Optical coherence tomography with new interferometer

An optical coherence tomography apparatus ("OCT") which examines an object, which OCT apparatus comprises:

• a source of short coherence radiation;
• a coupler which:
• (a) couples a first portion of the radiation to a reference arm;
• (b) couples a second portion of the radiation to a sample arm;
• (c) combines radiation transmitted thereto from the reference arm and the sample arm;
• and (d) couples the combined radiation to an analyzer;
• wherein:
• the reference arm transmits the first portion of the radiation to a measurement range variation apparatus and transmits radiation output from the measurement range variation apparatus back to the coupler;
• the sample arm transmits the second portion of the radiation to the object and transmits radiation scattered by the object back to the coupler;
• and
• the measurement range variation apparatus comprises:
• a beamsplitter which transmits a portion of the radiation incident thereupon in a direction from the reference arm to a first reflector;
• second and third reflectors disposed to reflect radiation incident thereupon along a second direction;
• and
• a scanner coupled to scan the first reflector.

A measurement range variation apparatus for use in a reference arm of an optical coherence tomography apparatus comprises:

• a transmitter which transmits a portion of radiation incident thereupon;
• a translator coupled to translate the transmitter;
• a reflector which reflects radiation transmitted by the transmitter, which transmitter reflects a portion of the reflected radiation;
• a scanner coupled to scan the reflector;
• and
• an encoder which measures the position of the transmitter.

A measurement range variation apparatus for use in a reference arm of an optical coherence tomography apparatus comprises:

• a beamsplitter which transmits a portion of radiation incident thereupon in a direction to a first reflector;
• second and third reflectors disposed to reflect radiation incident thereupon along a second direction;
• a scanner coupled to scan the first reflector;
• a translator coupled to translate the third reflector;
• and
• an encoder which measures the position of the third reflector.

A method for examining an object which comprises the steps of:

• generating short coherence radiation;
• coupling a first portion of the radiation into a reference arm and a second portion of the radiation into a sample arm;
• in the reference arm, transmitting the first portion of the radiation to a measurement range variation apparatus which comprises a transmitter which transmits a portion of the radiation incident thereupon;
• a reflector which reflects radiation transmitted by the transmitter, which transmitter reflects a portion of the reflected radiation;
• and a scanner coupled to scan the reflector;
• in the sample arm, transmitting the second portion of the radiation to the object;
• combining radiation scattered by the object with radiation obtained from the measurement range variation apparatus;
• and
• analyzing the combined radiation.

A method for examining an object which comprises the steps of:

• generating short coherence radiation;
• coupling a first portion of the radiation into a reference arm and a second portion of the radiation into a sample arm;
• in the reference arm, transmitting the first portion of the radiation to a measurement range variation apparatus which comprises a beamsplitter which transmits a portion of the radiation incident thereupon in a direction from the reference arm to a first reflector;
• second and third reflectors disposed to reflect radiation incident thereupon along a second direction;
• and a scanner coupled to scan the first reflector;
• in the sample arm, transmitting the second portion of the radiation to the object;
• combining radiation scattered by the object with radiation obtained from the measurement range variation apparatus;
• and
• analyzing the combined radiation.