Super-resolution imaging of extended objects
Apparatus and methods for super-resolution imaging of extended objects utilize a scanned illumination source with a small spot size. Sub-images composed of highly-overlapping point spread functions are captured and each sub-image is iteratively compared to a series of brightness combinations of template point spread functions in a dictionary. The dictionary is composed of highly-overlapping point spread functions. Each sub-image is associated with a best-match template combination solution, and the best-match reconstructions created by best-match solutions are combined into a super-resolution image of the object.
1. The method of super-resolution imaging an extended object comprising the steps of:
(a) providing an illumination source configured to illuminate the object with an illumination spot having an illumination spot area at the object;
(b) scanning the illumination spot across the object;
(c) capturing a series of sub-images of the object wherein the sub-image detection region area substantially exceeds the illumination spot area;
(d) providing a dictionary of templates comprising PSFs;
(e) comparing each sub-image to combinations of highly-overlapping PSF templates from the dictionary, while varying intensities of individual PSF templates, to find a best-match solution for that sub-image; and
(f) creating a best-match reconstruction of each sub-image from the best-match solution for that sub-image.
2. The method of claim 1 further comprising the step of combining best-match reconstructions from step (f) to form a super-resolution image of the object.
3. The method of claim 1 wherein step (c) captures overlapping sub-images.
4. The method of claim 1 wherein step (e) utilizes a non-negative least-squares optimization algorithm.
5. The method of claim 1 further including the step of:
(b)(1) applying a phase adjustment to an imaging path prior to step (c); wherein the phase adjustment produces depth-encoded sub-images of the object having point spread functions (PSFs) which vary according to depth range.
6. The method of claim 5 further including the step of decoding depth range within sub-images based upon the phase adjustment.
7. The method of claim 6 further including the step of super-resolving axial information within sub-images based upon the phase adjustment.
8. The method of claim 1 wherein the object includes fluorescent photo-emitters excited by the illumination spot.
9. The method of claim 1 wherein the detection region area is approximately an order of magnitude greater than the illumination spot area.
10. Apparatus for generating a super-resolution image of an extended object comprising:
an illumination source configured to illuminate the object with an illumination spot having an illumination spot area at the object;
scanning apparatus configured to scan the illumination spot across the object;
a camera configured to capture a series of sub-images of the object wherein the area of the detected region substantially exceeds the area of the illumination spot; and
a processor configured to—
provide a dictionary of templates comprising PSFs,
compare each sub-image to combinations of highly-overlapping PSF templates from the dictionary to find a best-match solution for that sub-image, and
create a best-match reconstruction of sub-image from the best-match solution.
11. The apparatus of claim 10 wherein the processor is further configured to combine best-match reconstructions and form a super-resolution image of the object.
12. The apparatus of claim 10 further comprising a phase mask disposed in an imaging path, the phase mask configured to produce depth-encoded sub-images of the object having point spread functions (PSFs) which vary according to depth-range.
13. The apparatus of claim 12 wherein the processor is further configured to decode depth-range within sub-images.
14. The apparatus of claim 12 wherein the phase mask is a circular caustic.
15. The apparatus of claim 10 wherein the illumination spot is configured to excite fluorescent particles of the object.