White light diffraction tomography of unlabeled live cells
Methods for obtaining a tomographic phase image of a specimen, either in transmission or in scatter. A specimen is illuminated by a temporally incoherent source and light collected in transmission or scattering is used to generate a scattered phase image of the specimen in multiple axial planes. The scattered field is solved for in wavevector space, and a derived instrument function is deconvolved to obtain specimen susceptibility in wavevector space. The specimen susceptibility is transformed to obtain a three-dimensional phase tomogram of the specimen.
1. A method for obtaining a tomographic phase image of a specimen, the method comprising:
a. illuminating the specimen with substantially temporally incoherent light through an objective of high-numerical aperture, the temporally incoherent light characterized by a focus;
b. stepping the focus of the temporally incoherent light to a sequence of successive focal planes within the specimen;
c. forming a scattered phase image of the specimen in an image plane where the scattered phase image of the specimen corresponds to each of the successive focal planes;
d. solving for the scattered field in wavevector space;
e. deconvolving a derived instrument function to obtain specimen susceptibility in wavevector space; and
f. transforming the specimen susceptibility to derive a three-dimensional phase tomogram of the specimen.
2. A method in accordance with claim 1 , wherein the specimen is substantially transparent in a visible portion of the electromagnetic spectrum.
3. A method in accordance with claim 1 , wherein the specimen is opaque in a visible portion of the electromagnetic spectrum.
4. A method in accordance with claim 1 , wherein the specimen is substantially transparent in an infrared portion of the electromagnetic spectrum.
5. A method in accordance with claim 1 , wherein forming a scattered phase image of the specimen in an image plane corresponds to measuring a temporal cross-correlation function between a scattered field and a reference plane wave.
6. A method in accordance with claim 5 , wherein the reference plane wave traverses the specimen.
7. A method in accordance with claim 1 , wherein the specimen is a biological cell.
8. A method in accordance with claim 1 , wherein forming a scattered phase image includes combining a plurality of interferograms obtained with distinct phase retardation rings.
9. A method in accordance with claim 1 , wherein forming a phase image includes obtaining a single interferogram from an off-axis type interferometer.
10. A method in accordance with claim 9 , wherein the off-axis type interferometer is a diffraction phase microscope.