Night Vision Goggle Projection Device Split-Pupil Folding Mechanism
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Night vision goggles suffer from objective lens vignetting, which limits the field of view when using external projectors, making it difficult to achieve a 40° circular field of view without increasing the size and weight of the goggles.
Innovation Solution
A projection device with a 'split-pupil' folding mechanism that uses multiple folding surfaces to redirect projector rays, ensuring they are parallel and coincident with external scene rays, thereby covering the full 40° field of view with minimal obscuration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If a conventional projector approach is used to project an external image through the night vision goggle objective lens, then the projected image can be displayed, but the field of view is limited to 20°-32° due to objective lens vignetting, resulting in significant visual area loss (36% at maximum 32°)
Solution Approach 1:
The patent divides the projection optical path into multiple segments using a folding mechanism with multiple folding surfaces (first folding surface, second folding surface). This segmentation allows the projection rays to be redirected in steps, enabling the projected image to cover the full 40° field of view without requiring a single large, complex projection optic assembly.
2Area of stationary object
If the projector exit pupil is increased to overcome objective lens vignetting and achieve full 40° field of view coverage, then the field of view is improved, but the projection optic assembly becomes extremely bulky and heavy
Solution Approach 1:
The patent uses a folding mechanism that redirects projection rays through multiple folding surfaces, effectively changing the spatial dimensionality of the optical path. This allows the projection system to achieve full 40° field of view coverage without increasing the physical size and weight of the projection optic assembly, as the folding surfaces compact the optical path into a smaller form factor.
3Area of stationary object
If the projector exit pupil is increased to overcome objective lens vignetting, then the field of view is improved, but the projection optic assembly becomes extremely bulky
Solution Approach 1:
The patent employs a folding mechanism with multiple folding surfaces that redirects the projection optical path through folded dimensions. This dimensional transformation allows the system to achieve full 40° field of view coverage while maintaining a compact projection optic assembly volume, avoiding the need for an exceptionally large projection exit pupil.
4Object-affected harmful factors
If a pinhole cap is attached to reduce stray light reflections and increase depth of field, then light control is improved, but the edge field ray bundles are completely obscured, reducing the total field of view
Solution Approach 1:
The patent applies different optical treatments to different regions of the objective lens. The folding surfaces are positioned and oriented to redirect projection rays specifically for edge field regions, while the pinhole cap controls stray light for central field regions. This local optimization allows the system to achieve both stray light control and full 40° field of view coverage.
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
The solution allows for a 40° field of coverage without substantial size or weight increases, maintaining normal goggle functionality by effectively addressing vignetting issues in night vision goggles.
Implementation Method 1
a folding device comprising at least two folding surfaces positioned to split an exit pupil of the projector optical path into two or more separated segments. Each folding surface captures and redirects a portion of the projector rays
Data Source
AI summary
A projection device for use with a night vision goggle system includes: a display source; a projector lens assembly positioned to accept light from the display source and provide a projector optical path having a plurality of projector rays; and a folding device comprising at least two folding surfaces positioned to split an exit pupil of the projector optical path into two or more separated segments. Each folding surface captures and redirects a portion of the projector rays to be parallel and coincident with corresponding rays produced by an external scene which pass through an objective lens of the night vision goggle system.