Best Lab Equipment

Here are some more information for Light Sources:

If you're interested only in energy efficiency, then the CFL bulbs are more efficient than LED diodes. They provide you with more light and use less energy. And we all know than in off-grid systems it's better and cheaper to save energy than to produce it.

But this energy efficiency should not be the only cause to make this choice. There other important features that you need to consider.

First of all, typical CFL bulb requires alternating current (AC) voltage. And to have AC voltage in off-grid system you need an inverter. Inverter is plugged to battery bank (that provides only direct current (DC) voltage) and produces AC voltage.

It's much easier to use LED lights in off-grid systems, because LEDs work on DC current as well. To be more specific, single LED diode works on DC current. So you don't need any expensive hardware (a good inverter will not be cheap) to run your LED lights from your off-grid systems.

The difference in LED/CFL efficiency is somewhat balanced by the efficiency of DC-->AC transition in the inverter. This device, unfortunately, has efficiency less than 100%. Nevertheless, the total inverter + CFL efficiency is greater than for LED light that uses DC voltage.

The CFL emit light in all directions while the LEDs give more concentrated light beam. Because of that, the CFL lights work better as main light sources for entire rooms, while hung on the ceiling, and LEDs are used to provide light on smaller areas, like on a single desk. LEDs are often connected in a form of light bulb (with a Edison screw) that's capable of being installed in a conventional fixture, but can also be connected in a form of LED strips that can be used for hallways or decoration purposes.

As you can see, CFL and LED lights would probably work best in an off-grid system if used together.

Krzysztof Lis is a MSc in mechanical engineering. Since 2003 he runs a website about renewable energy sources and alternative car fuels. He's on the road to his off-grid (autonomous) house.

Removal of Hair by Light Sources

The introduction of various light sources for hair removal is a result of the growing demand for a rapid, noninvasive method for hair removal. Light source of hair removal commonly focuses on ruby, alexandrite, diode, and Nd:YAG lasers and intense pulsed light sources. These devices are designed to target either an endogenous chromophore (melanin) or an exogenous chromophore (carbon suspension, photosensitizer, and exogenous dye). Laser hair removal is one of the most recent systems of hair removal to be introduced. Today, a large number of specific laser systems are available in the market that makes the customer a bit apprehensive about their attributes, selection, treatment protocols and effects. Laser hair removal is one of the light sources of hair removal.

Light can destroy hair follicles by a number of ways such as thermal, photomechanical or photochemical with generation of toxic mediators like singlet oxygen or free radicals.

Thermal mechanism for hair removal has recently been introduced to induce selective damage to hair follicles. It is based on the principles of selective photothermolysis. This principle predicts that selective thermal damage of a pigmented target structure will result when sufficient quantity of light at a given wavelength is absorbed by the target in a time equal to or less than the thermal relaxation time of the target.

In the visible to near-infrared region, melanin is the natural chromophore for targeting hair follicles. Lasers or light sources that operate in the red or near-infrared wavelength region lie in an optical window of the spectrum in which selective absorption by melanin is combined with deep penetration into the dermis. Therefore, deep and selective heating of the hair shaft, the hair follicle epithelium, and the heavily pigmented matrix is possible in the 600nm to 1100nm region. However, melanin in the epidermis presents a competing site for absorption. Selective cooling of the epidermis has been shown to minimize epidermal injury.

Photomechanical destruction of hair has been attempted with very short nanosecond pulses. This has been done by the help of Q-switched 1064-nm Nd:YAG lasers, with and without carbon suspension. Short pulses used to target hair follicles result in rapid heating of the chromophore (melanin). It leads to photo acoustic shock waves that cause focal photomechanical disruption of the melanocytes but not complete follicular disruption. Therefore, the Q-switched Nd:YAG lasers are not likely to produce long-term hair removal.

A distinction needs to be made between permanent and complete hair loss. Complete hair loss refers to a lack of regrowing hairs. It may be either temporary or permanent. Laser treatment usually produces complete but temporary hair loss for 1-3 months, followed by partial but permanent hair loss. Histological observations show damage predominantly in hair follicles with large, pigmented shafts, while hair follicles with small hypo pigmented shafts do not demonstrate any morphological change.

Immediately after laser treatment, the hair shaft shows fragmentation with focal rupture into the follicular epithelium and thermal damage to the surrounding follicular epithelium. The extent of thermal damage is dependent on the pulse width but retains confinement on the spatial scale of the follicle itself. Histological changes are almost guaranteed in the person undergoing laser hair removal. However, such form of hair removal should be carried out in the supervision of a qualified dermatologist as it involves considerable degree of expertise.

About the Author

The author is well versed with the problems of today’s times. He has a clinic in which he gives solutions and various hair loss remedy for problems like hirsutism, dandruff and alopecia.

Are there any other examples of reflecting light sources other than mirrors and water?

i really need three more sources for my homework and i cant think of any others! help!

The Moon
The Planets
Everything you can 'see' during the day

Tavoris Cloud-Glen Johnson Fight Not Happening On April 10th
by James Slater - Bad news for fans of the light-heavyweights. It has been reported by various sources how the scheduled April 10th clash between IBF 175-pound champ Tavoris Cloud and top contender and former champ Glen Johnson has been called off.

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