Simple high efficiency optical coherence domain reflectometer design

A method for performing optical coherence domain reflectometry comprising the steps of:

• a. guiding light from a light source through a polarizing beam splitter and a non-polarizing beam splitter and splitting the light into a sample arm leading to a sample, and a reference arm leading to a reflector;
• b. combining the light waves returned from the sample arm and reference arm and guiding said light waves back to said polarizing beam splitter;
• c. rotating the polarization direction of the returned light waves to an orthogonal direction prior to reentering the polarizing beam splitter;
• and
• d. at said polarizing beam splitter, channeling said combined and returned light waves having an orthogonal polarization direction to a detector arm for interference signal extraction and processing.

An optical coherence domain reflectometry (OCDR) system comprising:

• a. a source arm with a light source;
• b. a polarizing beam splitter (PBS) having an input port optically connected to said source and three output ports;
• c. a sample arm leading to a sample, and optically connected to a first output port of said polarizing beam splitter;
• d. a reference arm leading to a reflector, and optically connected to a second output port of said polarizing beam splitter;
• e. a polarization manipulator for rotating the polarization of light waves returning from the sample and reference arms to an orthogonal direction, said polarization manipulator being defined by two elements, one each in said sample arm and reference arm respectively;
• f. a detector collecting light combined by said polarizing beam splitter, returned from said sample and reference arms in an orthogonal polarization state, and directed through a third output port of said polarizing beam splitter to a detector arm for interference signal detection and processing;
• and
• g. a polarizer located in said detector arm prior to said detector and azimuthally oriented to extract an interference signal from the orthogonally polarized light from said sample and reference arms.

A method for performing optical coherence domain reflectometry comprising the steps of:

• a. guiding light from a light source through a polarizing beam splitter and splitting light into a sample arm leading to a sample, and a reference arm leading to a reflector;
• b. rotating the polarization direction of the returned light waves from said sample and reference reflector to an orthogonal direction prior to reentering the polarizing beam splitter;
• c. at said polarizing beam splitter, combining the light waves returned from the sample arm and reference arm, and channeling said combined and returned light waves having an orthogonal polarization direction to a detector arm for interference signal extraction and processing;
• and;
• d. in said detector arm, passing the combined light waves through a polarizer which is azimuthally oriented in a manner to extract an interference signal from the orthogonally polarized light from said sample and reference arms.

An apparatus for performing optical coherence domain reflectometry on a sample comprising:

• a light source for generating a light beam;
• a path splitter for dividing the beam into a first portion that travels along a sample path and a second portion that travels along a reference path, with the portions of said beam traveling down and back along said paths and then being recombined at said path splitter;
• at least one detector for measuring the recombined beam and generating output signals that correspond to an interferometric response;
• a polarizing beam splitter, said polarizing beam splitter being either functionally combined with the path splitter or being independent of the path splitter and located in the path of the light beam between the light source and the path splitter;
• at least one polarization rotating element for rotating the polarization of the light beam after first passing through the polarizing beam splitter in a manner such that when the recombined beam returns to said polarizing beam splitter, the recombined beam will be redirected away from said light source and to the at least one detector;
• and
• a processor for evaluating the sample based on the output signals generated by the detector.

A method for performing optical coherence domain reflectometry on a sample comprising the steps of:

• a) generating a light beam;
• b) polarizing the beam;
• c) splitting the beam using a non-polarizing beam splitter into a first portion that travels along a sample path and a second portion that travels along a reference path, with the portions of said beam traveling down and back along said paths and then being recombined;
• d) rotating the polarization of the light portions returning from the sample and reference paths;
• e) redirecting the combined beam along a measurement path using a polarizing beam splitter separate from the non-polarizing beam splitter and wherein the non-polarizing beam splitter is located downstream from said polarizing beam splitter;
• f) measuring the recombined beam and generating output signals that correspond to an interferometric response;
• and
• g) evaluating the sample based on the generated output signals.