U.S. patent number RE32,598 [Application Number 06/524,696] was granted by the patent office on 1988-02-09 for feature extraction system for extracting a predetermined feature from a signal.
Invention is credited to John U. White.
United States Patent |
RE32,598 |
White |
February 9, 1988 |
Feature extraction system for extracting a predetermined feature
from a signal
Abstract
A fluorescence spectrophotometer in which the optical system for
the excitation monochromator includes an arrangement for forming an
image of the exit slit of the monochromator adjacent a first
surface of the sample being evaluated and for forming an aperture
image adjacent a second surface of the sample. Fluorescence from
the sample is directed to an emission monochromator which likewise
has an arrangement for forming an image of the emission
monochromator's entrance slit adjacent a third surface of the
sample and for forming an aperture image adjacent a fourth surface.
The optical components are arranged such that the images of the
slits lie in a single plane defined by the axial rays of the
excitation and fluorescence beams, and in several advantageous
arrangements the slit images are oriented at 90.degree. from the
slits themselves. The intensity of the output signal may be further
increased by locating mirrors behind the sample holder to direct
the light back through the sample for a second pass. This is a
Reissue of a Patent which was the subject of a Reexamination
Certificate No. B1 4,022,529, dated May 10, 1977, Request No.
90/000,155.
Inventors: |
White; John U. (Darien,
CT) |
Family
ID: |
27061574 |
Appl.
No.: |
06/524,696 |
Filed: |
August 19, 1983 |
Current U.S.
Class: |
356/318;
250/458.1; 356/301; 356/324 |
Current CPC
Class: |
G01J
3/4406 (20130101); G01N 2021/6421 (20130101); G01N
2021/6419 (20130101) |
Current International
Class: |
G01N
21/64 (20060101); G01J 3/44 (20060101); G01N
021/64 (); G01N 021/65 () |
Field of
Search: |
;356/301,317,318
;250/458.1,459.1,461.1 ;350/420,421 |
References Cited
[Referenced By]
U.S. Patent Documents
Other References
Oldenberg; "On the Intensity of Illumination in Spectrographs"
JOSA, vol. 22 #8, Aug. 1932, pp. 441-455. .
Richardson; "An Image Slicer for Spectrographs" Publications of The
Astronomical Society of the Pacific (PASP) vol. 78 #pp. 436 &
437. .
"The SPF-1000", Bulletin 2423-1, American Instrument Co., Inc.,
Silver Springs, Maryland 20910, printed in U.S.A. Feb. 1968. .
Brochure by Farrand Optical Co. 1974. .
"Analytical Biochemistry" vol. 16, pp. 438-449, 1966. .
Cary Instruments brochure 1968. .
"Spectroscopy" pp. 290-293, Oct. 10, 1974. .
"JASCO-Report" vol. 11, No. 10, Oct. 25, 1974. .
Diagram entitled "FP-4 Fluoresence Spectrophotometer" (undated).
.
"Model FP-4 Fluorescence Spectrophotometer," Japan Spectroscopic
Co. Ltd. Feb. 1974. .
Sheet entitled "JASCO MPF-4 Optional Accessories" (undated). .
Brochure entitled "Model FP-3 Hitachi Fluorescence
Spectrophotometer" (undated). .
"Fluorescence Lifetimes: Theory, Instrumentation, and Application
of Nanosecond Fluorometry"; Spencer pp. 104-122; 1970..
|
Primary Examiner: McGraw; Vincent P.
Attorney, Agent or Firm: Robinson, Jr.; Lee C.
Parent Case Text
.Iadd.This application is a continuation of Ser. No. 36,994, filed
May 8, 1979 and now abandoned..Iaddend.
Claims
What is claimed is: .[.1. Apparatus for measuring radiation from a
sample, the apparatus comprising, in combination:
a source of radiation;
excitation monochromator means for isolating an excitation beam of
monochromatic radiation from said source, the excitation
monochromator means having an excitation entrance slit for
receiving radiation from said source, an excitation exit slit, and
means for directing the excitation beam through said excitation
exit slit;
means cooperating with the excitation monochromator means for
directing the excitation beam to said sample and for forming an
image of the excitation exit slit adjacent the sample;
emission monochromator means for isolating radiation from said
sample, the emission monochromator means having an emission
entrance slit for receiving an emission beam of radiation from said
sample, an emission exit slit, and means for directing
monochromatic radiation from the emission beam through said
emission exit slit;
means cooperating with the emission monochromator means for
directing the emission beam to the emission entrance slit and for
forming an image of said emission entrance slit adjacent the
sample;
said excitation beam and said emission beam having principal rays
which intersect at said sample, and each of said images having a
longitudinal axis which lies in the plane defined by said principal
rays; and
radiation detecting means for receiving the monochromatic radiation
from the exit slit of the emission monochromator means..]. .[.2.
Apparatus as defined in claim 1, in which the longitudinal axis of
the excitation exit slit image extends in a direction parallel to
the principal ray of the emission beam, and the longitudinal axis
of the emission entrance slit image extends in a direction parallel
to the principal ray of the
excitation beam..]. 3. Apparatus .[.as defined in claim 1, in
which.]. each of said images .[.is anamorphic.]. .Iadd.being
anamorphically distorted; for measuring fluorescent radiation from
a sample, the apparatus comprising, in combination:
a source of radiation;
excitation monochromator means for isolating an excitation beam of
monochromatic radiation from said source, the excitation
monochromator means having an excitation entrance slit for
receiving radiation from said source, an excitation exit slit, and
means for directing the excitation beam through said excitation
exit slit;
means cooperating with the excitation monochromator means for
directing the excitation beam to said sample and for focusing an
image of the excitation exit slit on the sample;
emission monochromator means for isolating radiation from said
sample, the emission monochromator means having an emission
entrance slit for receiving an emission beam of radiation from said
sample, an emission exit slit, and means for directing
monochromatic radiation from the emission beam through said
emission exit slit;
means cooperating with the emission monochromator means for
directing the emission beam to the emission entrance slit and for
focusing an image of said emission entrance slit on the sample;
means for introducing distortion in each of said images;
said excitation beam and said emission beam having principal rays
which intersect at said sample, and each of said images having a
longitudinal axis which lies in the plane defined by said principal
rays, each point along said emission entrance slit being filled
with radiation of equal intensity corresponding to irradiation of
the sample with radiation from substantially the entire length of
said excitation exit slit; and
radiation detecting means for receiving the monochromatic radiation
from
the exit slit of the emission monochromator means..Iaddend. .[.4.
Apparatus for measuring radiation from a sample, the apparatus
comprising, in combination:
a source of radiation;
excitation monochromator means for isolating an excitation beam of
monochromatic radiation from said source, the excitation
monochromator means having an excitation entrance slit for
receiving radiation from said source, an excitation exit slit, and
means for directing the excitation beam through said excitation
exit slit;
means cooperating with the excitation monochromator means for
directing the excitation beam to said sample and for forming an
image of the excitation exit slit adjacent the sample;
emission monochromator means for isolating radiation from said
sample, the emission monochromator means having an emission
entrance slit for receiving an emission beam of radiation from said
sample, an emission exit slit, and means for directing
monochromatic radiation from the emission beam through said
emission exit slit;
means cooperating with the emission monochromator means for
directing the emission beam to the emission entrance slit and for
forming an image of said emission entrance slit adjacent the
sample;
said excitation beam and said emission beam having principal rays
which intersect at said sample, and each of said images having a
longitudinal axis which lies in the plane defined by said principal
rays, the excitation exit slit and the emission entrance slit
having longitudinal axes which extend in directions perpendicular
to said plane; and
radiation detecting means for receiving the monochromatic radiation
from the exit slit of the emission monochromator means..]. .[.5.
Apparatus for measuring radiation from a sample, the apparatus
comprising, in combination:
a source of radiation;
excitation monochromator means for isolating an excitation beam of
monochromatic radiation from said source, the excitation
monochromator means having an excitation entrance slit for
receiving radiation from said source, an excitation exit slit, and
means for directing the excitation beam through said excitation
exit slit;
means cooperating with the excitation monochromator means for
forming an image of said excitation exit slit adjacent said
sample;
emission monochromator means for isolating radiation from said
sample, the emission monochromator means having an emission
entrance slit for receiving an emission beam of radiation from said
sample, an emission exit slit, and means for directing
monochromatic radiation from the emission beam through said
emission exit slit;
means cooperating with the emission monochromator means for forming
an image of said emission entrance slit adjacent said sample;
said excitation beam and said sample beam having principal rays
which intersect at said sample, and each of said images having a
longitudinal axis which lies in the plane defined by said principal
rays; and
radiation detecting means for receiving the monochromatic radiation
from
the exit slit of the emission monochromator means..]. .[.6.
Apparatus for measuring radiation from a sample having pairs of
opposed surfaces, the apparatus comprising, in combination:
a source of radiation;
excitation monochromator means for isolating an excitation beam of
monochromatic radiation from said source, the excitation
monochromator means having an excitation entrance slit for
receiving radiation from said source, an excitation exit slit, and
means for directing the excitation beam through said excitation
exit slit;
a first optical system cooperating with the excitation
monochromator for forming a real image of said excitation exit slit
in close juxtaposition with a first surface of said sample;
emission monochromator means for isolating radiation from said
sample, the emission monochromator means having an emission
entrance slit for receiving an emission beam of radiation from said
sample, an emission exit slit, and means for directing
monochromatic radiation from the emission beam through said
emission exit slit;
a second optical system cooperating with the emission monochromator
means for forming an image of said emission entrance slit in close
juxtaposition with a second surface of said sample;
said excitation beam and said sample beam having principal rays
which intersect at said sample, and each of said images having a
longitudinal axis which lies in the plane defined by said principal
rays; and
radiation detecting means for receiving the monochromatic radiation
from the exit slit of the emission monochromator means..]. .[.7.
Apparatus as defined in claim 6, which further comprises, in
combination:
reflective means in facing relationship with a third and a fourth
surface of said sample in position to direct radiation from said
excitation base and said sample back toward said sample..]. .[.8.
Apparatus as defined in claim 6, in which each of said optical
systems includes a pair of mirrors oriented at 45.degree. angles
with respect to the principal ray of the radiation incident
thereto..]. .[.9. Apparatus as defined in claim 8, in which one of
the mirrors in each said pair is spherically concave..]. .[.10.
Apparatus for measuring radiation from a sample, the apparatus
comprising, in combination:
a source of radiation;
excitation monochromator means for isolating an excitation beam of
monochromatic radiation from said source, the excitation
monochromator means having an excitation entrance slit for
receiving radiation from said source, an excitation exit slit
defining a first limiting aperture, and means for directing the
excitation beam through said excitation exit slit, the excitation
monochromator means including means defining a second limiting
aperture for the excitation beam;
means cooperating with the excitation monochromator means for
directing the excitation beam to said sample and for forming first
and second images adjacent the sample of the respective first and
second limiting apertures;
emission monochromator means for isolating radiation from said
sample, the emission monochromator means having an emission
entrance slit defining a third limiting aperture for receiving an
emission beam of radiation from said sample, an emission exit slit,
and means for directing monochromatic radiation from the emission
beam through said emission exit slit, the emission monochromator
means including means defining a fourth limiting aperture for the
emission beam;
means cooperating with the emission monochromator means for
directing the emission beam to the emission entrance slit and for
forming third and fourth images adjacent the sample of the
respective third and fourth limiting apertures;
said excitation beam and said emission beam having principal rays
which intersect at said sample;
radiation detecting means for receiving the monochromatic radiation
from the exit slit of the emission monochromator means..]. .[.11.
Apparatus for measuring radiation from a sample having pairs of
opposed surfaces, the apparatus comprising, in combination:
a source of radiation;
excitation monochromator means for isolating an excitation beam of
monochromatic radiation from said source, the excitation
monochromator means having an excitation entrance slit for
receiving radiation from said source, an excitation exit slit
defining a first limiting aperture, and means for directing the
excitation beam through said excitation exit slit, the excitation
monochromator means including means defining a second limiting
aperture for the excitation beam;
means cooperating with the excitation monochromator means for
forming a first image of said first limiting aperture adjacent a
first surface of said sample and a second image of said second
limiting aperture adjacent a second surface of said sample;
emission monochromator means for isolating radiation from said
sample, the emission monochromator means having an emission
entrance slit defining a third limiting aperture for receiving an
emission beam of radiation from said sample, an emission exit slit,
and means for directing monochromatic radiation from the emission
beam through said emission exit slit, the emission monochromator
means including means defining a fourth limiting aperture for the
emission beam;
means cooperating with the emission monochromator means for forming
a third image of said third limiting aperture adjacent a third
surface of said sample and a fourth image of said fourth limiting
aperture adjacent a fourth surface of said sample;
said excitation beam and said emission beam having principal rays
which intersect at said sample, and each of said images having a
longitudinal axis which lies in the plane defined by said principal
rays; and
radiation detecting means for receiving the monochromatic radiation
from the exit slit of the emission monochromator means..]. .[.12.
Apparatus for measuring radiation from a sample having pairs of
opposed surfaces, the apparatus comprising, in combination:
a source of radiation;
excitation monochromator means for isolating an excitation beam of
monochromatic radiation from said source, the excitation
monochromator means having an excitation entrance slit for
receiving radiation from said source, an excitation exit slit
defining a first limiting aperture, and means for directing the
excitation beam through said excitation exit slit, the excitation
monochromator means including means defining a second limiting
aperture for the excitation beam;
a first optical system cooperating with the excitation
monochromator means for forming a first image of said first
limiting aperture adjacent a first surface of said sample and a
second image of said second limiting aperture adjacent a second
surface of said sample;
emission monochromator means for isolating radiation from said
sample, the emission monochromator means having an emission
entrance slit defining a third limiting aperture for receiving an
emission beam of radiation from said sample, an emission exit slit,
and means for directing monochromatic radiation from the emission
beam through said emission exit slit, the emission monochromator
means including means defining a fourth limiting aperture for the
emission beam;
a second optical system cooperating with the emission monochromator
means for forming a third image of said third limiting aperture
adjacent a third surface of said sample and a fourth image of said
fourth limiting aperture adjacent a fourth surface of said
sample;
said excitation beam and said emission beam having principal rays
which intersect at said sample, and each of said images having a
longitudinal axis which lies in the plane defined by said principal
rays;
the longitudinal axis of said first image extending in a direction
parallel to the principal ray of the emission beam, and the
longitudinal axis of said third image extending in a direction
parallel to the principal ray of the excitation beam; and
radiation detecting means for receiving the monochromatic radiation
from the exit slit of the emission monochromator means..]. .[.13.
Apparatus as defined in claim 12, in which the longitudinal axis of
said second image extends in a direction parallel to the principal
ray of the emission beam, and the longitudinal axis of said fourth
image extends in a direction
parallel to the principal ray of the excitation beam..]. 14.
Apparatus for measuring .Iadd.fluorescent .Iaddend.radiation from a
sample having pairs of opposed surfaces, the apparatus comprising,
in combination:
a source of radiation;
excitation monochromator means for isolating an excitation beam of
monochromatic radiation from said source, the excitation
monochromator means having an excitation entrance slit for
receiving radiation from said source, an excitation exit slit
defining a first limiting aperture, and means for directing the
excitation beam through said excitation exit slit, the excitation
monochromator means including means defining a second limiting
aperture for the excitation beam;
a first optical system for directing the excitation beam toward
said sample, the first optical system forming a first
.[.anamorphic.]. .Iadd.anamorphically distorted .Iaddend.image of
said first limiting aperture adjacent a first surface of said
sample and forming a second .[.anamorphic.]. .Iadd.anamorphically
distorted .Iaddend.image of said second limiting aperture adjacent
a second surface of said sample.Iadd., said first and second sample
surfaces being in spaced opposed relationship with each
other.Iaddend.;
emission monochromator means for isolating radiation from said
sample, the emission monochromator means having an emission
entrance slit defining a third limiting aperture for receiving an
emission beam of radiation from said sample, an emission exit slit,
and means for directing monochromatic radiation from the emission
beam through said emission exit slit, the emission monochromator
means including means defining a fourth limiting aperture for the
emission beam;
a second optical system for receiving the emission beam from said
sample and directing the same to the entrance slit of the emission
monochromator means, the second optical system forming a third
.[.anamorphic.]. .Iadd.anamorphically distorted .Iaddend.image of
said third limiting aperture adjacent a third surface of said
sample and forming a fourth .[.anamorphic.]. .Iadd.anamorphically
distorted .Iaddend.image of said fourth limiting aperture adjacent
a fourth surface of said sample.Iadd., said third and fourth sample
surfaces being in spaced opposed relationship with each other and
being angularly disposed with respect to said first and second
sample surface.Iaddend.;
said excitation beam and said emission beam having principal rays
which intersect at the sample, and each of said images having a
longitudinal axis which lies in the plane defined by said principal
rays; and
radiation detecting means for receiving the monochromatic radiation
from
the exit slit of the emission monochromator means. 15. Apparatus as
defined in claim 14, in which the excitation beam has extreme rays
between said first and second images which illuminate a volume of
said sample in the approximate shape of a right rectangular prism,
and the emission beam has extreme rays between said third and
fourth images which are illuminated by radiation from a volume of
said sample in the approximate shape of a right rectangular prism.
.[.16. Apparatus for measuring radiation from a sample having pairs
of opposed surfaces, the apparatus comprising, in combination:
a source of radiation;
excitation monochromator means for isolating a monochromatic beam
of radiation from said source, the excitation monochromator means
having an excitation entrance slit for receiving radiation from
said source, an excitation exit slit defining a first limiting
aperture, and means for directing the monochromatic beam through
said excitation exit slit, the excitation monochromator means
including means defining a second limiting aperture for the
monochromatic beam;
means cooperating with the excitation monochromator means for
dividing the monochromatic beam into an excitation beam and a
reference beam;
a first optical system for directing the excitation beam toward
said sample, the first optical system forming a first image of said
first limiting aperture adjacent a first surface of said sample and
forming a second image of said second limiting aperture adjacent a
second surface of said sample;
emission monochromator means for isolating radiation from said
sample, the emission monochromator means having an emission
entrance slit defining a third limiting aperture for receiving an
emission beam of radiation from said sample, an emission exit slit,
and means for directing monochromatic radiation from the emission
beam through said emission exit slit, the emission monochromator
means including means defining a fourth limiting aperture for the
emission beam;
a second optical system for receiving the emission beam from said
sample and directing the same to the entrance slit of the emission
monochromator means, the second optical system forming a third
image of said third limiting aperture adjacent a third surface of
said sample and forming a fourth image of said fourth limiting
aperture adjacent a fourth surface of said sample;
said excitation beam and said emission beam having principal rays
which intersect at the sample, and each of said images having a
longitudinal axis which lies in the plane defined by said principal
rays;
radiation detecting means for receiving the monochromatic radiation
from the exit slit of the emission monochromator means; and
means for receiving said reference beam and for directing the same
to said radiation detecting means..]. .[.17. Apparatus as defined
in claim 16, in which the reference beam receiving means includes a
rotary chopper in position to alternately interrupt said reference
beam and said emission beam..]. .[.18. Apparatus as defined in
claim 16, in which the longitudinal axis of said first and second
images extend in directions parallel to the principal ray of the
emission beam, and the longitudinal axes of said third and fourth
images extend in directions parallel to the principal ray of the
excitation beam..]. .[.19. Apparatus as defined in claim 16 which
further comprises, in combination:
a rotary support member for pivoting said sample into a position in
which said first sample surface is in facing relationship with the
excitation beam and said third sample surface is in facing
relationship with the emission beam..]. .[.20. Apparatus as defined
in claim 16, in which the first optical system, the second optical
system and the reference beam receiving means are optically equal
to one another..]. .[.21. Apparatus for measuring radiation from a
sample having pairs of opposed surfaces, the apparatus comprising,
in combination:
a source of radiation;
excitation monochromator means for isolating an excitation beam of
monochromatic radiation from said source, the excitation
monochromator means having an excitation entrance slit for
receiving radiation from said source, an excitation exit slit, and
means for directing the excitation beam through said excitation
exit slit;
means cooperating with the excitation monochromator for forming a
first distorted image of said excitation exit slit adjacent said
sample;
emission monochromator means for isolating radiation from said
sample, the emission monochromator means having an emission
entrance slit for receiving an emission beam of radiation from said
sample, an emission exit slit, and means for directing
monochromatic radiation from the emission beam through said
emission exit slit;
means cooperating with the emission monochromator means for forming
a second distorted image of said emission entrance slit adjacent
said sample, said second distorted image having a length to width
ratio equal to that of said first distorted image;
said excitation beam and said sample beam having principal rays
which intersect at said sample;
reflective means including a pair of concave reflecting surfaces
adjacent said sample in position to receive the respective
excitation and emission beams from said sample and to direct the
beams back through the sample for a second pass, each of said beams
traversing approximately the same volume of the sample as the beam
approaches and is reflected by the corresponding reflecting
surface; and radiation detecting means for receiving the
monochromatic radiation from the exit slit of the emission
monochromator means..]. .[.22. Apparatus as defined in claim 21, in
which each of said reflecting surfaces is spherically concave..].
.[.23. Apparatus for measuring radiation from a sample having pairs
of opposed surfaces, the apparatus comprising, in combination:
a source of radiation;
excitation monochromator means for isolating an excitation beam of
monochromatic radiation from said source, the excitation
monochromator means having an excitation entrance slit for
receiving radiation from said source, an excitation exit slit
defining a first limiting aperture, and means for directing the
excitation beam through said excitation exit slit, the excitation
monochromator means including means defining a second limiting
aperture for the excitation beam;
means cooperating with the excitation monochromator means for
forming a first image of said first limiting aperture adjacent a
first surface of said sample and a second image of said second
limiting aperture adjacent a second surface of said sample;
emission monochromator means for isolating radiation from said
sample, the emission monochromator means having an emission
entrance slit defining a third limiting aperture for receiving an
emission beam of radiation from said sample, an emission exit slit,
and means for directing monochromatic radiation from the emission
beam through said emission exit slit, the emission monochromator
means including means defining a fourth limiting aperture for the
emission beam;
means cooperating with the emission monochromator means for forming
a third image of said third limiting aperture adjacent a third
surface of said sample and a fourth image of said fourth limiting
aperture adjacent a fourth surface of said sample;
said excitation beam and said emission beam having principal rays
which intersect at said sample;
reflective means including a pair of concave reflecting surfaces
adjacent said sample in position to receive the respective
excitation and emission beams from said sample and to direct the
beams back through the sample for a second pass, each of said beams
traversing approximately the same volume of the sample as the beam
approaches and is reflected by the corresponding reflecting
surface; and
radiation detecting means for receiving the monochromatic radiation
from the exit slit of the emission monochromator means..]. .[.24.
Apparatus for measuring radiation from a sample, the apparatus
comprising, in combination:
a source of radiation;
excitation monochromator means for isolating monochromatic
radiation from said source, the excitation monochromator means
receiving radiation from said source and having an excitation exit
slit defining a first aperture and means including a second
aperture for directing a part of the received radiation through
said excitation exit slit in the form of a monochromatic excitation
beam;
first means cooperating with the excitation monochromator means for
directing the excitation beam to said sample and for forming an
image of the excitation exit slit adjacent the sample;
emission monochromator means for isolating radiation from said
sample, the emission monochromator means having an emission
entrance slit for receiving an emission beam of radiation from said
sample;
second means cooperating with the emission monochromator means for
directing the emission beam to the emission entrance slit and for
forming an image of said emission entrance slit adjacent the
sample;
said excitation beam and said emission beam intersecting at said
sample; and
radiation detecting means for receiving monochromatic radiation
from the emission monochromator means;
said first and second beam directing means including means for
forming the respective slit images adjacent said sample with their
longitudinal axes
lying in the plane defined by said intersecting beams..]. .[.25.
Apparatus for measuring radiation from a sample, the apparatus
comprising, in combination:
a source of radiation;
excitation monochromator means for isolating an excitation beam of
monochromatic radiation from said source, the excitation
monochromator means receiving radiation from said source, the
excitation monochromator means receiving radiation from said source
and having an excitation exit slit defining a first aperture and
means including a second aperture for directing a part of the
received radiation through said excitation exit slit in the form of
a monochromatic excitation beam;
first means cooperating with the excitation monochromator means for
directing the excitation beam to said sample and for forming a
distorted image of the excitation exit slit adjacent the
sample;
emission monochromator means for isolating radiation from said
sample, the emission monochromator means having an emission
entrance slit for receiving an emission beam of radiation from said
sample;
second means cooperating with the emission monochromator means for
directing the emission beam to the emission entrance slit and for
forming a distorted image of said emission entrance slit adjacent
the sample;
said excitation beam and said emission beam having axial rays which
intersect at said sample; and
radiation detecting means for receiving the monochromatic radiation
from the emission monochromator means;
said first and second beam directing means including means for
forming said distorted slit images with their longitudinal axes
lying in a plane defined by said intersecting beams..]. .[.26.
Apparatus as defined in claim 25 wherein the exit slit of said
excitation monochromator means and the entrance slit of said
emission monochromator means are both horizontal..]. .[.27.
Apparatus as defined in claim 25 wherein the exit slit of said
excitation monochromator and the entrance slit of said emission
monochromator are both vertical, said first and second beam
directing means including means for rotating said images ninety
degrees..]. 28. Apparatus for measuring .Iadd.fluorescent
.Iaddend.radiation from a sample, the apparatus comprising, in
combination:
a source of radiation;
excitation monochromator means for isolating an excitation beam of
monochromatic radiation from said source, the excitation
monochromator means including means defining first and second
limiting apertures;
first means cooperating with the excitation monochromator means for
directing the excitation beam to said sample and for .[.forming.].
.Iadd.focusing .Iaddend.a first .Iadd.anamorphically
.Iaddend.distorted image .[.adjacent.]. .Iadd.on .Iaddend.the
sample of one of said first and second limiting apertures, said
first .Iadd.anamorphically .Iaddend.distorted image having a length
to width ratio larger than the length to width ratio of the
corresponding aperture;
emission monochromator means for isolating an emission beam of
radiation from said sample, the emission monochromator means
including means defining third and fourth limiting apertures;
second means cooperating with the emission monochromator means for
directing the emission beam to the emission monochromator means and
for .[.forming.]. .Iadd.focusing .Iaddend.a second
.Iadd.anamorphically .Iaddend.distorted image .[.adjacent.].
.Iadd.on .Iaddend.the sample of one of said third and fourth
limiting apertures, said second .Iadd.anamorphically
.Iaddend.distorted image having a length to width ratio equal to
that of said first distorted image and larger than the length to
width ratio of the corresponding aperture;
said excitation beam and said emission beam having axial rays which
intersect at said sample, and each of said images having a
longitudinal axis which lies in the plane defined by said
intersecting .[.beams.]. .Iadd.rays.Iaddend.; and
radiation detecting means for receiving monochromatic radiation
from the
emission monochromator means. 29. Apparatus as defined in claim 28
wherein said first and second beam directing means respectively
.[.form.]. .Iadd.focus .Iaddend.third and fourth distorted images
.[.adjacent.].
.Iadd.on .Iaddend.the sample of the other limiting apertures. 30.
Apparatus as defined in claim 29 wherein the .Iadd.sample has pairs
of opposed sides, and wherein the .Iaddend.distorted images of the
apertures of the excitation monochromator means are respectively
adjacent two opposite sides of said sample and the distorted images
of the apertures of the emission monochromator means are
respectively adjacent two other
opposite sides of said sample. 31. Apparatus as defined in claim 30
wherein the distorted images of said apertures adjacent said sample
all have approximately the same length.
Description
BACKGROUND OF THE INVENTION
This invention relates to radiation measuring apparatus and more
particularly to fluorescence spectrophotometers of the type in
which a sample is irradiated with light of one wavelength and its
emission spectrum is observed through the use of a monochromator
and a detection system. As used herein and in the appended claims,
the term "light" includes not only visible light but also radiation
having wavelengths longer and shorter than the visible
spectrum.
In the measurement of fluorescence and exitation spectra it is
customary to illuminate a sample with monochromatic light from an
intense source and to observe the light emitted by the sample with
a monochromator and a photoelectric detection system. Either the
excitation or the emission wavelength may be scanned to record the
intensity of the spectrum as a function of excitation or emission
wavelength.
Heretofore, radiation measuring apparatus of the foregoing type
exhibited certain disadvantages. One of the more significant
problems was the comparatively low intensity of the output signal
particularly in measuring the spectra of dilute materials. In the
usual form of apparatus a magnified image of the light source was
focused on the entrance slit of the excitation monochromator, and a
reduced image of the exit slit was focused on the sample by means
of a first optical system. Fluorescence from the sample was
collected by a second optical system and was focused on the
entrance slit of an emission monochromator such that the signal at
the exit slit of this latter monochromator was proportional to the
intensity of the light at the selected wavelength. Attempts to
increase the intensity of the signal commonly included a reduction
in height of the image of the excitation monochromator's exit slit.
These attempts were only partialy successful, however, and the
measured intensity continued to be insufficient to obtain readings
of the desired accuracy for low intensity samples.
SUMMARY
One general object of this invention, therefore, is to provide new
and improved apparatus for measuring the intensity of light emitted
by a sample with respect to the intensity of the light exciting the
sample.
More specifically, it is an object of this invention to provide
radiation measuring apparatus which is effective to produce a high
intensity fluorescence signal.
Another object of the invention is to provide a fluorescence
spectrophotometer utilizing comparatively simple optical components
which is economical to manufacture and reliable in operation.
In a preferred embodiment of the invention, the apparatus comprises
a radiation source and an excitation monochromator for isolating an
excitation beam of monochromatic radiation from the source. The
excitation monochromator includes first and second limiting
apertures for the monochromatic radiation which are respectively
formed by the excitation exit slit and the monochromator's
dispersing means. The radiation is received by a first optical
system, and is directed toward the sample being evaluated to cause
the sample to emit fluorescence. A second optical system collects
fluorescence from the sample and focuses a beam of the collected
radiation on the entrance slit of an emission monochromator to
produce a monochromatic emission beam at the monochromator's exit
slit. In a manner similar to that of the excitation monochromator,
the emission monochromator includes third and fourth limiting
apertures which are formed by the emission entrance slit and the
dispersing means and are imaged adjacent the sample. The emission
beam from the exit slit is received by a photoelectric detector to
provide a signal proportional to the intensity of the fluorescent
light emitted by the sample at the selected wavelength.
In accordance with one feature of the invention, the longitudinal
axes of the slit images adjacent the sample lie in a single plane
defined by the axial rays of the excitation and fluorescence beams.
In some cases this is accomplished by an anamorphic mirror and lens
arrangement in each of the optical systems which orients the images
at ninety degree angles with respect to the exit and entrance slits
of the respective excitation and emission monochromators, while in
other embodiments the slits themselves are oriented parallel to the
plane. The arrangement is such that each point along the entrance
slit of the emission monochromator is filled with light of an
intensity corresponding to illumination of the sample with light
from all points along the length of the excitation monochromator's
exit slit, with the result that a very substantial increase in the
intensity of the output signal is achieved.
In accordance with another feature of several particularly
advantageous embodiments of the invention, an image of the first
limiting aperture is formed adjacent a first surface of the sample,
and an image of the second limiting aperture is formed adjacent a
second surface of the sample. Similarly, an image of the third
limiting aperture is formed adjacent a third surface of the sample,
and an image of the fourth limiting aperture is formed adjacent a
fourth surface of the sample. .Iadd.For a particular instrument
employing simple lenses the positions of the various images
relative to the sample will of course change during variations in
wavelength, but in these embodiments it is important that a given
image be located adjacent the specified sample surface over at
least a substantial portion of the wavelength range for which the
instrument is designed. .Iaddend. The widths of the slits
advantageously are of the same order of magnitude, and the
magnification is chosen to make the height of each radiation beam
passing through the sample about the same at each of the sample
surfaces, to provide an additional improvement in the output
intensity.
In accordance with a further feature of certain embodiments of the
invention, the extreme rays between the images of the two apertures
in the excitation monochromator illuminate a sample volume in the
approximate shape of a right rectangular prism, and the extreme
rays between the two images of the apertures in the emission
monochromator are illuminated from a sample volume which similarly
is in the shape of a right rectangular prism. The width of the beam
passing through the sample is comparatively uniform and is
maintained as small as practical, with the result that the
intensity of the output signal is further increased.
The present invention, as well as further objects and advantages
thereof, will be understood more clearly and fully from the
following description of certain preferred embodiments, when read
with reference to the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a simplified schematic plan view of a fluorescence
spectrophotometer in accordance with one illustrative embodiment of
the invention.
FIG. 1A is an enlarged schematic plan view of the light paths
adjacent the sample holder of the spectrophotometer shown in FIG.
1.
FIG. 1B is an enlarged fragmentary isometric view of the sample
holder and optical systems for the spectrophotometer of FIG. 1.
FIG. 2 is a simplified schematic elevational view of a portion of
the spectrophotometer shown in FIG. 1, as seen from the line 2--2
in FIG. 1.
FIG. 3 is a simplified schematic plan view of a fluorescence
spectrophotometer in accordance with another illustrative
embodiment of the invention.
FIG. 4 is a simplified schematic elevational view of a portion of
the spectrophotometer of FIG. 3, as seen from the line 4--4 in FIG.
3.
FIG. 5 is an enlarged plan view of the sample holder employed in
the spectrophotometer of FIGS. 3 and 4.
DESCRIPTION OF CERTAIN PREFERRED EMBODIMENTS
Referring to FIG. 1 of the drawings, there is shown a schematic
representation of a fluorescence spectrophotometer having a xenon
arc or other suitable source 10 of visible or invisible light.
Light from the source 10 is collected by an ellipsoidal mirror 11
and is focused onto the entrance slit 12 of an excitation
monochromator 13. The entrance slit 12 is of rectangular
configuration with its longitudinal axis extending in a direction
perpendicular to the plane of the drawing. The monochromator 13 is
of the .[.Ebert.]. .Iadd.Czerney-Turner .Iaddend.type and includes,
in addition to the entrance slit 12, a collimating mirror 15, a
diffraction grating 16, a telescope mirror 17 and an exit slit 18
which likewise has its longitudinal axis extending perpendicular to
the plane of the drawing. The light entering the entrance slit 12
is reflected by the mirror 15 to the grating 16 and then from the
mirror 17 to the exit slit 18. The periphery of the grating 16
forms a limiting aperture 19, for purposes that will become more
fully apparent hereinafter.
The light emerging from the excitation slit 18 is in the form of a
monochromatic excitation beam. The monochromatic beam is received
by a first optical system which comprises superimposed flat and
spherical mirrors 20 and 21, a cylindrical lens 22 and a spherical
lens 23. The mirrors 20 and 21 are oriented at 45.degree. angles
with respect to the principal ray of the incident beam to direct
the light upwardly and then horizontally toward the lenses 22 and
23. The mirrors 20 and 21 reflect the excitation beam at right
angles to its original direction.
The convex spherical lens 23 focuses the excitation beam on a
sample holder or cell indicated generally at 25. The sample cell 25
is of square configuration and includes opposed pairs of flat
surfaces 26 and 27, and 28 and 29. As best shown in FIG. 1A, the
lens 23 forms a real horizontal image 30 of the aperture defined by
the excitation exit slit 18. The image 30 is located closely
adjacent the surface 26 of the sample cell 25.
In addition to the excitation exit slit image 30, the first optical
system is effective to form an image 31 of the grating aperture 19.
The image 31 is located in close proximity with the surface 27 of
the sample cell 25, that is, the surface opposite that adjacent the
image 30. The longitudinal axis of each of the images 30 and 31
lies in a single plane parallel to the plane of the drawing.
It will be noted that the flat angular mirror 20 and the spherical
angular mirror 21 serve to orient the images 30 and 31 at right
angles to the direction of the exit slit 18. Thus, the mirrors 20
and 21 rotate the images through a 90.degree. angle such that their
longitudinal dimensions are parallel to the plane of the drawing.
The mirrors 20 and 21, together with the lenses 22 and 23, form the
excitation optical system for the instrument and direct the
excitation beam from the exit slit 18 to the sample 25. The optical
system is anamorphic, and its magnification is such that the length
and width of the exit slit image 30 are approximately equal to the
length and width of the aperture image 31, respectively. With this
arrangement, the extreme rays between the images 30 and 31
illuminate a sample volume in the approximate shape of a right
rectangular prism. The width of the beam passing through the sample
is comparatively uniform and is maintained as small as practical,
with the result that the intensity of the beam is substantially
increased.
To provide a further increase in the intensity of the light beam
passing through the sample 25, a spherical mirror 32 is located a
short distance behind the sample adjacent the sample surface 27
opposite that facing the excitation monochromator 13. The mirror 32
directs the excitation beam back through the sample for a second
pass.
The excitation beam passing through the sample 25 excites the
sample and causes it to emit fluorescence of a wavelength different
from that of the exciting light. This fluorescence is emitted in
all directions. A portion of the emitted fluorescence is collected
by a spherical lens 33 and is directed thereby through a
cylindrical lens 34 to a spherical off-axis mirror 35 and a flat
off-axis mirror 36. The lenses 33 and 34 and the mirrors 35 and 36
form an anamorphic emission optical system which is identical with
the excitation optical system comprising the mirrors 20 and 21 and
the lenses 22 and 23. In a manner similar to that of the mirrors 20
and 21, the mirrors 35 and 36 are oriented at 45.degree. angles
with respect to the principal rays of the emission beam collected
from the sample 25. To further increase the intensity of the
emission beam, a spherical mirror 37 is positioned a short distance
behind the sample 25 in facing relationship with the sample surface
29. The mirror 37 collects additional fluorescence from the sample
and directs it through the emission optical system.
The fluorescent emission beam from the emission optical system is
directed by the spherical mirror 36 to the entrance slit 39 of an
emission monochromator 40. This entrance slit is of rectangular
configuration and has its longitudinal axis extending in a
direction perpendicular to the plane of the drawing. The
monochromator 40 is similar to the excitation monochromator 13 and,
in addition to the entrance slit 39, includes a collimating mirror
42, a diffraction grating 43, a telescope mirror 44 and an exit
slit 45 parallel to the entrance slit. The fluorescence enters the
entrance slit 39, is reflected by the collimator 42 to the grating
43 and is then focused by the telescope 44 on the exit slit 45. The
periphery of the grating 43 defines a limiting aperture 46.
The light emerging from the exit slit 45 comprises a selected,
highly monochromatic portion of the luminescent emission from the
sample 25. The emerging light is received by a photoelectric
detector 50 which is of conventional construction and preferably is
of a type which exhibits high sensitivity at the particular
wavelengths of interest. The detector 50 produces an output signal
proportional to the intensity of the light from the exit slit
45.
The spherical lens 33 in the optical system for the emission
monochromator 40 forms an optical image 52 of the aperture defined
by the emission entrance slit 39. This image is located in close
juxtaposition with the surface 28 of the sample cell 25. Similarly,
an optical image 53 of the grating aperture 46 is formed adjacent
the opposite surface 29 of the sample cell. By reason of the
off-axis angular orientation of the mirrors 35 and 36, the
longitudinal axes of the images 52 and 53 lie in a single plane
parallel to the plane of the drawing and at right angles to the
longitudinal axis of the entrance slit 39. The extreme rays between
the images 52 and 53 outline a sample volume in the approximate
shape of a right rectangular prism, and the width of the beam
passing through the sample is comparatively uniform and is as small
as practical.
The principal rays of the beam from the excitation monochromator 13
and the beam approaching the emission monochromator 40 intersect at
the sample cell 25. The longitudinal axis of each of the anamorphic
aperture images 30, 31, 52 and 53 lies in a plane defined by these
principal rays. The exit slit 18 for the excitation monochromator
13 and the entrance slit 39 for the emission monochromator 40, on
the other hand, extend in directions perpendicular to the plane
defined by the principal rays. The image 30 of the exit slit 18 is
parallel to the path of the emission beam, and the image 52 of the
entrance slit 39 is parallel to the path of the excitation beam.
The arrangement is such that each point along the entrance slit 39
is filled with light of an intensity corresponding to the
irradiation of the sample with light from the entire length of the
exit slit 18.
The resulting increase in the amount of fluorescent light collected
by the entrance slit 39 in theory may be as large as the length to
width ratio of the image 30 of the exit slit 18. In terms of the
properties of the monochromators, and with slit and grating images
of equal length and equal width, the ratio is equivalent to the
square root of the ratio of the length of the exit slit multiplied
by the angular slit aperture in a plane including the longitudinal
axis of the slit divided by the width of the slit multiplied by the
angular aperture at the slit in the transverse plane. Because of
varying slit widths and aberrations the predicted increase, while
still substantial, may not be realized particularly for
comparatively large length to width ratios. In cases in which the
actual height of the beam is approximately the same adjacent the
opposite surfaces of the sample, however, the actual increase
closely approaches the theoretical value, and signal increases may
be achieved which are approximately 5 to 10 times that realized by
conventional fluorescence instrumentation.
In the excitation and emission optical systems the spherical
.[.lenses.]. .Iadd.mirrors .Iaddend.introduce a degree of
astigmatism in the slit and grating images. This astigmatism is
corrected by the cylindrical lenses in the systems. The systems
have anamorphic properties that distort the slit and grating images
in such a way that they both have the same length to width
ratio.
The mirrors 32 and 37 serve to direct the respective excitation and
emission beams back through the sample 25 for a second pass. The
mirrors 32 and 37 are spherically concave with centers of
curvatures at the center of the sample. With this arrangement each
of the mirrors forms an image of the facing surface of the sample
adjacent the opposite surface and also forms an image of the
opposite surface adjacent the facing surface. The increase in
intensity as a result of these mirrors is almost four times the
intensity of instruments in which the mirrors are omitted.
The embodiment illustrated in FIGS. 1 and 2 employs the respective
pairs of angular mirrors 20 and 21 and 35 and 36 to orient each of
the slit images 30 and 52 in a direction parallel to the direction
of travel of the light of the other beam. This same result may be
achieved through the use of various other optical systems which
eliminate the need for angularly disposed mirrors. In the
embodiment shown in FIGS. 3 and 4, for example, the slits
themselves are located such that they extend in directions parallel
to the direction of the opposite beam. The instrument of these
latter figures includes a xenon arc light source 60 and an
ellipsoidal mirror 61 which focuses the light onto the entrance
slit 62 of an excitation monochromator 63. Contrary to the
embodiment illustrated in FIGS. 1 and 2, the entrance slit 62 has a
longitudinal axis which lies in the plane of the drawing. A
selected, monochromatic portion of the light from the entrance slit
62 is reflected by a concave diffraction grating 65 onto an exit
slit 70 which likewise has a longitudinal axis lying in the plane
of the drawing. As in the case of the previously described
embodiment, the periphery of the grating 65 forms a limiting
aperture 71 for the monochromatic light.
The monochromatic excitation beam emerging from the exit slit 70 is
received by a first optical system which includes a torroidal lens
72 and a beam splitter 74. The beam splitter 74 illustratively is
in the form of a flat quartz plate. A known fraction of this light
passes through the splitter 34 and is directed by a concave
spherical mirror 75 to a convex spherical lens 76.
The lens 76 focuses the excitation beam from the mirror 75 on a
sample cell 78. The configuration of the cell 78 is similar to that
of the cell 25 (Fig. 1) described heretofore and includes pairs of
opposed surfaces 80 and 81 and 82 and 83. The lens is effective to
form a real horizontal image of the aperture defined by the
excitation exit slit 18, and this image is located between the lens
and the sample surface 80. Similarly, a real horizontal image of
the grating aperture 71 is formed adjacent the opposite sample
surface 81.
As best shown in FIG. 5, the sample cell 78 is supported adjacent
the periphery of a rotatable table 85. The table 85 is of circular
configuration and includes three additional sample cells 88, 89 and
90 which may contain different fluorescent materials and likewise
are provided with the opposed pairs of surfaces 80 and 81 and 82
and 83. The various sample cells are spaced at 90.degree. intervals
on the table 85 such that the sample being evaluated may be readily
changed merely by pivoting the table through a corresponding
angle.
A pair of mirrors 95 and 96 is located adjacent each of the sample
cells 78,88,89 and 90 in spaced juxtaposition with the surfaces 81
and 83, respectively. The mirrors 95 and 96 are optically
transparent except for spherically concave reflective surfaces 99
and 100 on their rear faces. Contrary to the sample mirrors in the
embodiment of FIGS. 1 and 2, these surfaces are positioned at the
approximate locations of the corresponding grating images with
their centers of curvatures at the approximate locations of the
associated slit images. The slit images are reimaged back on
themselves to further increase the intensity of the output
signal.
Fluorescence from the sample 78 is collected by a convex spherical
lens 105 (FIG. 3) in the emission optical system for the
instrument. The fluorescent emission beam then passes through a
lens 107 and is focused by a lens 108 on the entrance slit 109 of
an emission monochromator 110. The longitudinal axis of the
entrance slit 109 lies in the plane of the drawing and is in
coplanar relationship with that of the excitation exit slit 70.
The emission beam entering the exit slit 109 is received by a
concave diffraction grating 112 having a grating aperture 113 and
is directed to an exit slit 114. The longitudinal axis of this
latter slit is coplanar with that of the remaining slits. The
fluorescence emerging from the exit slit 114 is received by a
reflecting prism 115 and is directed thereby to a photoelectric
detector 116 to provide an output signal proportional to the
intensity of the light from the exit slit.
The emission optical system between the sample 78 and the entrance
slit 109 is optically the same as the excitation optical system
between the exit slit 70 and the sample except for the use of the
cylindrical lens 107 in place of the spherical mirror 75. The
emission optical system forms images of the exit slit 109 and the
grating aperture 113 in respective juxtaposition with the surfaces
82 and 83 of the sample.
The longitudinal axes of the excitation exit slit 70 and the
emission entrance slit 109 lie in a single plane defined by the
principal rays of the beam from the excitation monochromator 63 and
the beam approaching the emission monochromator 110. The images of
the slits 70 and 109, together with the images of the grating
apertures 71 and 113, similarly have longitudinal axes which lie in
this plane. As in the previously described embodiment, each point
on the emission entrance slit 109 is filled with light of an
intensity corresponding to the irradiation of the sample with light
from the entire length of the excitation exit slit 70. The
resulting increase in intensity is further enhanced through the use
of the mirrors 95 and 96 adjacent the sample cell in the manner
described heretofore.
As has been explained, the beam splitter 74 serves to pass a known
fraction of the light from the excitation monochromator 63 to the
mirror 75, the lens 76 and the sample 78. The remaining fraction is
reflected by the splitter 75 through successive lenses 122 and 123
to the reflection prism 115 and then to the photoelectric cell 116.
The remaining fraction is used as a reference beam and is
periodically interrupted by a continuously rotating chopper 120
between the lens 123 and the photocell 116. The chopper 120 is
oriented between the lenses 107 and 108 in position to also
periodically interrupt the fluorescent emission beam. As will be
understood, the chopper is provided with suitable cutouts (not
visible in the drawings) to simultaneously admit fluorescence to
the photocell and block the reference beam and to thereafter block
the fluorescent beam and pass the reference beam to the
photocell.
The photoelectric cell 116 is thus alternately illuminated by light
from the luminescent sample 78 and by reference light from the
excitation monochromator 63. The light detected by the photocell is
alternately representative of the unknown luminescent intensity
from the sample and the intensity of the reference beam.
Through the use of conventional electrical circuitry, the output
signals from the photocell may be translated into a net output
signal corresponding to the ratio of the net sample signal to the
net reference signal.
In each of the illustrated embodiments of the invention the
excitation and emission beams are directed back for a second pass
through the sample by the concave spherical mirrors 32 and 37 (FIG.
1) or by the concave spherical mirrors 95 and 96 (FIG. 3). One
advantage of this arrangement over the conventional use of flat
mirrors is that the radiation reflected by each mirror illuminates
approximately the same volume of the sample as the radiation
approaching the mirror. Extraneous signals due to scattering
effects are thus maintained at a minimum, and substantially the
full benefit of the mirrors is achieved in providing the desired
increase in intensity.
The terms and expressions which have been employed are used as
terms of description and not of limitation, and there is no
intention in the use of such terms and expressions of excluding any
equivalents of the features shown and described or portions
thereof, but it is recognized that various modifications are
possible within the scope of the invention claimed.
* * * * *