Micromirror Optical Scanning Device Angle Detection
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Solution Overview
Problem
Existing optical scanning devices using micromirror devices face challenges in accurately detecting the angle of the mirror portion due to temperature-dependent sensitivity and material deterioration, leading to low accuracy and efficiency, especially when using strain sensors, and previous methods with beam splitters result in poor light efficiency and optical noise.
Innovation Solution
An optical scanning device design that includes a micromirror device with a reflecting surface, actuators for biaxial movement, a light source, a light deflector without a beam splitter, and a position detector to guide the light beam to the back surface of the mirror, enabling precise angle detection through precession or spiral motion, improving light efficiency and accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a beam splitter is used to guide light to the back surface of the mirror portion, then the light beam can be directed to the position detector, but the light efficiency deteriorates due to double dimming and optical noise is generated
Solution Approach 1:
The patent removes the beam splitter from the optical path and directly guides the light beam from the light source to the back surface of the mirror portion. This extraction of the problematic component eliminates the double dimming effect and optical noise generation while maintaining the light guidance capability through a simplified optical path.
2Device complexity
If a strain sensor is used to detect the angle of the mirror portion, then the detection method is simple, but the detection accuracy deteriorates due to temperature dependence and material deterioration
Solution Approach 1:
The patent replaces the strain sensor (mechanical/electrical detection method) with an optical detection method using a position detector. By shining light on the back surface of the mirror portion and detecting the reflected light position, the system achieves temperature-independent and deterioration-resistant angle detection while maintaining reasonable system complexity.
3Loss of energy
If the light beam is made incident on the back surface from an oblique direction to avoid beam splitter, then the beam splitter is eliminated, but the image becomes distorted making data processing difficult
Solution Approach 1:
The patent positions the light source and optical system such that the light beam incidents on the back surface of the mirror portion at a perpendicular angle (normal incidence). This creates an equipotential optical path where the reflected light maintains its spatial distribution, avoiding image distortion while eliminating the need for a beam splitter and maintaining high light efficiency.
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 enhances the efficiency and accuracy of angle detection for the mirror portion by eliminating the need for beam splitters, reducing optical noise, and maintaining consistent light incidence on the position detector, thereby improving the overall performance of the optical scanning device.
Implementation Method 1
a light source that emits a light beam; a light deflector that deflects the light beam emitted from the light source; an optical system that guides the light beam deflected by the light deflector to a back surface of the mirror portion, which is a surface opposite to the reflecting surface
Data Source
AI summary
The optical scanning device includes: a micromirror device including a mirror portion that has a reflecting surface for reflecting incident light, a first actuator that allows the mirror portion to swing around a first axis parallel to the reflecting surface in a case where the mirror portion is stationary, and a second actuator that allows the mirror portion to swing around a second axis parallel to the reflecting surface and orthogonal to the first axis; a light source that emits a light beam; a light deflector that deflects the light beam emitted from the light source; an optical system that guides the light beam deflected by the light deflector to a back surface of the mirror portion, which is a surface opposite to the reflecting surface; and a position detector that detects a position of the light beam deflected by the back surface.