Lasers are useful because they emit a small, monochromatic and uniform light which can make it appropriate for laser applications such as DVDs, medical and laser printers. The major benefit with lasers is that unlike ordinary light emitters, light from lasers never disperse to the external environment.
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This implies that the light that hits specific areas will be stronger and will provide a much better image. The light may even be as small as a pixel and this can provide very precise image for those concerned.
Lasers are also crucial in the creation of portable devices like laptops and mobile phones as they enable full color generation (IEC, 2011).
It should be noted that lasers have come a long way from the past. They have been crucial in the music and entertainment industries because they paved the way for transformation of the recording process. Now data in the form of words, music or movies can be available in a high capacity, clear, easily portable and less fragile format.
Previously, storage was done through the use of vinyl and these were bulky and noisy methods so this was definitely a great leap. Lasers have also transformed the retail industry through bar code technology.
In the past, supermarket employees needed to place price stickers in all commodities but thanks to the introduction of laser bar codes, it was now possible to record a product’s price without looking for its sticker. Furthermore, lasers have been instrumental in the industry of medicine.
Laser technology has revolutionized corrective surgery for the eyes and teeth. People can do away with spectacles after undergoing a laser operation and thus transform their very own lives.
In order to fully understand the benefits of lasers, it is essential to look at the classification systems. All lasers fall in four categories which are determined by an international panel that gathers annually. The first class consists of low power visible and invisible light.
It consists of beams that are found within products such as CDs and DVDs. As stated earlier, these are useful in storage of data. Laser printers can also be found in this category. They are very useful in digital printing and have produced superior printed images (IEC, 2011). The second class consists of visible light with low power.
Examples found here include laser levels. These levels were used to replace plumb lines and conventional levels. Laser levels have proved to be more reliable as they do not depend on the users’ bias. This category also consists of bar codes and is critical in inventory systems.
Lastly, class 2 lasers consist of Picop engines which are used to make full color images in portable devices like mobile phones (IEC, 2011). Class 3 is made up of light that has intermediate power and thus consists of laser pointers which are used in making presentation.
They replaced the traditional stick pointers and are brighter and more precise. They eliminate the need to be near the pointed item since one can point at the object even if one is standing far from it. A sub category of class three lasers consist of all the high power invisible light and visible light beams.
These consist of medical lasers which are used in various applications such as correcting tumors, elimination of eye problems and dental surgery. The major advantage here is that medical lasers make surgeries more effective and precise while alleviating pain.
This eliminates the need for use of anesthesia during operation procedures (IEC, 2011). The last category consists of visible light or invisible light with very high power. Typical lasers include scientific and industrial lasers. The industrial lasers are quite useful in handling metal i.e. cutting and welding.
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They are more efficient that typical methods because they are easily automated and they also achieve the same rate of work at a very high speed. Scientific lasers are also classified as class four lasers. These are used in spectroscopy in order to identify molecules and also identify materials under analysis (IEC, 2011).
There are several reasons why lasers are advantageous in their various uses as compared to previously used devices. First, lasers are accurate; they are straight and precise and can reach targets without being compromised. The quality of work produced is much higher than others whether this is in photography, printing, surgery or storage.
Lasers facilitate non contact so that work can be achieved easily and simply. In cases such as surgery, non contact is particularly advantageous because it minimizes instances of infection. In other industries, non contact prevents distortion of the materials under consideration.
Lasers have high resolution so they deliver very precise work. They are also immensely flexible and can be used in a variety of media, industries and materials. They are also cost effective because they get the work done in a simpler and better way than expected.
In order to understand why it is so hard to duplicate a hologram, it is vital to first look at the process of making it. Certain tools are vital in creating the hologram. A laser is crucial in this process and will normally involve a red one. There are many sources of these lasers but the most reliable one is helium neon.
Other kinds of laser sources like pointers are normally unstable and will not create high quality work. Lenses are also another vital tool in this process. Their purpose is not the same as in conventional photography because they are not used to focus light. Here, the reverse occurs since a beam needs to be spread out through this method. The beam splitter is the next device used in holography.
Also, prisms and even mirrors are utilized in the process of splitting beams that will be later used for image creation. All mirrors must be crystal clear because any contamination found on those surfaces will ruin the image. A film will also be needed but this is not a conventional photographic film. It is a holographic film which permits the recording of extremely high resolution light.
A hologram must be able to record even the most minor changes in light so it must have fine film (Smith, 1976). The following arrangement needs to be followed in order to achieve that precise final image: One should start with the laser which should be followed by the beam splitter whose function (as the name suggests) will be to split up the light into two.
This should be followed by a mirror which should target the beam to a lens. The purpose of the lens is to spread the light such that the beam can be made wider than it really is. The first beam which can be considered as the reference beam will fall on the photographic film while the other one will come into contact with the emulsion as a reference beam.
The different dark and light fringes will then be illuminated on the film such that a three dimensional image of the object is seen. The two rays are blended together to create a very unique image.
The reason why a hologram is difficult to replicate is that it is an interference pattern. Just like two waves in a pond of water, in this method of photography, two sources of light come into contact with one another they will have certain patterns of cancellations or reinforcements which will be manifested as either dark or light fringes.
Since the two sources of light under consideration are going to give divergent views of the item being seen then the viewer will know more about the depth and breadth of the item and this will be recorded as 3D in the mind of the viewer (Okoshi, 2011). Since the hologram gives images of objects in 3D, then one will need to be very precise in order to create the image.
There is a lot of work that is involved in this process and anyone trying to replicate the same may have to be as precise as the original photographer yet this is highly unlikely. The traditional photographic film simply records light from a certain point; a pretty straight forward process that can be easily achieved by anyone but the same cannot be said of hologram films.
In holograms, the main objective is to record an interference patterns. In order for one to see the hologram, it is necessary to shine light that is a replica of the reference beam. In the hologram, one laser emits light which is then split into two. Since these two beams come from the same source then they are just like one another.
A photographic film will not yield the same results if a reference beam does not match the object beam (Graham, 2003). In other words, it will not be possible to view an image of the object if different lasers are used. Consequently, holograms make it so difficult to duplicate images and that is the reason why they are used in credit cards and other high security documents.
Another reason why duplication is difficult is that the photographer needs to get a recording medium that can read the interference pattern formed by the two beams. In other words, it needs to have the exact same resolution that the hologram film used in the previous case.
Usually, when the two beams combine to form an interference pattern, there will be fringes and spaces formed between those respective groups. The film or medium used to construct this film needs to be such that it also falls within the range of frequencies of the fringes.
Once there is a lack of synchronization between these two then the image formed will appear to be dim and poorly resolved (Zelenska, 1970). This need to look for a hologram media that responds precisely to the inference patterns increases the difficulty of replicating the hologram.
Any relocation of the object will immediately compromise the integrity of the image. Even the slightest vibrations will cause distortion hence the reason why very still rooms need to be used.
Graham, S. (2003). Practical Holography. NY: Taylor and Francis
Okoshi, T. (2011). Three dimensional imaging techniques. NJ: Atara press
Smith, H. (1976). Principles of holography. NY: Taylor and Francis
Zelenska, K. (1970). Effect of film resolution and size in holography. Optical society of America Journal, 60, 34-43
International Electrotechnical Commission (IEC). (2011). Laser products classification. IEC report, No 60825-1