Optical Distance Meter Shutter with Attenuation Plate
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Solution Overview
Problem
Conventional electric optical distance meters face challenges in achieving accurate distance measurements due to varying reflectivity targets, as the output power of the light source needs to be adjusted, leading to errors when measuring high or low reflectivity targets, and the internal optical path's input power level is not comparable between the two cases.
Innovation Solution
An electric optical distance meter with a shutter that switches between external and internal optical paths, using blocking plates and an attenuation plate to control the light path, ensuring the reference light's input power is comparable by attenuating the light when a low reflectivity target is used and allowing unattenuated light when a high reflectivity target is used, with a shutter position detector for reliable operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the output power of the light source is increased to obtain sufficient distance measuring light for high accuracy measurement with low reflectivity targets, then the measurement precision for low reflectivity targets is improved, but cyclic error occurs when measuring high reflectivity targets because the light becomes too strong
Solution Approach 1:
The patent applies a variable attenuator in the internal optical path that dynamically adjusts its attenuation level based on the detected reflectivity of the target. When a low reflectivity target is detected, the attenuator reduces attenuation to allow sufficient light to reach the detector. When a high reflectivity target is detected, the attenuator increases attenuation to prevent cyclic error. This dynamic adjustment resolves the contradiction between needing strong light for low reflectivity targets and avoiding excessive light for high reflectivity targets.
Solution Approach 2:
The patent changes the attenuation parameter of the internal optical path based on target reflectivity characteristics. By detecting the reflectivity and adjusting the attenuation level accordingly, the system optimizes the light intensity reaching the detector for different target types, thereby resolving the contradiction between measurement precision and reliability across different reflectivity conditions.
2Reliability
If the output power of the light source is decreased to avoid cyclic error when measuring high reflectivity targets, then the measurement reliability for high reflectivity targets is improved, but the input power level of the reference light becomes extremely low making accurate distance measurement impossible
Solution Approach 1:
The variable attenuator dynamically adjusts its attenuation level based on target reflectivity detection. For high reflectivity targets, it increases attenuation to prevent cyclic error. For low reflectivity targets, it decreases attenuation to maintain sufficient light intensity. This dynamic control allows the system to achieve both reliable measurements for high reflectivity targets and accurate measurements for low reflectivity targets.
Solution Approach 2:
The system changes the attenuation parameter of the internal optical path based on detected target reflectivity. By adjusting the attenuation level dynamically, the system ensures that the reference light maintains an appropriate intensity level for accurate measurement across different target types, resolving the contradiction between reliability and precision.
3Device complexity
If a conventional optical path switching device with blocking plates is used to switch between internal and external optical paths, then the device complexity is reduced, but the shutter cannot simultaneously block both paths when needed
Solution Approach 1:
The patent divides the shutter mechanism into multiple independent components: a first blocking plate for blocking the external optical path and a second blocking plate for blocking the internal optical path. This segmentation allows each plate to independently control its respective path, enabling the shutter to simultaneously block both paths when needed while maintaining relatively simple device complexity.
Solution Approach 2:
The patent combines multiple blocking plates and an attenuator into a single integrated shutter assembly that rotates as one unit. This merging approach allows the shutter to simultaneously control both optical paths through the coordinated action of multiple components within a single rotating structure, achieving reliable dual-path blocking without significantly increasing device complexity.
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 ensures accurate distance measurements with fewer errors by maintaining comparable reference light strength for both high and low reflectivity targets, allowing for optimal light source output adjustment based on target reflectivity.
Implementation Method 1
an attenuation plate which is placed at one of the two locations where the blocking plates are not arranged and between the blocking plates, and attenuates the distance measuring light entering the internal optical path when the target is of a low reflectivity
Implementation Method 2
blocking plates which are arranged at two locations symmetric with respect to the rotating axis, and alternately block the respective distance measuring lights entering the external optical path and the internal optical path
Implementation Method 3
a light source for emitting a distance measuring light to a target placed on a measurement point
Implementation Method 4
a light receiving device for receiving the distance measuring light reflected and returned from the target
Data Source
AI summary
An electric optical distance meter is provided that makes an input power level of a reference light entering a light receiving device via an internal optical path comparable between low and high reflectivity targets. The electric optical distance meter has a shutter 50 for switching between an external optical path Po, through which a distance measuring light emitted by a light source is placed to and from a target, and the internal optical path Pi is placed from the light source to the light receiving device, where the shutter has: a rotating axis 55; blocking plates 56 which are arranged at two locations symmetric with respect to the rotating axis, and alternately block the respective distance measuring lights L entering the external optical path and the internal optical path; and an attenuation plate 57 which is placed at one of the two locations where the blocking plates are not arranged and between the blocking plates, and attenuates the distance measuring light entering the internal optical path when the target is of a low reflectivity.