Single trace multi-channel low coherence interferometric sensor
Interferometers and autocorrelator based sensors are disclosed that are configured to have multiple sample arms which can be scanned and the backscattered low coherence source light from a sample resolved in a single sweep of one or more variable delays of the sensor. Borescopes and catheters capable of scanning multiple sections or areas of materials and tissues using these sensors are described.
1. A sensor comprising:
at least one light source:
two or more sample arms, each sample arm having a different pathlength coupled to the at least one light source, wherein light from the at least one light source is propagated through the two or more sample arms to a sample and backscattered light is collected from the sample and propagated back through the two or more sample arms;
one or more reference arms, each having an adjustable delay to the at one light source, wherein light from the light source is propagated through the one or more reference arms and reflected back to through the one or more reference arms to make reference light and wherein each adjustable delay is capable of modifying the pathlength of a reference arm to match the pathlength of each of the two or more sample arms;
a coupler configured to combine backscattered light from the two or more sample arms and reference light from the one or more reference arms to produce an interference signal; and
a detector coupled to the coupler that detects the interference signal and produces an output signal; and
a processor coupled to the detector that resolves the output signals from the detector in a single trace wherein a single trace represents a sweep of the adjustable delay of the one or more reference arms and includes resolved interferometric signals for each of the two or more sample arms.
2. The sensor of claim 1 , wherein each of the two or more sample arms include a variable delay.
3. The sensor of claim 1 , wherein the at least one light source is a low coherence light source.
4. The sensor of claim 1 , wherein the processor produces an output proportional to the interference between the backscattered light and reference arm light for each of the two or more sample arms.
5. The sensor of claim 1 , further comprising a housing covering at least a portion of the two or more sample arms and bringing the two or more sample arms together.
6. The sensor of claim 5 , wherein the housing is a catheter.
7. The sensor of claim 5 , wherein the housing is a guidewire.
8. The sensor of claim 1 , further comprising an activating light source.
9. The sensor of claim 1 , further comprising a random time modulator coupled to the adjustable delays of the one or more reference arms to average out noise.
10. The sensor of claim 1 , wherein the adjustable delay modifies the pathlength of the reference arm by means selected from adjusting the physical length of the reference arm, adjusting the optical length of the reference arm, adjusting the refractive index of the reference arm, providing an optical delay and combinations thereof.
11. The sensor of claim 1 , wherein the adjustable delay is selected from a movable mirror, a piezoelectric stretcher and combinations thereof.
12. The sensor of claim 1 , further comprising one or more devices selected from splitters, couplers, circulators, reflectors, Faraday rotators, lenses, multiplexers and combinations thereof.
13. The sensor of claim 1 , configured to make radial scans of a cavity.
14. The sensor of claim 13 , wherein the cavity is an artery.
15. The sensor of claim 1 , further comprising an optical head that directs light from the two or more sample arms toward the sample.