Luminous transmittance

Light transmittance (luminous transmittance, light transmissivity). The ability of a material to pass incident hght through it, whether specular or diffuse. ASTM (www.astm.org) prescribes several tests of this property in plastics. Transmissivity is... 

Tables 4—6 Ust ASTM methods used for the characterization of PB and PMP. A number of specialized methods were developed for testing particular articles manufactured from polyolefins several of these determine the performance of PB and PMP film, including the measurement of the film s dart impact strength and tear strength. Dart impact strength is measured by dropping a heavy dart with a round tip on a stretched film. Tear resistance, which reflects the film s resistance to tear propagation, is measured with the Ehnendorf tear tester. Two values for the tear strength are usually reported, one in the machine dkection of the film and the other in the transverse dkection. Pipes manufactured from PB are tested by pressurizing them internally with water the time-to-burst failure is determined at various temperatures (46). The standard test method for haze and luminous transmittance (ASTM D1003) is used for the measurement of PMP optical characteristics.

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. 

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

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 Hardy-type spectrophotometer may be used for determining luminous reflectance, transmittance, and color of polymers (ASTM-791). The transmittance of plastic films is measured by ASTM-D1746. 

Most commercial acrylic sheets have an index of refraction of about 1.5 and a total luminous transmittance of about 90%. PC sheet has an index of refraction of about 1.6 and a total luminous transmittance of about 88%, Polysulfone sheet (IJdel) has an index of refraction of about 1.63 and a total luminous transparency of 80%. 

This last usage has given rise to a number of specitic applications of the term density, Thus, the luminous density is the luminous energy found in a unit volume of space The specular density is the logarithm of the reciprocal of the specular transmittance, and so on. 

ASTM D 1003-92 (1992) Haze and luminous transmittance of transparent plastics. 

The relevant data concerning spectral features, colorability, expressed as luminous transmittance Y as perceived by the human eye, and accelerated weatherability for... 

USEPA 1 Calculation of tristimulus values from transmittance values Dominant wavelength (nm) Hue, luminance (%) Purity (%) Use of a set of wavelengths (between 410 and 670 nm)... 

Haze and Luminous Transmittance ASTM D1003 provides two methods for measuring light transmittance and haze in planar sections of transparent plastics. The method making use of a hazemeter is briefly described. 

ASTM D1003-92, "Standard Test Method for Haze and Luminous Transmittance of Transparent Plastics," Philadelphia (1992). 

Transmittance (t) - Ratio of the radiant or luminous flux at a given wavelength that is transmitted to that of the incident radiation. Also called transmission factor. [1]... 

For sequential imaging of TIRF using the laser and then IRM using the epi-illumination, use the Selection Prism (arrow b in Fig. lb) at the junction of the split box at the rear port (beamsplitter) to allow 20% transmittance from the epi-il-lumination and 80% laser beam power to be routed to the sample (rrrNote 15). 

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