Definition of CCD image sensor

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Photonics Dictionary

CCD image sensor: A CCD image sensor, or charge-coupled device image sensor, is a type of electronic device used to convert optical images into electronic signals. It is a key component in digital cameras, camcorders, and various imaging systems.

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The CCD image sensor consists of an array of light-sensitive pixels, each capable of converting photons (light) into electrical charge. The basic operation of a CCD image sensor involves the following steps:

Photon detection: When light strikes the surface of the CCD sensor, it generates electron-hole pairs within the semiconductor material of each pixel. The number of electron-hole pairs produced is proportional to the intensity of the incident light.

Charge accumulation: The electron-hole pairs generated in each pixel are collected and stored as an electrical charge in potential wells within the pixel structure. The charge accumulated in each pixel corresponds to the brightness or intensity of the light falling on that pixel.

Charge transfer: The accumulated charge is then transferred through a series of potential wells in each row and column of pixels. This transfer process is facilitated by applying clock voltages to the electrodes of the CCD sensor, causing the charge packets to move along the rows and columns towards the output amplifier.

Signal readout: The charge packets are read out from the CCD sensor one row at a time and converted into analog voltage signals by the output amplifier. These analog signals are then digitized by an analog-to-digital converter (ADC) to produce digital image data.

CCD image sensors offer several advantages, including high sensitivity, low noise, and excellent image quality. They are capable of capturing detailed images with good color reproduction and dynamic range, making them suitable for various applications such as digital photography, scientific imaging, and surveillance.

However, CCD image sensors also have some limitations, including relatively high power consumption, slower readout speeds compared to CMOS sensors, and susceptibility to blooming and smearing effects in high-intensity light conditions. Despite these limitations, CCD sensors remain widely used in many imaging applications where high-quality image performance is critical.