All-Reflective Anastigmat Optics for Extended Elevation FOV
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Solution Overview
Problem
Conventional airborne sensor systems have limited elevation field of view (FOV) due to size and spectral bandwidth constraints, which restricts their infrared search and track (IRST) capabilities, and attempts to increase FOV using refractive optics result in severe limitations such as low transmission and high thermal sensitivity.
Innovation Solution
The use of an all-reflective four-mirror reimaging anastigmat for on-gimbal afocal foreoptics and an all-reflective five-mirror reimaging anastigmat for off-gimbal imaging optics, combined with a scanning coelostat mirror, to achieve an extended elevation FOV of at least 5 degrees while maintaining compatibility with existing pod-mounted packaging and spectral capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If refractive optics are used to increase elevation FOV, then the elevation field of view is extended, but spectral bandwidth is severely limited and transmission is reduced
Solution Approach 1:
The patent replaces refractive optical elements with reflective optical elements (mirrors). Specifically, it uses a five-mirror anastigmat system with all-reflective optics to achieve extended elevation FOV without the spectral limitations of refractive materials. The reflective surfaces eliminate chromatic aberration and enable operation across broad spectral ranges from visible to infrared wavelengths.
Solution Approach 2:
The patent changes the optical design parameters by transitioning from a conventional three-mirror anastigmat to a five-mirror anastigmat configuration. This parameter change enables the system to achieve an aperture-FOV product of 10-12 inch-degrees while maintaining full spectral bandwidth and avoiding the limitations of refractive optics.
2Reliability
If aperture-FOV product is extended to 10-12 inch-degrees, then IRST capability is improved, but device complexity increases
Solution Approach 1:
The patent segments the optical system into distinct functional modules: a five-mirror anastigmat for extended FOV imaging, a separate laser module for active illumination and ranging, and integrated detector arrays for multi-spectral detection. This segmentation allows each subsystem to be optimized independently while maintaining overall system performance.
Solution Approach 2:
The patent implements a multi-functional sensor system that combines passive infrared detection with active laser illumination and ranging capabilities in a single integrated platform. The five-mirror anastigmat serves multiple functions by providing extended FOV for both imaging and laser beam delivery, reducing the need for separate optical paths and simplifying the overall system architecture.
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 provides a significantly increased elevation FOV, achieving fast scanning over a wide field of regard with high transmission and low thermal sensitivity, while maintaining all spectral options and image quality, thus enhancing IRST and reconnaissance capabilities.
Implementation Method 1
an all-reflective, reimaging four-mirror anastigmat... configured to receive and collimate electromagnetic radiation to provide a collimated beam
Implementation Method 2
a scanning coelostat mirror configured to direct the electromagnetic radiation to the afocal foreoptics and to sweep a field of view of the imaging detector over a field of regard larger than the field of view
Data Source
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AI summary
An optical sensor system having an extended elevation field of view and in which the optics are configured around an all-reflective four-mirror reimaging anastigmat used for afocal foreoptics and an all-reflective five-mirror reimaging anastigmat used for imaging optics. One example of an optical sensor system includes afocal foreoptics configured to receive and collimate electromagnetic radiation, the afocal foreoptics including an all- reflective, reimaging four-mirror anastigmat, an imaging detector, focal imaging optics positioned between the afocal foreoptics and the imaging detector and configured to receive the collimated beam of electromagnetic radiation from the afocal foreoptics and to focus the beam of electromagnetic radiation onto the imaging detector, the focal imaging optics including a reimaging five-mirror anastigmat, wherein a field of view of the system is determined at least in part by a combination of the afocal foreoptics and the focal imaging optics and covers at least 5 degrees in elevation.