Lights and Lasers

Lights and Lasers

1. Morse Code

   • Dots and dashes
   • Signalling lamps (short and long flashes of light).
   • Digital signal

2. Sending Signals

   • Signals sent by light, electricity, microwaves or radio waves are almost instant.
   • Advantages & Disadvantages:
     • Can it been seen?
     • Can the wires be cut?
     • How far does the signal have to travel?

3. Laser Light

   • Single frequency, in phase, low divergence.
     • White light- different frequencies, different colours, out of phase.
   • CD's and DVD's: Surface is pitted, Light shone onto surface and difference in reflection shows information.
     • Pits represent digital signal.

4. Critical Angle

   • Light travelling from one material to another, it refracts.
   • More dense material to less dense material, angle of incidence is smaller than angle of refraction.
   • Angle of refraction= 90, angle of incidence is called the Critical angle.
   • TIR= angle of incidence is bigger than critical angle.
   • Computer data and phone conversations are transmitted along optical fibres (200,000 km/s).

5. Endoscopy

   • See inside the body without surgery.
     • Light passes along optical fibers to illuminate body.
     • Light is reflected.
     • Light reflected travels through another set of optical fibers to eyepiece or camera.