MEMS Optical Device for Compact Projection
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Solution Overview
Problem
Existing optical scanning systems for devices like wafer defect scanners and projectors are not compact enough to be applicable in small devices such as handheld projectors, while maintaining high-quality image projection.
Innovation Solution
The use of microelectromechanical systems (MEMS) with a configuration of a horizontal planar scanning reflector, a fixed concave mirror, and a vertical planar reflector, arranged to direct a laser beam in a scanning motion, allowing for compact and high-quality image projection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If traditional optical scanning systems are used, then high-quality image projection is achieved, but device size becomes too large for handheld applications
Solution Approach 1:
The patent implements a nested optical configuration where the concave mirror is positioned within the optical path between the laser source and the scanning mirrors. The optical components are arranged in a compact nested layout where the concave mirror's focal point coincides with the intersection of the scanning mirrors' rotational axes, allowing multiple optical elements to occupy overlapping or adjacent spatial volumes, thereby reducing the overall device footprint while maintaining optical performance
Solution Approach 2:
The patent utilizes three-dimensional spatial arrangement by positioning the concave mirror at a specific depth along the optical axis, with its focal point aligned with the scanning mirrors' rotation axis intersection. This vertical stacking and angular arrangement of optical components in multiple dimensions enables compact integration without compromising the beam scanning quality and image projection performance
2Volume of moving object
If MEMS mirrors with limited area are used, then device size is reduced, but beam quality and coverage are compromised
Solution Approach 1:
The patent employs a concave spherical mirror with a specific radius of curvature (e.g., 10mm) positioned at a precise distance from the laser source. This curved reflective surface focuses and shapes the laser beam, compensating for the limited aperture size of the MEMS mirrors. The spherical geometry enables effective beam confinement and quality maintenance despite the small mirror areas, allowing compact MEMS devices to achieve projection quality comparable to larger traditional systems
3Area of stationary object
If the beam is scanned across a large area, then coverage is improved, but spot size uniformity deteriorates
Solution Approach 1:
The patent implements local quality optimization by using a collimated laser beam as input, which maintains a substantially uniform beam diameter across the entire scanning range. The collimation ensures that the spot size remains consistent at both the center and edges of the projection area. Additionally, the concave mirror is positioned and sized to provide appropriate beam conditioning locally across different field positions, maintaining spot uniformity throughout the extended projection area
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 compact and high-quality image projection in small devices by optimizing the placement and movement of reflective elements, ensuring consistent beam size and quality across the projection area.
Implementation Method 1
an optical device for projecting a light beam comprises a substantially horizontal planar scanning reflector (4), a fixed concave mirror (6) and substantially vertical planar scanning reflector (8), all arranged serially in the path for directing an incident laser beam
Data Source
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AI summary
An optical device is provided for projecting a light beam. The device comprises a first planar reflector movable about a first axis is disposed in a path of a focused light beam for deflecting the incident light beam; a concave reflective surface fixed in position located in the path of the deflected light beam, has a circular shape extending along at least one of its axis and is spaced apart from the planar reflector by a distance which is approximately equal to the radius of that circular shape; and a second planar reflector moveable about a second axis located in a plane substantially vertical to a plane comprising the first axis and wherein the second planar reflector is positioned in the path of the light reflected by the concave reflective surface such that the light beam is projected onto a target plane with a substantially flat field of focus.