Electro-optical Distance Meter Secondary Light Source
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Solution Overview
Problem
Conventional electro-optical distance meters face accuracy issues due to temperature changes and light quality variations, leading to measurement errors caused by differences in the quality of distance measuring light and internal reference light, as well as positional changes of the photodetector.
Innovation Solution
The electro-optical distance meter employs a condenser lens, scattering plate, and optical fiber to create a secondary light source with uniform light components, ensuring that all light components from the secondary source enter the optical fiber, and a light attenuation filter to adjust light amounts, thereby equalizing the quality of the distance measuring light and internal reference light, and improving measurement accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the internal reference light is obtained by dividing the distance measuring light, then the internal reference light has the same quality as the distance measuring light, but the quality of the received light changes depending on the position where the received luminous flux is located within the luminous flux of the internal reference light
Solution Approach 1:
The patent applies preliminary action by pre-processing the internal reference light through condensing and scattering operations before it reaches the photodetector. The scattering plate creates a secondary light source that emits light components uniformly in all directions, ensuring that regardless of the photodetector's position, the received light quality remains consistent. This preliminary transformation of the light's spatial distribution resolves the issue of position-dependent quality variations.
2Temperature
If the photodetector's support position changes in correspondence with temperature change, then the photodetector's position changes with respect to the internal reference light, but this results in distance measurement error
Solution Approach 1:
The patent applies parameter changes by transforming the internal reference light's spatial distribution parameters through condensing and scattering operations. The scattering plate converts the directional luminous flux into a secondary light source with uniform emission in all directions, changing the angular distribution parameter. This makes the system insensitive to photodetector position changes caused by temperature variations, as the light quality remains consistent from any position within the uniform emission pattern.
3Quantity of substance
If a limited part of the luminous flux of the internal reference light is received by the photodetector, then the quality of the received light is affected by the brightness distribution and luminance speckles, but the quality differs from the light receiving quality of the distance measuring light
Solution Approach 1:
The patent introduces an intermediary scattering plate between the internal reference light source and the photodetector. This scattering plate acts as a mediator that receives the directional luminous flux and re-emits it as a secondary light source with uniform brightness distribution. The intermediary transforms the light's spatial characteristics, eliminating the brightness distribution and luminance speckles effects, and ensures the received light quality matches that of the distance measuring light.
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 ensures that the qualities of the reflected distance measuring light and internal reference light are the same, enhancing measurement accuracy and reliability against environmental changes.
Implementation Method 1
a condenser lens for condensing the internal reference light
Implementation Method 2
a scattering plate for scattering the internal reference light condensed by the condenser lens and for forming a secondary light source
Implementation Method 3
an optical fiber for receiving the internal reference light emitted from the secondary light source and for leading to the photodetector
Data Source
AI summary
An electro-optical distance meter comprises a light source for emitting a distance measuring light, a distance measuring optical system for leading a distance measuring light to a photodetector, an internal reference optical system for leading a part of the distance measuring light as an internal reference light to the photodetector, and an arithmetic processing unit for performing a distance measurement based on light receiving results of the distance measuring light and the internal reference light, wherein the internal reference optical system comprises a condenser lens, a scattering plate for scattering the internal reference light and for forming a secondary light source, and an optical fiber for leading the internal reference light to the photodetector and the internal reference optical system is constituted in such a manner that a light component of the internal reference light emitted from an arbitrary point within a whole surface of the secondary light source enters the optical fiber.