Fizeau Interferometer Calibration for Measurement Precision
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Fizeau type interferometers are prone to errors due to external factors like air fluctuations and variations in manufacturing and assembly, affecting measurement accuracy.
Innovation Solution
An optical system with a polarized light phase shift optical circuit and an information processing device that splits light into normal and delay paths, using image capture elements to detect and calibrate the intensities of divided light beams, and identifies phase values to correct for optical path differences, thereby reducing errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a Fizeau type interferometer is used to measure surface shape, then measurement capability is provided, but measurement precision deteriorates due to errors from air fluctuation, vibration, and manufacturing variations
Solution Approach 1:
The patent applies preliminary action by performing calibration measurements before actual surface shape measurements. The calibration process uses a reference plate to establish baseline optical characteristics and phase values, which are then used to correct subsequent measurements. This preliminary calibration step compensates for systematic errors from manufacturing variations and assembly misalignments, improving measurement precision while maintaining system reliability.
Solution Approach 2:
The patent implements feedback through an iterative calibration and measurement process. The system measures interference patterns, calculates phase values, compares them against calibration data, and applies corrections to improve measurement accuracy. This closed-loop feedback mechanism continuously reduces the influence of environmental factors like air fluctuation and vibration on measurement results.
2Measurement precision
If calibration parameters are identified for each image capture element, then measurement accuracy improves, but device complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the calibration process into individual elements. Each image capture element (pixel or sensor element) receives its own set of calibration parameters including phase values and intensity normalization factors. This element-by-element calibration approach enables precise correction of local variations across the detector array, improving overall measurement accuracy despite the increased computational complexity.
Solution Approach 2:
The patent uses parameter changes by adjusting and optimizing multiple calibration parameters for each image capture element. These parameters include phase offsets, intensity scaling factors, and interference pattern characteristics. By systematically varying and calibrating these parameters during the initial reference plate measurement, the system achieves high measurement accuracy without requiring complex hardware modifications.
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 calibrating optical characteristics and correcting phase differences, leading to improved precision in determining the shape of measured objects.
Implementation Method 1
a polarizing beam splitter that splits light having a coherence length shorter than a difference in optical path length between a normal optical path and a delay optical path
Implementation Method 2
a separator where the normal light and the delay light are individually emitted at a reference flat and the separator divides the reflected light that reflects off the reference flat into a plurality of light beams
Implementation Method 3
a plurality of image capture elements that respectively detect the intensities of the plurality of divided light beams
Implementation Method 4
two beams of reflected light from the parallel light reflecting off a reference surface of the reference plate and a test surface of the test object are leveraged to create interference fringes having equal thicknesses
Data Source
AI summary
An optical system includes a polarized light phase shift optical circuit that includes a polarizing beam splitter that splits light having a coherence length shorter than a difference in optical path length between a normal optical path and a delay optical path having an optical path length longer than the normal optical path, the light being split into normal light, which travels along the normal optical path, and delay light, which travels along the delay optical path; a separator where the normal light and the delay light are individually emitted at a reference flat and the separator divides the reflected light that reflects off the reference flat into a plurality of light beams; and a plurality of image capture elements that respectively detect the intensities of the plurality of divided light beams, and the optical system also includes an information processor that includes a calibrator.