Double-Sided MEMS Mirror Optical Module for Ranging
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Solution Overview
Problem
In distance sensors using different MEMS mirrors for laser emission and reception, synchronization of vibration frequencies and swing angles is required, leading to system complexity and potential accuracy deterioration due to synchronization deviations.
Innovation Solution
The use of a double-sided MEMS mirror in a coaxial optical system, where the emission and reception optical paths share the same mirror, helps synchronize the vibration frequencies and swing angles, simplifying the system and improving accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If different MEMS mirrors are used for laser emission and reception, then stray light suppression is improved, but system complexity increases and synchronization accuracy deteriorates
Solution Approach 1:
The optical system is segmented into emission and reception paths, each with dedicated MEMS mirrors. The emission-side MEMS mirror handles laser scanning while the reception-side MEMS mirror handles scattered light collection, allowing independent optimization of each path while maintaining overall system functionality.
Solution Approach 2:
A beam splitter is introduced as an intermediary component to separate the emission and reception optical paths. This mediator allows the use of different MEMS mirrors for each function while maintaining a compact coaxial structure, resolving the conflict between path separation and system compactness.
2Object-affected harmful factors
If different MEMS mirrors are used for laser emission and reception, then stray light suppression is improved, but synchronization accuracy deteriorates
Solution Approach 1:
Position detection sensors are introduced to provide feedback on the actual positions of both MEMS mirrors. This feedback mechanism enables real-time synchronization adjustment, ensuring that the emission and reception mirrors operate in coordination despite being physically separate components.
Solution Approach 2:
The mechanical synchronization between two separate MEMS mirrors is replaced with an electronic control system that uses position sensors and coordinated actuation. This substitution allows for more precise and flexible synchronization without relying on mechanical coupling between the mirrors.
3Device complexity
If a single MEMS mirror is used in coaxial optical system, then device complexity is reduced, but stray light enters the light receiving element
Solution Approach 1:
The single MEMS mirror function is segmented into two separate MEMS mirrors, each dedicated to a specific optical path (emission and reception). This segmentation allows stray light generated by the emission mirror to be directed away from the reception element while maintaining the simplicity of individual mirror operations.
Solution Approach 2:
The optical system transitions from a symmetric single-mirror coaxial configuration to an asymmetric dual-mirror configuration where the emission and reception paths are deliberately differentiated. This asymmetry in mirror placement and optical path design effectively directs stray light away from the light receiving element.
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 reduces system complexity and enhances accuracy by ensuring synchronized vibration frequencies and swing angles, effectively addressing the challenges faced in previous systems.
Implementation Method 1
A distance sensor using a micro electro mechanical systems (MEMS) mirror for laser scanning
Implementation Method 2
optical paths of emission and transmission/reception are branched using a deflection beam splitter or the like
Implementation Method 3
a distance to an object is measured using a time from when an object is irradiated with a laser until scattered light from the object reaches a measuring instrument
Data Source
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AI summary
To provide an optical module that can synchronize a vibration frequency and a swing angle without complicating a system. An optical module including: a double-sided mirror that rotates or undergoes pendulum motion about at least one rotation axis; a plane mirror disposed at an angle of 45 degrees from a horizontal surface on a back surface side of the double-sided mirror; and a uniaxial retroreflective mirror disposed at an angle of 45 degrees from the horizontal surface on a front surface side of the double-sided mirror, in which an axis of retroreflective is perpendicular to the horizontal surface and a normal line of the uniaxial retroreflective mirror.