Fourier ptychographic retinal imaging methods and systems
Certain embodiments pertain to Fourier ptychographic retinal imaging methods and systems that focus on a retina of an eye to acquire a sequence of raw retinal images, construct a full-resolution, complex retinal image from the sequence of raw retinal image and correct the aberration in the full-resolution, complex retinal image to generate a substantially aberration-free retinal image.
1. A Fourier ptychographic retinal imaging method, the method comprising:
focusing on a retina of an eye, wherein focusing on the retina comprises moving one or both of the eye and a focusing lens to provide an optical path between the retina and the focusing lens that is approximately a sum of a focal length of the eye and a focal length of the focusing lens;
illuminating the eye with plane wave illumination;
acquiring, using one or more image sensors, a sequence of raw retinal images based on light reflected from the retina, wherein the sequence of raw retinal images is acquired while light reflected from the retina is passed by an aperture to the one or more image sensors as the aperture is sequentially shifted to different locations at the Fourier plane of an approximate plane of the retina, wherein the sequence of raw retinal images corresponds to regions in Fourier space;
after acquiring the raw retinal images, reconstructing a complex full resolution image of the retina with phase image data recovered by iteratively updating regions in Fourier space with data from the plurality of raw retinal images; and
correcting aberration in the reconstructed complex full resolution image of the retina to generate a substantially aberration-free, full resolution retinal image.
2. The Fourier ptychographic retinal imaging method of claim 1 , wherein correcting aberration comprises using an annealing procedure.
3. The Fourier ptychographic retinal imaging method of claim 1 , wherein illuminating the retina with plane wave comprises illuminating the retina with pulses of monochromatic light.
4. The Fourier ptychographic retinal imaging method of claim 3 , further comprising synchronizing the timing of the pulses of monochromatic light with sampling times for acquiring the sequence of raw retinal images and modulation of the apertures to different locations at the Fourier plane.
5. The Fourier ptychographic retinal imaging method of claim 3 , further comprising receiving control signals at an aperture modulator, the one or more image sensors and an illumination source, wherein the received control signals synchronize the timing of the pulses of monochromatic light from the illumination source with the exposure times for acquiring the sequence of raw retinal images by the one or more image sensors and with the locating of the apertures at different locations at the Fourier plane by the aperture modulator.
6. A Fourier ptychographic retinal imaging method, the method comprising:
receiving a sequence of raw retinal images of a retina of an eye from an imaging system, wherein the sequence of raw retinal images is acquired by one or more image sensors of the imaging system, wherein the sequence of raw retinal images is based on light reflected from the retina while an aperture modulator sequentially shifts an aperture to different locations at the Fourier plane of an approximate plane of the retina and while an illumination source provides plane wave illumination propagated to the eye through an optical system;
reconstructing a complex full resolution image of the retina with phase and amplitude image data recovered by iteratively updating regions in Fourier space with data from the plurality of raw retinal images; and
correcting aberration in the reconstructed complex full resolution image of the retina to generate a substantially aberration-free, full resolution retinal image.
7. The Fourier ptychographic retinal imaging method of claim 6 , wherein correcting aberration comprises executing instructions to use operations of an annealing process.
8. The Fourier ptychographic retinal imaging method of claim 7 , further comprising sending control signals to the imaging system, the aperture modulator, and the illumination source, wherein the control signals synchronize illumination provided by the illumination system with sampling times of the imaging system and with different locations of the aperture at the Fourier plane modulated by the aperture modulator.
9. A Fourier ptychographic retinal imaging system for imaging a retina of an eye, the system comprising:
an illumination source configured to provide plane wave illumination;
an aperture modulator configured to sequentially shift an aperture to different locations at the Fourier plane of an approximated plane of the retina;
an imaging system with one or more image sensors configured to acquire a sequence of raw retinal images based on light reflected from the retina;
an optical system for propagating the plane wave illumination to the eye and for propagating light reflected from the retina to the imaging system; and
a processor in communication with the imaging system to receive a signal with image data comprising the sequence of raw retinal images, the processor configured to execute instructions for reconstructing a complex full resolution image of the retina with phase and amplitude image data recovered by iteratively updating regions in Fourier space with data from the plurality of raw retinal images, wherein the processor is further configured to execute instructions for correcting aberration in the complex full resolution image to generate a substantially aberration-free, full resolution image of the retina.
10. The Fourier ptychographic retinal imaging system of claim 9 , wherein the illumination source is configured to provide pulses of plane wave illumination, wherein the pulses are synchronized with sampling times of the imaging system and time for modulating the aperture to different locations at the Fourier plane.
11. The Fourier ptychographic retinal imaging system of claim 10 , wherein the illumination source monochromatic light.
12. The Fourier ptychographic retinal imaging system of claim 9 , wherein the instructions for correcting aberration includes instructions for using an annealing procedure.
13. The Fourier ptychographic retinal imaging system of claim 9 , wherein the aperture modulator provides neighboring apertures that overlap by at least 60%.
14. The Fourier ptychographic retinal imaging system of claim 9 , wherein the aperture modulator provides neighboring apertures that overlap by at least 70%.
15. The Fourier ptychographic retinal imaging system of claim 9 , wherein the aperture modulator is a spatial light modulator configured to digitally address to shift the aperture to the different locations across the Fourier plane.
16. The Fourier ptychographic retinal imaging system of claim 9 , wherein the aperture modulator is a digital micromirror device.
17. The Fourier ptychographic retinal imaging system of claim 9 , wherein the imaging system is a high speed digital camera.
18. The Fourier ptychographic retinal imaging system of claim 9 , wherein the imaging system configured to acquire images in a range of about 200 frames per second to 500 frames per second.
19. The Fourier ptychographic retinal imaging system of claim 9 , wherein the optical system comprises a first polarizing beam splitter for reflecting plane wave illumination received from the illumination source toward the eye.
20. The Fourier ptychographic retinal imaging system of claim 9 , wherein the sequence of images acquired has a number in the range of 200 to 500, wherein the images are acquired in less than about 0.5 seconds.
21. The Fourier ptychographic retinal imaging system of claim 9 , wherein the sequence of images acquired has a number in the range of 200 to 500, wherein the images are acquired in less than about 1.0 second.