminated areas of specimens frequently found requiring forensic analysis will often be directly applicable to microscopic IRS analysis.

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Valence electron energy loss spectroscopy in reflection geometry

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100153865 ◽

1989 ◽

Vol 47 ◽

pp. 378-379

Author(s):

J. Liu ◽

J. M. Cowley

Keyword(s):

Energy Loss ◽

Valence Electron ◽

Interband Transition ◽

Specular Reflection ◽

Three Dimensional ◽

Electron Excitation ◽

Transmission Electron ◽

Yield Information ◽

Valence Bands ◽

Excitation Processes

The low energy loss region of a EELS spectrum carries information about the valence electron excitation processes (e.g., collective excitations for free electron like materials and interband transitions for insulators). The relative intensities and the positions of the interband transition energy loss peaks observed in EELS spectra are determined by the joint density of states (DOS) of the initial and final states of the excitation processes. Thus it is expected that EELS in reflection mode could yield information about the perturbation of the DOS of the conduction and valence bands of the bulk crystals caused by the termination of the three dimensional periodicity at the crystal surfaces. The experiments were performed in a Philipps 400T transmission electron microscope operated at 120 kV. The reflection EELS spectra were obtained by a Gatan 607 EELS spectrometer together with a Tracor data acquisition system and the resolution of the spectrometer was about 0.8 eV. All the reflection spectra are obtained from the specular reflection spots satisfying surface resonance conditions.

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