This paper presents the travelling of light with respect to different mediums on a special subject mentioned as total internal reflection. Also discussed are applications of total internal reflection mainly majoring in fiber optics in medicine and advantages of fiber optics.
As per normal circumstances if light is travelling into a medium with a higher refraction index, the result is that, it tends to bend towards the normal. Additionally, when light crosses into a medium with a lower refraction index it tends to bend away from the normal, provided the angle it intersects the boundary with is less than the critical angle (Adams, 2008). Certainly, if light intersects the boundary at an angle more than the critical angle, it will not penetrate into the second medium but all of the light is to be reflected back into the first medium. Hence, this is known as total internal reflection (critical angle is generally, defined as the incidence angle that provides refraction angle of 90-degrees), (Das & Gupta, 2006).
Applications
- Diamonds have the ability to shine brightly due to their shape as they are cut, then this provides a extremely fertile ground for total internal reflection. Light hits inside of the diamond at a larger angle than the critical angle and hence all light rays are reflected hence its ability to shine brightly.
- The fiber optic cable applies this phenomenon and large amounts of data are transmitted by through total internal reflection of laser light. This is possible owing to its construction and materials used. Light bounces from one surface to the opposite surface in the cable from one end to the other
- The microscope and telescope, which uses compound lenses, is said to have total internal reflection since the final angle that the light intersects the image is larger than the critical angle since it is said to have multiplied as it travels through the several compound lenses (Das & Gupta, 2006).
Fiber optics in medicine
An optical fiber can be explained as a flexible length of transparent pure glass with width not larger than human hair, which has the ability to transmit messages in modulated light waves through application of the light phenomenon of total internal reflection (Adams, 2008). Total internal reflection is afforded owing to a transparent core surrounded by a transparent cladding that has a lower refraction index thus total internal reflection and light is restricted in the core acting as a wave-guide. These optical fibers can be laid into a cable in a special arrangement and accorded respective terminations, (Das & Gupta, 2006). Fiber optic has many applications ranging from communication to medicine but in this article, we are interested in the application in medicine field.
The technology of fiber optics can be traced from the invention of “optical telegraph” in early 1790’s, by the French Chappe brothers. Later in 1840’s it was proved that light could travel through jets of water by physicists Jacques Babinet and Daniel Collodon. Perhaps, in 1854 John Tyndall proved that light signals could be bent by a stream of water, in 1880 Graham Bell patented the photo phone an optical telephone and so on until to the present day technology. In medicine, Doctors Roth and Reuss can trace the birth of use of fiber optic technology from Vienna in 1888 that used bent glass rods to illuminate body cavities (Das & Gupta, 2006).
In modern day, the practical fiber optic has helped in the advancement of medicine and its practices mainly in the area of surgery, for example laparoscopic surgery, plastic surgery among others. The main instrument that applies this technology is the endoscope in illumination and image production.
The endoscope
The endoscope came into existence more than 130 years ago and there before surgery was used as a diagnostic tool but it proved a waste of time, money, and great risks death being the most catastrophic. The arrival of the endoscope has proved to be advantageous to humanity to a great extent (Das & Gupta, 2006). It is a device, which consists of a flexible and rigid tube, a lens system and, light delivery structure. In some cases, an additional channel to facilitate entry of numerous surgical tools. An endoscope can be considered as a flexible telescope, which helps a physician to examine the internal organs and cavities as well due to the availability of several optical cables. Every optical cable is composed of many optical fires that run the full length of the cable. One of the cables carries light from the outside to illuminate the internal organ, the second one has a lens attached to the end that reaches the organs to transmit images and the others have surgical instruments attached to at their ends (Smith, 1998).
Advantages of fiber optic
Fiber optics is highly reliable in transmission of high power laser beams from a fixed point within a factory so that it can be distributed to the various machines and robots to provide them with laser machining capability. One can achieve a transmission of data across very long distances that nearly no loss is experienced due to the use of optical amplifiers such as erbium doped silica fibers and owing that fiber does not radiate the signal to the surrounding (Smith, 1998).
The fiber optic cable is able to withstand explosive environment and cannot be affected by lightning and electromagnetic waves since it is made of pure silica, which is a excellent electrical insulator. The fiber optic is highly resistant to chemical corrosion making it highly reliable. The optic fiber has a small size and weight since it ranges from 10 to 50 micrometers making them advantageous to use where small size and weight are of importance like the airplanes, satellites among others (Das & Gupta, 2006).
The fiber optics is considered economical since it is of low cost and is highly available. The fiber as discussed is made of silica, which is in abundance thus making it cost effective. Due to its ability to withstand destruction, maintenance is minimized as well as the cost accompanying it.
Fiber optics is easy to install and upgrade, since it can be installed with the same tools as used to install the copper cables with small adjustments due to their relative small size. The fiber optic cable can also be twisted or bend easily without damage making it superior to manipulation. The manufacturer also ensures that it meets the demand due to growth of population in the next 15 to 20years.
There is a high security of data since no one can detect the signal inside the fiber unless one interferes with the fiber to get hold of the signal that can be detected by security surveillance compared to the copper cables. This property is due to the ability of the fiber not to radiate the signal (Adams, 2008).
The fiber optics has also mad surgery and internal cross-examination a more safe practice with fewer risks involved. Small cuts are made on the surface of the body to allow the cable to penetrate and the finish is with fewer marks on the epidermis. With fiber optics, one is able to transmit large bandwidths of data at exceptionally high transmission speed and, frequency on very small size of cable making it very effective for high communication across great distances thus its adaptation to the modern world situation (Smith, 1998).
References
Adams, J. (2008). Emergency Medicine. New York: John Wiley & Sons.
Das, B., & Gupta, B. (2006). Fiber Optic Sensors: Principles and Applications. Cambridge: Cambridge Press.
Smith, B. (1998). Careers in Fiber Optics. London: Wiley.