Total internal reflection
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?- Created by: Jasmin
- Created on: 08-04-13 11:42
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- Total Internal Reflection
- Optical fibres
- Very thin glass fibres that are designed to transmit light or infrared radiation
- Work by bouncung waves off the sides of a thin inner core of glass or plastic
- Waves enter one end of fibre and reflected repeatedly until emerges at other end
- Can only happen when a wave travels through a ddense substance e.g, glass/water towards a less dense substance like air
- Angle of reflection = angle of incidence
- If the angle of incidence is
- Less than critical angle
- Most of the light passes out, but little is internally reflected
- Equal to critical angle
- Emerging ray comes out along the surface -quite a bit of internal reflection
- Greater than critical angle
- No light comes out, all internally reflected = total internal reflection
- Critical angle = angle of incidence of a light ray in a transparent substance that produces refraction along the boundary
- Less than critical angle
- Value of critical angle depends on refractive index
- Dense material, high refractive index, low critical index, total internal reflection - more light
- Refractive index = 1/sin c (critical angle)
- Occurs when angle of incidence of a light ray in a transparent substance is greater than the critical angle
- Endoscopes
- Thin tube containing optical fibres that let surgeons examine inside the body
- 2 bundles of optical fibres - one to carry light to area and other to carry image back so can be viewed
- Image can be seen directly or by using a digital camera full - colour moving image on TV screen
- ADV = surgeons can now perform many operations by cutting small holes - keyhole surgery
- Optical fibres
- Value of critical angle depends on refractive index
- Dense material, high refractive index, low critical index, total internal reflection - more light
- Refractive index = 1/sin c (critical angle)
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