Optical Distance Measurement with Refractive Index Compensation
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Solution Overview
Problem
Optical distance measurement accuracy decreases due to changes in the refractive index of the distance measurement space, particularly influenced by temperature, atmospheric pressure, and machining oil mist in machining environments.
Innovation Solution
An optical distance measurement device that splits laser light into measurement and reference beams, with separate optical systems to calculate optical path lengths and refractive indices, allowing for accurate distance measurement despite changes in the refractive index of the measurement space.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If optical distance measurement is performed using interferometry, then measurement speed and non-contact capability are improved, but measurement accuracy deteriorates when refractive index changes occur in the measurement space
Solution Approach 1:
The patent introduces a reference light path that travels through the same measurement space as the measurement light. By comparing the optical path length of the measurement light with that of the reference light, the system can detect and compensate for refractive index changes in the measurement space, thereby maintaining measurement accuracy while using high-speed interferometric methods
Solution Approach 2:
The system uses the interference signal between measurement light and reference light to provide feedback about environmental conditions in the measurement space. This feedback enables real-time compensation for refractive index variations, allowing the system to maintain accuracy during high-speed measurements
2Ease of manufacture
If the optical path length is converted to distance using a fixed refractive index, then calculation simplicity is improved, but measurement accuracy deteriorates when actual refractive index changes
Solution Approach 1:
The patent dynamically determines the refractive index of the measurement space by comparing optical path lengths measured through different media (e.g., air and vacuum reference). This allows the system to adapt to changing environmental conditions while maintaining accurate distance calculations, rather than using a fixed refractive index assumption
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 device effectively suppresses decreases in measurement accuracy caused by refractive index changes, ensuring precise distance measurement and improved machining precision by continuously calculating and adjusting for refractive index variations.
Implementation Method 1
a splitter to split laser light into measurement light and reference light
Implementation Method 2
a first optical system to irradiate a target object with the first measurement light generated by the measurement light splitter and to receive first reflected light reflected by the target object
Implementation Method 3
a second optical system to emit the second measurement light generated by the measurement light splitter toward a space between the first optical system and the target object
Implementation Method 4
a reflector to reflect the second measurement light emitted from the second optical system and passing through the space toward the second optical system
Implementation Method 5
interference light is generated by causing the reference light and reflected light obtained by reflecting the measurement light on a target object to interfere with each other
Data Source
AI summary
A first optical path length from an emission surface of a first optical system to a reflection surface of a target object is calculated on the basis of first reflected light received by the first optical system and reference light generated by a splitter. A second optical path length from an emission surface of the second optical system to a reflection surface of a reflector is calculated on the basis of second reflected light reflected by the reflector and received by the second optical system and the reference light generated by the splitter A refractive index of a space is calculated on the basis of the second optical path length, and a distance from the emission surface of the first optical system to the reflection surface of the target object is calculated on the basis of the refractive index and the first optical path length.