Electron Multiplier Global Shutter Using Low-Voltage Bias
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Solution Overview
Problem
Conventional night vision systems using analog image intensifiers face challenges with excessive gain under bright light conditions, leading to eye strain and increased power consumption, electromagnetic interference, and delayed response times due to large voltage shifts and high voltage gating.
Innovation Solution
A night vision system that applies a small negative voltage across the semiconductor gain layer of the electron multiplier, specifically between 1 to 2 volts, to control electron flow and provide a low voltage global shutter, effectively limiting gain and preventing excessive brightness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If large voltage shifts and high voltage gating are used to control gain in analog image intensifiers, then gain control is achieved, but power consumption increases, electromagnetic interference occurs, and response time delays
Solution Approach 1:
The patent changes the voltage parameter from conventional high voltage (hundreds to thousands of volts) to low voltage (1 to 2 volts) applied across the semiconductor gain layer. This parameter change enables gain control while dramatically reducing power consumption and eliminating electromagnetic interference associated with large voltage swings.
Solution Approach 2:
The patent substitutes the conventional electrical gating mechanism (using high voltage switches and relays) with a direct low-voltage electrical field effect across the semiconductor material. This replacement eliminates the mechanical and high-voltage electrical components that cause interference and power loss.
2Reliability
If large voltage shifts are used to shutter the image intensifier output, then brightness control is achieved, but response time increases due to voltage swing delays
Solution Approach 1:
The patent changes the voltage parameter from large voltage shifts (hundreds to thousands of volts) to small voltage changes (1 to 2 volts) across the semiconductor gain layer. This enables rapid response times because the small voltage can be applied and removed instantly without the inertia and delay associated with large voltage swings in conventional systems.
3Reliability
If high voltage gating is used to limit electron flow, then gain limitation is achieved, but electromagnetic interference increases
Solution Approach 1:
The patent changes the voltage parameter from high voltage (hundreds to thousands of volts) to low voltage (1 to 2 volts). This parameter change achieves gain limitation through the electrical field effect in the semiconductor while eliminating electromagnetic interference, as the low voltage is insufficient to generate significant electromagnetic radiation.
4Reliability
If conventional analog image intensifiers are used, then image intensification is achieved, but system size and weight increase due to beam combiners and digital displays
Solution Approach 1:
The patent makes the image intensifier itself multi-functional by enabling it to operate in both full-intensity mode and shuttered mode (blocking light). This eliminates the need for separate beam combiners and digital displays that would add weight, as the intensifier tube itself can perform the function of light modulation that previously required additional 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
This solution efficiently reduces electron emission, minimizing eye strain, power consumption, and electromagnetic interference while maintaining image visibility under bright conditions, and provides faster response times by eliminating the need for large voltage swings.
Implementation Method 1
The photocathode detects infrared light in the form of photons from an object, and the image intensifier amplifies or multiplies the resulting photoelectrons
Implementation Method 2
an electron multiplier arranged between a photocathode and a sensor anode... amplifies or multiplies the resulting photoelectrons
Implementation Method 3
A shutter voltage between 1 to 2 volts... is applied between a first surface and a substantially parallel, opposed second surface of the silicon membrane
Data Source
AI summary
A night vision system along with an image intensifier tube and method for shuttering the continued draw of electrons from an electron multiplier are provided. The night vision system includes the electron multiplier, or possibly two electron multipliers, each comprising a silicon membrane. A shutter voltage is applied between a first surface and a substantially parallel, opposed second surface of the silicon membrane to discontinue draw of electrons through the electron multiplier and for substantially discontinuing display of an image from the image intensifier tube under certain bright light conditions. Utilizing a global shutter control on the electron multiplier, and the significantly lower voltage for such control mitigates power consumption within the image intensifier, as well as electromagnetic interference and delay response time. A relatively low voltage negative bias shutter voltage on only the electron multiplier selectively provides global shutter to the image intensifier device.