Transmittance Transparencies

G.3.2.4 Transmittance, Transparency, and Translucency. The descriptions of absorption processes and their relationship to transmittance and color in the preceding section serve to underscore the relationship first presented by Eq. (6.70)—namely, that the fractions of light reflected, absorbed, and transmitted must sum to unity. In this... 

Opacity or transparency is important when the amount of light to be transmitted is a consideration. These properties are usually measured as haze and luminous transmittance. As reviewed haze is defined as the percentage of transmitted light through a test specimen that is scattered more than 2.5° from the incident beam. Luminous transmittance is the ratio of transmitted light to incident light. Table 5-7 provides the optical and various other properties of different transparent plastics. 

Different dianhydrides have been syndiesized or are commercially available, and some structures arc shown in Fig. 5.9.64-66 An improved method for preparation of cyclobutanetetracarboxylic dianhydride (CBDA) by photochemical dimerization of die maleic anhydride has been developed by Nissan.67 The polyimide obtained by condensation of CBDA widi oxydianiline gives a transparent and colorless material. The transmittance of 50-pm-thick film is 82% and the UV cutoff is 310 nm. 

The purpose of employing various light incidents when using a microscope was to distinguish between different crystals such as mineral crystals (e.g., clays, silicons, NaOH, etc.) from surfactant crystals (30-33). It was found that under transmittant light only bituminous hydrocarbons were non-transparent (absorb light) and appeared either... 

Turbidimetry is ideally suited to detect the temperature at which a transparent polymer solution turns opaque. The temperature corresponding to the onset of the increase of the scattered light intensity is usually taken as the cloud-point temperature, TcP, although some authors define the cloud point as the temperature for which the transmittance is 80% (or 90%) of the initial value. This technique is commonly known as the cloud-point method [199]. Turbidimetry was employed, for instance, to show that the cloud-point temperature of aqueous PNIPAM solutions does not depend significantly on the molar mass of the polymer [150]. 

The entrance window is a relevant part of the sensor. Common glasses as well as most transparent plastics block UV radiation. Standard UV-transmitting materials like quartz and sapphire are expensive. For UVA and to some extent the UVB special glasses but also plastics like some PMMA-derivatives or some silicon gels are available with a reasonable transmittance down to about 330 nm. For UVC applications with the important 254 nm line of Hg, quartz remains the standard solution. 

Surprisingly, transparency to the laser light was observed in a 0.5 im thick plasma slab (much thicker than the skin depth) obtained by ultra-fast ionization of a plastic foil at a density orders of magnitude higher than nc [4]. The effect was observed at laser intensities corresponding to ao 1. Figure 8.1 shows the measurements of plasma transmittivity in that experiment vs. the intensity on target of a focused Ti Sa laser pulse (30 fs, 800 nm). 

Transmitters, smart pressure, 20 663-665 Transosteal dental implants, 3 345 Transparency... 

ISO 13468, Parts 1 2, Plastics - Determination of the total luminous transmittance of transparent materials, 1996-1999. 

On the other hand, if the calorimetric cell is transparent, then Et, E[, E, and E[ have to be determined for example by using data for the transmittance of the media and fluorescence and phosphorescence quantum yields (see following discussion). 

ISO 1600 1990 Plastics - Cellulose acetate - Determination of light absorption on moulded specimens produced using different periods of heating ISO 13468-1 1996 Plastics - Determination of the total luminous transmittance of transparent materials - Part 1 Single-beam instrument ISO 13468-2 1999 Plastics - Determination of the total luminous transmittance of transparent materials - Part 2 Double-beam instrument ISO 14782 1999 Plastics - Determination of haze for transparent materials... 

The light transmittance of transparent polyamides is of the order of 85% up to more than 90% with a refractive index of 1.516, for example. 

Amorphous PET is transparent with light transmittance ranging from 80% up to 92%, haze of roughly 0.3-1.3% and a refractive index of about 1.575. Glass Polymers are specially designed to mimic thick glass for packaging cosmetics and healthcare products. 

Clear films in thin widths, for example 0.025 mm, are transparent in the visible light, near-UV and near-infrared spectrum with a transmittance of about 90% and haze of a few percent. Refractive indices are roughly 1.46. 

General-purpose grades of cellulosics are transparent or translucent. Certain grades in thick films or sheets, 1.5 mm thick for example, have transmittances superior to 90% with a haze inferior to 8%. Refractive indices are roughly 1.47-1.48. 

The transmittance spectrum of a titania nanotube-film (transparent) on glass is shown in Fig. 5.33. The optical behavior of the Ti02 nanotube-arrays is quite similar to that reported for mesostructured titanium dioxide [133], The difference in the envelope-magnitude encompassing the interference fringe maxima and minima is relatively small compared to that observed in titania films deposited by rf sputtering, e-beam and sol-gel methods [134],... 

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