Total light transmittance

A measure of the color developed by impurities when trimeUitate esters are produced can be correlated with the anhydride color measurement. The method measures the color difference in light transmittance between a trimellitic solution and a 3.0 N sodium hydroxide solution as a reference. The difference in light transmittance or AH (total color difference) is obtained using a colorimeter. 

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... 

A special application of the high light transmittance of some polymers is the flexible light conductor, the so-called/ifcre optics. This is a bundle of PMMA fibres, in which each fibre is coated by a thin layer of another polymer, e.g. PE. Due to total reflection at the wall, light can be transported without noticeable loss of intensity along such a fibre, so that images can be transferred. 

Light transmittance (ASTM D1003-00) Current carrying ability interconnect resistance (N/A) Hydrolytic stability (IPC-TM-650, TM 2.3.10) Voids, delamination (acoustic microscopy) (MIL-STD-883, Method 2030) Total mass loss, water vapor recovery, and volatile condensable materials (ASTM E595)... 

Light absorbance (absorbance, absorptivity). The percentage of the total luminous flux incident upon a test specimen that is neither reflected from, nor transmitted through the specimen. Compare light reflectance and light transmittance. 

ISO, Glass in Building—Determination of Light Transmittance, Solar Direct Transmittance, Total Solar Energy Transmittance and Ultraviolet Transmittance, and Related Glazing Factors. International Standards Organization, Switzerland (1990). 

Total hemispherical transmittance is measured by the use of an integrating sphere to collect the light scattered at all angles. 

Light Reflectance (reflectance, reflectivity) The fraction of the total luminous flux incident upon a surface that is reflected, generally a function of the color (wavelength) of the light. (Johnson SF (2001) History of light and colour measurement A science in the shadows. Taylor Francis, UK Saleh BEA, Teich MC (1991) Fundamentals of photonics. Wiley, New York) See also Light Absorbance and Light Transmittance. 

Transmittance can be used to monitor aggregation. As the cells aggregate, there are fewer total particles to scatter light and, hence, more light is transmitted. This is the same principle behind aggregometers. We monitor this transmittance change on the SLM fluorometer (28). 

If the nonlinear inerease of the reffaetive index is elose to its linear eontrast, the transmittanee of the strueture B ean be less or greater than its linear transmittanee depending on a, ai (P = 3, solid line in Fig. 16). If the nonlinear inerease of the refraetive index is greater than its linear contrast, the transmittance of the strueture B is always greater than its linear transmittanee (P = 5, dashed line in Fig. 16). In the limit of very intensive light beams (P > 20) the transmittanee is total, = 1 (dotted line in Fig. 16). 

Many techniques are based on this principle and can be used for the analysis of all types of samples. The spectrum obtained from reflected light is not identical to that obtained by transmittance. The spectral composition of the reflected beam depends on the variation of the refractive index of the compound with wavelength. This can lead to specular reflection, diffuse reflection or attenuated total reflection. Each device is designed to favour only one of the above. The recorded spectrum must be corrected using computer software. 

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