Confocal Sensor Measurement Head for High-Temperature Lens Alignment
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Solution Overview
Problem
Confocal displacement sensors experience decreased measurement reliability and accuracy in high temperature environments due to lens misalignment and deformation of resin materials, which affect the positional relationship of optical components.
Innovation Solution
A measurement head for a confocal displacement sensor is designed with a metal housing, glass lenses, and a biasing member or thermal expansion member to restrict lens movement and maintain alignment, using stainless steel for the housing and polyimide for the optical fiber coating to withstand high temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the measurement head is arranged in a high temperature environment to measure the displacement of the measurement object, then the measurable range is expanded, but the positional relationship of the lenses changes due to thermal expansion and deformation, causing a decrease in measurement accuracy
Solution Approach 1:
The patent changes the material parameters of the lenses from resin to glass, which has a lower thermal expansion coefficient and higher thermal stability. This parameter change allows the measurement head to maintain lens alignment and optical performance in high temperature environments, enabling accurate measurement while expanding the measurable range.
Solution Approach 2:
The patent uses composite material construction where the housing is made of metal (stainless steel) and the lenses are made of glass, rather than using resin for both. This composite approach combines the thermal stability of metal and glass to create a measurement head that can withstand high temperature environments while maintaining measurement accuracy.
2Ease of manufacture
If resin materials are used for the lenses to reduce manufacturing complexity, then the ease of manufacture is improved, but the lenses deform in high temperature environments, causing a decrease in measurement reliability
Solution Approach 1:
The patent changes the material parameter from resin to glass for the lenses. Glass has superior thermal stability and dimensional stability at high temperatures compared to resin, which prevents deformation and maintains measurement reliability in high temperature environments.
Solution Approach 2:
The patent applies different material qualities to different parts of the measurement head: the housing uses metal for structural stability, while the lenses use glass for optical stability. This local quality differentiation ensures that each component performs optimally under high temperature conditions, maintaining overall measurement reliability.
3Measurement precision
If the lenses are fixed rigidly in the housing to maintain alignment, then the measurement precision is improved, but the device complexity increases due to additional positioning structures
Solution Approach 1:
The patent changes the material parameter of the lenses from resin to glass, which has lower thermal expansion. This reduces the need for complex compensation mechanisms, allowing simpler fixation structures to maintain precise alignment even in high temperature environments.
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 design effectively suppresses the decrease in measurement reliability in high temperature environments by maintaining lens alignment and stability, ensuring accurate displacement measurements.
Implementation Method 1
a biasing member that is made of metal and biases some or all of the plurality of lenses including the first lens by an elastic force in the one direction
Implementation Method 2
a thermal expansion member that is made of polyimide and is provided at a position separated from the first movement restricting portion in the axial direction inside the housing, in which some or all of the plurality of lenses including the first lens are held between the first movement restricting portion and a fixing member
Implementation Method 3
a plurality of lenses that is made of glass, includes a first lens, is accommodated inside the housing to be aligned in an axial direction of the housing and to be movable in the axial direction, and converges the light guided to the first end portion by the optical fiber on a measurement object through the second end portion
Implementation Method 4
an optical fiber that is connected to the first end portion of the housing and guides light generated from the white light source to the first end portion of the housing
Data Source
AI summary
Provided is a measurement head and a confocal displacement sensor which are capable of suppressing a decrease in reliability of measurement in a high-temperature environment of the confocal displacement sensor. The measurement head is a measurement head for a confocal displacement sensor having a white light source. The measurement head has a configuration in which a plurality of glass lenses are accommodated in a head metal housing. A metal spring member biases the plurality of glass lenses including the lens toward the +x direction in a state where the lens abuts on the ring screw is provided in the head metal housing. Or a thermal expansion polyimide member provided inside the metal housing.