Optical Wavefront Measuring Device for Aspheric Decentration
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Solution Overview
Problem
Current optical measurement methods, such as probe metrology and Fizeau interferometry with Computer Generated Hologram (CGH), face challenges like surface damage, high costs, and limited dynamic range when measuring aspheric optical surfaces, making it difficult to accurately assess decentration and aberrations in optics under test.
Innovation Solution
An optical wavefront measuring device and method utilizing a rotational spindle, light source module, and wavefront sensor with High Dynamic Range (HDR) imaging to capture camera frames at different exposures, analyzing wavefront phases and ray slopes at various azimuthal directions to determine aberrations and decentration, thereby overcoming alignment errors and limitations of traditional wavefront sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional Fizeau interferometry with CGH is used to measure aspheric optical surfaces, then measurement precision is improved, but device complexity and manufacturing cost increase due to custom CGH design and strict alignment requirements
Solution Approach 1:
The patent uses a standard wavefront sensor to capture and process intensity distribution images, creating a digital representation of the wavefront. Through iterative optimization algorithms, the system reconstructs the wavefront phase information without requiring physical CGH elements, thereby simplifying the measurement system while maintaining precision for aspheric surfaces
Solution Approach 2:
The patent replaces the mechanical/optical CGH alignment system with a computational approach. Instead of physically aligning CGH elements, the system uses image processing and iterative optimization algorithms to achieve wavefront reconstruction, eliminating complex mechanical alignment requirements while maintaining measurement precision
2Use of energy by moving object
If traditional wavefront sensor is used to measure aspheric aberration, then dynamic range is improved compared to interferometry, but measurement precision deteriorates due to limited dynamic range when measuring large aspheric aberrations
Solution Approach 1:
The patent divides the wavefront measurement into multiple intensity distribution images captured at different azimuthal directions. By segmenting the measurement process into multiple directional scans and combining the results through iterative optimization, the system extends the effective dynamic range while maintaining precision for large aspheric aberrations
Solution Approach 2:
The patent adds the azimuthal direction dimension to the measurement process. Instead of measuring only in the radial direction, the system captures intensity distributions at multiple azimuthal angles, effectively extending the measurement dynamic range by utilizing angular information while maintaining precision through iterative reconstruction
3Measurement precision
If probe metrology is used to measure optical surfaces, then measurement precision is improved for surface profile, but reliability deteriorates due to potential surface damage from contact measurement
Solution Approach 1:
The patent replaces contact-based probe metrology with non-contact optical measurement. By using wavefront sensing and intensity distribution analysis, the system achieves surface profile measurement precision without mechanical contact, thereby eliminating the risk of surface damage and improving measurement reliability
4Measurement precision
If CGH is used to assist measurement of aspheric optics, then measurement precision is improved, but productivity deteriorates due to time-consuming custom design and manufacturing processes
Solution Approach 1:
The patent uses standard, off-the-shelf wavefront sensors and optical components instead of custom-designed CGH elements. By copying the wavefront modulation function through computational algorithms rather than physical elements, the system achieves aspheric measurement precision using readily available components, dramatically improving productivity and reducing lead time
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 enables accurate measurement of aspheric wavefronts with non-uniform light intensity, reduces measurement errors, and provides a cost-effective solution for assessing optical aberrations without the need for custom CGH or null optics, improving measurement precision and flexibility.
Implementation Method 1
a wavefront sensor for acquiring one or more camera frames with different exposures when the optics under test at a plurality of azimuthal directions
Data Source
AI summary
A device and method for measuring the decentration of optics under test is provided. The device comprises a rotational spindle for loading and rotating the optics under test, a light source module for providing incident light beam to the optics under test, and a wavefront sensor for receiving testing light beams with different exposures from the optics under test at a plurality of azimuthal directions.