Corrector Diffractive Optical Element for Telescope Chromatic Aberration
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Solution Overview
Problem
Large aperture, space-based telescopes with transmissive diffractive optics face challenges in correcting chromatic aberrations efficiently due to the need for significant processing power and large corrective optics, which are undesirable in terms of size and mass.
Innovation Solution
A system incorporating a diffractive primary optical element and a corrector diffractive optical element in the form of a blaze type multiple order diffraction grating, configured to receive light at a high incidence angle and reflect it at a high exit angle, allowing for chromatic correction across multiple diffraction orders with a smaller and lighter corrector optic, utilizing an aft optical assembly with convex and concave mirrors in a cylindrical Littrow configuration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of stationary object
If a transmissive diffractive optic is used as the primary collecting element, then mass efficiency and stowed size are improved, but chromatic aberrations are introduced that require correction
Solution Approach 1:
A corrector diffractive optical element is introduced as an intermediary component between the primary diffractive optic and the detector. This corrector element specifically addresses the chromatic aberrations introduced by the primary element, enabling the system to achieve both mass efficiency and reliable broadband imaging capability
Solution Approach 2:
The corrector diffractive optical element operates at high incidence angles (e.g., 30-60 degrees) rather than near-normal incidence, fundamentally changing the operational parameters to achieve chromatic correction with a smaller, lighter element while maintaining broadband performance
2Reliability
If digital processing of data from multiple detectors is used to correct chromatic effects, then chromatic correction is achieved, but processing power requirements and detector noise increase
Solution Approach 1:
The patent replaces digital signal processing methods with an optical solution using a corrector diffractive optical element. This substitutes computational correction with physical optical correction, eliminating the need for significant processing power while achieving the same chromatic correction goal
Solution Approach 2:
The optical system performs chromatic correction automatically through the physical properties of the corrector diffractive optical element, without requiring external processing or additional detectors. The system corrects itself optically rather than requiring computational intervention
3Ease of manufacture
If a corrector diffractive optical element is designed with small angle of incidence, then manufacturing is simplified, but the size and mass of the corrector element increase
Solution Approach 1:
The patent changes the operational parameter from small angle of incidence to high angle of incidence (30-60 degrees). This parameter change enables the corrector element to achieve the required chromatic correction power in a more compact form factor, reducing both size and mass while remaining manufacturable
4Adaptability or versatility
If a corrector diffractive optical element is designed with large exit angle, then chromatic correction bandwidth is improved, but the size of the corrector element increases
Solution Approach 1:
By operating at high incidence angles and utilizing the specific diffraction geometry, the system achieves large effective exit angles and broad chromatic correction bandwidth without requiring a physically large corrector element. The high-angle operation enables more efficient use of the diffractive structure
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 effectively corrects chromatic aberrations while minimizing the size and mass of the corrective optic, providing greater bandwidth and reducing processing power requirements, thus enabling efficient broad-band imaging in space-based telescopes.
Implementation Method 1
the dispersion of light wavelengths (i.e. chromatic aberrations) by the diffractive primary optical element
Implementation Method 2
The corrector diffractive optical element may be in the form of a blaze type multiple order diffraction grating that produces multiple diffraction orders
Implementation Method 3
The corrector diffractive optical element is configured to receive light at a high incidence angle, and to reflect and diffract at least some of the received light at a high exit angle
Implementation Method 4
a first convex mirror that is configured to reflect light diffracted by the primary optical element to a first concave mirror. The first concave mirror can, in turn, reflect light to the corrector diffractive optical element
Data Source
AI summary
Methods and systems for correcting chromatic aberrations in a telescope incorporating a diffractive primary optical element are provided. In particular, a corrective optic assembly that includes a corrector diffractive optical element (DOE) is described. The corrective optic assembly provides light to the corrector DOE at a high incidence angle. Moreover, light is reflected from the corrector DOE at a high exit angle comprising a cylindrical Littrow configuration allowing for greater bandwidth and smaller size.