Catoptric Imaging System Arc-Shaped Field Vignetting
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Imaging optical systems face challenges in designing small field radii without causing vignetting, especially when imaging arc-shaped object fields, which requires complex aspheric mirror surfaces and increases the difficulty in interferometric testing.
Innovation Solution
The optical system arranges pupil planes outside multiple pass-through regions between non-obscured mirrors, allowing for the design of mirrors with slight deviations from spherical surfaces, enabling the use of arc-shaped object fields without vignetting and reducing the need for high asphericities, while maintaining high numerical aperture and allowing for efficient separation of imaging ray bundles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the field radius is reduced to achieve compact system design, then the system size is reduced, but vignetting occurs between mirrors
Solution Approach 1:
The patent transitions from a conventional planar field layout to a three-dimensional arc-shaped field arrangement. By positioning the object field on an arc centered on the optical axis and utilizing multiple pass-through regions at different axial positions, the system achieves compact lateral dimensions while maintaining sufficient angular separation between mirrors to prevent vignetting. This dimensional reconfiguration allows the beam to traverse the same lateral region multiple times at different heights, effectively packing the optical path into a smaller volume.
Solution Approach 2:
The patent employs dynamic ray tracing and optimization to determine the precise mirror curvatures, positions, and orientations that enable multiple beam passes through the same region without vignetting. The optical design dynamically adjusts the beam path through careful selection of mirror parameters, allowing the system to achieve compact dimensions while maintaining full field illumination. The dynamic optimization process balances the competing requirements of small size and vignetting-free operation.
2Manufacturing precision
If high asphericities are used to correct image errors in small field radius systems, then image quality is improved, but manufacturing and testing difficulty increases
Solution Approach 1:
The patent changes the fundamental parameter of field geometry from a conventional rectangular or circular field to an arc-shaped field centered on the optical axis. This parameter change fundamentally alters the image error distribution, transforming complex high-order aberrations into lower-order errors that can be corrected with moderate asphericities. The arc-shaped field configuration naturally reduces the magnitude of required aspheric corrections, making mirrors manufacturable with standard precision techniques and testable with conventional interferometric methods.
3Ease of operation
If pupil planes are positioned in multiple pass-through regions, then optical path control is improved, but vignetting and ray bundle interference occur
Solution Approach 1:
The patent segments the optical system into distinct functional zones: object field region, multiple pass-through regions, intermediate image planes, and final image field region. By carefully positioning pupil planes in specific segments (avoiding them from coinciding with multiple pass-through regions), the system maintains optical path control while preventing vignetting. The segmentation allows independent optimization of each region, ensuring that pupil planes are located where they can effectively control the beam without interfering with the multiple pass-through geometry.
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 configuration enables the design of imaging optical systems with small field radii that avoid vignetting, facilitates image error correction, and simplifies interferometric testing by reducing the parent diameter of mirrors, while maintaining high numerical aperture and efficient ray separation.
Implementation Method 1
imaging rays in the light path between non-obscured mirrors of the imaging optical system pass several times through at least one multiple pass-through region
Data Source
AI summary
In certain aspects, imaging optical systems with a plurality of mirrors image an object field in an object plane into an image field in an image plane. In the light path between non-obscured mirrors, imaging rays pass through at least one multiple pass-through region between spaced-apart planes which are arranged parallel to the object plane and/or parallel to the image plane. The imaging optical systems have at least one pupil plane. The pupil plane is arranged outside the multiple pass-through region between the non-obscured mirrors. This can provide an imaging optical system which provides for an easier correction of image errors.