Optical in-vivo monitoring systems

• US 20080097221A1
• Filed: 02/17/2004
• Published: 04/24/2008
• Est. Priority Date: 02/17/2004
• Status: Active Grant

• Current Assignee: Joseph Florian
• Original Assignee: Joseph Florian
• Inventors: Florian, Joseph
• Granted Patent: US 7,729,748 B2
• Time in Patent Office: Days
• US Class Current: 600/476
• CPC Class Codes: A61B 2562/146 for optical coupling
• CPC Class Codes: A61B 5/02433 for infrared radiation
• CPC Class Codes: A61B 5/14552 Details of sensors specially adapted therefor
• CPC Class Codes: A61B 5/681 Wristwatch-type devices

Abstract

Systems for highly efficient, in-vivo collection of modulated infra-red light are presented. Specifically, these devices are arranged in an important format with a view to integration with a wristwatch or other wearable device. An optical aperture of large surface area, specially distributed in an annular ring, receives radiation having been modulated in a tissue test site by blood flow. Radiation received about the annular aperture is redirected by a blazed grating or similar optical element at near perpendicular angles, into a radially distributed, condensing light pipe array and further toward a common axis. Radiation converges on the axis, thus increasing the energy density of the collected signal, before it is further directed via a conic element to a detector such as a photodiode. In some versions, these highly specialized optical paths may be formed into a single element of inexpensive plastic or other rigid substrate.

Claims

1. ) A thin-disk optical coupling element comprising:

an entrance aperture;

a beam turning element;

a waveguide array; and

an exit aperture,

said entrance aperture comprising a planar annular region of a bottom surface of said thin-disk,

said beam turning element formed in or on said thin-disk is arranged to redirect beams incident substantially orthogonal thereon in a radially inward direction towards said waveguide array,

said waveguide array is formed in a central or inner portion of said thin-disk, the waveguide array comprising a plurality of pie-wedge shaped members, and

said exit aperture being at least one surface prepared such that light beams from said waveguide array passes there through and exits the thin disk at an appreciably higher energy density than the beams energy density at entry to the thin-disk.

2. ) A thin-disk optical coupling of claim 1, said beam turning element is further characterized as a grating of periodic structures arranged with circular symmetry, said structures being disposed on a thin-disk surface opposite the surface in which the entrance aperture lies.

3. ) A thin-disk optical coupling of claim 2, said grating being a cylindrically symmetric blazed type grating formed of a plurality of surface relief repeat structures in a top surface of said thin-disk, each repeat structure forming a concentric circle having a radius different each of the other repeat structures.

4. ) A thin-disk optical coupling of claim 2, said grating being a symmetric phase type grating characterized as a hologram optical element.

5. ) A thin-disk optical coupling of claim 1, each of said entrance and exit apertures, said beam turning element, and said waveguide array being symmetric about a system symmetry axis,

said entrance aperture is polished smooth, the aperture being about between 0.5 and 5 cm², having an opaque void at its center, and

said exit aperture is comprised of a plurality of curved surfaces lying in a cylinder.

6. ) A thin-disk optical coupling of claim 1, said waveguide array comprised of pie-wedge elements is further defined as having side surfaces and air slits between those side surfaces to provide interfaces operable for promoting total internal reflections within the pie-wedge elements, said side surfaces being planar polished surfaces whereby light beams falling thereon remain within the pie-wedge elements and continue to propagate generally towards the system symmetry axis.

7. ) A thin-disk optical coupling of claim 1, further comprising a mirror element;

said mirror element being coupled with said waveguide array whereby light from the waveguide array falls upon the mirror element and is reflected toward said exit aperture.

8. ) A thin-disk optical coupling of claim 7, said mirror is a conic surface formed directly on the thin-disk element and concentric with the system axis.

9. ) A thin-disk optical coupling of claim 8, said exit aperture is formed on the top surface of the thin-disk element, the opposite surface with respect to the entrance aperture, whereby light leaves the thins disk on the axis and upwardly away from the tissue test site.

10. ) A thin-disk optical coupling of claim 1, said coupling is operable for condensing light in accordance with an entrance to exit aperture ratio greater than 3.

11. ) Optical in-vivo monitoring systems for monitoring states of living tissues comprising:

an illumination source;

an optical coupling element; and

a photodetector,

said illumination source arranged to transmit a beam into a tissue test site, said optical coupling element concentric therewith said illumination source, being arranged to receive modulated light from the tissue test site and transmit received light at a sufficiently higher energy density to said photodetector.

12. ) Optical in-vivo monitoring systems of claim 11, said optical coupling element is further defined as an optical collection and condensing element having an entrance aperture and an exit aperture whose area ratio exceeds about 3.

13. ) Optical in-vivo monitoring systems of claim 11, said photodetector is arranged on axis with said illumination source, the illumination source lying between the tissue test site and the photodetector.

14. ) Optical in-vivo monitoring systems of claim 11, said optical coupling element is further defined as a thin-disk optical coupling element comprising:

an entrance aperture;

a beam turning element;

a waveguide array; and

an exit aperture, said entrance aperture comprising a planar annular region of a bottom surface of said thin-disk, said beam turning element formed in or on said thin-disk is arranged to redirect beams incident substantially orthogonal thereon in a radially inward direction towards said waveguide array, said waveguide array is formed in a central or inner portion of said thin-disk, the waveguide array comprising a plurality of pie-wedge shaped members, and said exit aperture being at least one surface prepared such that light beams from said waveguide array passes there through and exits the thin disk at an appreciably higher energy density than the beams energy density at entry to the thin-disk.

15. ) Optical in-vivo monitoring systems of claim 11, further comprising:

an opaque region;

a lens;

a computer; and

indicator in the watch face,

said opaque region being disposed on a central portion of the thin-disk bottom surface whereby light from the illumination source is blocked from entering the thin-disk unless it has passed first through a sufficient amount of tissue,

said lens being coupled with a semiconductor light source to form an optical illumination beam symmetric about a system axis whereby light from the source is transmitted into tissue at a test site,

said computer is coupled to said photodetector whereby electric signals produced at the photodetector can be analyzed and processed in accordance with appropriate software running thereon and the computer is further coupled to the indicator whereby information may be graphically presented to a user.

16. ) Optical in-vivo monitoring systems of claim 11, said lens is arranged to form an illumination beam into a cone whereby light enters a tissue test site and tends to scatter radially outwardly from the system symmetry axis.

17. ) Methods of in-vivo optical monitoring, comprising the steps:

illuminating tissue test site via an emitting semiconductor;

receiving light which has sufficiently interacted with tissue via large scatter path length at a large annular aperture;

turning light received at said aperture radially inward toward a symmetry axis;

concentrating beam via TIR reflections in pie-wedge light pipe array; and

converting received modulated optical beam to electrical impulses at a photodetector.

18. ) Methods of in-vivo optical monitoring of claim 17, further comprising the step extinguishing light which has interacted with tissue for less than an optical path of 5 mm at an opaque beam block concentric with said illumination source.

19. ) Methods of in-vivo optical monitoring of claim 17, said ‘

concentrating beam’

step is further defined as causing light which enters an exit aperture to be transmitted through a sufficiently smaller exit aperture coupled to a photodetector.

20. ) Methods of in-vivo optical monitoring of claim 17, further comprising the step:

processing said electrical impulses to determine the state of said tissue site including a pulse rate.