Image sensor

Sensor Technology Comparison:
– CCD and CMOS sensors are based on MOS technology.
– CCD sensors are used in high-end broadcast quality video cameras.
– CMOS sensors are commonly used in still photography and consumer goods.
– Both sensors capture light and convert it into electrical signals.
– CMOS sensors have an amplifier for each pixel.

Performance Evaluation:
– Image sensor performance is based on dynamic range and signal-to-noise ratio.
– Larger sensor size improves dynamic range and signal-to-noise ratio.
– More photons hit larger pixels in a given integration time.
– Evaluation can be standardized using EMVA1288.
– Lower light sensitivity is a key performance metric.

Exposure-Time Control:
– Exposure time in image sensors can be controlled by mechanical or electronic shutters.
– Electronic shutters can be global or rolling.
– Global shuttering requires storage circuits for charge retention.
– Rolling shuttering exposes rows sequentially for readout.
– Electronic shuttering is more common in modern image sensors.

Color Separation Techniques:
– Color image sensors use different mechanisms for color separation.
– Integral color sensors use color filter arrays on monochrome sensors.
– Bayer pattern is a common color filter array pattern.
– Foveon X3 sensor uses layered pixel sensors for color separation.
– 3-CCD sensors use dichroic prisms for color separation.

Specialty Sensors and Historical Development:
– Specialty sensors are used in various applications like thermography and astronomy.
– Sony developed a curved sensor to reduce Petzval field curvature.
– Early analog sensors for visible light were video camera tubes.
– CCD and CMOS sensors are advancements in solid-state semiconductor image sensors.
– Active-pixel sensors like NMOS APS and CMOS sensors have evolved and dominated new applications.

Image sensor (Wikipedia)

An image sensor or imager is a sensor that detects and conveys information used to form an image. It does so by converting the variable attenuation of light waves (as they pass through or reflect off objects) into signals, small bursts of current that convey the information. The waves can be light or other electromagnetic radiation. Image sensors are used in electronic imaging devices of both analog and digital types, which include digital cameras, camera modules, camera phones, optical mouse devices, medical imaging equipment, night vision equipment such as thermal imaging devices, radar, sonar, and others. As technology changes, electronic and digital imaging tends to replace chemical and analog imaging.

The two main types of electronic image sensors are the charge-coupled device (CCD) and the active-pixel sensor (CMOS sensor). Both CCD and CMOS sensors are based on metal–oxide–semiconductor (MOS) technology, with CCDs based on MOS capacitors and CMOS sensors based on MOSFET (MOS field-effect transistor) amplifiers. Analog sensors for invisible radiation tend to involve vacuum tubes of various kinds, while digital sensors include flat-panel detectors.