Optical examination apparatus

• US 5,032,024 A
• Filed: 05/01/1989
• Issued: 07/16/1991
• Est. Priority Date: 02/06/1989
• Status: Expired due to Fees

• Current Assignee: Hamamatsu Photonics KK
• Original Assignee: Hamamatsu Photonics KK
• Inventors: Cope, Mark
• Primary Examiner(s): McGraw, Vincent P.
• Assistant Examiner(s): KEESEE, LACHARLES
• Application Number:
  US07/345,260
• Time in Patent Office: 806 Days
• Field of Search: 128/633, 128/634, 356/73.1, 356/435, 356/41, 356/419, 356/73, 350/96.24, 350/96.22, 350/96.20, 350/96.15, 358/901, 250/227
• US Class Current: 356/41
• CPC Class Codes: A61B 5/14553 specially adapted for cerebral tissue
• CPC Class Codes: G01J 1/10 by comparison with reference light or electric value provisionally void
• CPC Class Codes: G01J 3/02 Details
• CPC Class Codes: G01J 3/0218 using optical fibers
• CPC Class Codes: G01N 21/255 Details, e.g. use of specially adapted sources, lighting or optical systems
• CPC Class Codes: G01N 21/532 with measurement of scattering and transmission

Abstract

An optical examination apparatus for optically examining density, distribution, etc. of oxygen in an object to be examined such as organic tissue like brain tissue, of man or animal compressing a light source, an optical fibre bundle having one end on which light emitted from the light source is incident and which is divided at the other end into a first and second branch with a predetermined ratio of division, transmitted and scattered light detection means for detecting light is emitted from the first branch of the fibre bundle and transmitted through and scattered by the object to be examined, monitoring light detection means for detecting monitoring light emitted from the second branch fibre bundle, normalization means for normalizing an output of the transmitted and scattered light detected means on the basis of an output from the monitoring light detection means, representative sampling means for ensuring that the light output from the second branch fibre bundle is representative of that output by the light source. The representative sampling means may be provided by distributing the optical fibres forming the second branch fibre bundle uniformly over the one end of the optical fibre bundle or may comprise a mode scrambler interposed between the one end of the optical fibre bundle and the light source to distribute light from the light source over the whole fibre bundle.

Claims

1. An optical examination apparatus, for optically examining characteristics of oxygen in an object including the density and distribution of oxygen in the object, comprising:

a light source for emitting light having an intensity and a luminous pattern;

an optical fibre bundle having a first end for receiving said light emitted by said light source and a second end which is divided into a first branch fibre bundle for emitting an examination light onto the object so that said examination light is transmitted through and scattered by the object and a second branch fibre bundle for emitting a monitoring light, said monitoring light having an intensity and said first and second branch fibre bundles having a predetermined ratio of division where the first fibre bundle includes a substantially greater number of fibres than the second fibre bundle;

a transmitted and scattered light detection means for detecting light from said first fibre bundle and for providing a signal corresponding to said examination light transmitted through and scattered by the object;

a monitoring light detection means for detecting light from said second fibre bundle and for providing a signal corresponding to said monitoring light;

normalization means for normalizing said signal provided by said transmitted and scattered light detection means in accordance with said signal provided by said monitoring light detection means; and

means for distributing irregularities in light intensity of said light emitted by said light source throughout the total area of the first end of said optical fibre bundle, and for emitting light at said second branch fibre bundle having an intensity corresponding to the predetermined ratio of the total light received at said first end of said optical fibre bundle.

2. The optical examination apparatus according to claim 1, wherein said means for distributing irregularities in light intensity comprises optical fibres forming said second branch fibre bundle and being uniformly distributed in the predetermined ratio relative to the fibres forming said first bundle throughout said first end of said optical fibre bundle.

3. The optical examination apparatus according to claim 1, wherein said means for distributing irregularities in light intensity comprises a glass rod interposed between said first end of said optical fibre bundle and said light source for uniformly distributing said irregular light intensity emitted by said light source onto said first end of said optical fibre bundle.

4. The optical examination apparatus according to claim 1, wherein said light source comprises a plurality of light sources for emitting light of different wavelengths and wherein said optical fibre bundle comprises a plurality of fibre bundles each associated with one of said plurality of light sources, respectively.

5. The optical examination apparatus according to claim 1, wherein said light source comprises at least one semiconductor laser.

6. The optical examination apparatus according to claim 1, wherein said light emitted by said light source is in the near infrared region of the electromagnetic wave spectrum.