Multi-channel low coherence interferometer
A multi-channel low coherence interferometer having sensing and reference arms, at least one of which has variable delay. The sensing arm includes an optical switch for connecting to two or more probe arms. The distal ends of the probe arms collect source light backscattered from a sample. The backscattered light collected by the distal end of a probe arm is combined with reference light and a low coherence interferometric signal is produced by a sweep of a variable delay of the device or a sweep of a variable frequency laser light source. The interference signal produced by the interaction of reference and sensing light at a detector measures backscattered light, which may be used to characterize the sample. The low coherence interferometric signals can provide information about the morphology, physical nature, composition, and properties of the sample. The device may be used to discriminate between finished surfaces and corroded surfaces, healthy and diseased tissue, and can sample the material or tissue in two or more areas. Versions of the invention include devices that are interferometers and or autocorrelators.
1. A system for determining a characteristic of a sample, the system comprising:
a light source for providing a light;
a splitter receptive to said light from said light source to produce a sensing light portion and a reference light portion, said splitter having an asymmetrical ratio such that said sensing light portion is greater than said reference light portion;
a sensing light path comprising,
a light path configured to communicate said sensing light portion from said splitter and said sensing light portion reflected from the sample,
a plurality of probe light paths configured to direct said sensing light portion at the sample and to receive said sensing light portion reflected from the sample, and
an optical switch selectable to define communication between said light path and a selected at least one of said probe light paths;
a reflecting device;
a reference light path configured to communicate said reference light portion from said splitter, said reference light path further configured to direct said reference light portion at said reflecting device and to receive said reference light portion reflected from said reflecting device;
means for generating an interference condition between said sensing light portion reflected from the sample and said reference light portion reflected from said reflecting device;
a detector receptive to said sensing light portion reflected from the sample and said reference light portion reflected from said reflecting device, said detector generating a signal indicative of an interference of said sensing light portion reflected from the sample and said reference light portion reflected from said reflecting device; and
processing means configured to determine a characteristic of the sample from said signal indicative of said interference of said sensing light portion reflected from the sample and said reference light portion reflected from said reflecting device.
2. The system of claim 1 wherein said asymmetrical ratio is about x:100−x, where 100−x represents a relative amount of said sensing light portion and x represents a relative amount of said reference light portion in said asymmetrical ratio.
3. The system of claim 1 wherein said optical switch is digitally selectable.
4. The system of claim 1 wherein the sample comprises a biological sample.
5. The system of claim 1 wherein said probe light paths are configured as a catheter.
6. A method for determining a characteristic of a sample, the method comprising:
asymmetrically splitting a light from a light source into a sensing light portion and a reference light portion, said sensing light portion being greater than said reference light portion;
selecting a probe light path from a plurality of probe light paths, said probe light paths forming a portion of a sensing light path;
directing said sensing light portion by means of said sensing light path, including the selected at least one of said probe light paths, at the sample;
receiving said sensing light portion reflected from the sample by means of said sensing light path, including the selected at least one of said probe light paths;
directing said reference light portion by means of a reference light path at a reflecting device;
receiving said reference light portion reflected from said reflecting device by means of said reference light path;
generating an interference condition between said sensing light portion reflected from the sample and said reference light portion reflected from said reflecting device;
detecting said sensing light portion reflected from the sample and said reference light portion reflected from said reflecting device, to generate a signal indicative of an interference of said sensing light portion reflected from the sample and said reference light portion reflected from said reflecting device; and
determining a characteristic of the sample from said signal indicative of said interference of said sensing light portion reflected from the sample and said reference light portion reflected from said reflecting device.
7. The method of claim 6 wherein said light comprises a broadband light.
8. The method of claim 6 wherein said light comprises laser lights.
9. The method of claim 6 wherein the sample comprises a biological sample.