Specific principle of CCD detector: take MOS capacitor type as an example: a layer of SiO2 is generated on the surface of p-type Si, and then a layer of polysilicon is evaporated on the surface as the electrode. A voltage is applied to the p-type Si substrate of the electrode, and a low potential energy region is formed under the electrode.
The potential well. The depth of the potential well depends on the voltage. The higher the voltage, the deeper the well.The photogenerated electrons are stored in the well.The number of photogenerated electrons is proportional to the intensity of the light. So the amount of charge stored reflects the brightness of the point.
The charge stored in millions of photosensitive cells forms an image of the charge corresponding to the image.
Advantages of CCD detector: 1. High spatial resolution; 2.2. Small geometric distortion;3. Good uniformity.