The same trick was used in WW1 when soldiers needed to see over the trenches to keep an eye on the enemy. In exams, y ou need to be able to draw a ray diagram like this, getting the angles right They use periscopes made from prisms, totally internally reflecting the light from the surface to the operator’s eye at the bottom of the picture. Properly angled mirrors are OK to see over the fence at the football match, but submarines need a bit more clarity. Periscopes are devices to ‘see over’ from the Greek. This is a well-lit endoscopy image from a fortunately healthy human stomach.
#Optical fibre tir tv#
A piece of optical fibre can direct light into body cavities and receive TV images back, enabling doctors to make accurate diagnoses. If we want to see inside the body, an endoscope allows us to do so. In this image, only one layer of core is shown for greater clarity.Įlectrical signals and light can be transmitted for long distances using total internal reflection in a length of optical fibre, by using carefully chosen glasses with slightly different refractive indices, bundled together in lots of fibres. However, some of the light signal degrades within the fibre, mostly due to impurities in the glass. This is almost exactly what happens in an optical fibre, except that mirrors tend to scatter the light too much, so we arrange for it to be totally internally reflected inside layers of different glasses with reflective cladding around the outside.īecause the cladding does not absorb any light from the core, the light wave can travel great distances. What if the hallway is very winding with multiple bends? You might line the walls with mirrors and angle the beam so that it bounces from side-to-side all along the hallway. What if the hallway has a bend in it? You could place a mirror at the bend to reflect the light beam around the corner.
Just point the beam straight down the hallway – light travels in straight lines, so there’s no problem. Suppose you want to shine a torch beam down a long, straight hallway.
0 kommentar(er)
