FIBER OPTIC PRESSURE DETECTOR

• US 3,686,958 A
• Filed: 02/22/1971
• Issued: 08/29/1972
• Est. Priority Date: 02/22/1971
• Status: Expired due to Term

• Current Assignee: David B. Murray, John H. Porter
• Original Assignee: David B. Murray, John H. Porter
• Inventors: Porter, John H., Murray, David B.
• Primary Examiner(s): Prince, Louis R.
• Assistant Examiner(s): Shoon, Frederick
• Application Number:
  US05/117,448
• Time in Patent Office: 554 Days
• Field of Search: 73/398R,46 350/96B 128/2.9R,2.5DE,2.5N
• US Class Current: 73/705
• CPC Class Codes: A61B 5/031 Intracranial pressure
• CPC Class Codes: G01L 9/0007 using photoelectric means G01L9/0076 takes precedence

Abstract

A sensor unit precisely monitors ambient pressure within a confined space, such as intracranial pressure of a human patient, utilizing fiber optic light guides. A pair of light guides pass within a pneumatic line into a flexible envelope which is implanted in the skull. Of the external ends of the guides, one faces a light source and the other a photocell. Within the envelope the guide ends are so arranged with respect to light beam modulating mechanism responsive to envelope distortion due to change in relative pressure that a well-defined light beam passing between the ends is either '"'"''"'"''"'"''"'"'on'"'"''"'"''"'"''"'"' or '"'"''"'"''"'"''"'"'off.'"'"''"'"''"'"''"'"' The condition of the beam is sensed by the photo-cell which in turn operates pneumatic controls acting through the pneumatic line correspondingly to adjust repeatedly the internal pressure in the envelope so that it continuously spans the ambient pressure, thus providing a measure thereof.

Claims

1. For use in apparatus for precisely monitoring ambient pressure within a confined space, said apparatus including a light source, a light detector, a source of fluid under pressure, control means for controlling the pressure of said fluid in accordance with light or darkness sensed by said detector and display means for displaying said pressure, a sensor unit comprising an envelope adapted to be placed within the confined space;

a pneumatic line in communication with the envelope interior and adapted to be connected to said fluid source;

a pair of light guides each having an internal end terminating within the envelope and, of whose external ends, one faces the light source and the other the light detector;

said envelope having at least one wall movable in response to change of relative pressure between the envelope interior and the confined space;

light beam modulating mechanism mounted within said envelope and relatively movable with respect to said internal ends responsive to movements of said movable wall;

said internal ends and said mechanism being so disposed and arranged that in one position of said mechanism a beam of light will pass between said internal ends and, in another position of said mechanism, passage of said beam will be blocked;

so that said control means acting through said pneumatic line will adjust the internal pressure in said envelope in accordance with the light condition sensed by said detector, thereby causing said mechanism repeatedly to shift between its two positions whereby the internal pressure in the envelope continuously spans a range of pressures sufficiently close to said ambient pressure to provide a measure thereof.

2. The combination of claim 1 wherein said light modulating mechanism comprises a shutter interposed between said internal ends and movable between a first position wherein it blocks said beam and a second pOsition wherein it permits passage of said beam.

3. The combination of claim 2 wherein said envelope has opposed walls movable with respect to each other and said shutter is carried by the interior surface of one of said walls.

4. The combination of claim 1 wherein said light modulating mechanism comprises a reflector serving in one position to reflect said beam from one internal end to the other and in another position to prevent such reflection.

5. The combination of claim 4 wherein said interior ends are side by side with their faces facing in the same direction and said reflector is arranged to move between a light blocking position engaging both faces and a light reflecting position spaced from and opposite both faces.

6. The combination of claim 4 where wherein said interior ends are side by side with their faces facing in the same direction and said reflector comprises a pair of disk elements each providing a concave reflecting surface and movable from a mating position with each other wherein said reflecting surfaces cooperate to form a single concave reflector opposite said ends for reflecting light from one to the other, to a separated position wherein said reflecting surfaces are no longer opposite said ends thereby preventing the reflective transmission of light therebetween.

7. The combination of claim 1 wherein said light guides are carried within said pneumatic line from said envelope to a point exterior of said confined space.

8. The combination of claim 7 wherein said light guides are composed of fiber optic elements.