Displacement Meter Optical Path Segmentation for Specular Reflection
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Solution Overview
Problem
Conventional non-contact in-plane displacement meters face challenges in achieving high illumination efficiency, particularly when measuring objects with strong specular reflection components like metal, leading to insufficient light amounts, heat generation, and reduced light source lifespan, as well as limitations in design due to physical interference between illumination and light receiving optical systems.
Innovation Solution
A displacement meter design featuring a light source with a ring-shaped light intensity distribution, a light deflection portion with a central opening, and a first lens unit that collects and focuses light efficiently, reducing light loss and stray reflections, allowing for robust measurement regardless of working distance changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the amount of illumination light is increased to measure objects with strong specular reflection components, then the light amount for measurement is improved, but heat generation increases and light source lifespan is shortened
Solution Approach 1:
The optical system is segmented into separate illumination and light receiving optical systems with different incident angles. The illumination optical system uses a larger incident angle to maximize light amount for specular reflection surfaces, while the light receiving optical system is positioned to collect reflected light without requiring increased illumination intensity, thus avoiding heat generation issues.
Solution Approach 2:
Different parts of the optical system are optimized for different functions: the illumination optical system is designed with a larger incident angle to maximize light delivery to the measurement object, while the light receiving optical system is positioned at a specific angle to efficiently collect reflected light. This local optimization allows sufficient light amount without requiring excessive illumination intensity that would cause heat generation.
2Loss of energy
If the incident angle of illumination light is increased to reduce light loss, then illumination efficiency is improved, but physical interference between illumination and light receiving optical systems occurs
Solution Approach 1:
The optical system is divided into separate illumination and light receiving subsystems with distinct optical paths. The illumination optical system uses a larger incident angle to improve illumination efficiency and reduce light loss, while the light receiving optical system is positioned at a different angle to avoid physical interference. This segmentation allows each subsystem to be optimized independently without compromise.
3Ease of manufacture
If a half mirror is used in the coaxial epi-illumination optical system to deflect light, then the system can be configured, but light amount loss occurs and effective light amount is reduced
Solution Approach 1:
The patent extracts the light deflection function from the illumination path by using a separate light receiving optical system positioned at a different angle. Instead of using a half mirror that splits and loses light, the design directly positions the light receiving system to collect reflected light, eliminating the light amount loss associated with half mirror reflection.
4Reliability
If polarizing optical elements are used to prevent ghost reflections, then reflected light interference is reduced, but cost increases
Solution Approach 1:
The optical system is segmented into separate illumination and light receiving paths with different incident angles. This spatial separation inherently prevents ghost reflections from entering the light receiving system, eliminating the need for additional polarizing optical elements and reducing system cost while maintaining measurement reliability.
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 solution enables high illumination efficiency, reduces light loss, and allows for robust displacement measurement across varying working distances and object types, including metal, without compromising the light source's lifespan or increasing costs.
Implementation Method 1
an illumination optical system that forms a light intensity distribution at a predetermined position on an optical axis by using light from the light source
Implementation Method 2
a light deflection portion that has an opening on the optical axis and a reflection part configured to reflect light of the light intensity distribution formed by the illumination optical system
Implementation Method 3
a first lens unit that collects light reflected by the reflection part and illuminates a measurement object
Data Source
AI summary
A displacement meter includes: a light source; an illumination optical system which forms a light intensity distribution at a predetermined position on an optical axis by using light from the light source such that a light intensity at a peripheral portion of the light intensity distribution is stronger than a light intensity at a center portion of the light intensity distribution; a light deflection portion which has an opening on the optical axis and a reflection part reflecting light of the light intensity distribution formed by the illumination optical system at the predetermined position; a first lens unit which collects light reflected by the reflection part and illuminates a measurement object; a sensor array which detects light reflected by the measurement object and passing through the opening of the light deflection portion through the first lens unit; and a measurement unit which detects a displacement of the measurement object by using outputs of the sensor array at different timings.