What is Micochannel Plate (MCP)?
The Microchannel Plate (MCP) is a large array of channel electron multipliers that are widely used in micro-light image intensifiers. In the micro-light image intensifier, the electron image emitted by the photocathode enters the MCP under the cathode electric field, and is amplified in the MCP before being output at the output end. Since the gains of the channels in the MCP are the same, the electron image is mapped onto the output surface after being amplified during the transmission process in the MCP. The micro-light image intensifier (referred to as an image intensifier or image tube) is an imaging device, in the process of transmitting electron images in the MCP channels, in addition to requiring intensity to be amplified, the contrast must not be reduced, that is, the resolution must be high enough. Each channel of the MCP is equivalent to one pixel, so to improve its resolution, the most efficient way is to further reduce the channel size of the MCP.
How the microchannel plate works
The Microchannel plate is made of many electron multipliers channel. The structure of each channel is the same, including:
Channel holes, Channel walls, Input electrodes, and Output electrodes.
A certain DC working voltage is applied between the input and output electrodes, which creates a field distribution from low to high on the channel electron multiplier’s channel wall, allowing electrons to move in the channel and have enough kinetic energy to collide with the channel wall to produce secondary electrons. In addition, the applied working voltage generates current, which supplements the electron emission on the channel wall. From the electrons input into each channel, after multiple secondary electron multiplications within the channel, the number of electrons is multiplied when output from the output end.
What are major specification of a microchannel plate?
Refer to the diameter of one channel,Smaller Channel diameter will have a higher spatial resolution
Channel Wall Thickness
Noise related factor, reducing wall thickness may improve SNR in some cases. But it is restricted by the length of microchannel plate, improving SNR may lose some Gain as a result.
Open Area Ratio
The holey area percentage on the microchannel plates,OAR limits upper detection sensitivity of Microchannel plates, (a OAR around 68% will be sufficient for most of the cases)
Gain of the microchannel plate is highly correlated with aspect ratio. (The length of the microchannel plate to channel diameter)
In terms of the Microchannel plates input electrode, reducing the depth of the MCP input electrode can reduce the noise factor of the MCP. However, further reducing the input electrode depth increases the difficulty of the manufacturing process and also causes uniformity issues.
Ion Blocking Layer
An ion blocking thin layer is often used in Microchannel Plates (MCP) to improve the lifetime of the photocathode. The ion blocking membrane helps to prevent ions generated during the operation of the MCP from reaching the photocathode, which can degrade its performance over time. The ions can cause a reduction in the quantum efficiency of the photocathode and also cause damage to the photocathode surface. By preventing ions from reaching the photocathode, the ion blocking membrane can help to extend the lifetime of the photocathode.
Can I Stack microchannel plates for a higher gain?
Yes, you can stack multichannel plate together. Below is an example for your reference:
If the Typical Gain of one MCP is 10**4
Stacking two Microchannel plates will be around 10**6 to 10**7
Stacking three Microchannel plates will be around 10**8 to 10**9
Can you show me examples of Microchannel plates applications?
Microchannel plates (MCPs) are widely used in a variety of applications due to their high gain and fast response time. Some examples of applications where MCPs are used include:
- Electron multipliers: MCPs are used as electron multipliers in various instruments such as mass spectrometers and particle detectors.
- Imaging intensifiers: MCPs are used in imaging intensifiers to amplify low-light level signals, making them useful in applications such as night vision systems and scientific cameras.
- Time-of-flight mass spectrometry: MCPs are used in time-of-flight mass spectrometers to detect and amplify ions, allowing for the identification of molecules based on their mass-to-charge ratio.
- Particle detectors: MCPs are used in particle detectors to detect and amplify the signals from particles such as cosmic rays, neutrons, and protons.
- Laser-induced fluorescence spectroscopy: MCPs are used in laser-induced fluorescence spectroscopy to amplify the signals from the fluorescence of molecules, allowing for the identification and quantification of the molecules present in a sample.
- X-ray detectors: MCPs are used in x-ray detectors to amplify the signals from x-ray photons, making them useful in medical imaging and industrial inspection.
- Mass spectrometry imaging: MCPs are used in mass spectrometry imaging to amplify the signals from the ions toenhance the resolution and sensitivity of the images, enabling the visualization of molecular distributions in various samples such as biological tissues, polymers, and materials.
- Electron microscopy: MCPs are used in electron microscopy to amplify the signals from the electrons, allowing for the visualization of very small structures and features at high resolution.