Medical uses of light

Endoscope: Thin tube containing opical fibres

• 1 to carry light -1 to carry an image back
• Image seen on eyepiece or screen
• called Key Hole surgary, good as doctors only need to cut a tiny hole

Pules oximeters use light to check the oxygen levels in the blood 

Haemoglobian carries oxygen from lungs to cells. It changes colour due oxygen content. Lots of oxygen - Red (oxyhaemoglobian) Lackign oxygen - Purply(reduced haemoglobin) 

How it works

• Trasmitter emits two beams of light (red & infared). It also has a photo detector to measure light.
• These are placed either side of the finger (or ear lobe etc)
• Beams of light are passed through the finger, some of the light is then absorbed by the blood.
• It is the difference in light intensity before the light passes through the blood, and after, that is used to measure the oxygen levels in the blood