Optical measurement method and apparatus thereof

Chemistry: analytical and immunological testing – Involving an insoluble carrier for immobilizing immunochemicals

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356317, 356318, 356244, 356246, 385 12, 385129, 385130, 422 57, 422 58, 422 8205, 422 8208, 422 8211, 4352871, 4352872, 4352887, 435808, 436164, 436165, 436172, 436527, 436805, G01N 33534, G01N 33552

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active

058588000

DESCRIPTION:

BRIEF SUMMARY
TECHNICAL FIELD

The present invention relates to an optical measurement method and apparatus thereof, and more particularly to an optical measurement method and apparatus thereof which are suitable to cases. One of the cases is a case which introduces an exciting light into a slab-type optical waveguide, propagates the exciting light within the slab-type optical waveguide in a total reflection manner so as to generate an evanescent wave component, excites fluorescent substance by the evanescent wave component which fluorescent substance exist in vicinity of a face of the slab-type optical waveguide which face totally reflects the exciting light, and detects a fluorescent light component by a detector which fluorescent light is a part of the generated fluorescent light and is introduced into the slab-type optical waveguide through the face and is outgone from the slab-type optical waveguide thereafter. The other of the cases is a case which introduces an exciting light into a total reflection prism, totally reflects the exciting light by a total reflection face of the total reflection prism so as to generate an evanescent wave component, excites fluorescent substance by the evanescent wave component which fluorescent substance exist in vicinity of the total reflection face, and detects a fluorescent light component by a detector which fluorescent light is a part of the generated fluorescent light and is introduced into the total reflection prism through the total reflection face and is outgone from the total reflection prism thereafter.


BACKGROUND ART

From past, a method is proposed which introduces an exciting light into a slab-type optical waveguide, propagates the exciting light within the slab-type optical waveguide in a total reflection manner so as to generate an evanescent wave component, excites fluorescent substance by the evanescent wave component which fluorescent substance exist in vicinity of a face of the slab-type optical waveguide which face totally reflects the exciting light, and detects a fluorescent light component by a detector which fluorescent light is a part of the generated fluorescent light and is introduced into the slab-type optical waveguide through the face and is outgone from the slab-type optical waveguide thereafter. When a light propagating within a medium having a larger refractive index totally reflects at a boundary face of the medium and a medium having a smaller refractive index, the evanescent wave is a light component which exist within the medium having smaller refractive index and within a limited region with respect to the boundary face. Specifically, when is is supposed that refractive indexes of the medium are n1, n2 (where n1<n2), a wavelength of the light is .lambda., a incident angle is .theta., an intensity of an incident light is I0, an intensity of a light at a point which is apart from the boundary face by a distance z is I, a specific refractive index is n (=n2
1), a distance of a point from the boundary face (invasion depth) is dp which point makes an electric field strength to be 1/e of that of the boundary face of the optical waveguide. The intensity I depends upon the distance Z and is expressed with equation (1) .
Therefore, it is understood by analyzing the equation (1) that an evanescent wave exists within a limited region with respect to the boundary face (refer tp M. Born & E. Wolf "Principle Of Optics I"). Wherein, it is assumed that the incident angle .theta. is greater than a critical angle .theta.c {.theta.c=sin.sup.-1 (n1
2)}.
As to evanescent wave, not only penetrating of a light to lower refractive index side but also propagating of a light from lower refractive index side to higher refactive index side satisfy the foregoing. That is, a rate of a light which propagates to fluorescence dye et al. by an angle which is greater than the critical angle is expressed with the equation (1) similarly, which fluorescent dye et al. exists at a position apart from the boundary face by a distance z. Therefore, only light which is generated at

REFERENCES:
patent: 4810658 (1989-03-01), Shanks et al.
patent: 4818710 (1989-04-01), Sutherland et al.
patent: 4857273 (1989-08-01), Stewart
patent: 4978503 (1990-12-01), Shanks et al.
patent: 5512492 (1996-04-01), Herron et al.
patent: 5538850 (1996-07-01), King et al.

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