Laser Distance Measurement with Multi-Pulse Signal Integration
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Solution Overview
Problem
Existing laser measuring instruments face limitations in measurement distance due to the need for larger objective lenses and higher laser output, which increase size and weight, restricting flight altitude and scanning range when mounted on small unmanned aerial vehicles.
Innovation Solution
A laser measuring method and instrument that performs multiple irradiations of pulsed light at a measuring point, integrates light receiving signals, and adjusts scanning speed and light emission cycles to enhance measurement distance without increasing instrument size or laser output, using a scanning unit with optical prisms for deflection and a timing generating circuit for controlled light emission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the diameter of the objective lens is increased to enable measurement of farther distances, then the measurement distance is improved, but the size and weight of the measuring instrument increase
Solution Approach 1:
The patent applies periodic action by emitting pulsed laser beams at multiple time points instead of continuous emission. The light emission cycle is set to emit pulsed light multiple times while the light passes the measuring point, accumulating reflected light signals periodically to improve measurement distance capability without requiring larger optical components.
Solution Approach 2:
The patent changes the temporal parameters of light emission by setting a specific light emission cycle that allows multiple pulses within the light travel time. This parameter change enables the accumulation of reflected light from multiple emissions, effectively increasing the measurable distance without physically enlarging the objective lens.
2Measurement precision
If the output of the pulsed laser beam is increased to enable measurement of farther distances, then the measurement distance is improved, but the radiation output of the laser diode is limited
Solution Approach 1:
Instead of increasing the power of single laser pulses, the patent uses periodic emission of multiple lower-power pulses. The light emission cycle is configured to emit pulses at intervals that allow the light to travel to the measuring point and return, accumulating sufficient reflected light energy over multiple cycles without exceeding laser diode power limits.
Solution Approach 2:
The patent maintains continuous measurement capability by emitting pulses in a continuous cycle rather than using high-power intermittent pulses. The light emission cycle ensures that useful measurement action continues through accumulation of multiple reflected light signals, achieving long-distance measurement without requiring high peak power that would exceed diode limits.
3Productivity
If the light emission cycle is shortened to increase scanning speed, then the productivity is improved, but the light receiving amount decreases
Solution Approach 1:
The patent resolves this contradiction by using periodic multi-pulse emission within each measurement cycle. Even though the overall light emission cycle is short for high scanning speed, multiple pulses are emitted within each cycle, and their reflected light signals are accumulated. This maintains sufficient light receiving amount while enabling fast scanning through the shortened cycle.
Solution Approach 2:
The patent merges multiple light receiving signals from successive pulses into a single accumulated signal for distance calculation. By combining the reflected light information from multiple pulses emitted within the light emission cycle, the system maintains adequate light receiving amount despite the short cycle duration required for high scanning speed.
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
Enables long-distance measurement with reduced light emitter duty ratio, contributing to cost reduction and extended emitter life, while maintaining compact size and weight suitable for small unmanned aerial vehicles.
Implementation Method 1
a reflected light is received, a reciprocating time of the pulsed laser beam is detected
Implementation Method 2
a reciprocating time of the pulsed laser beam is detected, and a distance to the object to be measured is determined
Implementation Method 3
a photodetector is used as a light receiving element, light receiving signals acquired by multiply irradiating the pulsed light by two or more times are integrated
Data Source
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AI summary
A laser measuring instrument comprises a light emitter, a driver, a scanning unit, a light receiving signal processing module for detecting a reciprocating time per pulsed light of a distance measuring light and performing a distance measurement, and a timing generating circuit for issuing a timing signal, wherein the timing generating circuit is configured to issue a timing signal for making the light emitter pulse-emit in a short cycle and a timing signal for pausing a light emission, the driver is configured to make the light emitter pulse-emit according to the timing signals, a light emission time interval in the short cycle is set such that a measuring point is multiply irradiated with the pulsed light by two or more times within a time when the pulsed light passes the measuring point, and the light receiving signal processing module is configured to integrate acquired light receiving signals and to carry out the distance measurement.