1. Reading from a charge coupled device (ccd) © D Hoult 2010 ODWS

2. Each pixel in a ccd consists of a photoelectric cell and a capacitor (to store the charge emitted) © D Hoult 2010 ODWS

3. Each pixel in a ccd consists of a photoelectric cell and a capacitor (to store the charge emitted) The voltage across the capacitor is proportional to the charge stored © D Hoult 2010 ODWS

4. Each pixel in a ccd consists of a photoelectric cell and a capacitor (to store the charge emitted) The voltage across the capacitor is proportional to the charge stored and hence to the intensity of the illumination of the pixel © D Hoult 2010 ODWS

5. The pixels in this diagram have been magnified... © D Hoult 2010 ODWS

6. The pixels in this diagram have been magnified... quite a lot ! © D Hoult 2010 ODWS

7. This ccd has not yet been exposed to light © D Hoult 2010 ODWS

8. After exposure, the capacitors in the illuminated pixels now store a small charge © D Hoult 2010 ODWS

9. The data are read 1 pixel at a time © D Hoult 2010 ODWS

10. First, all the voltages are “shifted” towards a special row of pixels at one end of the chip © D Hoult 2010 ODWS

11. First, all the voltages are “shifted” towards a special row of pixels at one end of the chip © D Hoult 2010 ODWS

12. First, all the voltages are “shifted” towards a special row of pixels at one end of the chip © D Hoult 2010 ODWS

13. Now the data voltages are “shifted”, one at a time, towards a pixel at the end of that special row © D Hoult 2010 ODWS

14. After each shift, the voltage in the special pixel is read and stored in memory © D Hoult 2010 ODWS

15. After each shift, the voltage in the special pixel is read and stored in memory, in this case, zero © D Hoult 2010 ODWS

16. voltage = V © D Hoult 2010 ODWS

17. voltage = 0 © D Hoult 2010 ODWS

18. voltage = 0 © D Hoult 2010 ODWS

19. voltage = V © D Hoult 2010 ODWS

20. voltage = 0 © D Hoult 2010 ODWS

21. voltage = V © D Hoult 2010 ODWS

22. voltage = 0 © D Hoult 2010 ODWS

23. voltage = 0 © D Hoult 2010 ODWS

24. voltage = V © D Hoult 2010 ODWS

25. voltage = V © D Hoult 2010 ODWS

26. voltage = V © D Hoult 2010 ODWS

27. voltage = V © D Hoult 2010 ODWS

28. voltage = V © D Hoult 2010 ODWS

29. voltage = 0 © D Hoult 2010 ODWS