MOEM Pixel Structure for Reflective Spatial Optical Modulation
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Solution Overview
Problem
The existing design and manufacturability of galvanic light valve (GLV) devices for reflective spatial optical modulation are complex and not readily producible with acceptable precision tolerance in semiconductor fabrication, limiting their yield and practicality compared to Digital Mirror Devices (DMD) and Liquid Crystal On Silicon (LCOS) technologies.
Innovation Solution
A micro optical-electrical-mechanical (MOEM) pixel structure with a static bottom metal reflector and a movable top metal reflector on a semiconductor substrate, supported by bendable arms and limited by minimum and maximum spacing limiters, allows for precise modulation of incident illumination through optical apertures, achieving binary precision in reflection or diffraction across a wide light spectrum.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If GLV devices are designed with complicated MOEMS array microstructures to achieve precise optical modulation, then modulation precision and optical efficiency are improved, but manufacturing complexity and fabrication difficulty increase significantly
Solution Approach 1:
The device is segmented into simple, repeating unit cells where each cell contains minimal microstructures (reflectors and support beams). This segmentation allows precise optical modulation to be achieved through uniform replication of simple structures rather than through complex monolithic designs, thereby reducing manufacturing difficulty while maintaining precision
Solution Approach 2:
The invention achieves precise optical modulation by controlling geometric parameters (reflector spacing, beam dimensions, aperture sizes) rather than through structural complexity. By optimizing these parameters within simple MOEMS structures, the device achieves high precision optical control without requiring complicated microstructures that would be difficult to manufacture
2Productivity
If GLV devices use complicated MOEMS microstructures to achieve binary precision modulation, then gray-scale capability and modulation speed are improved, but device yield and manufacturability deteriorate
Solution Approach 1:
The invention replaces complex mechanical MOEMS structures with a simplified system based on electrostatic actuation between parallel reflectors. The modulation function is achieved through electrical control of reflector spacing rather than through complicated mechanical linkages or moving parts, enabling high-speed modulation while significantly improving ease of semiconductor fabrication
Solution Approach 2:
The device uses identical, replicated unit cells across the array where each cell is a copy of the simple basic structure. This copying approach allows high-yield manufacturing through standard semiconductor fabrication processes while achieving the required modulation performance through the collective action of many identical simple elements rather than through complex unique structures
3Manufacturing precision
If minimum spacing limiters are fabricated at the bottom sides of bendable arms to constrain reflector spacing, then manufacturing precision is improved, but device complexity increases
Solution Approach 1:
The minimum spacing limiters are fabricated as fixed structures on the substrate before the MOEMS structures are assembled. By pre-establishing the spacing constraints in the substrate layer, the invention ensures precise reflector spacing without requiring complex active control mechanisms or post-fabrication adjustments, thereby improving precision while minimizing added complexity
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 design simplifies the manufacturing process and enhances the manufacturability of spatial optical modulation arrays, enabling precise modulation of light with improved gray-scale capability, modulation speed, and optical efficiency, while maintaining acceptable precision tolerance.
Implementation Method 1
Upon similar or opposite electrical charging by the pixel circuitry, the top metal reflector moves farther from or closer to the static bottom metal reflector due to electrical compulsion or attraction
Implementation Method 2
allow incident illumination through the movable rigid composite plate unto the bottom metal reflector to form the pair of optical reflectors
Implementation Method 3
The pixel structure in one embodiment includes a static bottom metal reflector built on a semiconductor substrate containing a CMOS-based pixel circuitry, and a pairing top metal reflector on top of a rigid composite plate which is readily movable vertically
Implementation Method 4
providing modulation of incident illumination in a closely binary precision mode of reflection or diffraction over a wide spectrum of light wavelength
Data Source
AI summary
A spatial optical modulation array device includes regularly packed micro optical-electrical-mechanical pixels in a planner configuration on a semiconductor substrate, each pixel electrically actuated independently and thus operated optically in the binary modes, reflection and diffraction to incident illumination. Subject to the electrostatic contraction or compulsion driven by a pixel circuitry, the top metal reflector is placed accurately at the minimum or maximum spacing from the static bottom metal reflector in an odd or even integral multiple of a quarter wavelength within visual light spectrum, so that diffraction or reflection in destructive or constructive interference is achieved respectively and thus incident illumination modulated independently in closely binary modes at each micro optical-electrical-mechanical pixel.