Optical coherence tomography with graded index fiber for biological imaging
A system for optical coherence tomography includes a source of optical radiation, an optical fiber, and a graded index fiber attached to a distal end of the optical fiber. The optical fiber and the graded index fiber are together configured to provide a common path for optical radiation reflected from a reference interface at a distal end of the graded index fiber and from a target.
1. A system for optical coherence tomography, comprising:
a source of optical radiation;
an elongate catheter body having a side-opening window therein;
an optical fiber extending within the elongate catheter body, the optical fiber having a core providing a common path for optical radiation reflected from a reference interface and a target;
a lens attached to a distal end of the optical fiber, the lens configured to focus optical radiation through the side-opening window to a focal point in the target, wherein a beam diameter at the focal point is between 10 and 60 microns;
receiving electronics configured to receive the optical radiation reflected from the reference interface and the target; and
a processor to generate an image of the target based upon the optical radiation received by the receiving electronics;
wherein the system is configured such that a secondary reflection of optical radiation from a secondary interface positioned between the optical fiber and the lens is less than −60 dB.
2. The system of claim 1 , wherein the diameter is between 20 and 40 microns.
3. The system of claim 1 , wherein the focal point is less than 1 mm from an outer edge of the elongate catheter body.
4. The system of claim 1 , wherein the reference interface is configured to provide a reference reflection of between −28 and −42 dB.
5. The system of claim 1 , further comprising an interface medium at the reference interface and in optical contact with the lens.
6. The system of claim 5 , wherein the interface medium is an adhesive.
7. The system of claim 1 , wherein the system is configured such that the receiving electronics operate in a total noise range that is within 5 dB of the shot noise limit.
8. The system of claim 1 , wherein the elongate catheter body further includes a cutter thereon.
9. The system of claim 1 , wherein the elongate catheter body is an atherectomy catheter.
10. The system of claim 1 , wherein the elongate catheter body is an occlusion crossing device.
11. The system of claim 1 , wherein the elongate catheter body includes a guidewire lumen.
12. The system of claim 1 , wherein the image has a resolution of 6-15 microns.
13. The system of claim 1 , further comprising a display configured to display the images generated by the processor.
14. The system of claim 1 , wherein the lens is a graded index lens.