Puzzle me this

1234567891011121314151617181920
Across
  1. 1. the bouncing back of a wave off a surface
  2. 4. the number of times the pattern of a wave repeats in a given time
  3. 8. the maximum distance the wave moves from its rest position
  4. 9. a tool used to turn white light to colored light and back
  5. 12. a material through which light does not pass
  6. 14. the passage of a wave through a medium
  7. 17. causes the particles in a medium to move parallel to the direction the wave is moving
  8. 19. the transfer of energy by a wave to the medium through which it travels
  9. 20. a wave that travels only through matter
Down
  1. 2. the highest point of a wave
  2. 3. a lens that is thicker on the sides than the middle
  3. 5. a lens that is thicker in the middle than the sides
  4. 6. the lowest point of a wave
  5. 7. a material that allows almost all light striking it to pass through, and through which objects can be seen clearly
  6. 10. a wave in which the disturbance is perpendicular to the direction it travels
  7. 11. a medium that only lets certain colors go through
  8. 13. a transparent object with at least one curved side that causes light to change direction
  9. 15. the distance between one point of a wave and the same point on the next wave
  10. 16. a material in which a wave travels
  11. 18. a pocket of space that contains little or no matter