Speckle reduction in optical coherence tomography by path length encoded angular compounding

An apparatus for irradiating a sample, comprising:

• a) an interferometer forwarding an electromagnetic radiation;
• and
• b) a sample arm receiving the electromagnetic radiation, the sample arm including an arrangement which is configured to produce at least two radiations from the electromagnetic radiation so as to irradiate the sample, and to delay a first radiation of the at least two radiations with respect to a second radiation of the at least two radiations, wherein the arrangement has at least one of:
• first optical section with a refractive index of at least 1.5, the first section being structured to propagate the at least two radiations,
• a second section which has silicon, the second section being structured to propagate the at least two radiations.

A method for irradiating a sample, comprising:

• a. providing an electromagnetic radiation from an interferometer;
• b. in a sample arm, producing at least two radiations from the electromagnetic radiation so as to irradiate the sample, a first radiation of the at least two radiations being delayed with respect to a second radiation of the at least two radiations;
• c. providing a further electromagnetic radiation, wherein the interferometer receives the first, second and further radiations and forms a resultant signal based on the first, second and further radiations;
• and
• d. generating a first image based on the first radiation, a second image based on the resultant signal and a further image based on the first and second images,
• wherein the first and second images are different from one another, and
• wherein the further image has a signal to noise ratio that is improved according to the equation:
• SNR
• ACPE
• =
• (
• S
• OCT
• )
• var
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• S
• OCT
• ]
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• wherein SNRACPE is the signal to noise ratio, SOCT is an amplitude of a high-pass filtered OCT signal that is associated with the resultant signal, m is a thickness of the arrangement, ui is an amplitude of a demodulated OCT signal that is associated with the resultant signal at a spatial location, and N=2m−1.

An apparatus for imaging, comprising:

• a. a sample arm receiving an electromagnetic radiation, the sample arm including an arrangement which is configured to produce at least two radiations from the electromagnetic radiation so as to irradiate a sample, and to delay a first radiation of the at least two radiations with respect to a second radiation of the at least two radiations;
• b. a device receiving the first and second radiations from the sample arm and at least one third radiation from a reference arm, wherein the first and second radiations interfere with the third radiation;
• c. at least one spectral separating arrangement which cooperates with the sample arm, and separates spectrum of at least one of the first, second and third radiations into frequency components;
• and
• d. at least one detection arrangement including a plurality of detectors, each detector capable of detecting at least a portion of at least one of the frequency components;
• e. a reference arm providing a further electromagnetic radiation, wherein the interferometer receives the first, second and further radiations, and forms a resultant signal based on the first, second and further radiations;
• and
• f. a processing arrangement generating a first image based on the first radiation, a second image based on the resultant signal and a further image based on the first and second images,
• wherein the first and second images are different from one another, and
• wherein the further image has a signal to noise ratio that is improved according to the equation:
• SNR
• ACPE
• =
• (
• S
• OCT
• )
• var
• ⁡
• [
• S
• OCT
• ]
• ⁢
• ∝
• ∑
• i
• =
• 1
• N
• ⁢
• ⁢
• u
• i
• ∑
• i
• =
• 1
• N
• ⁢
• ⁢
• u
• i
• 2
• ,
• wherein SNRACPE is the signal to noise ratio, SOCT is an amplitude of a high-pass filtered OCT signal that is associated with the resultant signal, m is a thickness of the arrangement, ui is an amplitude of a demodulated OCT signal that is associated with the resultant signal at a spatial location, and N=2m−1.

An apparatus for obtaining information associated with a sample, comprising;

• a first arrangement configured to separating at least one first electro-magnetic radiation into a first radiation and a second radiation forwarded to a sample, wherein the first and second radiations having different path lengths;
• a second arrangement configured to received third and fourth radiations from the sample associated with the first and second radiations and a fifth radiation received from a reference, and generate at least one interference signal as a function of the third, fourth and fifth radiations;
• a third arrangement configured to generate:
• first data associated with the third radiation which includes a first speckle pattern and second data associated with the fourth radiation which includes a second speckle pattern, and
• third data associated with the sample based on the first and second data that has a speckle pattern the amount of which is smaller that the amount of at least one of the first speckle pattern or the first speckle pattern.

An apparatus for obtaining information associated with a sample, comprising;

• a first arrangement configured to separating at least one first electro-magnetic radiation into a first radiation and a second radiation forwarded to a sample, wherein the first and second radiations having different path lengths;
• a second arrangement configured to received third and fourth radiations from the sample associated with the first and second radiations and a fifth radiation received from a reference, and generate at least one interference information as a function of the third, fourth and fifth radiations;
• and
• a third arrangement configured to generate data corresponding to an amount of a ranging depth within the sample associated with the second arrangement, wherein a difference between the path lengths of the first and second radiations is equal or greater than the ranging depth.