Introduction
Laser is a name that is derived from Light Amplification by Stimulated Emission of Radiation. Laser machines usually give out light in that is in form of electromagnetic radiation via a process called optical amplification that uses simulated emitted photons.
The emitted lasers contain an elevated level of spatial and temporal coherence that are very hard to get when using majority of the present forms of technology. Laser beams can be directed towards very minute objects, because of their ability to gain high irradiance powers. A laser is made up of a gain medium, which is put inside a high reflective optical cavity and a source of energy for the gain medium that must have the ability to amplify light by stimulated emission.
The gain medium takes up pumped energy that is used to increase the quantum energy of electrons. An increase in the amount of particles in a specific excited state will lead to population inversion; hence, light amplification, when such numbers are above the quantity of particles in lower energy states.
This is caused by the large amount of stimulated emission that will pass through an object as compared to the amount of energy that is absorbed. The amplification of light will result in the development of an optical amplifier, which may develop into a laser, in case it is put in a resonant optical cavity. Lasers normally function in two primary modes namely uninterrupted or pulsed mode.
These two modes depend on the method in which power required to energize the formed lasers is supplied. In most scenarios, lasers are called continuous waves when they show signs of maintaining power stability over long durations of time and the high power frequency has minimal effects on the intended application (Slusher, 1999, pp. 71-79).
Uses of Lasers
One primary use of lasers is in optical research and education laboratories. For example, since the invention of the Helium-Neon gas laser, there has been numerous discoveries on the use of discharges to amplify light consistently. This type of laser has the ability of operating under different wavelengths; hence, the vast number of educational researches that are associated with it. Secondly, lasers find wide application in industries more so for cutting and welding.
As a result of the ability of Carbon dioxide lasers to give out high quantities of energy at a go, this energy can be used to cut heavy metals faster, as compared to most traditional methods. Moreover, some manufacturing and processing plants use laser interferometers to ascertain distances and displacements, more in areas of heavy machinery. Additionally, lasers play a central role when it comes to classifying varying species of chemicals and ascertaining the development most chemical processes.
This is possible because lasers have the power to energize molecules to a fluorescing point. Lasers also find wide application in grocery shops, more so supermarkets in barcode scanners to identify goods. This has greatly enhanced operations in supermarkets, because they help to provide all the details of goods by just passing the bar code reader across the bar codes that are normally embedded on goods.
In medicine, lasers are very useful in surgery. Primary applications of lasers in this field include the use of lasers as hot scalpels for cutting tissues, in LASIK eye surgery, in the treatment of glaucoma and macular degeneration, and during the removal of birthmarks and tattoos. Lasers can also be applied in some medical procedures such treating of kidney stones and during the process of angioplasty.
On the other hand, Lasers are also important in most military operations. High-power lasers are normally used as defense tools when it comes to attacking enemies in most deadly missions that require the use of range finders and detonation of bombs and missiles in definite areas. In addition, there is a wide use of lasers in military communications systems, to give clear communications, more so when in enemy zones (Hecht, Ewing, & Hitz, 2001, pp. 3-9).
Holograms
Holograms are three-dimensional images that are primarily obtained using photographic projection. They are different from three-dimensional graphics in that, unlike in three dimensional reality where illusion of depth is used and the image is normally projected in a two-dimensional surface, all products of holograms are in three-dimension; hence, they do not need any specific viewing apparatus. There are two classes of holograms namely reflection and transmission holograms.
The former case uses laser or white light reflecting services to develop a three dimensional object, where as in the latter case three-dimension images are usually made using monochromatic light. A holographic device is primarily made up of lasers, beam splitters, mirrors, lenses, and holographic films. Lasers are the primary elements of any hologram, because they are used to produce real images in addition to determining the color of the image.
The function of the beam splitter is to divide the beam of light that has been projected to its surface using mirrors and prisms where as mirrors are used to direct light in order to ensure that it hits the required targets. On the other hand, lenses are used to develop holographic images, whereas the holographic film primarily helps to capture the holographic images (Winslow, 2007, 6-16).
How to make holograms
Holograms are made by dividing laser light into two different beams, whereby one of the beams is focused on an object and the other beam is focused straight to the film. At point of union of these two beams on a film, an interference will that is in form of microscopic bright and dark lines will result; hence, leading to formation of a hologram.
If one is viewing a hologram using the instant hologram film, it is not compulsory to develop it, but all that is required is to put the hologram in its original location, after which it should be lighted with a single beam that should be produced directly from a laser.
Once the resulting holographic interference has diffracted, the laser light that goes through the holographic interference will result in a three-dimensional representation of the real item. Through holography, presently, individuals are able to record fields of light that can be reconstructed in the absence of primary fields of light.
This technological innovation almost works using the same analogy used in recording of sounds, because sound can also be encoded in method that will facilitate future retrieval of such sounds when needed. Any form of holographic recording is usually in form of a random intensity structure and not in a regular format.
This is normally the case primarily because, there are numerous interferences that can cause multiple reflections in the glass plate where the photographic emulsion is fixed. Illumination of the resulting hologram by the main beam will result in formation of a light field that has shares the same properties with the light field that was formed by the real object, because of the diffracting effects of the hologram.
Therefore, although the main object is removed, the formed field will enable individuals looking into the hologram to observe an image that is similar to the original object. These like images are called virtual images, because they are identical recoded representations of the original objects. Although some people have successfully duplicated some holograms, this process is complex and very difficult, because to duplicate a hologram, one has to find an identical laser that made the hologram for visualization purposes.
Getting a laser with waves that are in phase, peak-to-peak, and trough-to-trough is very hard, because coherence in this properties is the only element that will enable an individual to duplicate laser. This is the case due to the fact that, these properties are the primary determinant of the ability of a laser light to interfere with itself in order to give out the desired interference patterns (Feller, kasper, & Emil, 2001, pp. 4-37 and Jeong, Aumiller, Iwasaki, & Blythe, 2009, p.1).
Generally, the formation of a hologram primarily depends on two primary processes namely interference and diffraction. The former case results due to superimposing of wavefronts, where as the latter results due to encountering of an opaque object by a wave.
Applications of Holograms
Holograms are used in numerous commercial applications that include in compact disks that use them to process light, in spinning scanners that are widely used in stores, in high resolution spectrometers, in medical laboratories (when conducting non-destructive testing of samples), and in military aircrafts to manufacture head up displays.
In addition, they can be used in phase conjugation studies, to prevent the use of counterfeit cards, in the manufacture of Femto-second lasers, to produce bar codes that are used to identify goods in stores using holographic scanners, and in creating holographic gratings that use high resolution spectrometers.
On the other hand, holograms are likely to revolutionize the world of computers, because of the new invention of producing hard drives called Holostore that uses holographic memory systems for keeping large amounts of information (Jeong, 2010, pp. 392-407)..
Reference List
Feller, S. A., & Kasper, E. J. (2001). The complete book of holograms: how they work and how to make them. New York: John Wiley and Sons. Web.
Hecht, J., Ewing, J. J., & Hitz, B. C. (2001). Introduction to laser technology. Institute of Electrical and Electronics Engineers: New York. Web.
Jeong, T. H. (2010). Basic principles and applications of holography. Fundamantals of Photonics. Web.
Jeong, T. H., Aumiller, R., iwasaki, M., & Blythe, J. (2009). Simple holography. Web.
Slusher, R. E. (1999). Laser technology. Reviews of Modern Physics, 17(2): 471-479. Web.
Winslow, L. (2007). Holographic technologies of the future. Web.