Interferometric Surface Distance Measurement for Eccentric Optical Systems
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing apparatuses for measuring surface distances in optical systems fail to obtain accurate measurements when target surfaces have significant eccentricity, as they cannot effectively handle large deviations in the center of curvature positions.
Innovation Solution
An acquiring apparatus utilizing a first light source to illuminate an index chart with asymmetrical patterns, a measurement optical system, an image sensor, an interferometer, and a calculating unit to measure distances between target surfaces by capturing interference signals from index and target lights, ensuring conjugate relationships between specific optical elements to account for eccentricities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional measuring apparatuses are used to measure surface distance, then the measurement process is simple, but accurate measurement cannot be obtained when target surfaces have large eccentricity
Solution Approach 1:
The patent employs an asymmetrical index chart with a specific asymmetric pattern that allows the measurement system to distinguish and compensate for eccentricity in target surfaces. The asymmetry in the index chart creates a reference that, when imaged, reveals the degree and direction of surface eccentricity, enabling accurate measurement despite large deviations from the optical axis.
Solution Approach 2:
The patent introduces an interferometer as an intermediary device that combines with the imaging system. The interferometer generates interference fringes that encode both the position and eccentricity information of the target surface. This intermediary mechanism allows the system to extract precise measurement data even when the target surface is significantly decentered.
2Ease of operation
If the measurement system is designed for simple operation, then ease of use is improved, but the system cannot handle target surfaces with large eccentricity
Solution Approach 1:
The patent creates a measurement system that performs multiple functions through a unified approach. The same imaging system with the asymmetrical index chart serves both to locate the target surface and to measure its eccentricity. The interferometer simultaneously provides interference patterns for position measurement and eccentricity characterization, eliminating the need for separate complex alignment procedures.
3Device complexity
If conventional imaging methods are used, then the system configuration is simple, but the system cannot provide accurate distance measurement for surfaces with large eccentricity
Solution Approach 1:
The asymmetrical index chart serves as a reference object that, when imaged, produces an asymmetric pattern that directly indicates the eccentricity of the target surface. By analyzing the asymmetry in the captured image, the system can calculate the magnitude and direction of surface deviation without requiring complex additional sensors or alignment mechanisms.
Solution Approach 2:
The interferometer acts as an intermediary that transforms the physical position and eccentricity of the target surface into optical interference patterns. These patterns can be captured by a standard image sensor and processed to extract precise measurement data, effectively bridging the gap between simple imaging capability and high-precision measurement requirement.
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
Enables precise measurement of surface distances in optical systems with large eccentricity by using asymmetrical index charts and interferometry, allowing for accurate alignment and distance calculation even when surfaces are significantly decentered.
Implementation Method 1
an interferometer including a second light source, and configured to divide light from the second light source into target light and reference light, and to acquire an interference signal by causing the reference light and the target light that has been emitted from a first point, reflected on the plurality of target surfaces, and incident on a second point via the measurement optical system to interfere with each other
Implementation Method 2
a measurement optical system including an objective lens and configured to cause index light emitted from the chart to enter a target optical system
Data Source
AI summary
An acquiring apparatus includes a first light source, a measurement optical system, an image sensor, an adjusting unit, an interferometer, and a calculating unit configured to calculate a distance between adjacent target surfaces among the plurality of target surfaces based on an interference signal. The index surface, a surface containing the first point, a surface containing the second point, and the light receiving surface have a conjugate relationship with each other with respect to the measurement optical system.