Freeform Three-Mirror Imaging System with Movable Aperture
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Solution Overview
Problem
Conventional freeform surface off-axial three-mirror imaging systems are limited by a fixed working distance, which restricts their ability to maintain high-resolution imaging when the working distance is changed.
Innovation Solution
A freeform surface off-axial three-mirror imaging system with movable apertures and polynomial freeform surface mirrors, allowing for adjustable working distances and improved aberration correction, enabling high-resolution imaging across a range of distances from 125 mm to infinity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional freeform surface off-axial three-mirror imaging systems are designed for a certain distance object, then high-resolution imaging is achieved at that specific working distance, but the system cannot maintain high-resolution imaging when the working distance is changed
Solution Approach 1:
The patent implements a movable aperture stop that can be positioned at different locations along the optical path. By dynamically adjusting the aperture position between at least two distinct positions, the system adapts to different working distances (from 125 mm to infinity) while maintaining diffraction-limited imaging performance. This dynamic reconfiguration allows the same optical system to serve multiple working distance requirements without sacrificing image quality.
2Measurement precision
If freeform surfaces are used to reduce aberrations and simplify structure, then imaging quality is improved, but the system becomes complex when multiple aperture positions are added for adjustable working distance
Solution Approach 1:
The aperture stop serves multiple functions: it defines the entrance pupil for different working distances, acts as a field stop, and enables the system to switch between different imaging configurations. By making the aperture movable rather than fixed, a single component performs the work of what would otherwise require multiple dedicated aperture stops for different working distances, thereby reducing overall system complexity while maintaining versatility.
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
The system achieves high imaging quality and flexibility by maintaining diffraction-limited modulation transfer functions and low wave aberrations across varying working distances, ensuring high-resolution images regardless of the object distance.
Implementation Method 1
Feature rays exiting from a light source would be successively reflected by the primary mirror (102), the secondary mirror (104) and the tertiary mirror (106) to form an image on the detector (108)
Data Source
AI summary
A freeform surface off-axial three-mirror imaging system comprising a primary mirror, a secondary mirror, a tertiary mirror, and a detector. The secondary mirror defines a first location and a second location. Each reflective surface of the primary mirror, the secondary mirror and the tertiary mirror is an xy polynomial freeform surface. A working distance of the freeform surface off-axial three-mirror imaging system is greater than 125 mm.