The helium neon laser is a gas laser which has a gain medium of a helium and neon mixture. This mixture is placed inside a capillary tube of small bore and the mixture is excited by an electrical discharge of direct current. Typical He Ne lasers which are used at a commercial level are small when compared to other gas lasers. It has 3 components: the laser tube, the power supply and the packaging. The power supply is a high voltage supply.
Many scientific and industrial uses
There are many scientific and industrial uses of these red He Ne lasers. They are used in laboratories for demonstration in optics. These lasers are easy to operate and are available at low cost and this is why they are popular over other visible lasers. This laser is also used in the device which is used for reading the optical disk.
First to be used commercially
These lasers were the first to be used with commercial applications of broadband as they could be easily adjusted for generating a visible red beam. Visible infra-red beams can be easily used for projecting straight lines for surveying, alignment, irrigation and construction. Surveyors use this for taking precise readings from distances especially when some terrains are inaccessible. Eye surgeons also started using this laser for welding detached retinas without making an incision in the eye.
Where they are used today
You can also see the use of the helium neon laser in physics laboratories but they need to be handled with a lot of care. He Ne lasers are found in bar code readers. They are used in surgery for positioning infrared cutting beams. These are also widely used in holography. Holography is a technique to record light scattered from any object. This recorded light is used for reconstructing images.
Can work in green or red
This laser is too bright and it may affect your eyes if you stare at it directly. It is constructed to work in red at about 632.8 nm and it can be constructed to operate in green at about 543.5 nm and at 1523 nm in infrared. Its design is quite simple when compared to the modern standards and there are only 3 components. This operates by stimulated emission and amplification of light. Just because it is so inexpensive and it has so many advantages, it is widely used in industries and in research.
Not the most powerful
This laser is certainly not the most powerful laser and they are not even as efficient as other lasers but they still have the advantage that it has the ability of emitting a beam of good quality and it can emit visible light. Other lasers are 10 times more efficient than the helium neon laser but they cannot emit visible light with as much efficiency. He Ne lasers also don't need any consumables like cryogenic gases or sapphire rods and as they do not generate too much heat, there is no need for cooling devices. The beam quality is good and the beam stays focused even at long distances. This is why the commercial use of He Ne lasers is increasing gradually.
source: http://EzineArticles.com/6269955
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