Compliant Anode Assembly for Night Vision Image Intensifiers
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Solution Overview
Problem
Existing proximity focused night vision image intensifiers face challenges in achieving accurate cathode to anode assembly dimensional control, leading to increased production costs, component yield loss, and reliability issues due to complex manufacturing processes and inadequate compliance in vacuum sealing, which affects image sharpness and durability under shock and vibration.
Innovation Solution
The implementation of a spring support structure that flexibly mounts the anode assembly to the vacuum package, with insulating spacers affixed to the anode assembly to manage force versus displacement, eliminating the need for molten braze or solder at the vacuum seal and ensuring reliable wire-bonding, while maintaining low leakage currents and minimizing weight and size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a spacer is attached to the photocathode to specify the vacuum gap, then the cathode to anode dimensional control is improved, but the manufacturing complexity and cost increase
Solution Approach 1:
The patent introduces an intermediary compliant layer between the photocathode and anode assembly that acts as a mediator to absorb dimensional variations. This compliant layer, rather than requiring precise mechanical spacers, allows the anode to flexibly conform to the photocathode position, thereby achieving accurate dimensional control without complex spacer attachment processes.
Solution Approach 2:
The patent changes the physical state of the anode assembly by making it compliant rather than rigid. This parameter change allows the anode to dynamically adjust its position to match the photocathode, achieving precise dimensional control through material property modification rather than through complex mechanical positioning structures.
2Manufacturing precision
If the vacuum gap is minimized to reduce transit time, then image sharpness is improved, but the electric field strength increases causing increased photocathode dark current
Solution Approach 1:
The patent makes the anode assembly dynamic and compliant rather than static and rigid. This allows the anode to flexibly adjust its position to optimize the vacuum gap distance, enabling the system to maintain minimal gap for image sharpness while accommodating variations that would otherwise require larger safety margins and increasing dark current.
3Manufacturing precision
If precise dimensional tolerances are specified for components, then image quality is improved, but production costs increase
Solution Approach 1:
The patent changes the compliance parameter of the anode assembly, transforming it from a rigid component requiring tight tolerances to a flexible component that can accommodate broader tolerances. This parameter change allows standard manufacturing processes to produce components within relaxed specifications while still achieving the required image quality, thereby reducing production costs.
4Stability of the object's composition
If the anode assembly is rigidly mounted to the vacuum package, then structural stability is improved, but compliance with the photocathode position deteriorates
Solution Approach 1:
The patent segments the anode assembly into multiple parts: a rigid mounting structure for structural stability and a compliant section for positional adjustment. This segmentation allows the rigid portion to provide overall structural support while the compliant portion flexibly adapts to the photocathode position, simultaneously achieving both structural stability and positioning precision.
Solution Approach 2:
The patent employs a thin compliant layer or flexible structure between the rigid anode mounting and the photocathode. This flexible element maintains structural integrity while allowing the anode to conform to the photocathode position, thereby achieving both structural stability and precise positioning.
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 approach achieves high accuracy in cathode to anode assembly dimensional control, reduces production costs, enhances sensor reliability under shock and vibration, and maintains image sharpness with low leakage currents, demonstrating a cost-effective and reliable method for manufacturing proximity focused image intensifiers.
Implementation Method 1
a resilient spring assembly attached in part to the vacuum package assembly and in part to a back surface of the anode
Implementation Method 2
the photocathode having a bottom face comprising a photo-emissive surface
Implementation Method 3
The image information contained in the intensity pattern of the electrons emitted from the photocathode is transferred across the vacuum gap of the sensor by accelerating the electrons through an electric field. The electric field is established by biasing the photocathode and the anode to different voltages.
Data Source
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AI summary
An image intensifier contains a photocathode assembly (120) including a vacuum window to generate photoelectrons in response to light, a vacuum package (110) and an anode assembly (130) to receive the photoelectrons. The anode assembly is mounted to the vacuum package via a compliant, springy, support structure (160). The anode additionally includes one or more insulating spacers (140) on the surface facing the photocathode so as to precisely index the position of the anode assembly with respect to the photocathode surface. The photocathode and vacuum window assembly is pressed into the vacuum package to generate a sealed leak tight vacuum envelope. During the photocathode assembly to vacuum package assembly pressing operation, the inner surface of the photocathode assembly contacts the insulating spacer/spacers of the anode assembly, thereby compressing the compliant support structure. This structure and assembly method result in a precisely indexed photocathode to anode assembly sealed image intensifier.