Rectangular Aperture Stop Three-Mirror Anastigmat for Compact Remote Sensing
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Solution Overview
Problem
Current remote sensing systems face limitations in achieving improved object space resolution, such as ground sampled distance (GSD), without increasing system package size, particularly in multi-band systems like telescopes and airborne surveillance systems.
Innovation Solution
The use of a three-mirror anastigmat (TMA) optical device with a non-circular, rectangular aperture stop that maximizes light collection and reduces system size by eliminating optical distortions like spherical aberration and coma, allowing for increased GSD without increasing the overall system size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional circular aperture stop is used in a TMA system, then the optical path is simple and manufacturing is easier, but the light collection area is reduced and object space resolution is limited
Solution Approach 1:
The patent applies asymmetry by replacing the conventional circular aperture stop with a rectangular aperture stop in the TMA system. This rectangular aperture stop has a larger area than a circular aperture of equivalent dimension, thereby increasing the light collection area and improving object space resolution without increasing the overall system size. The rectangular geometry allows for more efficient packing of light rays across the optical path.
2Measurement precision
If the system package size is increased to improve object space resolution, then more light can be collected and resolution is improved, but the system becomes larger and less suitable for compact applications
Solution Approach 1:
The patent changes the geometric parameter of the aperture stop from circular to rectangular, which fundamentally alters the light collection characteristics. This parameter change allows the system to achieve improved object space resolution and increased light collection area within the same package size, effectively decoupling resolution improvement from system size increase.
3Area of stationary object
If a rectangular primary mirror is used to define the aperture stop, then the light collection area is maximized, but manufacturing precision requirements increase
Solution Approach 1:
The patent segments the optical system into distinct functional components: the rectangular primary mirror that defines the aperture stop, the TMA optical train that corrects aberrations, and the detector plane. This segmentation allows each component to be optimized independently, with the rectangular mirror specifically designed for maximum light collection while the TMA system handles the correction of geometric distortions that arise from the non-circular aperture.
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 enhances light collection area and GSD while maintaining or improving optical performance metrics like f-number and focal length, reducing the overall size, weight, and cost of the system, making it suitable for compact reconnaissance and surveillance applications.
Implementation Method 1
a concave primary mirror to collect and focus electromagnetic radiation
Implementation Method 2
a curved secondary mirror to reflect the electromagnetic radiation focused by the primary mirror
Implementation Method 3
a concave tertiary mirror to focus the electromagnetic radiation reflected by the secondary mirror
Data Source
AI summary
An off-axis optical system having a rectangular aperture stop to control rays of incident electromagnetic radiation passing through the optical system along an optical path is provided. The optical system includes one or more optical surfaces along the optical path, each surface being configured to change a direction of each ray on the surface based on a location of the ray relative to the surface. At least one of the surfaces is conjugate to and has the same shape as the rectangular aperture stop. In one embodiment, each optical surface is shaped to avoid vignetting the rays. In one embodiment, the optical system is a three-mirror anastigmat (TMA) and includes a concave primary mirror to collect and focus the electromagnetic radiation; a curved secondary mirror to reflect the electromagnetic radiation focused by the primary mirror; and a concave tertiary mirror to focus the electromagnetic radiation reflected by the secondary mirror.