Imager Optical System with Tilted Beam Deflector for High Contrast
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Solution Overview
Problem
Existing compact optical systems for mobile near-eye displays (NEDs) face challenges in achieving high contrast due to light leakage through non-ideal splitter layers, leading to reduced image quality and increased background brightness.
Innovation Solution
The implementation of a beam deflector with a tilted beam path between the light source, reflector, and light modulator, where the active surfaces of the light source and light modulator enclose an angle greater than 0°, allowing for selective deflection and suppression of unmodulated light portions, thereby preventing light leakage into the projection optical system and maintaining high contrast.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional transmissive displays are used, then the structure is simple, but the filling factor is low and resolution is reduced due to pixel structure visibility
Solution Approach 1:
The patent inverts the conventional transmissive display approach by using a reflective display technology (LCoS) where liquid crystal cells are applied to a silicon substrate with a reflecting surface on the underside. This inversion allows light to be modulated from the opposite side, achieving a very high filling factor for an almost pixel-free display with high resolution while maintaining structural simplicity through the use of standard semiconductor manufacturing processes
2Volume of moving object
If splitter layers are used to compact the optical system, then the system size is reduced, but light leakage occurs and contrast is degraded
Solution Approach 1:
The patent extracts and eliminates the problematic splitter layers from the optical system. Instead of using beam splitters to compact the illumination and projection paths, the invention employs a telecentric optical design where the illumination optical system and projection optical system are separated but both achieve telecentricity, thereby removing the source of light leakage while maintaining compact dimensions through optimized optical path folding and component placement
Solution Approach 2:
The patent changes the optical parameters of the system by implementing telecentric illumination and projection, where the chief rays are parallel to the optical axis at the aperture stop. This parameter change allows for precise control of light paths, eliminates the need for splitter layers, and maintains high contrast by preventing stray light from entering the projection path, while still achieving a compact form factor through careful optimization of focal lengths and component positions
3Manufacturing precision
If LCoS display is used, then high filling factor and resolution are achieved, but the system requires precise alignment and has limited angular tolerance
Solution Approach 1:
The patent applies equipotentiality by making both the illumination optical system and projection optical system telecentric. This creates an optical environment where the chief rays are parallel to the optical axis at the aperture stops, establishing an equipotential condition that provides increased alignment tolerance. The telecentric design ensures that small misalignments do not significantly affect the optical performance, thereby easing operational requirements while maintaining the high resolution capabilities of the LCoS display
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 configuration enables the realization of compact and small-sized imagers with high contrast values by ensuring that unmodulated light is not projected, reducing background brightness and enhancing image clarity in NEDs.
Implementation Method 1
a beam deflector, adapted to deflect light beams within the imager
Implementation Method 2
a reflector with a main plane, adapted to reflect light beams incident from the direction of the beam deflector in the direction of the beam deflector
Implementation Method 3
a light modulator with an active surface, adapted to modulate light beams incident from the direction of the beam deflector and to reflect them in the beam deflector
Data Source
AI summary
Described are an imager and an optical system with an imager. The imager includes a beam deflector to deflect light beams within the imager, a light source with an active surface, to emit light beams in the direction of the beam deflector, a reflector with a main plane, to reflect incident light beams from the direction of the beam deflector in the direction of the beam deflector, a light modulator with an active surface, to modulate incident light beams from the direction of the beam deflector and to reflect them in the direction of the beam deflector. The beam deflector is between the reflector and the light modulator. The main plane of the reflector and the active surface of the light modulator enclose an angle of greater than 0° which faces the beam deflector.