Freeform Off-Axis Three-Mirror Optical System Compact Design
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Solution Overview
Problem
Conventional freeform surface off-axis three-mirror optical systems have larger volumes and less compact structures, limiting their application in high-tech imaging systems that require smaller and more compact designs while maintaining high performance.
Innovation Solution
A freeform surface off-axis three-mirror optical system is designed with a smaller volume and more compact structure by employing a specific configuration of mirrors and an aperture stop, utilizing sixth-order polynomial freeform surfaces for the mirrors and optimizing the optical path to achieve a smaller volume and improved imaging quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conventional freeform surface off-axis three-mirror optical system is designed, then the imaging quality can be maintained, but the volume and structural compactness deteriorate
Solution Approach 1:
The patent introduces freeform surfaces with sixth-order polynomial equations that operate in additional spatial dimensions, allowing the optical system to achieve compact folding of light paths. This enables the system to maintain imaging quality while reducing overall volume by utilizing non-traditional surface geometries that fold the optical path more efficiently within a smaller physical envelope.
Solution Approach 2:
The patent employs asymmetric freeform surfaces rather than symmetric conventional mirror surfaces. The sixth-order polynomial freeform surfaces allow asymmetric control of light reflection, enabling the optical system to achieve compact configuration while maintaining diffraction-limited imaging performance across the field of view.
2Volume of stationary object
If the optical system volume is reduced for compactness, then the structural complexity increases
Solution Approach 1:
The patent divides the optical system into three distinct mirror components, each with specific freeform surface characteristics defined by sixth-order polynomials. This segmentation allows each mirror to be optimized independently for its specific function while contributing to the overall compact configuration, managing structural complexity through modular design.
Solution Approach 2:
The patent utilizes parameter optimization of sixth-order polynomial coefficients for each freeform surface to achieve the desired compact configuration. By systematically adjusting these mathematical parameters, the system achieves minimal volume while maintaining imaging quality, transforming a complex design problem into a parameter optimization task.
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 significantly smaller volume and excellent imaging quality, with a modulation transfer function close to the diffraction limit and a small RMS wavefront error, making it suitable for applications like earth observation and multi-spectral thermal imaging.
Implementation Method 1
A light emitted from an object at infinity enters the freeform surface off-axis three-mirror optical system and reflects on the primary mirror to form a first reflected light beam
Implementation Method 2
The first reflected light beam irradiates and reflects on the secondary mirror to form a second reflected light beam
Implementation Method 3
The second reflected light beam irradiates on the tertiary mirror and reflects on the tertiary mirror to form a third reflected light beam
Data Source
AI summary
A freeform surface off-axis three-mirror optical system comprises a primary mirror, a secondary mirror, a tertiary mirror, an aperture stop located on the secondary mirror, and an image surface. An incident light beam emitted from an object irradiates and is reflected on the primary mirror to form a first reflected light beam. The first reflected light beam irradiates and is reflected on the secondary mirror to form a second reflected light beam. The second reflected light beam passes through the incident light beam, and then irradiates and is reflected on the tertiary mirror to form a third reflected light beam. The third reflected light beam passes through the incident light beam and does not pass through the secondary mirror, and finally reaches the image surface for imaging. A reflective surface of each of the primary mirror, the secondary mirror, and the tertiary mirror is an xy polynomial freeform surface.