Imaging Module Ghosting Reduction via Immersion Fluid
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Solution Overview
Problem
Polarization conversion devices in head mount displays cause ghosting and degrade image clarity due to light reflection when in contact with air, leading to unwanted virtual images at the user's eye.
Innovation Solution
An imaging module comprising a display screen, a glued lens set, a first phase retarder, and a polarizer, where the first phase retarder is positioned between the polarizer and the lens to avoid air contact, reducing reflections and including additional components like beam-splitters and quarter-wave plates to manage polarization and light path effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If polarization conversion devices are provided on the display screen in direct contact with air, then light can be refracted and reflected smoothly in the catadioptric optical path, but light reflection occurs at the air interface causing ghosting and degrading image clarity
Solution Approach 1:
The patent introduces an intermediary substance (optical adhesive or immersion fluid) between the polarization conversion device and the air environment. This intermediary eliminates the air interface, preventing light reflection while maintaining optical path functionality. The adhesive layer serves as a mediator that allows smooth light transmission without creating reflective boundaries.
Solution Approach 2:
The patent creates an inert optical environment by filling the housing cavity with an immersion fluid that has optimized refractive index properties. This inert fluid environment replaces the problematic air interface, eliminating reflection issues while maintaining the catadioptric optical path's refraction and reflection functions.
2Volume of moving object
If a catadioptric optical path is designed inside the head mount display to reduce device volume, then light is propagated back and forth many times in limited space achieving magnification, but polarization conversion devices cause ghosting that degrades picture clarity
Solution Approach 1:
The optical adhesive or immersion fluid acts as an intermediary that enables the compact catadioptric design to function without ghosting. By eliminating air interfaces within the folded optical path, the intermediary substance allows multiple light reflections and refractions to occur smoothly, maintaining both the volume reduction and image clarity requirements.
Solution Approach 2:
The patent changes the optical parameters of the environment by introducing substances with specific refractive indices. This parameter change eliminates the refractive index mismatch between air and optical components, preventing reflection while maintaining the compact optical path design's magnification capability.
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 reduces ghosting and ensures clear imaging by minimizing light reflections, enhancing the clarity and magnification of the displayed picture while maintaining a compact optical path.
Implementation Method 1
polarization conversion devices are provided on display screens... the light emitted by a display screen needs to have a uniform polarization state
Implementation Method 2
a catadioptric optical path is usually designed inside the head mount display, so that light is propagated back and forth many times in a limited space, resulting in magnification in its imaging
Implementation Method 3
a polarization reflector provided on a light-emergent surface of the second lens
Data Source
AI summary
Disclosed are an imaging module and a head mount display, wherein, the imaging module comprises a display screen, a glued lens set, a first phase retarder and a polarizer. The display screen has a light-emergent surface for emitting light. The glued lens set is provided in a light-emergent direction of the display screen and comprises a first lens and a second lens which are glued and sequentially provided along a propagation direction of light. The first phase retarder is provided on a light-incident surface of the first lens. The polarizer is provided on a surface of the first phase retarder facing away from the first lens.