Green laser pointers were first commercially sold in the year 2000. They operate at the wavelength of 532 nm. Laser diodes of this wavelength are not available so the green light is obtained by the use of "DPSSFD" laser technology.

The process:-

A very high-powered Infrared laser diode working at 808 nm pumps a tiny block of Nd: YVO4 that generates light at 1,064 nm. This feeds a potassium titanyl phosphate intracavity frequency doubler crystal that produces green light of a visible 532 nm wavelength. High-powered green lasers use lithium triborate instead of KTP.

Features:-

An infrared filter, which is behind the mirror completely, removes the radiation of infrared spectrum from the output beam. In order to reduce cooling problems and prolong battery life, some green lasers operate in pulse or quasi-continuous-wave (QCW) mode. The Class III a laser product gives an output power of 5mw. This is the one of highest-powered street legal laser. Some green lasers even have an output of 10 mw, which has a range of 20,000 feet in darkness. Some even have a 3-second delay feature as these are high-powered lasers and can blind a person. Some laser point extenders are also available. They work by using lenses to minimize the beam spread of a laser. Its price starts from 55$. Majority of them have a life of around 3000 hours.

Applications:-

Green lasers can be used for a variety of roles. They can be used as pointing devices. The ability to form a continuous line in the dark is an added advantage; this has lead to its usage as rescue lights as it can be seen from miles away. It as been used for laser light shows. It is also used for sky gazing as a person can pinpoint a star by using the green laser. It can also be as laser pointers for guns, rifles. In the movie Alien vs. Predator it was used as a pointing device on some G36k carbines.

Advantages:-

The green laser has many advantages. It is fifty times brighter than a red laser because of which it can be seen from miles away, this helps in being rescued if a person is lost. It can also be used in high-tech weapons for aiming purposes. Because of its high range, Green laser pointers can be equipped in different kinds of weapons. High and low temperatures do not affect the performance of Green laser pointers so in case a person is lost in a desert, he can still use Green laser pointers to call for help, in other case, even if a person is lost some where in mountains all covered with ice, he can still use it.

Disadvantages:-

Due to its high power it can permanently damage a person's eye. As it can form a continuous line of light that might reveal a person's position so it cannot be used in stealthy operations or by SWAT.



Article Source: http://EzineArticles.com/?expert=Luigi_Castagna

The future of higher education will involve:

A) The same traditional classroom structure we’ve had for hundreds of years;

B) It does not matter- dolphins will take over the earth;

C) Robots will teach us all; or

D) The use of interactive software in combination with distance learning to supplement current programs

Okay, so you probably don’t think that artificial intelligence will advance so rapidly that robots will become our primary teachers and you probably don’t even think dolphins will take over the earth! What you might be aware of is that the internet is changing the way that education is being administered. You may have taken a distance-ed course or you may have even taken a class that came with a nifty little software package that let you work with the material.

The problem, however, is that not all subjects can be administered through a computer. Sure, one could argue that programs such as accounting, history, or statistics could be completely learned from a distance. After all, these subjects do not necessarily require any face-to-face interaction, but what about programs that do? Clearly, learning a language without face-to-face interaction would be like training for a marathon by running on a treadmill. Marketing and communication programs require face-to-face interactions so that students can learn to make persuasive arguments and presentations. All of the science labs require the presence of students. After all, how many of you would want a doctor that had only practiced on a virtual human. So if the computer cannot solve all our educational needs, what is the answer?

The answer is an integrated approach. If you are anything like this author, you learn 100 times better when you are engaged in the material. Thus, a really well done CD or internet site with interactive games and quizzes will force the students to interact with the material. This distance learning approach must be used as a supplement to traditional classroom methods as it cannot be a substitute for team building, face-to-face questions and answers, or building oral communication skills. All that said, many things currently done in the classroom can be moved online. Group discussions and question sessions can be accomplished via forums and chat sessions, certain scientific concepts learned in lab can be learned through interactive video, and even certain grammar basics of languages can be learned through interactive voice recognition software.

In high school and even some college courses, I was bored out of my mind as long-winded, verbose (yes, that was redundant on purpose) lecturers would go on and on about historical battles or the biochemistry translation process. At the time, I just figured such subjects were inherently boring. After all, how excited could one get about the battle of 1812 or the process by which proteins are formulated? But as I grew older, I became interested in things that I thought I disliked! A movie or an interesting article might turn me on to a subject I previously thought was about as interesting as paint drying. What the heck was going on? I was more engaged in the subject matter, that’s what! And so my crystal ball tells me that even though professors may be going nowhere, fun, educational, interactive games- well, they’re coming!



Article Source: http://EzineArticles.com/?expert=Craig_Zeff