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  1. 1. Seeing Invisible Things Chapter 1 - Imaging
  2. 2. Seeing Invisible Things <ul><li>We will find out: </li></ul><ul><li>The types of radiation in the electromagnetic spectrum </li></ul><ul><li>How to use the wave equation in imaging </li></ul><ul><li>Understand the terms ‘pixel’ and ‘resolution’ </li></ul>
  3. 3. Electromagnetic Spectrum <ul><li>Contains 7 types of radiation </li></ul><ul><li>Humans can see visible radiation – detected by eyes </li></ul><ul><li>Other types of radiation Can be used in imaging, e.g. X-Ray, Infra Red, Gamma. </li></ul>But why are they different? Are they similar in any way?
  4. 4. Speed, Frequency and Wavelength <ul><li>If </li></ul><ul><li>Speed = Distance / Time </li></ul><ul><li>what is the speed of a wave..? </li></ul>
  5. 5. Speed, Frequency and Wavelength <ul><li>Wave Speed = Frequency x Wavelength </li></ul><ul><li>For all electromagnetic waves, speed = </li></ul><ul><li>300 000 000 m/s </li></ul><ul><li>or </li></ul><ul><li>3 x 10 8 m/s </li></ul>
  6. 6. Distances… <ul><li>Can we use our knowledge of light speed to calculate distances? </li></ul>Questions 10S
  7. 7. Pixels and Resolution <ul><li>If you look at a digital image closely, you can see: </li></ul><ul><ul><li>Pixels with different brightness </li></ul></ul><ul><ul><li>Rows and columns of pixels – the number of these determines the resolution </li></ul></ul><ul><ul><li>The resolution also determines how much detail you can see </li></ul></ul>

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