# Optical Fibers and Lasers

In Glogpedia

by Katga95
Last updated 7 years ago

Discipline:
Science
Subject:
Physics

Optical FibresAn optical fibre is a thin rod of high-quality glass. Very little light is absorbed by the glass. Light getting in at one end undergoesrepeated total internal reflection,even when the fibre is bent, and emerges at the other end.

Uses of Optical Fibres and Lasers

Total internal reflection is when a light reflects off of the inside wall of a denser medium.

Critical Angle The critical angle is the angle above which total internal reflection occurs.It varies depending on the refractive index of the material - the lower the refractive index, the higher the critical angleThe critical angle of a material can be calculated using this equation: refractive index = 1/sin c where c is the critical angle in degrees ° Worked example 1Step 1: Calculate sin c sin 49° = 0.75 Step 2: Substitute the value of sin c into the equation refractive index = 1 ÷ sin c refractive index = 1 ÷ 0.75 = 1.33

EndoscopesEndoscopes also use optical fibres. A doctor can insert a bundle of optical fibres into the body. Some carry light into the body, and some carry light reflected off internal body surfaces back out. This allows the doctor to see the inside of the body clearly – and help them diagnose diseases like cancer, or see what they are doing during keyhole surgery.

I am Willebrord Snellius! I am a Dutch atsronomer amd mathematician from 1591-1626. I formulated Snell's Law in 1621.

Review of Snell's Law...By using Snell's Law we can calculate three things:1. Index of Refraction2. Angle of incidence3. Angle of refraction_________________The formula:n1sinθ1= n2sinθ2_______________________What they mean:n1 and n2= the two incidences of refraction of the two mediaθ1 and θ2= The angle of incidence and the angle of refraction________________Application!Now let's try and find the angle of refraction for a diamond with an angle of incidence being 20 ° (from air to the diamond...)

Lasers can shine a high intensity light into an endoscope which is good for the keyhole surgey. This cuts or destroys tissue.

Disadvantagesthere may be complications such as poor technique may damage the internal organs, too much force can cause excessive bleeding, and most importantly infection can occur if the endoscope is not cleaned properly.

Key Points:1 - Angle of incidence is equal to the angle of reflection2 - At a certain angle the refracted ray follows a path exactly along the surface of the dense medium. This angle is called critical angle.

Lasers

Uses of Lasers:Due to their high intensity, narrow beam and high precision, lasers can be used for surgery that was previously extremely difficult and dangerous. They are now used in cosmetic surgery for removal of scars, wrinkles, birthmarks, blood vessels and hair and can also be used in laser eye surgery to alter the surface of the cornea on a microscopic scale in order to correct sight.

The denser the material the higher the refractive index

Uses of EndoscopesThere are many different reasons to perform an endoscopy. For example, your doctor may order an endoscope if you have bleeding, pain, difficulty swallowing, and a change in bowel habits.To prevent and screen for cancerTo find cancer earlyTo diagnose and find out the stage of cancerLooking at causes of symptoms e.g. in people having trouble swallowing To get a tissue sampleTo get a better and closer lookDestroying or removing cancer cells, Endoscopes can be used to take out or destroy small cancers. Small instruments passed through an endoscope can be used to cut out small growths.Surgery to take out cancer, Many types of endoscopic tools have been developed to let doctors perform minimally invasive surgery. This is sometimes called keyhole surgery. Instead of making one long surgical incision (cut), several small cuts are made in the skin – usually in the chest or abdomen. Long, thin instruments are then put through the cuts or “holes” to reach the inside of the body. A video endoscope – a thoracoscope– is put through one of the holes so that the surgeon can see inside during the operation.

AdvantagesSafetyAside from its simplicity, endoscopy is also low-risk.It is a much less invasive procedure than the open surgery as it only requires a small incision in the body whereas open surgery requires deep incisions.recovery is quicker and there is less swelling, scarring and risk of infection