Interference Objective Lens for High-Accuracy 3D Shape Measurement
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing three-dimensional shape measuring devices using the focal point method face challenges in improving measurement accuracy without requiring additional components like projection systems or interference light generation means, and they struggle with measuring surfaces with low luminance changes, such as mirror surfaces.
Innovation Solution
The proposed solution involves a three-dimensional shape measuring device equipped with an interference objective lens that separates measurement light into reference and measurement light, generating multiplexed light with interference fringes. This device scans the surface, captures images with improved contrast due to interference fringes, and processes the images to calculate the three-dimensional shape.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If texture patterns are projected on the surface to be measured to improve contrast, then measurement accuracy is improved, but device complexity increases due to requiring a projection system
Solution Approach 1:
The patent introduces an interfering unit as an intermediary component that generates reference light and combines it with measurement light to create interference fringes. This intermediary mechanism improves measurement accuracy by enhancing surface contrast through optical interference, while avoiding the need for complex projection systems by using a more integrated optical approach within the objective lens structure.
2Measurement precision
If interference light generation means and light shielding plate are added to improve measurement accuracy, then measurement accuracy is improved, but device complexity and operational complexity increase
Solution Approach 1:
The patent merges the interference light generation function directly into the objective lens structure by integrating the interfering unit within the lens assembly. This consolidation eliminates the need for separate interference light generation means and light shielding plates, reducing device complexity while maintaining the ability to generate interference fringes for improved measurement accuracy.
Solution Approach 2:
The interfering unit within the objective lens serves multiple functions: it generates reference light, combines it with measurement light, and creates interference fringes all within a single integrated component. This multi-functionality reduces the overall number of components needed and simplifies the device structure while achieving improved measurement accuracy.
3Measurement precision
If the microscope scans in the height direction to measure three-dimensional shape, then measurement capability is achieved, but measurement time increases
Solution Approach 1:
The patent implements continuous scanning of the objective lens in the height direction while continuously capturing images at multiple focal depths. This continuous action allows for efficient data acquisition across the entire depth range, improving measurement speed while maintaining three-dimensional shape measurement capability. The interference fringes provide continuous depth information throughout the scanning process.
4Measurement precision
If the depth of field is reduced to improve height direction resolution, then measurement precision is improved, but the range of measurable surfaces is reduced
Solution Approach 1:
The patent transitions from relying solely on depth of field for height measurement to using interference fringes in the optical path for depth information. By introducing this additional dimensional information through optical interference, the system achieves high height direction resolution without being constrained by a limited depth of field, thereby expanding the range of measurable surfaces while maintaining precision.
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 approach enhances measurement accuracy by improving contrast and reducing the need for additional components, allowing for easier integration with existing devices and reducing examiner effort. It also enables high-speed measurement with improved resolution, particularly suitable for surfaces with low luminance changes.
Implementation Method 1
an interference objective lens including an interfering unit configured to separate part of the measurement light emitted from the light source unit as reference light, emit the measurement light to the surface to be measured, emit the reference light to a reference surface, and generate multiplexed light of the measurement light returning from the surface to be measured and the reference light returning from the reference surface
Data Source
AI summary
A three-dimensional shape measuring device includes: an interference objective lens including an interfering unit configured to separate part of measurement light as reference light and generate multiplexed light of the measurement light returning from the surface to be measured and the reference light returning from a reference surface, and an objective lens configured to cause the measurement light to focus on the surface to be measured; a scanning unit configured to cause the interference objective lens to scan relatively with respect to the surface to be measured; an image capturing unit configured to repeatedly capture an image of the multiplexed light and output a plurality of captured images during scanning; and a first signal processing unit configured to calculate the three-dimensional shape of the surface to be measured, based on a result of comparing the sharpness of each pixel on the same coordinate of the plurality of captured images.