Optical principle

This behavior also leads to another typical optical property of the metallic effect the flop- or two-tone-effect. This effect describes the fact that, at metallic effect coatings. 

100% (diffuse) scattering - 0% gloss uniform light distribution in all directions Metallic effect somewhere in between  

Flop-effect different lightness under different 

The physical parameters for the metallic effect, which influence the ratio between reflection and scattering and thereby the flop effect, the lightness and brightness, the brilliance and sparkle, the gloss and the distinctiveness of image (DOI) etc. etc. can simply be described in terms of particle size, particle shape (morphology), particle size distribution and particle orientation in the film 

The influence of particle size is rather clear the coarser the particles, the more reflection, and the finer the particles, the more scattering. Coarse particles cause the so-called high sparkle effect . 

In pigments that simulate natural pearl effects, the simplest case is a plateletshaped particle with two phase boundaries P, and P2 at the upper and lower surfaces of the particles, i.e., a single, thin, transparent layer of a material with a higher refractive index than its surroundings. For small flakes with a thickness of approx. 100 nm, the physical laws of thin, solid, optical films apply [5.203]. 

Multiple reflection of light on a thin solid film with a high refractive index (Fig. 72) causes interference effects in the reflected light and in the complementary transmitted light. For the simple case of nearly perpendicular incidence, the intensity of the reflectance (/) depends on the refractive indices (n1, n2), the layer thickness (d), and the wavelength (A) [5.204], [5.205]  

With the given n1 and n2 values, the maximum and minimum intensities of the reflected light - seen as interference colors - can be calculated and agree well with experimental results [5.206]. Refractive indices of materials commonly used in nacreous pigments follow  

Natural pearl (guanine, hypoxanthine) 1.85 Fe203 (hematite) 2.9 

In practice, platelet crystals are synthesized with a layer thickness d calculated to produce the desired interference colors (iridescence) [5.206], [5.207], Most nacreous pigments now consist of at least three layers of two materials with different refractive indices (Fig. 73). Thin flakes (thickness ca. 500 nm) of a material with a low refractive index (mica) are coated with a highly refractive metal oxide (e.g., Ti02, layer thickness ca. 50-150 nm). This results in particles with four interfaces that constitute a more complicated but still predictable thin film system. The behavior of more 

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James R W 1965 The Optical Principles of the Diffraction of X-Rays (Cornell University Press) ch III... 

Adaptive Optics principles,performance and challenges Strehl ratio is given by... 

Optical principles are based on the fact that technical gases have distinct absorption spectra in different wavelength ranges of electromagnetic radiation. The widespread infrared spectral photometries uses the fact, that certain gases absorb infrared radiation in a characteristic manner. 02 and N2 are IR-inactive and therefore other compounds in air or flue gas can be easily detected. This technique has a very high selectivity for single compounds and shows only a few cross-sensitivities. 

Single-Mode Fiber Optics Principles and Applications, Luc B. Jeunhomme... 

S.W.WILKINS A.W.STEVENSON, Nucl. Inst. Meth., A269,321 (1988). R.W.JAMES, The optical principles of the diffraction of X-rays (Ox Bow Press, Connecticut 1982) p. 308. ... 

R.W.JAMES, The optical principles of the diffraction of X-rays (Ox Bow Press, Connecticut, 1982). 

Acousto-Optic Signal Processing Theory and Implementation, edited by Norman J. Berg and John N. Lee Electro-Optic and Acousto-Optic Scanning and Deflection, Milton Gottlieb, Clive L. M. Ireland, and John Martin Ley Single-Mode Fiber Optics Principles and Applications,... 

FIG. 1.19 Basic optical principle governing the operation of an optical microscope (a) the geometry on which the resolving power d of a microscope is based (b) detail showing how light from both sources must be intercepted by the lens to become part of the image. 

Figure 71. Optical principles of conventional and luster pigments A) Conventional pigment that absorbs and scatters light B) Metal effect pigment with complete regular reflection C) Natural pearl composed of alternating layers of protein and CaC03 D) Nacreous pigment the pearl is simulated by parallel orientation of the pigment platelets...

Nacreous and Interference Pigments. The optical principles of nacreous (interference) pigments are shown in Figure 72 for a simplified case of nearly normal incidence without multiple reflection and absorption. At the interface P, between two materials with refractive indices n t and n2, part of the beam of light L, is reflected (L,) and partially transmitted (i.e., refracted) (L2). The intensity ratios depend on n, and n2. In a multilayer arrangement, as found in pearl or pearlescent and iridescent materials (Fig. 71 C), each interface produces partial reflection. After penetration through several layers, depending on the size and difference between n1 and n2,... 

To establish a quantitative basis for comparing the performance of dispersive and FT spectrometers, it is necessary to review first the optical principles governing the operation of each type of instrument. The primary purpose here will be to... 

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