Facts On the Helium Neon Laser

Laser stands for Light Amplification by the Stimulated Emission of Radiation. These devices works when the light is amplified and there is stimulated emission. For a stimulated emission the electricity is passed on to the laser gas. When the electricity is discharged the electrons collide with the gas atoms that further impart the energy on to them. Once the atoms are energized they remain in an unstable condition wherein some of the electrons have already shifted to a level with much higher levels of energy. The atoms that are fully charged quickly go back to the original state when the electrons present go back to the normal condition. These devices are constructed in a quite simple design. The helium neon laser consists of three important parts and function according to the process of amplification of light and stimulated emissions.

Comprised of three important parts

They comprise of three important parts and operate by following the process of emission that is stimulation and amplification of light. Due to their several advantages over other kinds of lasers, these devices are widely being used for various applications in the research industry. The three components of these devices are structured packaging, power supply of high voltage and the laser pipe. The laser pipe is a glass tube that is sealed and consists of mirrors, electrodes and laser gas. The size of the tube varies with each other from more than a few cm of diameter and numerous meters in length. The gas in the laser is a mix of neon and helium. The proportion of these gases may range from anywhere respectively between 4:1 and 5:1.

Electrodes at the end of each tube

The electrodes that are situated at the end of each tube with the help of a gas discharge electricity. The functions of the mirror that is present at the tube ending aim to increase the effectiveness. The electric supply is necessary to provide the needed high voltage. A voltage supply of 10kv is required to start the emission of the laser and to sustain a continuous supply of 1-2 kV is required. The packaging of helium neon lasers includes mounts necessary for the laser pipe and also for the power supply. In some cases the helium-neon lasers consist of shutters for safety to stop accidental exposure and also prevents external optics from fine tuning the beam.

Advantages of the helium neon laser

The helium neon laser has several advantages over other kinds of laser. In general, lasers have an efficiency of one percent but the efficiency of helium neon lasers is nearly ten times more. The helium neon laser delivers power of around 75 mw. The edge that helium neon lasers have over other lasers is that they are capable of emitting visible light, have a beam of good quality and are affordable too. Other lasers don't have the capability to emit light on the other hand helium neon lasers have the capability to emit a red beam at around 632.8nm. These lasers generally don't require any cryogenic gases, sapphire rods etc or any other consumables. Its laser beam also stays focused over long distances.

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Helium Neon Laser Basics

A Helium neon laser refers to a kind of gas laser with a gain medium consisting of a mix of neon and helium inside bore capillary tubes, generally excited through the discharge of DC electric current. Also called a He Ne laser, it is used for several purposes, primarily industrial usage.

The first lasers

The very first helium neon lasers had an emission at around 1.15 µm in infrared and were the very first examples of gas lasers. However lasers which functioned at a visible wavelength found favor with a larger number of people, numerous other neon related transitions were researched upon for identifying the ones wherein population inversion could be achieved. As it is, 633 nm had the biggest gain in the visible spectrum, thereby making it the preferred wavelength for most helium neon lasers that were manufactured. However there are other infrared and visible lasing wavelengths that are possible. By making use of a mirror coating with the peak reflectance of the other wavelengths, helium neon lasers can be engineered for using those transitions. Thereby we get visible lasers in red, orange, green and yellow colors.

The lasing transitions

Lasing transitions may range from 100 µm in far infra-red to around 540 nm in visible. Now, since the visible transition at other wavelengths than 633 nm does not have higher gain, such lasers usually have low output powers. Moreover, these are more expensive too. The best and the most popular helium neon laser functions at a 632.8 nm wavelength in the red portion of a visible spectrum.

The gas mixture

The mix of neon and helium gases is in a ratio of approximately 10:1, and is contained at lower pressure within glass envelopes. The energy source of a laser is through the high voltage discharge of electricity that is passed through gas between the electrodes within the tubes. 3 to 20 mA DC current is usually needed for the CW operation. The optical cavity of a laser generally features 2 concave mirrors. It may also feature one concave and one plane mirror, with one having high reflectance while an output-coupler mirror allows approximately one per cent transmission. Gain bandwidth in He Ne lasers is dominated by the Doppler broadening instead of pressure broadening because of lower gas pressure, which makes it quite narrow.

Several industrial and scientific uses

As it is, the helium neon laser has several industrial as well as scientific uses. Such lasers are broadly used for laboratory demonstration in optical research or study because of the comparatively lower cost as well as ease of operation. A consumers application of the red helium neon laser is the laser disc player, by Pioneer. In this device a laser is used for reading the optical disks.

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The Helium Neon Laser - Excellent for Commercial Purposes

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.

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The Helium-Neon Laser: Easy to Operate and Low in Price

The Helium-Neon laser is also known as the He Ne laser. Actually, it is a sort of gas laser which consists of a capillary tube with a small bore and it is filled with a mixture of inert gases like helium and neon. The whole apparatus is energized by a DC electrical discharge.

A popular kind of laser

The first gas laser emitted infrared light but the helium neon laser which can operate at a visible wavelength is more popular. To improvise the device, many neon transitions were properly examined in order to get a neon transition with population inversion. The most popular choice of the visible spectrum that the Helium Neon laser uses is 633 nm. However, there are other ranges also which can be used in the manufacturing of this apparatus.

Mirror coatings

When a Helium Neon laser is made by using a wavelength of light other than 633 nm, mirror coatings at their maximum reflectance are used. Generally, red, orange, yellow and green transitions of the visible light are used to manufacture Helium Neon lasers. When these lasers make use of a visible transition other than 633 nm, they have lower gain and as a result of which they have not much output power and would cost you more. The most commonly known Helium Neon laser which is also the best operates at the wavelength of 632.8 nm and lies in the red part of the visible spectrum. This He Ne laser was manufactured at Bell telephone laboratories in 1962. Prior to that in 1960, the apparatus was successfully demonstrated.

The gain medium

The medium inside the He Ne laser is known as the gain medium which is a mixture of the inert gases helium and neon. These two gases are mixed in the ratio of 10:1 and were contained in a glass covering at a low pressure. A high voltage electric discharge which is passed through the mixture of inert gases filled between the two electrodes is the energy source or pump of the He Ne laser. To run the laser, a DC voltage of 3 to 20mA is needed.

The optical cavity

Moreover, the laser has an optical cavity which comprises of two concave mirrors or a plane and a concave mirror. Out of these two mirrors, one should have very high reflecting power and the other mirror called the output coupler mirror should allow only one per cent transmission.

The cavity length

Helium Neon lasers which are used commercially are small in size and their cavity length ranges from between 15 cm to 50 cm, although in order to achieve higher power sometimes the optical length goes up to one meter. However, the optical power ranges from between 0.5 to 50 mW. The widely used red He Ne laser has a wavelength of 633 nm. Lasing modes of the apparatus have a wavelength of around.001 nm.

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An Overview of the Helium Neon Laser

Though there are different kinds of lasers available, the helium neon laser is the best option. It is called by this name because the gain system consists of a mixture of both gases due to which it has been named like this. Therefore it is also called a gas laser due to the presence of gases. This mixture is filled in a small tube called a capillary tube. The ratio of the gases is about 10:1 which is perfect for the set up. Then low pressure is applied to the glass system so that the gases compress along with the electrical discharge. The electrodes which are used in the set up are connected to the glass tube and gas is passed through it. At the cathode end you have the output coupler and at the anode end you have the high reflector.

Population inversion

The helium neon laser is based on the concept of population inversion. In this process collision of electrons takes place with the gas mixture due to which the electrons get in the excited state. This means that they were initially in the ground state but due to collision they entered into the high energy state. Sometimes due to a higher collision, a metastable state is also reached which may not be common in other reactions. During the reaction lots of energy is generated which can be used in different forms. Doppler's effect will also come in to play because numerous activities are taking place at the same time.

Getting a better understanding

You will understand the concept better when you do it practically. If you feel the need you can use the Internet option and avail the information regarding the helium neon laser. You can also see the diagrams through which all these things will be clear before you. It will become easy for you to understand how things are going on and what reactions will take place. Even the set up as well as its operation will be clear to you and one will have no problem regarding it. You can also get to know about the fields in which this laser is used and how it can prove beneficial. One can explore the historical background that exists in the development phase of this type of laser. More dominantly this kind of laser performs well in the visible spectrum.

Practical demonstration the best way to understand

Thus you can say that there are lots of facts which are related to the helium neon laser. Apart from its workings, there are so many other interesting things that you would like to know and explore. Demonstration is the best way to understand things and get your information. If you want things to be clear to you then you have to see it practically and only then it is possible that you will have a complete comprehension. Hence through the Internet you will be able to collect lots of information about this laser and the wide applications in which it can be used.

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