Fizeau Lens Aspheric Compensation Interferometry
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Solution Overview
Problem
Conventional Fizeau interferometry systems face challenges in reducing parts count, size, and cost while maintaining measurement accuracy, particularly due to the complexity and high manufacturing costs of aspheric lenses, which require precise fabrication and validation, often necessitating a separate test fixture.
Innovation Solution
The use of a lens assembly with at least one aspheric surface within the Fizeau interferometer optics, combined with a removable reference plate for direct testing and validation of the aspheric surface, allowing for reduced parts count and simplified manufacturing without the need for a separate test fixture.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional complex optics designs with multiple lens elements are used to create a perfect spherical wavefront, then measurement accuracy is improved, but device complexity, parts count, size, weight, and cost increase
Solution Approach 1:
The complex multi-element lens system is segmented into a single aspheric lens element that incorporates multiple optical functions (collimation, focusing, wavefront shaping) into one component, reducing parts count while maintaining measurement accuracy
Solution Approach 2:
The patent employs an aspheric lens surface instead of conventional spherical surfaces to achieve perfect spherical wavefront generation with a single element, eliminating the need for multiple lens elements and complex alignment requirements
2Device complexity
If diffractive optical elements (DOE) are used to simplify lens design and reduce parts count, then device complexity is reduced, but manufacturing cost and design complexity increase
Solution Approach 1:
The patent uses a refractive aspheric lens surface that can be manufactured using conventional precision optical fabrication techniques, avoiding the high cost and complexity of DOE design and fabrication while achieving the same wavefront correction goals
3Device complexity
If aspheric lenses are used to reduce parts count and simplify design, then device complexity is reduced, but manufacturing precision requirements and validation complexity increase
Solution Approach 1:
The aspheric lens is designed to serve dual functions: it creates the spherical wavefront for measurement and simultaneously provides its own reference surface for validation, eliminating the need for separate test fixtures and simplifying the validation process
Solution Approach 2:
The aspheric lens incorporates multiple functions including wavefront generation, reference surface provision, and self-validation capability, reducing the need for additional components and simplifying both manufacturing and validation processes
4Measurement precision
If multiple lens elements are used to achieve proper light bending angles, then measurement accuracy is improved, but device size, weight, and cost increase
Solution Approach 1:
The patent consolidates multiple lens elements into a single aspheric lens that performs all necessary optical functions (collimation, focusing, angle adjustment) in one component, dramatically reducing weight while maintaining measurement accuracy
Solution Approach 2:
The aspheric surface geometry is specifically designed to bend light at the required angles and generate spherical wavefronts, replacing multiple spherical lens elements and reducing overall optics weight
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 reduces the complexity and cost of Fizeau interferometry optics by enabling direct testing and validation of aspheric surfaces within the interferometer itself, improving measurement accuracy and efficiency while minimizing additional hardware requirements.
Implementation Method 1
a lens assembly in the path of the incident light beam and comprising at least one lens element, wherein one of the at least one lens elements has an aspheric surface and wherein one of the at least one lens elements further provides the reference spherical surface
Implementation Method 2
a beamsplitter disposed to direct the incident light beam toward the sample spherical surface and to direct a test light reflected from the sample spherical surface and a reference light reflected from a reference spherical surface toward an interferometric imaging apparatus
Implementation Method 3
In interferometry, highly precise surface measurement is obtained for various types of optical components using interference fringes that are generated between light reflected from a reference surface and light from a surface under test
Data Source
AI summary
An imaging system for obtaining interferometric measurements from a sample spherical surface has a light source for providing an incident light beam, a beamsplitter disposed to direct the incident light beam toward the sample spherical surface and to direct a test light reflected from the sample spherical surface and a reference light reflected from a reference spherical surface toward an interferometric imaging apparatus. There is a lens assembly in the path of the incident light beam, with at least one lens element, wherein one of the at least one lens elements has an aspheric surface and wherein one of the at least one lens elements further provides the reference spherical surface facing the sample spherical surface. A reference plate is temporarily disposed in the path of the incident light beam for measuring the aspheric surface itself and is removable from the path of the incident light beam for obtaining interferometric measurements from the sample spherical surface.