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pallavi12
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how is the image recognised after electron multiplication (by secondary emission) in a Micro channel plate in the intensifier of ICCD
Electron multiplication occurs when an incoming photon strikes a photocathode, releasing an electron. This electron then travels through a series of dynodes, each with a higher positive voltage, causing the electron to accelerate and release multiple secondary electrons. These secondary electrons are then collected and amplified, resulting in a stronger signal and a brighter image.
Dynodes are metal electrodes with increasingly positive voltages, typically ranging from 100-1500 volts. These dynodes act like a cascade, accelerating the electrons released by the photocathode and causing them to release more secondary electrons. The number of dynodes used in a device depends on the desired level of amplification.
The amplified signal is detected through a phosphor screen, which converts the electrons into visible light. This light is then captured by a CCD (charge-coupled device) or CMOS (complementary metal-oxide-semiconductor) sensor, which converts the light into an electronic signal that can be further processed and displayed as an image.
The quality of the amplified image can be affected by various factors such as the sensitivity and efficiency of the photocathode, the number and efficiency of the dynodes, and the quality of the phosphor screen. Other factors such as temperature, noise, and voltage stability can also impact the image quality.
Electron multiplication is commonly used in imaging devices such as night vision goggles, electron microscopes, and digital cameras. It allows for low-light or microscopic images to be amplified and detected with higher sensitivity and resolution, making it an essential component in various scientific and medical applications.