MEMS Distance Measurement Apparatus with Dynamic Laser Control
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Solution Overview
Problem
Existing distance measurement apparatuses face challenges in accurately detecting scan position deviations due to environmental factors like temperature changes, leading to complications in structure and cost, and potential degradation of reference reflectors from excessive light absorption.
Innovation Solution
A distance measurement apparatus with a simple structure that includes a MEMS mirror for two-dimensional scanning, a reflecting member to cover part of the scan region, and a light receiving unit to detect light reflected from both the object and the reflecting member, with the laser light source control adjusting the emitted light to prevent saturation and maintain accurate reflectance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a separate light receiving means is disposed at the scan point to detect scan position deviation, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The light receiving means is configured to perform multiple functions: it detects both the scan position deviation signal (from the reference reflector) and the reflected light from the measurement object. This multi-functional design eliminates the need for separate detection devices, thereby improving measurement precision while avoiding increased device complexity.
2Reliability
If the reflectance of the reference reflector is reduced to prevent saturation, then reliability is improved, but manufacturing precision deteriorates due to increased light absorption and heat generation
Solution Approach 1:
The system dynamically adjusts the amount of laser light emitted based on the intensity of the deviation detection signal. When the reflector is close to the light source (high reflection risk), the laser intensity is reduced. This dynamic control allows the use of a reference reflector with higher reflectance without causing saturation, thereby maintaining reflectance stability while preventing output saturation.
3Measurement precision
If the amount of laser light is increased to improve detection accuracy, then measurement precision is improved, but loss of energy increases due to excessive light absorption by the reference reflector
Solution Approach 1:
The laser light source control means dynamically adjusts the laser emission intensity based on real-time feedback from the light receiving means. When the reference reflector is positioned close to the light source, the system automatically reduces laser intensity to minimize energy absorption by the reflector. This dynamic adjustment maintains sufficient signal intensity for accurate measurement while reducing energy loss.
4Volume of stationary object
If a reference reflector is disposed close to the laser light source for compact design, then volume is reduced, but object-affected harmful factors increase due to excessive light absorption and heat generation
Solution Approach 1:
The system uses dynamic control of laser light intensity to compensate for the close positioning of the reference reflector. When the reflector is positioned near the light source to reduce apparatus volume, the laser intensity is automatically reduced to prevent excessive light absorption and heat generation. This allows compact design while minimizing harmful thermal effects on the reflector.
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 allows for precise detection of scan position deviations with enhanced accuracy, reducing the need for separate light detectors and minimizing the impact of temperature changes on reflector degradation, thus improving measurement reliability and reducing apparatus size and cost.
Implementation Method 1
reflecting means, fixed to the casing, for covering a part of a scan region by the laser light or a periphery of the scan region, and reflecting the laser light
Implementation Method 2
light receiving means for receiving light reflected by the object to be measured and light reflected by the reflecting means, and outputting a received light signal
Data Source
AI summary
A distance measurement apparatus includes: a laser light source configured to emit emitted light to be applied to an object to be measured; a laser light source control circuit configured to control the laser light source; a MEMS mirror configured to two-dimensionally scan the object with the emitted light; a reflecting member configured to cover a part of a scan region, and reflect the emitted light; and a light detector configured to receive reflected light from the object to be measured and reflected light from the reflecting member, and output a received light signal. The laser light source control circuit sets, to a threshold value, an amount of the emitted light obtained when output of the light detector is saturated, and controls an amount of the emitted light such that the amount of the emitted light is less than the threshold value.