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US 2026/0309620 A1Published application
All-Reflective Optical Imaging Spectrometer with Flat Dispersive Element
OwnerJames Johnsoninventor
Life of this patent
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Abstract
A slit-based imaging spectrometer that comprises five freeform mirrors provides low keystone distortion and low smile distortion. The spectrometer can have an f-number no larger than 2.2, a slit length of up to 28 mm, and fit within a standard Cubesat volume of 4U or less. The spectrometer can be readily scaled for longer slit lengths and large focal plane array detectors.
Claims20
An imaging spectrometer comprising:
- an entrance slit through which radiation enters the imaging spectrometer;
- a first freeform mirror having positive focal power arranged to receive and reflect the radiation that passed through the entrance slit;
- a second freeform mirror having positive focal power arranged to receive and reflect the radiation that reflected from the first freeform mirror;
- a third freeform mirror having negative or positive focal power arranged to receive and reflect the radiation that reflected from the second freeform mirror;
- a fourth freeform mirror having positive focal power arranged to receive and reflect the radiation that reflected from the third freeform mirror;
- a fifth freeform mirror having positive focal power arranged to receive and reflect the radiation that reflected from the fourth freeform mirror;
- a spectrally-dispersive optic arranged to receive, reflect and spectrally disperse the radiation that reflected from the fifth freeform mirror, where radiation reflected from the spectrally-dispersive optic passes back through the imaging spectrometer sequentially reflecting from the fifth freeform mirror, the fourth freeform mirror, the third freeform mirror, the second freeform mirror, and the first freeform mirror;
- and
- a detector array arranged to receive the radiation that passed back through the imaging spectrometer and reflected from the first freeform mirror.
6 more elements
A method of forming a spectrally-dispersed image, the method comprising:
- receiving radiation through an entrance slit of an imaging spectrometer;
- reflecting the radiation that passed through the entrance slit from a first freeform mirror mounted in the imaging spectrometer, the first freeform mirror having positive focal power;
- reflecting the radiation that was reflected from the first freeform mirror from a second freeform mirror mounted in the imaging spectrometer, the second freeform mirror having positive focal power;
- reflecting the radiation that was reflected from the second freeform mirror from a third freeform mirror mounted in the imaging spectrometer, the third freeform mirror having negative or positive focal power;
- reflecting the radiation that was reflected from the third freeform mirror from a fourth freeform mirror mounted in the imaging spectrometer, the fourth freeform mirror having positive focal power;
- reflecting the radiation that was reflected from the fourth freeform mirror from a fifth freeform mirror mounted in the imaging spectrometer, the fifth freeform mirror having positive focal power;
- reflecting and spectrally dispersing the radiation that was reflected from the fifth freeform mirror from a spectrally-dispersive optic, the spectrally-dispersive optic mounted in the imaging spectrometer such that the radiation reflected and spectrally dispersed from the spectrally-dispersive optic passes back through the imaging spectrometer sequentially reflecting from the fifth freeform mirror, the fourth freeform mirror, the third freeform mirror, the second freeform mirror, and the first freeform mirror;
- and
- imaging, with a detector array, a spectrally-dispersed image formed from the radiation that passed back through the imaging spectrometer and is formed at an image plane of the imaging spectrometer.
6 more elements
Dependencies are inferred from the claim text.