In modeling phosphor materials, there are many items which must be measured or inferred. For instance, one needs to characterize the absorption spectrum of the phosphor particle, the emission spectra, the quantum yield (or excitation spectrum), the mean free path of the phosphor, the particle size distribution, and the intensity distribution from interactions that do not result in a conversion.This equation implies that in an optical system, the source size, its projected angular extent, and its surrounding refractive index define a constant étendue value. If we try to squeeze this étendue into an area of the same size, but with a lower refractive index, and the projected solid angle of the source is already full (as in this case), there will be angular clipping of the flux. This is exactly what we see going on here.
étendue also has other consequences. For instance, if we want to collimate light from a Lambertian source (like a flat cast LED), it shows mathematically that the output aperture will have to increase in area as the angular extent of the light decreases. If you don't increase your aperture size, then light will be lost due to spatial clipping. If you like small aperture sizes, it pays to avoid diluting the source étendue if possible.As shown in Fig. 2b, we immersed the chip in a lower index material and allowed the output surface to grow in order to ease the étendue mismatch. Another approach to help this problem, now standard in the backlight display industry, is to use scattering (in this case textured) surfaces in combination with light-ray recycling.Whereas titanium takes over the place of most regular metal Optical frame, due to the diligent flexibility and compliance that the titanium allows. These additional options can go on forever, as there are so many new alternatives to the classic plastic or metal choices.One typical trait to plastic eyeglasses or sunglasses is that style of the frame will generally be thicker than that of a metal frame. This approach is utilized in many flip-chip GaN systems, including those with laser lift-off removal of the sapphire layer.
In Fig. 3a, we show a 2D image of how this type of recycling system works. Light is generated at the InGaN quantum well junction layer.Progress Cheap handmade acetate sunglasses now provides both sports athletes andfans with great lighting, while providing tailgaters with lessnoise and fumes. Progress Solar Solutions has introduced a mobile light tower that illuminates large outdoorareas using stored energy from the sun.The solarpowered generator eliminates the diesel fuel and maintenancerequired by historically used diesel light towers. If it goes upward, it encounters a textured interface at the GaN/silicone boundary and may refract and escape. If not,Distinguishing between different glasses frame materials can make a large impact on your subsequent style choices. Typically Rx glasses come in two main style materials: metal and plastic. However, though we typically regards our two main choices as simple as plastic and metal, technology has actually allowed us to produce better, more durable and viable options from these two alternatives. it is reflected downwards at a randomized angle and then encounters the highly reflective Ag surface at the bottom of the p-layer and goes through the chip again. Fig. 3b shows a 3D view of the chip structure with an example randomized texture. One consequence of this approach is that an electrode is required on the top surface. Once a phosphor model is created, one can adjust the phosphor density in the matrix, among other parameters, to tailor the spectrum to a desired color temperature. Also important for white LED sources is the color rendering index (CRI), or how well the spectrum can render a set of test colors. For LEDs, other metrics such as the newer color quality scale (CQS), similar to the CRI but using more saturated reference colors, and gamut area index (GAI), may also be important in a given phosphor design.
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