Diffraction grating based interferometric systems and methods

An interferometer comprising:

• a first low coherence light source and a second low coherence light source, each emitting light at a different wavelength;
• a first beam splitter in communication with the first and second light sources to split the light from the light sources into a sample light beam to be directed onto a sample and a reference light beam, wherein a reflected sample light beam is received by the interferometer from the sample;
• a diffraction grating positioned to the reference light beam;
• a second beam splitter positioned to receive the reference light beam and the reflected sample light beam, the second beam splitter forming two combined light beams;
• a first detector positioned to receive one of the combined light beams;
• and
• a second detector positioned to receive the other of the combined light beams.

An interferometer comprising:

• a low coherence light source;
• a first, fiber optic beam splitter;
• a first optical fiber optically coupling the light source to the first beam splitter, wherein the first beam splitter splits light received from the light source into a sample light beam and a reference light beam;
• a second optical fiber to convey the sample light beam onto a sample and to convey a reflected sample light beam received from the sample to the first beam splitter;
• a second beam splitter;
• a third optical fiber optically coupling the first beam splitter to the second beam splitter to convey the reflected sample light beam, at least in part, from the first beam splitter to the second beam splitter;
• a diffraction grating;
• a fourth optical fiber optically coupling the first beam splitter to the diffraction grating to convey the reference light beam, at least in part, to the diffraction grating;
• wherein the second beam splitter is positioned to receive the diffracted reference light beam and the reference light beam and the reflected sample light beam are combined in the second beam splitter to form a combined light beam;
• and
• a detector positioned to receive the combined light beam.

An interferometer comprising:

• a low coherence light source;
• a first fiber optic beam splitter;
• a first optical fiber optically coupling the light source to the first beam splitter, wherein the first beam splitter splits light received from the light source into a sample light beam and a reference light beam;
• an optical circulator having a first port, a second port and a third port, wherein light input to the first port exits the optical circulator from the second port and light entering the second port exits the optical circulator from the third port;
• a second optical fiber optically coupling the first beam splitter to the first port of the optical circulator;
• a third optical fiber to convey the sample light beam to a sample and to convey a reflected sample light beam received from the sample to the first beam splitter,
• a second beam splitter;
• a fourth optical fiber optically coupling the third port of the optical circulator to the second beam splitter, wherein the third optical fiber conveys the reflected sample light beam, at least in part, from the third port to the second beam splitter;
• a diffraction grating;
• a fifth optical fiber optically coupling the first beam splitter to the diffraction grating to convey the reference light beam, at least in part, to the diffraction grating;
• the second beam splitter being positioned to receive the diffracted reference light beam from the diffraction grating, wherein the reference light beam and the reflected sample light beam combine in the beam splitter to form a combined light beam;
• and
• a detector positioned to receive the combined beam.

An interferometer comprising:

• a low coherence light source;
• a first beam splitter in communication with the light source to split light from the light source into a sample light beam to be directed onto a sample and a reference light beam wherein a second light beam is received by the interferometer from the sample;
• a second beam splitter for generating two combined light beams from the reflected sample light beam and the reference light beam, wherein an optical path difference has been introduced into at least one of the reflected sample light beam and the reference light beam;
• first and second detectors, each positioned to receive one of the combined light beams;
• first and second polarization filters, each filtering light with respect to a different polarization, the first polarizing filter being between the second beam splitter and the first detector and the second polarizing filter being between the second beam splitter and the second detector.

A method of imaging a sample material comprising the steps of:

• splitting a low coherence light beam into a sample light beam and a reference light beam;
• directing the sample light beam onto a sample and receiving a reflected sample light beam from the sample;
• diffracting the reference light beam
• after the diffracting step, combining the reflected sample light beam with the diffracted light beam by a beam splitter to form a combined light beam;
• and
• detecting the combined light beam with a detector.

An interferometer comprising:

• a low coherence light source;
• a first beam splitter in communication with the light source to split light from the light source into a sample light beam to be directed onto a sample and a reference light beam, wherein a reflected sample light beam is received by the interferometer from the sample;
• a diffraction grating positioned to diffract reflected sample light beam;
• a second beam splitter positioned to receive the reflected sample light beam and the reference light beam, wherein the reflected sample light beam and the diffracted reference light beam are combined in the second beam splitter to form a combined light beam;
• and
• a detector positioned to receive the combined light beam from the second beam splitter.