Apparatus and method for controlling ranging depth in optical frequency domain imaging
Exemplary embodiments of an apparatus are provided. For example, the exemplary apparatus can include at least one first arrangement providing at least one first electro-magnetic radiation to a sample, at least one second electro-magnetic radiation to a first reference and at least one third electro-magnetic radiation to a second reference. A frequency of radiation provided by the first arrangement generally varies over time. The exemplary apparatus may also include at least one second arrangement which is configured to detect a first interference between at least one fourth electro-magnetic radiation associated with the first electro-magnetic radiation and at least one fifth electro-magnetic radiation associated with the second radiation. The second arrangement is also configured to detect a second interference between at least one sixth electro-magnetic radiation associated with the first electro-magnetic radiation and at least one seventh electro-magnetic radiation associated with the third radiation.
1. An apparatus comprising:
a first arrangement providing a first electro-magnetic radiation to a sample, a second electro-magnetic radiation to a first reference path and a third electro-magnetic radiation to a second reference path, wherein a frequency of radiation provided by the first arrangement varies over time; and
a second arrangement configured to simultaneously detect:
(i) all depth points for a first interference which is between a fourth electro-magnetic radiation associated with the first electro-magnetic radiation and a fifth electro-magnetic radiation associated with the second radiation, and
(ii) all depth points for a second interference which is between the fourth electro-magnetic radiation and a sixth electro-magnetic radiation associated with the third radiation.
2. The apparatus according to claim 1 , wherein an optical path length of the first reference path is substantially different from an optical path length of the second reference path.
3. The apparatus according to claim 2 , wherein the difference between the optical path length of the first reference and the optical path length of the second reference path is more than 500 μm.
4. The apparatus according to claim 1 , wherein the first reference path has a further arrangement to shift a frequency of the second electro-magnetic radiation.
5. The apparatus according to claim 4 , wherein the second reference path has an additional arrangement to shift a frequency of the third electro-magnetic radiation.
6. The apparatus according to claim 4 , wherein a magnitude of the shift of the frequency of the second electro-magnetic radiation is different from a magnitude of the shift of the frequency of the third electro-magnetic radiation.
7. The apparatus according to claim 1 , wherein the first electro-magnetic radiation has a spectrum whose mean frequency changes substantially continuously over time at a tuning speed that is greater than 100 Tera Hertz per millisecond.
8. The apparatus according to claim 1 , wherein the fourth radiation is provided from a particular location of the sample.
9. The apparatus according to claim 1 , further comprising a third arrangement which is configured to generate a depth profile for at least one portion of the sample based on the first and second interferences.