Collimator Design for Backscattered Electron Control in Image Intensifiers
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Solution Overview
Problem
Image intensifiers using microchannel plates suffer from the formation of halos around bright areas due to backscattered electrons that are reaccelerated and multiply, causing a fuzzy, bright zone that degrades image clarity.
Innovation Solution
Incorporating a collimator between the photocathode and microchannel plate, and another between the microchannel plate and phosphor screen, to absorb or redirect backscattered electrons, preventing them from contributing to the halo effect by positioning the collimators such that reacceleration is not possible, thereby ensuring electrons pass through channels or are absorbed by the collimator walls.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a microchannel plate is used to amplify electron signals, then image brightness is improved, but backscattered electrons cause halo effects that degrade image clarity
Solution Approach 1:
A collimator is introduced as an intermediary component between the photocathode and microchannel plate, and between the microchannel plate and phosphor screen. The collimator absorbs or redirects backscattered electrons before they can re-enter the microchannel plate and create halo effects, while allowing primary electrons to pass through and maintain image brightness.
Solution Approach 2:
The harmful backscattered electrons are extracted or removed from the electron multiplication path by the collimator. The collimator selectively absorbs these backscattered electrons that would otherwise re-enter the microchannel plate and cause image degradation, separating the useful electron signal from the harmful backscattered component.
2Manufacturing precision
If collimators are added to capture backscattered electrons, then image clarity is improved, but device complexity increases
Solution Approach 1:
The collimator serves multiple functions simultaneously: it collimates the electron beam to improve resolution, absorbs backscattered electrons to eliminate halo effects, and maintains overall image intensity by allowing primary electrons to pass through. This multi-functionality reduces the need for additional separate components.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Significantly reduces or eliminates the halo effect, resulting in a clearer and brighter image without compromising overall image intensity, as backscattered electrons are absorbed or redirected away from the intended multiplication path, enhancing image clarity and reducing dimness.
Implementation Method 1
The microchannel plate amplifies the signal, emitting a stream of several hundred electrons for each incoming electron
Implementation Method 2
a low light image is focused onto a photocathode, which converts the image to an electron image
Implementation Method 3
the emitted electrons are accelerated through another electric field and strike a luminescent screen that reconverts the amplified electron image into a visible image
Implementation Method 4
the emitted electrons are accelerated through an electric field and strike an input surface of an electron multiplier
Data Source
AI summary
Provided is an apparatus comprising a source which emits at least one of particles or radiation. The particles or radiation are emitted towards a target. Arranged between the source and the target is a microchannel plate. Also arranged between the source and the target is a collimator.