Three-Mirror Magnifying Imaging System with Intermediate Image
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Solution Overview
Problem
Existing magnifying imaging optical systems require high mirror quality, particularly for the last mirror, which is costly and challenging to produce due to stringent polishing requirements and cleanliness needs.
Innovation Solution
A magnifying imaging optical system with three mirrors, where the last mirror has a large transverse dimension ratio compared to its useful face and subaperture diameter, allowing for reduced production and operational quality demands, and featuring a concave/concave/convex mirror sequence that facilitates beam divergence and flexibility, along with an intermediate image for compact design and high light throughput.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the last mirror has a large useful face area to cover the image field, then the image quality is improved, but the manufacturing precision and cleanliness requirements increase significantly
Solution Approach 1:
The patent introduces a fourth dimension by placing an intermediate image plane within the optical path between the object and final image planes. This allows the beam path to fold back and illuminate different regions of the last mirror sequentially, effectively using a smaller physical mirror area to cover the required image field through temporal multiplexing of spatial regions.
Solution Approach 2:
The system employs dynamic beam steering using tiltable mirrors to redirect imaging beams across different field points. This dynamic redirection allows a single smaller mirror to serve multiple positions that would otherwise require a larger static mirror surface, reducing manufacturing precision requirements while maintaining full image field coverage.
2Measurement precision
If the useful face area of the last mirror is increased to reduce mixing of field point contributions, then the measurement precision is improved, but the device complexity and cost increase
Solution Approach 1:
By introducing the intermediate image plane as a fourth dimensional element in the optical path, the system enables sequential illumination of different mirror regions through beam folding. This maintains field point separation precision while using a compact mirror arrangement that reduces overall device complexity.
Solution Approach 2:
The optical path is segmented into multiple sequential segments using the intermediate image plane, allowing the beam to traverse different regions of the last mirror in sequence rather than simultaneously. This segmentation maintains measurement precision while enabling the use of smaller, less complex mirror components.
3Length of moving object
If the angle of incidence on the last mirror is increased to compact the beam path, then the device length is reduced, but the manufacturing precision requirements increase
Solution Approach 1:
The intermediate image plane enables the beam path to fold back through an additional spatial dimension, achieving compact device length through multiple small-angle reflections rather than requiring large-angle incidence that would demand higher mirror precision.
Solution Approach 2:
The system uses dynamically tiltable mirrors to control beam angles, allowing flexible adjustment of incidence angles to optimize device compactness while maintaining manufacturing feasibility through active beam steering rather than fixed high-precision mirror geometries.
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 reduces the complexity and cost of mirror production, enhances flexibility, and improves light throughput, making the system suitable for metrology and inspection applications with reduced requirements for mirror quality and cleanliness.
Implementation Method 1
A magnifying imaging optical system with three mirrors, where the last mirror has a large transverse dimension ratio compared to its useful face and subaperture diameter
Data Source
AI summary
A magnifying imaging optical system is disclosed that has precisely three mirrors, which image an object field in an object plane into an image field in an image plane. A ratio between a transverse dimension of the image field and a transverse dimension measured in the same direction of a useful face of the last mirror before the image field is greater than 3. In a further aspect, the magnifying imaging optical system is disclosed that has at least three mirrors, which image an object field in an object plane in an image field in an image plane. A first mirror in the beam path after the object field is concave, a second mirror is also concave and a third mirror is convex. An angle of incidence of imaging beams on the last mirror before the image field is less than 15°.