Eye-safe Laser Triangulation System Using Pulsed Line Projection
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Solution Overview
Problem
Current distance measurement technologies, such as ultrasonic ranging and traditional laser triangulation, face accuracy issues due to diffuse reflections and high eye hazard, and are costly and prone to interference.
Innovation Solution
An eye-safe laser triangulation system using a point pulse laser transmitter, optical projection to convert the laser into a line laser, a capturing unit, and image processing for 3D modeling, with a protective circuit to control laser duration and a narrowband filter to reduce noise, achieving low average power and improved stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If high-power laser is used for triangulation measurement, then measurement range and signal strength are improved, but eye safety deteriorates
Solution Approach 1:
The patent applies periodic pulsed laser emission instead of continuous wave operation. The laser transmitter emits short-duration laser pulses with duty cycle controlled to maintain average power below eye safety thresholds while providing sufficient peak power for accurate triangulation measurement. The cooperation unit synchronizes the laser emission with the image capturing unit to capture reflected light only during or immediately after pulse emission.
2Device complexity
If point laser is used for measurement, then device complexity is reduced, but measurement precision deteriorates due to diffuse reflection
Solution Approach 1:
The patent transforms the laser output from a point source to a line source by introducing an optical projection apparatus (cylindrical lens or lens pair). This dimensional transformation creates a line laser that illuminates a linear region on the target, providing sufficient reflected light for the image capturing unit while maintaining simple device structure. The line laser configuration improves signal strength without requiring complex multi-point scanning systems.
3Measurement precision
If high sensitivity receiving sensor is used to detect weak laser signals, then measurement capability is improved, but device cost increases
Solution Approach 1:
The patent implements preliminary light gathering and concentration actions before detection. The optical projection apparatus creates a structured line laser pattern that maximizes reflected light return. The cooperation unit synchronizes the image capturing unit to capture images only during or immediately after laser pulse emission, maximizing signal strength. This preliminary optimization of light distribution and timing allows the use of standard image sensors rather than requiring expensive high-sensitivity specialized detectors.
4Duration of action of moving object
If continuous laser emission is used, then measurement continuity is improved, but average power and eye hazard increase
Solution Approach 1:
The patent implements periodic pulsed emission where the laser transmitter operates in discrete pulses rather than continuous emission. The cooperation unit controls the timing to emit laser pulses only when needed for measurement cycles. This periodic operation maintains measurement capability while reducing average power consumption and ensuring eye safety compliance, as the low duty cycle keeps average power well below hazardous levels.
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 system enhances measurement accuracy, reduces eye hazards, and lowers costs by using line lasers and short-pulsed mode, effectively filtering noise and operating under sunlight conditions.
Implementation Method 1
the laser transmitter is configured to generate point pulse laser of a pulse laser beam
Implementation Method 2
the optical projection apparatus is disposed at a front end of the laser transmitter, and is configured to convert the point pulse laser into line laser
Implementation Method 3
the laser beam capturing unit is configured to capture reflected light obtained by the line laser at a target position to obtain a laser image
Implementation Method 4
A narrowband bandpass filter is provided at a front end of a camera of the photographic camera. A central wavelength of the narrowband bandpass filter is the same as a wavelength of laser emitted by the laser transmitter, that is, the narrowband bandpass filter is capable of filtering out effects of most natural light on the system.
Data Source
AI summary
The present disclosure provides an eye-safe laser triangulation measurement system, including a laser transmitter, an optical projection apparatus, a laser beam capturing unit, a cooperation unit, and an image processing apparatus. The laser transmitter is configured to generate point pulse laser of a pulse laser beam. The optical projection apparatus is disposed at a front end of the laser transmitter, and is configured to convert the point pulse laser into a line laser. The laser beam capturing unit is configured to capture reflected light obtained by the line laser at a target position to obtain a laser image. The cooperation unit is configured to control on and off of the laser transmitter, and control capture of the laser beam capturing unit. The image processing apparatus is configured to perform 3D modeling on the laser image to obtain a distance to the target position.