Total luminous intensity

As mentioned in the introduction, hydroperoxides can be measured by recording the area under the CL curve in an inert atmosphere i.e. the total luminous intensity (TLI). Kron et al. found that when measuring CL in inert atmosphere together with peroxide concentration, as measured by iodome-try, for oxidised polypropylene, proportional relationships were obtained when the TLI was plotted versus peroxide concentration (see Fig. 3) [60]. In addition, changes in melting temperature and polydispersity index with aging time have also been found to correlate with changes in the TLI [59]. 

Fig. 3 Concentration of peroxides (open circles) and total luminous intensity, TLI, (filled circles) of PP powder aged at 70 °C for different periods of time...

Fig. 1.27. Total luminous intensity and peroxide concentration for PP powder aged at 70°C. Reproduced by permission of G. Ahlblad, Royal Institute of Technology, Stockholm.

The number of lumens indicates the total amount of power but gives no indication of the density" of that power. This last measure is given by the luminous intensity ... 

Radiant intensity can be described as the amount of power (watt) heading in your direction, i.e., per steradian, from a light source. The total amount of power emitted by the source is the radiant flux (watt). If you integrate the radiant intensity over all solid angles, you get the total radiant flux. If it is weighted by the photopic response, then it is the luminous intensity and the luminous flux. 

The impact, friction and spark sensitivities of pyrotechnic formulations are assessed by the methods given in Chapter 3. The outlines of methods for the determination of burning rate, luminous intensity, IR intensity, and total obscuring power of smoke are given in this section. 

By definition, photometers do not respond to radiation in the infrared or the ultraviolet (Fig. 4-4a). They are light meters in the sense that they mimic human vision that is, they respond to photons in the visible region, similar to the light meter on a camera. A candle is a unit of luminous intensity, originally based on a standard candle or lamp. The current international unit is called a candela (sometimes still referred to as a candle ), which was previously defined as the total light intensity of 1.67 mm2 of a blackbody radiator (one that radiates maximally) at the melting temperature of pure platinum (2042 K). In 1979 the candela was redefined as the luminous intensity of a monochromatic source with a frequency of 5.40 x 1014 cycles s-1 (A, of 555 nm) emitting 0.01840 Js-1 or 0.01840 W (1.464 mW steradian-1, where W is the abbreviation for watt and steradian... 

Candela - A unit of luminous intensity the magnitude to the candela is such that the luminance of the total radiator, at the temperature of solidification of platinum, is 60 candelas per square centimeter. 

In photometry, illuminance is the total luminous flux incident on a surface, per unit area. It is a measure of the intensity of the incident light, wavelength-weighted by the luminosity function to correlate with human brightness perception. Similarly, luminous emittance is the luminous flux per unit area emitted from a surface. Luminous emittance is also known as luminous exitance. In Sl-derived units, these are both measured in lux (lx) or lumens per square meter (cdsrm ). In the CGS system, the unit of illuminance is the phot. One phot is equal to 10,000 lx. Illuminance was formerly often called brightness, but this leads to confusion with other uses of the word. 

The UV stability of the TCR film was tested in an environment similar to an LCD. The TCR was laminated with a polarizer and exposed to a high luminous intensity in a sunshine tester. It showed sufficient stability after 265 hours of irradiation with a total light dose of 67kWh/m which corresponds, for example, to 30 days of sunshine in Tokyo at August. 

A change in the system pressure also changes the volume and the intensity of the luminous gas phase (plasma), which not only changes the relative position of the polymer-collecting surface in the plasma, but also changes the ratio of polymer collected on the surface to the total amount of polymer formed. Consequently, a change in pressure may cause a change in the apparent deposition rate of plasma polymer. 

Although the current density at a given bias is reduced by blending, the luminous efficiency of the devices sharply increases. The inset to Fig. 10.34 plots the EL intensity versus current density for all four devices. All three doped LEDs show much higher EL output at a given current density. Both of these phenomena can be attributed to better current balance. It has been proposed that trapping of holes will cause a space-charge field to develop under bias, which reduces the total electric field at the anode and increases the field at the cathode.69 This additional field will block hole injection and facilitate electron injection. As holes are the majority carrier, the overall current density will decrease, but the carrier balance is much improved. The device efficiency (Cd/A) consequently increases from 0.04 for the PF2/6 LED to 0.08 for ST 755, 0.15 for ST 16/7, and 0.87 for TPTE. Thus, a 22-fold improvement of device efficiency was obtained. The color purity of the blend LEDs was also observed to improve with a reduction of the polyfluorene excimer band at 560 nm. 

Fig. 5.6. Some relative values of refractory radiation, gas radiation, and particulate radiation intensities for a specific flame and furnace. Total radiation is 6.5% higher with a luminous flame than with a nonluminous flame. Multiply Btu/ft hr by 0.01136 to obtain MJ/m h. Multiply feet by 0.3048 to obtain meters. Adapted from a paper by Mr. K. Endo of Nippon Steel, presented at the International Flame Research Foundation, Ijmuiden, Netherlands, about 1980.

Integrating sphere n. A sphere coated inside with a highly reflective, diffuse material and used for the measurement of luminous flux. If the internal surface is perfectly diffuse, the intensity of any part of the sphere is the same. Many instruments used for reflectance measurements utilize such a device for measuring the diffuse or total reflectance from a sample material relative to a reference material. 

Luminous flux (1925) n. The total visible energy emitted by a source per unit time. The SI unit is the lumen (Im), defined as the luminous flux emitted in a solid angle of Isteradian (sr, the solid central angle that cuts out of a spherical surface a square whose side is equal to the radius) by a point source having a uniform intensity of 1 cd. Therefore, llm = Icdsr. 

Light induced degradative effects on the polymeric materials are visible on then-surfaces and the depth at which their properties are affected represents an interesting subject [7]. It is why the most affected materials are the transparent or translucid ones. Systems which totally absorb luminous radiation, without occurring of diffusion phenomena, respect the Lambert-Beer law, where Zq is the incident light intensity, I is light intensity at depth x and a is light absorptivity ... 

---