Calibration method and apparatus for optical-response tissue-examination instrument

• US 4,725,147 A
• Filed: 09/17/1984
• Issued: 02/16/1988
• Est. Priority Date: 09/17/1984
• Status: Expired due to Term

• Current Assignee: Somanetics Corporation (Medtronic Plc)
• Original Assignee: Somanetics Corporation (Medtronic Plc)
• Inventors: Stoddart, Hugh F.
• Primary Examiner(s): ROSENBERGER, RICHARD A
• Application Number:
  US06/651,575
• Time in Patent Office: 1,247 Days
• Field of Search: 356/243, 356/236, 356/448, 356/432-433, 356/408, 356/246, 356/446, 250/252.1, 128/633, 128/665
• US Class Current: 356/433
• CPC Class Codes: G01N 21/274 Calibration, base line adjustment, drift correction

Abstract

The specification discloses apparatus and methodology for calibrating optical-response tissue-examination apparatus of the type having an optical probe with at least one light-sending terminal portion adapted for introducing light into a test subject and a terminal portion for receiving resulting light from such subject. The calibration apparatus includes a body having outer walls which enclose an internal area and define an inlet aperture and an outlet aperture adapted to receive the terminal portions of the optical probe in a manner to substantially preclude entry or exit of ambient light. Means are included within said body for conveying inlet light from the test probe along a tortuous path communicating with the outlet aperture. In a preferred embodiment, the body includes means defining an outlet aperture located near the inlet aperture, and another outlet aperture may also be provided generally opposite from the inlet aperture or at a similar position of substantially greater distance from the inlet than the first outlet aperture. Also, in a preferred embodiment, internal chambers are provided within the body, certain of which is or adapted to admit a removable sample of selected media, e.g., substances selected as analogs to the anticipated examination tissue, for example, water and/or fused quartz or carbon tetrachloride.

Claims

1. Apparatus for calibrating optical-response in-vivo tissue-examination apparatus of the type having an optical probe with at least one light-sending terminal portion adapted for introducing examination light into a living mammalian subject and a terminal portion for receiving resulting light from said mammalian subject, said apparatus comprising:

a body having outer walls defining and enclosing areas of internal space, said body having at least one inlet aperture and at least one outlet aperture;

means communicating with at least one of said inlet and one of said outlet apertures for cooperatively receiving said light-sending and said light-receiving terminal portions of said optical probe, in a manner substantially precluding entry and exit of ambient light; and

means within said body for guiding light energy admitted into said body at said inlet, including means for conveying at least certain of such light energy along at least one defined tortuous path through at least certain of said body spaces and communicating with said outlet aperture.

2. Optical probe calibration apparatus according to claim 1, and including means within said body defining at least one restricted aperture having an axis disposed at an angle with respect to the longitudinal axis of said body.

3. Optical probe calibration apparatus according to claim 1, and including a first diffusion chamber within said body adjacent to and communicating with said inlet aperture, and further including means defining at least one restricted aperture within said diffusion chamber for passing light out of said chamber which was admitted through said inlet aperture.

4. Optical probe calibration apparatus according to claim 3, and including means defining at least one additional diffusion chamber located adjacent said first diffusion chamber and in light-communication therewith.

5. Optical probe calibration apparatus according to claim 4, and including means defining at least one light-transmission path communicating through said additional diffusion chamber and in communication with a first outlet aperture of said body.

6. Optical probe calibration apparatus according to claim 5, wherein said first outlet aperture of said body is located generally adjacent said inlet aperture.

7. Optical probe calibration apparatus according to claim 6, and including at least one restricted aperture providing a light-conducting passage exiting from at least one of said diffusion chambers at a point remote from said first outlet aperture.

8. Optical probe calibration apparatus according to claim 7, and including means defining a second outlet aperture for passing light out of said body, said second outlet aperture being in light-communicating relation with said restricted aperture and providing a light-conducting passage which exits at a point remote from said first outlet aperture.

9. Optical probe calibration apparatus according to claim 8, and including at least one other diffusion chamber disposed between and in light-communicating relation with both said restricted aperture exiting from said additional diffusion chamber at a point remote from said first outlet aperture and said second outlet aperture.

10. Optical probe calibration apparatus according to claim 1, and including a chamber within said body for containing selected media, said chamber being disposed along and in light-intercepting relation with said light-transmission path.

11. Optical probe calibration apparatus according to claim 10, wherein said media-containing chamber comprises a removable receptacle, and including means defining an access opening in said body affording access to said receptacle while therewithin.

12. Optical probe calibration apparatus according to claim 11, wherein said receptacle is selectively removable from and reinsertable into said body by way of said access opening.

13. Optical probe calibration apparatus according to claim 12, and including a medium within said receptacle which has light-transmission characteristics similar to those for water.

14. Optical probe calibration apparatus according to claim 13, and including a second and different medium within said receptacle having light-transmission charcteristics different than those for water.

15. Optical probe calibration apparatus according to claim 14, wherein said second and different medium has light-transmission characteristics similar to those of carbon tetrachloride.

16. A wide-band attenuator and diffuser apparatus for use as a calibration interface between the sending and receiving terminal portions of an optical probe in an optical-response data-gathering apparatus, comprising:

a generally tubular body having substantially opaque walls;

said body having at least one light-admitting inlet and at least one light-exiting outlet; and

internal baffle wall means inside said body defining a labryinthine light-transmission path extending between said inlet and said outlet, said baffle wall means including a reflection wall within said body having at least a portion extending generally traversely across the extended axis of said inlet to reflect at least certain of the light rays entering said body back along the axis of said inlet and light-guiding wall means connected to said reflection wall and extending generally perpendicular thereto and along said extended axis.

17. The apparatus of claim 16, wherein said inlet and outlet are located at opposite end portions of said body.

18. The apparatus of claim 17, and including a secondary outlet located generally adjacent said inlet.

19. The apparatus of claim 16, and including a receptacle containing a predetermined medium other than air disposed at least partially within said body and at least partially across said light-transmission path such that at least certain of the light exiting said body passes through said receptacle and the medium therewithin.

20. The apparatus of claim 19, wherein said receptacle is removable from the reinsertable into said body to provide for use of different media.

21. The apparatus of claim 20, wherein said receptacle comprises a sample cell adapted to removably receive various selected media.