Off-axis Two-mirror Infrared Imaging System with Freeform Mirrors
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Solution Overview
Problem
Off-axis reflective optical systems used in infrared imaging face challenges in achieving a small F-number without increasing system size, which limits their compactness and efficiency for mid-to-long distance imaging.
Innovation Solution
The use of freeform surfaces for the primary and secondary reflecting mirrors in an off-axis two-mirror infrared imaging system, allowing for a compact design with a small F-number and high light input, enabling efficient medium and long-distance infrared imaging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the focal length is increased and F number is reduced for mid-to-long distance infrared imaging, then the imaging distance and resolution are improved, but the system size becomes too large
Solution Approach 1:
The patent employs an off-axis reflective optical system that breaks the rotational symmetry of conventional on-axis systems. By using asymmetric mirror arrangements (primary and secondary mirrors at different positions and orientations), the system achieves compact folding of the optical path, reducing the overall system volume while maintaining long focal length for mid-to-long distance imaging capability
Solution Approach 2:
The patent utilizes three-dimensional spatial arrangement of optical components, folding the optical path through multiple reflections between primary and secondary mirrors positioned in different spatial locations. This dimensional arrangement allows the optical path length (focal length) to be extended without proportionally increasing the system's linear dimensions, achieving compact size with long focal length
2Measurement precision
If freeform surfaces are used to correct off-axis aberrations, then the optical performance is improved, but the manufacturing complexity increases
Solution Approach 1:
The patent applies freeform surface technology to the primary and secondary mirrors, using mathematical surface descriptions with multiple parameters to define complex non-rotational symmetric shapes. These freeform surfaces enable precise correction of off-axis aberrations including coma and astigmatism, optimizing optical performance for wide-field infrared imaging
Solution Approach 2:
The freeform surfaces on the mirrors are specifically designed with asymmetric geometries that match the off-axis optical path configuration. This asymmetric surface design allows precise control of wavefront aberrations that cannot be corrected by conventional rotationally symmetric surfaces, achieving high optical performance in the off-axis reflective system
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 a compact and efficient infrared imaging solution with a small F-number, high light input, and improved image quality, suitable for applications like earth observation and unmanned driving.
Implementation Method 1
a primary reflecting mirror 102, a secondary reflecting mirror 104... The primary reflecting mirror 102 is located on the incident light path of the incident infrared light beam and reflects the incident infrared light beam to form a first reflected light beam
Implementation Method 2
The secondary reflecting mirror 104 is located on the reflected light path of the primary reflecting mirror 102 for reflecting the first reflected light beam, so that a second reflected light beam is formed
Data Source
AI summary
The present application relates to an off-axis two-mirror infrared imaging system including a primary reflecting mirror and a secondary reflecting mirror. The primary reflecting mirror is located on the incident light path of an incident infrared light beam and reflects the incident infrared light beam to form a first reflected light beam. The secondary reflecting mirror is located on the reflection light path of the primary reflecting mirror, and is used to reflect the first reflected light beam to form a second reflected light beam. The second reflected light beam reaches an image surface after passing through the incident infrared light beam. The reflective surfaces of the primary reflecting mirror and the secondary reflecting mirror are freeform surfaces. The secondary reflecting mirror and the image plane are respectively located on both sides of the incident infrared light beam.