Laser Surveying System with Variable Aperture for Distance Accuracy
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Solution Overview
Problem
Conventional laser surveying systems face accuracy issues due to the spreading of near-infrared laser beams, leading to increased errors when measuring distances deviating from standard distances, particularly because the beam diameter is fixed and not adaptable to varying measurement lengths.
Innovation Solution
A laser surveying system with a luminous flux diameter changing mechanism, allowing the beam diameter to be adjusted based on the distance to be measured, using a control unit to set the optimal beam diameter through preliminary measurements, and incorporating a projection optical system with adjustable aperture diameter and focal distance to match the beam diameter to the measurement distance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If near-infrared light is used as the distance measuring light, then the laser beam is invisible and causes no discomfort to the human eye, but the spreading angle is increased leading to increased measurement error
Solution Approach 1:
The patent applies a variable aperture diaphragm that can dynamically adjust the aperture diameter based on the distance to be measured. This dynamic adjustment compensates for the increased spreading angle of near-infrared light by narrowing the beam at longer distances, thereby maintaining measurement accuracy while preserving the safety benefits of near-infrared light.
Solution Approach 2:
The patent changes the aperture diameter parameter of the projection optical system based on the measurement distance. By varying the aperture diameter according to the distance to be measured, the system optimizes the beam spreading characteristics to maintain accurate measurements across different ranges while using safe near-infrared light.
2Measurement precision
If the beam diameter is set to match the standard measurement distance, then average measurement accuracy is improved, but error increases when the actual distance deviates from the standard measurement distance
Solution Approach 1:
The patent employs a dynamically adjustable aperture diaphragm that changes the aperture diameter based on the actual distance to be measured. This dynamic adaptation ensures that the beam diameter is optimized for each specific measurement distance, maintaining high accuracy across varying distances rather than being optimized for a single standard distance.
Solution Approach 2:
The system performs preliminary measurement to determine the actual distance before final measurement. Based on this preliminary information, the aperture diaphragm is adjusted in advance to the appropriate aperture diameter, ensuring optimal beam characteristics for the specific distance before the main measurement is taken.
3Measurement precision
If the beam diameter is made as small as possible, then measurement accuracy is improved, but the spreading angle increases leading to larger spot size at the object
Solution Approach 1:
The patent uses a dynamically controlled aperture diaphragm that adjusts the aperture diameter based on the measurement distance. This allows the system to achieve a small effective beam diameter at the object surface for improved accuracy, while the aperture adjustment compensates for the increased spreading angle over distance, maintaining a manageable spot size.
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 solution enhances measurement accuracy by allowing the beam diameter to be tailored to the specific distance, reducing errors and improving reliability across varying measurement lengths.
Implementation Method 1
a light source (36) for emitting a laser beam (40)
Implementation Method 2
a photodetection element (35) for performing photo-electric conversion of the reflected light received via the photodetection optical system (8)
Data Source
AI summary
A laser surveying system, comprising a light source for emitting a laser beam, a projection optical system for turning the laser beam from the light source to a parallel luminous flux, a scanning unit for projecting the luminous flux of the projected laser beam for scanning, a scanning direction detecting unit for detecting a scanning direction, a photodetection optical system for receiving a reflected light of the projected laser beam from an object to be measured, a photodetection element for performing photo-electric conversion of the reflected light received via the photodetection optical system, and a distance measuring unit for measuring a distance based on a signal from the photodetection element, wherein the projection optical system has a luminous flux diameter changing means, and a luminous flux diameter of the projected laser beam is enabled to be changed.