Systems and methods for shaping wavefronts in polychromatic light using phase shifting elements
View Patent ↗A system for producing polychromatic light having selectively shaped wavefronts includes a source for generating light beams of at least two wavelengths (λ 1 , λ 2 ). The beams are made up of a plurality of contiguous sub-beams that establish λ 1 and λ 2 wavefronts. From the source, the light is directed toward an optical phase shifting device which can include one or more arrays, with each array having a plurality of elements. Functionally, within a particular array, each element is independently adjustable to selectively alter the optical pathlength of a corresponding sub-beam. For light having two wavelengths (λ 1 , λ 2 ), a first array configuration is used to reshape the λ 1 wavelength light and a second array configuration is used to reshape the λ 2 wavelength light. After wavefront reshaping, the λ 1 and λ 2 wavelength light is directed onto a common beam path where it can be viewed, imaged or further processed.
1. A system for active wavefront shaping, said system comprising an optical phase shifting device for operating on input light having at least two wavelengths (λ 1 , λ 2 ), said input light forming at least one beam, with each beam having a plurality of contiguous sub-beams, said sub-beams establishing a λ 1 wavefront and a λ 2 wavefront, said device having at least one array of elements, with each element being independently adjustable to selectively alter the optical pathlength of a respective sub-beam to sequentially effectuate a first wavefront reshaping of said λ 1 wavelength light and a second wavefront reshaping of said λ 2 wavelength light, with said first reshaping being different from said second reshaping, and wherein said device is configured to place the λ 1 wavelength light and λ 2 wavelength light on a common beam path.
2. A system as recited in claim 1 wherein λ 1 is blue light in the wavelength range 435-480 nm, λ 2 is red light in the wavelength range 605-750 nm, and said input light has light of wavelength λ 3 , wherein λ 3 is green light in the wavelength range 500-560 nm.
3. A system as recited in claim 1 wherein said input light includes sequential pulses of said λ 1 wavelength light and said λ 2 wavelength light.
4. A system as recited in claim 1 wherein a said input light is a single beam of light, said beam simultaneously including λ 1 wavelength light and λ 2 wavelength light and said system includes a splitter for separating said λ 1 wavelength light from said λ 2 wavelength light.
5. A system as recited in claim 4 wherein said splitter is a filter wheel.
6. A system as recited in claim 1 wherein said optical phase shifting device has a first array of elements for reshaping said λ 1 wavelength light and a second array of elements for reshaping said λ 2 wavelength light.
7. A system as recited in claim 1 further comprising a detector positioned on the common beam path to receive the λ 1 wavelength light and λ 2 wavelength light and wherein said detector is selected from the group of detectors consisting of an eyepiece, a camera and a display.
8. A system as recited in claim 1 further comprising a wavefront sensor for measuring a λ 1 wavefront to produce a sensor output, said sensor output for use in programming said optical phase shifting device to effectuate wavefront reshaping of said λ 1 wavelength light.
9. A system as recited in claim 8 wherein said sensor is a Hartmann-Shack sensor.
10. A system as recited in claim 1 wherein said array of elements is an active mirror having a plurality of individual facets with each facet being independently moveable along a respective substantially parallel path.
11. A system as recited in claim 1 wherein said device includes a foil mirror, and said array of elements is a plurality of actuators for selectively deforming said foil mirror.
12. A system as recited in claim 1 wherein said array of elements is a liquid crystal array.
13. A system for active wavefront shaping, said system comprising:
a source for generating an input light having at least two wavelengths (λ 1 , λ 2 );
a splitter for temporarily separating the input light into a first light beam having a first wavelength λ 1 , and a second light beam having a second wavelength λ 2 , with each beam having a plurality of contiguous sub-beams, said sub-beams establishing a λ 1 wavefront and a λ 2 wavefront;
an array of elements, with each element being independently adjustable to selectively alter the optical pathlength of a respective sub-beam; and
a controller for sequentially configuring said array to reshape the λ 1 wavefront and the λ 2 wavefront.
14. A system as recited in claim 13 wherein said source emits pulses of λ 1 wavelength light at a pulse rate of greater than 50 hertz.
15. A system as recited in claim 13 wherein said splitter is a filter wheel.
16. A system for active wavefront shaping, said system comprising:
a source for generating light having a first wavelength λ 1 , and a second wavelength λ 2 ;
a splitter for dividing said light into a first beam having λ 1 wavelength light and a second beam having λ 2 wavelength light, each said beam having a plurality of contiguous sub-beams with said sub-beams establishing a λ 1 wavefront for said first beam and a λ 2 wavefront for said second beam;
a first array of elements to reshape said first beam, each said element being independently adjustable to selectively alter the optical pathlength of a respective sub-beam in said first beam;
a second array of elements to reshape said second beam, each said element being independently adjustable to selectively alter the optical pathlength of a respective sub-beam in said second beam; and
an optical combiner for directing said reshaped λ 1 wavelength wavefront and said λ 2 wavelength wavefront onto a common exit beam path.
17. A system as recited in claim 16 wherein said first array of elements is selected from an element array consisting of an active mirror having a plurality of individual facets with each facet being independently moveable along a respective substantially parallel path, a foil mirror having a plurality of actuators for selectively deforming said foil mirror, and a liquid crystal array.
18. A method for active wavefront shaping, said method comprising the steps of:
providing an optical phase shifting device operable on input light of at least two wavelengths (λ 1 , λ 2 ), said input light forming at least one beam of light, with each beam having a plurality of contiguous sub-beams, said sub-beams establishing a λ 1 wavefront and a λ 2 wavefront;
sequentially presenting said sub-beam with λ 1 wavefront and said sub-beam with λ 2 wavefront to the optical phase shifting device;
independently adjusting the optical phase shifting device to selectively alter the optical pathlength of a respective sub-beam for
independently reshaping said λ 1 wavefront and said λ 2 wavefront; and
combining said λ 1 wavefront and said λ 2 wavefront on a common beam path.
19. A method as recited in claim 18 further comprising the steps of:
establishing a base datum for said elements, said base datum corresponding to a plane wavefront;
measuring an individual deviation in phase shift for each of said sub-beams relative to corresponding sub-beams in said plane wavefront; and
using said measured deviations to adjust each said element to selectively shape said λ 1 wavefront and said λ 2 wavefront.
20. A method as recited in claim 19 wherein a plurality of elements establish a region and said array includes at least one said region, and wherein said method further comprises the steps of:
identifying said region with an integer “n” wherein all of the sub-beams incident on said elements in said “n” region have a respective total phase shift, said total phase shift including said individual phase shift deviation and a same modular phase shift from said plane wavefront, said modular phase shift being equal to nλ 1 ; and
compensating for said modular phase shift during said measuring step by subtracting nλ 1 from each said total phase shift to obtain said individual phase shift deviation.
21. A method as recited in claim 20 further comprising the steps of:
detecting boundary elements in said region wherein all said boundary facets have an (n+1)λ 1 modular phase shift with a zero individual phase shift deviation;
identifying an “n+1” region adjacent said boundary elements and outside said “n” region wherein all of the sub-beams incident on said elements in said “n+1” region have a respective total phase shift, said total phase shift including said individual phase shift deviation and a same modular phase shift from said plane wavefront, said modular phase shift being equal to (n+1)λ 1 ; and
compensating for said modular phase shift during said measuring step by subtracting (n+1)λ 1 from each said total phase shift to obtain said individual phase shift deviation.
22. A method as recited in claim 20 further comprising the steps of:
detecting boundary elements in said region wherein all said boundary elements have an (n−1)λ 1 modular phase shift with a zero individual phase shift deviation;
identifying an “n−1” region adjacent said boundary elements and outside said “n” region wherein all of the sub-beams incident on said elements in said “n−1” region have a respective total phase shift, said total phase shift including said individual phase shift deviation and a same modular phase shift from said plane wavefront, said modular phase shift being equal to (n−1)λ 1 ; and
compensating for said modular phase shift during said measuring step by subtracting (n−1)λ 1 from each said total phase shift to obtain said individual phase shift deviation.