Full-field interferential imaging systems and methods

Patent metadata

Field	Value
Publication number	US-2019167109-A1
Application number	US-201716320982-A
Country	US
Kind code	A1
Filing date	Jul 25, 2017
Priority date	Jul 26, 2016
Publication date	Jun 6, 2019
Grant date	—

Abstract

A system for the full-field interferential imaging of a sample, includes an illumination path with a light source, an interferometer with at least one first objective, and a separating element for receiving incident light waves via an input face and for forming an object arm for receiving the sample and a reference arm on which a reflection device is arranged, the reflection device being used to reflect incident light waves in a direction different from the direction of incidence. The separator element has a reflection coefficient and a transmission coefficient that are non-equal such that the proportion of the optical power of the incident light waves sent to the object arm is strictly larger than the proportion of the optical power of the light waves sent to the reference arm. The system also comprises a detection path comprising a two-dimensional image acquisition device, the illumination path and the detection path comprising a common path comprising \ input face of the separator element and being separated by a reflection element.

First claim

1 . A full-field optical-coherence-tomography system for imaging a sample, comprising:
an illumination channel comprising a light source for emitting incident light waves; an interferometer comprising: at least one first objective, the light source being arranged in proximity to an image focal plane of the first objective or in proximity to a plane conjugate with an image focal plane of the first objective; and a splitting element suitable for receiving, via an entrance face, the incident light waves and suitable for forming an object arm intended to receive the sample and a reference arm in which is arranged a reflecting device; and wherein the splitting element has a reflection coefficient and a transmission coefficient that are not equal, such that the proportion of the optical power of the incident light waves sent to the object arm is strictly higher than the proportion of the optical power of the light waves sent to the reference arm; the reflecting device is suitable for directing the incident light waves in a direction that is different from the direction of incidence, and the interferometer is suitable for producing, when the sample is placed in the object arm of the interferometer, at each point of an imaging field, interference between a reference wave obtained by reflection of incident light waves from an elementary surface of the reflecting device corresponding to said point of the imaging field and an object wave obtained by backscatter of incident light waves by a voxel of a slice of the sample at a given depth, said voxel corresponding to said point of the imaging field; a detection channel comprising a device for acquiring two-dimensional images, and wherein the device for acquiring two-dimensional images is positioned in a conjugate plane of the reflecting device and suitable for acquiring two-dimensional interferometric signals resulting from the interference produced at each point of the imaging field; the illumination channel and the detection channel comprise a common channel comprising said entrance face of the splitting element, and are separated by a reflecting element, which is positioned in proximity to an image focal plane of said first objective, or in proximity to a conjugate plane of said image focal plane of the first objective, said reflecting element being suitable for letting pass, in the detection channel, at least one portion of the light waves directed by the reflecting device of the reference arm and for letting pass, in the illumination channel, at least one portion of the incident light waves; a processing unit configured to calculate an image of the sample from said two-dimensional interferometric signals.

2 . The imaging system as claimed in claim 1 , wherein the reflection coefficient and the transmission coefficient of the splitting element are such that at least 90% of the optical power of the light waves incident on the splitting element are sent toward the object arm.

3 . The imaging system as claimed in claim 1 , wherein the reflecting element comprises a mirror that is inclined with respect to the optical axis of the first objective, and which is apertured for the passage of the incident light waves, the dimensions of the aperture being sufficiently small to not block all of the light waves directed into the detection channel.

4 . The imaging system as claimed in claim 1 , wherein the reflecting element comprises a mirror that is inclined with respect to the optical axis of the first objective in order to deflect toward the common channel the incident light waves, and that has dimensions that are sufficiently small to not block all of the waves directed into the detection channel.

5 . The imaging system as claimed in claim 1 , wherein the reflecting device comprises a reflective diffraction grating, for example a blazed grating.

6 . The imaging system as claimed in claim 1 , wherein the reflecting device comprises an inclined mirror.

7 . The imaging system as claimed in claim 1 , wherein the interferometer is a Michelson interferometer, said first objective being arranged in the common channel of the illumination and detection channels.

8 . The imaging system as claimed in claim 1 , wherein the interferometer is a Linnik interferometer and comprises said first objective in the reference arm of the interferometer, and a second objective in the object arm of the interferometer.

9 . The imaging system as claimed in claim 8 , wherein said objectives are microscope objectives.

10 . A full-field optical-coherence-tomography method for imaging a sample by means of an imaging system as claimed in claim 1 , comprising:
placing the sample in the object arm of the interferometer; producing, by means of said interferometer, for each point of an imaging field, interference between a reference wave obtained by reflection of incident light waves from the reflecting device of the reference arm of the interferometer, said elementary surface corresponding to said point of the imaging field, and an object wave obtained by backscatter of the incident wave by a voxel of a slice of the sample at a given depth, said voxel corresponding to said point of the imaging field; acquiring, for at least one value of the optical path difference between the object arm and the reference arm, at least one two-dimensional interferometric signal resulting from interference for each point of the imaging field; calculating an image of the sample from said two-dimensional interferometric signals.

Assignees

• Centre Nat Rech Scient

Inventors

• Auksorius Egidijus
• Boccara Albert Claude

Classifications

• A61B5/0066 Primary

  Optical coherence imaging · CPC title

• G01N2021/4709

  Backscatter · CPC title

• G01N21/47

  Scattering, i.e. diffuse reflection (G01N21/25, G01N21/41 take precedence {G01N21/55 takes precedence}) · CPC title

• G02B27/108

  for sampling a portion of a beam or combining a small beam in a larger one, e.g. wherein the area ratio or power ratio of the divided beams significantly differs from unity, without spectral selectivity · CPC title

• G01B9/02091

  Tomographic interferometers, e.g. based on optical coherence · CPC title