PIRA: 6D20.75


 Lab Equipment  Directions
  1.  Spectra Physics 248 high-powered laser and power supply strapped to white board with magnet strip and lab jack
  2. 18 mm lens and steel lens holder
  1.  Use the lens to spread the beam of the laser and direct the spread beam at a wall.
  2. Look at the speckles on the wall. Move your head right or left and see which way the speckles move (those far-sighted and near-sighted will see them move in opposite directions).
  3. Near-sighted people will also be surprised to find that if they remove their glasses the speckles are still in focus.