IN VIVO CAMERA WITH MULTIPLE SOURCES TO ILLUMINATE TISSUE AT DIFFERENT DISTANCES

• US 20090306474A1
• Filed: 05/29/2009
• Published: 12/10/2009
• Est. Priority Date: 06/09/2008
• Status: Active Grant

• Current Assignee: CapsoVision, Inc.
• Original Assignee: CapsoVision, Inc.
• Inventors: Wilson, Gordon C.
• Granted Patent: US 8,636,653 B2
• Time in Patent Office: Days
• US Class Current: 600/109
• CPC Class Codes: A61B 1/00006 of control signals
• CPC Class Codes: A61B 1/00009 of image signals during a use of endoscope
• CPC Class Codes: A61B 1/00016 using wireless means
• CPC Class Codes: A61B 1/0002 provided with data storages
• CPC Class Codes: A61B 1/00032 internally powered
• CPC Class Codes: A61B 1/00114 Electrical cables in or with an endoscope
• CPC Class Codes: A61B 1/00177 for 90 degrees side-viewing
• CPC Class Codes: A61B 1/041 Capsule endoscopes for imaging
• CPC Class Codes: A61B 1/0607 for annular illumination
• CPC Class Codes: A61B 1/0623 for off-axis illumination
• CPC Class Codes: A61B 1/0625 for multiple fixed illumination angles
• CPC Class Codes: A61B 1/0661 Endoscope light sources
• CPC Class Codes: A61B 1/0684 using light emitting diodes [LED]

Abstract

An in vivo endoscope illuminates tissue using multiple sources. Light from a short-range source exits a tubular wall of the endoscope through a first illumination region that overlaps an imaging region, and the light returns through the imaging region after reflection by tissue, to form an image in a camera. Light from a long-range source exits the tubular wall through a second illumination region that does not overlap the imaging region. The endoscope of some embodiments includes a mirror, and light from an emitter for the short-range source is split and reaches the first illumination region from both sides of an optical axis of the camera. Illuminating the first illumination region with split fractions of light results in greater uniformity of illumination, than illuminating directly with an un-split beam. The energy generated by each source is changed depending on distance of the tissue to be imaged.

Claims

1. An endoscope comprising:

a housing sufficiently small to travel through a gastrointestinal tract of a human;

a transmitter enclosed within said housing, to transmit image data to an external device;

a set comprising at least one sensor enclosed within said housing and coupled to said transmitter, said set supplying said image data to said transmitter;

wherein a first region of the housing is defined by an intersection of a surface of the housing with a first electromagnetic radiation entering the housing to form said image data;

a source enclosed within said housing, to generate second electromagnetic radiation exiting said housing;

wherein said source is positioned at a location whereby a majority of the second electromagnetic radiation exiting the housing passes through a second region of the housing not overlapping the first region;

wherein a portion of said first electromagnetic radiation arises from reflection of a fraction of said second electromagnetic radiation by said gastrointestinal tract.

2. The endoscope of claim 1 wherein:

said set is coupled to said transmitter by a processor comprised in the endoscope and enclosed within said housing;

additional electromagnetic radiation enters said housing to form additional data also supplied by said set to said processor; and

said processor excludes said additional data to obtain said image data supplied to said transmitter.

3. The endoscope of claim 1 wherein:

said set is coupled to said transmitter by a processor comprised in the endoscope and enclosed within said housing; and

said processor supplies said image data to said transmitter without any cropping.

4. The endoscope of claim 1 wherein:

the housing comprises a tubular wall and a pair of domes capping the tubular wall at opposite ends thereof, to form a capsule;

the source is surrounded by the tubular wall and each of the first region and said second region is on a surface of the tubular wall.

5. The endoscope of claim 1 wherein:

the source is hereinafter referred to as a first source;

the endoscope further comprises a second source enclosed within the housing;

the endoscope further comprises an annular wall enclosed within the housing;

a plurality of paths correspond to a plurality of rays originating from the second source, the plurality of paths pass through the annular wall to reach the housing and reflect therefrom to form within said housing, a mirror image of the second source in the absence of the annular wall; and

wherein the annular wall is opaque and positioned adjacent to the second source to block passage of the plurality of rays along said paths to prevent said formation of said mirror image by said plurality of rays.

6. The endoscope of claim 1 wherein:

the source is hereinafter referred to as a first source;

the housing has an aspect ratio greater than one;

a longitudinal plane passes through a longitudinal axis of the housing;

the endoscope further comprises a second source; and

the longitudinal plane passes through each of said first source and said second source.

7. The endoscope of claim 6 wherein:

said first source is offset from said second source in a direction of said longitudinal axis;

the endoscope has a pupil through which the first electromagnetic radiation enters the housing to form the image data; and

said pupil is located between said first source and said second source.

8. The endoscope of claim 1 wherein almost all of the second electromagnetic radiation passes through the second region.

9. The endoscope of claim 1 wherein:

the source is hereinafter referred to as a first source;

the location is hereinafter referred to as a first location;

the endoscope further comprises a second source enclosed within the housing, to generate third electromagnetic radiation exiting said housing;

wherein said second source is positioned at a second location whereby a majority of the third electromagnetic radiation exiting the housing passes through the first region.

10. A device comprising:

a housing sufficiently small to travel through a gastrointestinal tract of a human;

a source enclosed within said housing, said source comprising a pair of terminals with current passing therebetween and at least one emitter of electromagnetic radiation, said at least one emitter being powered through said pair of terminals;

an optical element enclosed within said housing and offset from said source, the optical element being located in a path of a portion of electromagnetic radiation emitted by the source, the optical element being located in said housing such that at least a fraction of said portion of electromagnetic radiation becomes incident on a surface of the housing from the optical element;

wherein the optical element is on a first side of a plane and the source is on a second side of said plane and all electromagnetic radiation from the source is emitted on the second side of said plane; and

at least one camera enclosed within said housing, wherein at least one image is formed in said at least one camera by reflection from the gastrointestinal tract of at least a fraction of said majority of said portion of said electromagnetic radiation.

11. The device of claim 10 wherein:

a first distance between the source and the camera is smaller than a second distance between the source and the optical element; and

the optical element comprises a reflective surface.

12. The device of claim 11 wherein:

the housing has an aspect ratio greater than one; and

a first offset in a direction of a longitudinal axis of the housing, between the source and the camera, is less than a second offset in said direction, between the source and the optical element.

13. The device of claim 10 wherein:

a first distance between the source and the camera is larger than a second distance between the source and the optical element; and

the optical element limits angular divergence of said fraction of light incident thereon from said source.

14. The device of claim 10 wherein:

the optical element has an input aperture facing the source and an output aperture separated from and opposite to the input aperture; and

angular divergence of electromagnetic radiation exiting the output aperture is less than angular divergence of electromagnetic radiation entering the input aperture.

15. The device of claim 14 wherein:

the optical element comprises a lens, and the lens reduces angular divergence between the input aperture and the output aperture.

16. The device of claim 14 wherein:

the optical element comprises a reflective surface, and said reflective surface is located between the input aperture and the output aperture oriented to reduce angular divergence of said electromagnetic radiation entering the optical element at the input aperture.

17. The device of claim 16 wherein:

the reflective surface is comprised in a concentrator.

18. The device of claim 17 wherein:

said reflective surface is defined by a truncated compound parabolic concentrator (CPC).

19. The device of claim 14 wherein:

the optical element has an additional input aperture and an additional output aperture; and

an additional portion of electromagnetic radiation enters the optical element through said additional input aperture and exits the optical element at said additional output aperture.

20. The device of claim 19 wherein:

the optical element comprises a reflective surface that reflects at least a fraction of said additional portion of electromagnetic radiation toward the additional output aperture.

21. The device of claim 20 wherein:

the reflective surface is one side of a layer, said layer having another side that reflects said electromagnetic radiation entering the input aperture; and

said layer comprises at least one of (a) a single metal layer or (b) a multi-layered stack of dielectric layer(s) and/or metal layer(s).

22. The device of claim 10 wherein:

a longitudinal plane passes through a point (hereinafter “

intersection point”

) formed by intersection of a surface of said housing with an optical axis of said camera, the longitudinal plane further passes through a center of curvature C of an arc AB, the arc AB being defined by intersection of said surface of said housing with a lateral plane parallel to the optical axis and passing through said intersection point, the lateral plane and the longitudinal plane being oriented perpendicular to one another; and

the optical element limits angular divergence of a majority of illumination rays emitted from the output aperture such that a projection on to said longitudinal plane, of an illumination ray in said majority, after reflection from said intersection point, makes an angle θ

i with a normal to said surface of said housing such that θ

i>

θ

FOV+α

wherein θ

FOV is half angle of a field of view of the camera projected in the longitudinal plane and α

is an angle between said normal to said surface and said optical axis.

23. The device of claim 10 wherein:

a first illumination ray emitted by the source is incident on the housing with angle of incidence θ

_i and is reflected with an identical angle of reflection θ

_i relative to a line N that bisects an angle formed by said first illumination ray and a reflected ray resulting from reflection of said first illumination ray by said housing;

a point U exists at the intersection of a first line collinear with the incident ray and a second line collinear with the reflected ray;

a first image forming ray forms an angle σ

with line N, said first image forming ray being comprised in a plurality of image forming rays, said plurality of image forming rays forming a cropped portion of said image supplied to a transmitter comprised in said device;

additional illumination rays from the source are restricted in angle such that θ

_i>

σ

for a majority of pairs of any additional illumination ray incident on the housing and a corresponding additional image forming ray comprised in said plurality of image forming rays;

the first image forming ray, when located within a free space between the housing and the camera, is collinear to a line passing through said point U and a pupil of the camera; and

said line is coplanar with said first illumination ray and said reflected ray.

24. The device of claim 10 wherein:

a surface of the optical element is a surface of a truncated compound parabolic concentrator; and

the optical element is of an annular shape comprising a plurality of spokes between an inner wall and an outer wall.

25. The device of claim 24 wherein:

the first light source comprises a light emitting diode (LED) encapsulated within a cavity of a package; and

the optical element is mounted on the package with at least a portion of an outer wall of the optical element overhanging an opening of the cavity.

26. The device of claim 25 wherein:

said opening is of an area larger than an area of an aperture of said optical element facing the source.

27. The device of claim 10 wherein:

said optical element is hereinafter first optical element;

a first distance between the source and the camera is smaller than a second distance between the source and the first optical element, and the first optical element comprises a reflective surface;

the device further comprises a second optical element; and

said first distance is greater than a third distance between the source and the second optical element, and the second optical element limits angular divergence of said fraction of light incident thereon from said source.

28. A method of in vivo imaging, comprising:

an endoscope emitting first electromagnetic radiation from a first region of a housing to illuminate a gastrointestinal tract;

said endoscope emitting second electromagnetic radiation from a second region of said endoscope to further illuminate said gastrointestinal tract;

wherein said first region is larger than said second region; and

said endoscope storing inside a memory at least a portion of an image formed by reflections, received through said first region, of said first electromagnetic radiation and said second electromagnetic radiation by said gastrointestinal tract.

29. The method of claim 28 wherein said emittings and said storing are performed when said endoscope is at a first location relative to the gastrointestinal tract, the method further comprising:

in response to movement of said endoscope to a second location at which a first increase Δ

d1 resulting from said movement, in a first distance d1 of the first region from the gastrointestinal tract is greater than a second increase Δ

d2 resulting from said movement, in a second distance d2 of the second region from the gastrointestinal tract when measured in a common direction, said endoscope automatically increasing radiant energy E2 emitted in the second electromagnetic radiation from said second region by a second amount Δ

E2 while increasing radiant energy emitted in the first electromagnetic radiation by a first amount Δ

E1, said first amount Δ

E1 being smaller than said second amount Δ

E2; and

subsequent to said increasings, said endoscope storing in said memory another portion of another image of said tract from said second location.

30. The method of claim 28 further comprising:

said endoscope generating the first electromagnetic radiation using a first source;

at least a first fraction of the first electromagnetic radiation from the first source being incident on the first region after reflection by an optical element located between the first source and the housing and at least a second fraction of the first electromagnetic radiation from the first source being incident on the first region without reflection by the optical element, said first fraction being greater than said second fraction;

wherein the optical element is on a first side of a plane and the first source is on a second side of said plane and all electromagnetic radiation from the first source is emitted on the second side of said plane; and

said endoscope generating the second electromagnetic radiation using a second source, a majority of the second electromagnetic radiation from the second source being incident on the second region without reflection between the second source and the housing;

wherein each source is enclosed within a housing of said endoscope and each source comprises a pair of terminals with current passing therebetween and at least one emitter of electromagnetic radiation powered through said pair of terminals.

31. The method of claim 28 wherein:

said endoscope transmits a majority of the first electromagnetic radiation after reflection by an optical element within said endoscope;

wherein the optical element is on a first side of a plane and a first source of the first electromagnetic radiation is on a second side of said plane and all electromagnetic radiation from the first source is emitted on the second side of said plane; and

said endoscope transmits a majority of the second electromagnetic radiation without reflection by said optical element.

32. The method of claim 31 further comprising:

said endoscope calculating an average luminance value for each sector in a plurality of sectors used to sense said image;

said endoscope calculating a difference between the average luminance value calculated for each sector and a target luminance value for said each sector; and

said endoscope computing a drive current for generating the second electromagnetic radiation, based at least partially on said difference.

33. The method of claim 32 wherein:

a change in said drive current is obtained based on a linear combination of a plurality of said differences individually calculated for each sector in said plurality of sectors.

34. The method of claim 33 wherein:

said linear combination comprises multiplication of a vector of said differences with a matrix of values, each value being selected to be one of a plurality of predetermined values based on drive current.