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US 11,490,037 B2Granted
Liquid crystal fourier transform imaging spectrometer
AssigneePalo Alto Research Center Incorporated
InventorsAlex Hegyi, Joerg Martini
Life of this patent
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Abstract
A method of operating a hyperspectral imaging device includes connecting electrodes on a liquid crystal variable retarder to a voltage source, rotating liquid crystal material in the liquid crystal variable retarder between a first orientation with a certain optical phase delay and a second orientation with a different optical phase delay, receiving a beam of light at an image sensor that has passed through the liquid crystal variable retarder, and producing an output signal from the image sensor.
Claims19
A method of operating a device that includes an image sensor comprising:
- performing a hyperspectral imaging operation comprising:
- applying a pre-computed, dynamic driving voltage waveform to electrodes on a liquid crystal variable retarder, the pre-computed dynamic driving waveform monotonically changing an optical retardance of the liquid crystal variable retarder as a prescribed function of time, the pre-computed dynamic driving waveform causing transitions between target retardance states of the liquid crystal variable retarder to occur faster than a response time of the liquid crystal variable retarder;
- receiving a first beam of light that has passed through the liquid crystal variable retarder at a focal plane of the image sensor, the liquid crystal variable retarder positioned between a first polarizer and an output polarizer to define a hyperspectral imaging (HSI) component, the HSI component arranged at a conjugate focal plane that is linked to the focal plane of the image sensor by relay optics;
- producing a first electrical output signal from the image sensor in response to the first beam of light, the first electrical output signal representing a hyperspectral image;
- and
- switching operation of the device between the hyperspectral imaging operation and a non-hyperspectral imaging operation, the non-hyperspectral imaging operation comprising:
- receiving a second beam of light at the focal plane of the image sensor;
- and
- producing a second electrical output signal from the image sensor in response to the second beam of light, the second electrical output signal representing a non-hyperspectral image.
6 more elements
A device configured to switchably perform a hyperspectral imaging operation and a non-hyperspectral imaging operation, the device, comprising:
- a liquid crystal variable retarder;
- a retardance controller configured to apply a pre-computed, dynamic driving voltage waveform to electrodes on the liquid crystal variable retarder, the pre-computed dynamic driving waveform monotonically changing an optical retardance of the liquid crystal variable retarder as a prescribed function of time, the pre-computed dynamic driving waveform causing transitions between target retardance states of the liquid crystal variable retarder to occur faster than a response time of the liquid crystal variable retarder;
- an image sensor;
- and
- relay optics, the liquid crystal variable retarder positioned between a first polarizer and an output polarizer to define a hyperspectral imaging (HSI) component, the HSI component arranged at a conjugate focal plane that is linked to a focal plane of the image sensor by the relay optics,
- wherein the device is configured to switch operation between the hyperspectral imaging operation and the non-hyperspectral imaging operation such that:
- during the hyperspectral imaging operation, the image sensor is arranged to receive a first beam of light that has passed through the liquid crystal variable retarder at a focal plane of the image sensor and to produce a first electrical output signal in response to the first beam of light, the first electrical output signal representing a hyperspectral image;
- and
- during the non-hyperspectral imaging operation, the image sensor is configured to receive a second beam of light at the focal plane of the image sensor and to produce a second electrical output signal in response to the second beam of light, the second electrical output signal representing a non-hyperspectral image.
6 more elements
A device, comprising:
- a retardance controller configured to apply a driving voltage waveform to electrodes of a liquid crystal variable retarder;
- an image sensor;
- and
- relay optics,
- wherein the device is configured to accept an add-on module comprising a hyperspectral imaging (HSI) component that includes the liquid crystal variable retarder positioned between a first polarizer and an output polarizer, the HSI component arranged at a conjugate focal plane linked to a focal plane of the image sensor by the relay optics, and
- the device configured to switch operation between a hyperspectral imaging operation and a non-hyperspectral imaging operation such that:
- during the hyperspectral imaging operation, the image sensor is arranged to receive a first beam of light that has passed through the liquid crystal variable retarder at a focal plane of the image sensor and to produce a first electrical output signal in response to the first beam of light, the first electrical output signal representing a hyperspectral image;
- and
- during the non-hyperspectral imaging operation, the image sensor is configured to receive a second beam of light at the focal plane of the image sensor and to produce a second electrical output signal in response to the second beam of light, the second electrical output signal representing a non-hyperspectral image.
6 more elements
Dependencies are inferred from the claim text.