1 CCD RAIN (PHOTONS) BUCKETS (PIXELS) VERTICAL CONVEYOR BELTS (CCD COLUMNS) HORIZONTAL CONVEYOR BELT ( SERIAL REGISTER ) MEASURING CYLINDER (OUTPUT AMPLIFIER)

2 CCD  All astronomical CCD’s are thin, backside illuminated  Consumer CCD’s are thick, frontside illuminated n-type silicon p-type silicon Polysilicon electrodes Incoming photons Anti-reflective (AR) coating 15  m n-type silicon p-type silicon Silicon dioxide insulating layer Polysilicon electrodes Incoming photons 625  m

3 CCD The serial register is bent double to move the output amplifier away from the edge of the chip. This useful if the CCD is to be used as part of a mosaic.The arrows indicate how charge is transferred through the device. Edge of Silicon 160  m Image Area Serial Register Read Out Amplifier Bus wires Photomicrograph of a corner of an EEV CCD.

4 CCD

5 Connection pins Gold bond wires Bond pads Silicon chip Metal,ceramic or plastic package Image area Serial register On-chip amplifier

6 CCD One pixel Channel stops to define the columns of the image Transparent horizontal electrodes to define the pixels vertically. Also used to transfer the charge during readout Plan View Cross section The diagram shows a small section (a few pixels) of the image area of a CCD. This pattern is reapeated. Electrode Insulating oxide n-type silicon p-type silicon Every third electrode is connected together. Bus wires running down the edge of the chip make the connection. The channel stops are formed from high concentrations of Boron in the silicon.

7 CCD Camera... Thermally Electrical feed-through Vacuum Space Pressure vessel Pump Port Insulating Pillars Focal Plane of Telescope Telescope beam Optical window CCD CCD Mounting Block Thermal coupling Nitrogen can Activated charcoal ‘Getter’ Boil-off Face-plate

8 CCD Camera CCD Temperature servo circuit board Platinum resistance thermometer Gold plated copper mounting block Top of LN2 can Pressure Vessel Signal wires to CCD Location points (x3) for insulating pillars that reference the CCD to the camera face-plate Aluminised Mylar sheet Retaining clamp ‘Spider’. The CCD mounting block is stood off from the spider using insulating pillars.

9 CCD Mosaic

10 CCD  Buried channel MOS type p-n type