U.S. patent application number 16/126998 was filed with the patent office on 2019-08-08 for spectrometer.
The applicant listed for this patent is MKS TECHNOLOGY (D/B/A SNOWY RANGE INSTRUMENTS), MKS TECHNOLOGY (D/B/A SNOWY RANGE INSTRUMENTS). Invention is credited to Shane A. Buller, Keith T. Carron, Mark A. Watson, Sean Patrick Woodward.
Application Number | 20190242751 16/126998 |
Document ID | / |
Family ID | 55631671 |
Filed Date | 2019-08-08 |
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United States Patent
Application |
20190242751 |
Kind Code |
A1 |
Carron; Keith T. ; et
al. |
August 8, 2019 |
SPECTROMETER
Abstract
Spectrometers and methods for determining the presence or
absence of a material in proximity to and/or combined with another
material are provided. In one particular example, a spectrometer is
provided that includes a light source, a detector and an optical
system. In this implementation, the light source is configured to
provide an excitation incident beam. The detector is configured to
detect a spectroscopy signal. The optical system is configured to
direct the excitation incident beam toward a sample at a non-zero
angle from a zero-angle reference. The optical system is further
configured to receive a spectroscopy signal from the sample and
provide the spectroscopy signal to the detector. The detector is
configured to remove a spectral interference component of the
spectroscopy signal.
Inventors: |
Carron; Keith T.;
(Centennial, WY) ; Buller; Shane A.; (Laramie,
WY) ; Watson; Mark A.; (Laramie, WY) ;
Woodward; Sean Patrick; (Laramie, WY) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
MKS TECHNOLOGY (D/B/A SNOWY RANGE INSTRUMENTS) |
Centennial |
WY |
US |
|
|
Family ID: |
55631671 |
Appl. No.: |
16/126998 |
Filed: |
September 10, 2018 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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14874378 |
Oct 2, 2015 |
10072984 |
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16126998 |
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62058926 |
Oct 2, 2014 |
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62192023 |
Jul 13, 2015 |
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62234522 |
Sep 29, 2015 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G01J 3/0297 20130101;
G01J 3/4412 20130101; G01N 2201/12 20130101; G01N 21/65 20130101;
G01J 3/021 20130101; G01J 3/10 20130101; G01J 3/027 20130101; G01J
3/0208 20130101; G01N 2201/0612 20130101; G01N 2021/4711 20130101;
G01N 2201/068 20130101; G01J 3/44 20130101 |
International
Class: |
G01J 3/44 20060101
G01J003/44; G01J 3/02 20060101 G01J003/02; G01N 21/65 20060101
G01N021/65; G01J 3/10 20060101 G01J003/10 |
Claims
1. A spectrometer comprising: a light source adapted to provide an
excitation incident beam; a detector adapted to detect a
spectroscopy signal; and an optical system adapted to direct the
excitation incident beam toward a sample at a non-zero angle from a
zero-angle reference, receive a spectroscopy signal from the sample
and provide the spectroscopy signal to the detector, wherein the
detector is adapted to remove a spectral interference component of
the spectroscopy signal.
2. The spectrometer of claim 1 wherein the detector is adapted to
remove the spectral interference component through spectral
subtraction.
3. The spectrometer of claim 1 wherein the detector is adapted to
remove the spectral interference component through spectral
subtraction of at least one known component.
4. The spectrometer of claim 1 wherein the detector is adapted to
remove the spectral interference component through spectral
subtraction of at least one known component stored in a
library.
5. The spectrometer of claim 4 wherein the library stores spectral
interference components of a plurality of known materials.
6. The spectrometer of claim 4 wherein the plurality of known
materials includes a plurality of containers.
7. The spectrometer of claim 4 wherein the plurality of known
materials includes a plurality of plastic containers.
8. The spectrometer of claim 1 wherein the detector is adapted to
receive a plurality of spectroscopy signals from the sample.
9. The spectrometer of claim 8 wherein the plurality of
spectroscopy signals correspond to a plurality of incident beams
directed toward the sample at different angles and/or offsets from
a zero-axis line.
10. A spectrometer comprising: a light source adapted to provide an
excitation incident beam; a detector adapted to detect a
spectroscopy signal; and an optical system adapted to direct the
excitation incident beam toward a sample at a non-zero angle from a
zero-axis reference, receive a spectroscopy signal from the sample
and provide the spectroscopy signal to the detector, wherein the
detector is adapted to compare a plurality of spectroscopy signals
corresponding to a plurality of incident beams directed toward the
sample from a plurality of different non-zero angles and/or offsets
from the zero-axis reference to identify at least one component of
the spectroscopy signal corresponding to the sample.
11. The spectrometer of claim 10 wherein the optical system is
adapted to receive the spectroscopy signal at least generally along
the zero-axis reference.
12. The spectrometer of claim 10 wherein the detector is adapted to
identify the at least one component of the spectroscopy signal
corresponding to the sample via spectral subtraction.
13. The spectrometer of claim 10 wherein the detector is adapted to
identify the at least one component of the spectroscopy signal
corresponding to the sample via spectral subtraction of at least
one known component.
14. The spectrometer of claim 10 wherein the detector is adapted to
identify the at least one component of the spectroscopy signal
corresponding to the sample via spectral subtraction of at least
one known component stored in a library.
15. The spectrometer of claim 14 wherein the library stores
spectral interference components of a plurality of known
materials.
16. The spectrometer of claim 14 wherein the plurality of known
materials includes a plurality of containers.
17. The spectrometer of claim 14 wherein the plurality of known
materials includes a plurality of plastic containers.
18. A method of measuring Raman scattering from layers within a
sample comprising: exciting Raman scattering at a nonzero angle
relative to a normal angle of incidence relative to the sample;
using multiple angles to interrogate the different depths within
the sample; collecting Raman spectra at the normal angle of
incidence to the surface; and using statistical methods to derive
the different layers within the sample.
19. (canceled)
20. (canceled)
21. (canceled)
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. application
number Ser. No. 14/874,378, filed Oct. 2, 2015, which claims the
benefit of provisional application numbers 62/058,926, filed Oct.
2, 2014, 62/192,023 filed Jul. 13, 2015 and 62/234,522 filed Sep.
29, 2015. All of which are hereby incorporated by reference,
including all appendices, as though fully set forth herein.
BACKGROUND
Field
[0002] The instant invention relates to spectrometers configured to
reduce interference caused by a material disposed adjacent
(directly or indirectly adjacent) and/or proximate (e.g., in close
proximity) to a sample of interest.
Background
[0003] It is well known that Raman spectroscopy can be performed at
angles other than zero degrees. The popular zero degree method,
also known as epi-illumination, has advantages with regard to
alignment. For example, the method described by Carron et al. in
U.S. Pat/ No. 7,403,281 entitled "Raman Spectrometer," which is
hereby incorporated by reference in its entirety as if fully set
forth herein, describes an epi-illumination scheme in which a
system operator does not need to align the laser excitation at the
sample with the collection optics and small aperture. This is
possible because the manufacturer pre-aligns the beams with a beam
splitter.
[0004] While this approach is creates an easy to use method for
Raman spectroscopy it can also create a problem when an
illumination beam of a spectrometer passes through a different
material to illuminate a sample. This may create a region of
interference 2 as illustrated in FIG. 1. The interference may arise
from a container material and/or a material between the container
surface and the desired sample. Dr. Carron in his PhD dissertation,
Surface Enhanced Resonance Raman, Resonance Hyper-Raman, and Hyper
Raman spectroscopy of Molecules Absorbed to Thin Metal Films (1985,
Northwestern University), describes a method of providing an
excitation signal 3 at an angle 4 to eliminate and/or reduce the
region of interference 2 shown in FIG. 1. FIG. 2, taken from
Carron's dissertation (page 151), illustrates this method. The
approach removed Raman scattering from a window material 6 or
solution 8 prior to the sample of interest 10.
[0005] FIG. 3 and FIG. 4 illustrate in detail the advantage of the
off-axis method used by Canon (1985). In FIG. 3, for example an
excitation signal 3 is directed toward a sample 10 at an off-axis
angle 4 by a minor 12. The excitation signal 3 travels through a
window material 6 and a solution 8 to the sample 10. FIG. 4
illustrates how a spatial filter 11 of a disperse Raman system may
be used to remove interference 12, collectively corresponding to
interference 13 from a window 6 and interference 14 from another
material, such as the solution 8, disposed prior to the sample 10.
The spatial filter 11, in contrast, passes an image/Raman
scattering 15 corresponding to the sample 10 to a detector. Raman
scattering from other materials (e.g., the window 6 and/or solution
8) or other interference such as fluorescence can be removed by the
spatial filter 11.
BRIEF SUMMARY
[0006] Spectrometers and methods for determining the presence or
absence of a material in proximity to and/or combined with another
material are provided. In one particular example, a spectrometer is
provided that includes a light source, a detector and an optical
system. In this implementation, the light source is configured to
provide an excitation incident beam. The detector is configured to
detect a spectroscopy signal. The optical system is configured to
direct the excitation incident beam toward a sample at a non-zero
angle from a zero-angle reference. The optical system is further
configured to receive a spectroscopy signal from the sample and
provide the spectroscopy signal to the detector. The detector is
configured to remove a spectral interference component of the
spectroscopy signal.
[0007] In other implementations, spectrometers and methods for
determining the presence or absence of a material in proximity to
and/or combined with another material are also provided. In this
implementation, the spectrometer includes a light source, a
detector and an optical system. The light source is configured to
provide an excitation incident beam. The detector is configured to
detect a spectroscopy signal. The optical system is configured to
direct the excitation incident beam toward a sample at a non-zero
angle from a zero-axis reference, receive a spectroscopy signal
from the sample and provide the spectroscopy signal to the
detector. The detector is further configured to compare a plurality
of spectroscopy signals corresponding to a plurality of incident
beams directed toward the sample from a plurality of different
non-zero angles and/or offsets from the zero-axis reference to
identify at least one component of the spectroscopy signal
corresponding to the sample.
[0008] In other implementations, further spectrometers and methods
for determining the presence or absence of a material in proximity
to and/or combined with another material are also provided. In one
implementation, for example, a system or method provide for
measuring Raman scattering from layers within a sample. The system
and method excite Raman scattering at a nonzero angle relative to a
normal angle of incidence relative to the sample. The system and
method also use multiple angles to interrogate the different depths
within the sample and collect Raman spectra at the normal angle of
incidence to the surface; and using statistical methods to derive
the different layers within the sample.
[0009] In yet other implementations, spectrometers and methods for
determining the presence or absence of a material in proximity to
and/or combined with another material are also provided. In one
implementation, for example, a system and method of measuring Raman
scattering from layers within a sample excite Raman scattering by
directing an excitation beam toward the sample at a nonzero angle
relative to a normal angle of incidence relative to the sample;
translat the using multiple angles to interrogate the different
depths within the sample; collect Raman spectra at normal incidence
to the surface; and use statistical methods to derive the different
layers within the sample.
[0010] In yet other implementations, spectrometers and methods for
determining the presence or absence of a material in proximity to
and/or combined with another material are also provided. In one
implementation, for example, a system and method of measuring Raman
scattering from layers within a sample excite Raman scattering at a
nonzero angle relative to a normal angle of incidence relative to
the sample; collect collecting Raman spectra at the normal angle of
incidence to the surface; collect a spectrum of a first layer
without ingredients; collect a spectrum of the first layer and a
second layer; and determine a spectrum of the second layer through
normalization against the spectrum of the first layer.
[0011] The foregoing and other aspects, features, details,
utilities, and advantages of the present invention will be apparent
from reading the following description and claims, and from
reviewing the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] FIG. 1 depicts an example of a region of interference in a
spectroscopy application due to epi-illumination.
[0013] FIG. 2 depicts an example method of providing an excitation
signal at an angle to eliminate and/or reduce the region of
interference shown in FIG. 1.
[0014] FIG. 3 depicts an example of the method of FIG. 2.
[0015] FIG. 4 depicts an example of the method of FIG. 2.
[0016] FIG. 5 depicts example implementation of a Raman system
including a non-zero angle excitation beam configured to excite
first and second layers of a sample.
[0017] FIG. 6 depicts an example implementation of a spectrometer
configured to reduce interference caused by a material disposed
adjacent (directly or indirectly) to a sample of interest.
[0018] FIG. 7 depicts an example system configured to examine
layers of a sample.
[0019] FIG. 8 depicts example of a spectral subtraction for a
mixture matching approach for the system shown in FIG. 7.
[0020] FIGS. 9, 10 and 11 depict example methods using multiple
data points at different angles where a multispectral method of
Principle Component Analysis or Independent Component Analysis was
used to extract the signal from the two layers.
[0021] FIG. 12A depicts an example implementation of a spectrometer
in which an optical system of the spectrometer is configured to
direct an incident beam toward one or more moveable mirrors of the
spectrometer.
[0022] FIG. 12B depicts an example implementation of a spectrometer
in which an optical system of the spectrometer is configured to
direct an incident beam toward one or more moveable mirrors of the
spectrometer.
[0023] FIG. 13 depicts an example implementation of a spectrometer
in which the optical system of the spectrometer includes separate
excitation and collection optical paths.
[0024] FIG. 14 depicts an example implementation of a spectrometer
configured to direct an incident beam at varying angles through a
common location at a surface of a sample and/or material.
[0025] FIG. 15 depicts an example implementation of a spectrometer
configured to direct an excitation beam toward the sample at
different angles.
[0026] FIG. 16 depicts an example implementation of a method for
determining one or more spectra corresponding to a second layer of
a sample.
[0027] FIG. 17 depicts an example implementation of a method of
using subtraction of a normalized standard deviation from an
average to produce a spectrum of a second layer.
[0028] FIG. 18 depicts another example implementation of a method
of using subtraction of a normalized standard deviation from an
average to produce a spectrum of a second layer.
[0029] FIG. 19 depicts an example implementation of a method of
extracting spectra for an external container layer and an internal
content layer disposed within the external container layer.
[0030] FIG. 20 depicts an example implementation of a system
configured to sample a material disposed within/behind an outer
layer.
[0031] FIG. 21 depicts another example implementation of a system
configured to sample a material disposed within/behind an outer
layer.
[0032] FIG. 22 depicts three example implementations of
spectroscopically sampling a surface with an incident spectroscopy
beam, such as a laser beam of a Raman spectrometer.
[0033] FIG. 23 depicts an example implementation of a statistical
method to isolate signals of trace discrete materials from an
overwhelming matrix background.
[0034] FIG. 24 depicts an example implementation of a dynamic
scattering system including spatial separation.
[0035] FIG. 25 depicts an example implementation of a method for
which in a trace residue present on a fingerprint imprinted on a
background material may be detected.
[0036] FIG. 26 depicts an example implementation of a spectroscopic
system in which an excitation beam is fixed at an angle to a
surface of a multi-layered sample.
[0037] FIG. 27 depicts an example implementation of a method to
identify a material through a barrier, such as a container.
[0038] FIG. 28A depicts an example of a signal that contains both a
container's spectrum and an ingredient's spectrum.
[0039] FIG. 28B depicts an example of a spectrum of a container
material that may be stored in a library.
[0040] FIG. 28C depicts an example of a spectrum of a material
within a container determined from the combined spectrum shown in
FIG. 28A and the library spectrum shown in FIG. 28C.
DETAILED DESCRIPTION
[0041] A spectrometer (e.g., a Raman or luminescence (e.g.,
fluorescence, phosphorescence, chemilluminescence) spectrometer) is
provided that reduces interference caused by a material disposed
adjacent (directly or indirectly adjacent) and/or proximate (e.g.,
in close proximity) to a sample of interest. In various
implementations, the material causing interference with a
spectroscopy signal of a sample of interest may include a container
(e.g., a test tube, plastic container, etc.) or another material
located proximate (e.g., in close proximity) to the sample of
interest. Although particular types of spectrometers are described
below (e.g., Raman and fluorescent), these are merely examples of
spectrometers that may be used in a similar manner to reduce
interference in a spectroscopy signal.
[0042] FIG. 5 illustrates an example implementation of a Raman
system including a non-zero angle excitation beam configured to
excite first and second layers of a sample. The first and second
layers may comprise individual layers of a sample, or may
correspond to a container or window (first layer) that is disposed
in front of a target sample (second layer). In addition, the first
and second layers may be directly adjacent to each other or
positioned such that one or more additional layers may be disposed
between the first and second layer and/or in front of/behind the
first and second layers relative to a spectrometer.
[0043] In the particular implementation shown in FIG. 5, for
example, the excitation beam is directed toward the first layer at
a non-zero angle (i.e., a non-zero angle from a line 20 generally
perpendicular to the sample) from a collection axis 22. The
excitation beam is directed toward an entry region 24 on a surface
of the first layer. The entry region 24 is offset from a collection
region 26 by a distance d. The excitation beam disperses through
the first layer to the second layer. Although in the particular
example shown in FIG. 5 the excitation beam is shown reaching and
exciting the second layer at a position generally perpendicular
within the sample to the collection region 26 at a surface of the
sample, the excitation beam need not be directed so that would
intersect the zero-axis line 20 within the second layer at the
position generally perpendicular within the sample to the
collection region. Rather, the excitation beam is generally
directed at a non-zero angle toward the zero-axis line 20 so that
intersections with the first and second layers correspond to
generally different distances from the collection region 26 as the
excitation beam disperses through the first and second layers of
the sample. In one implementation, for example, the excitation beam
may be shifted left or right from the position shown in FIG. 5 and
intersect or not intersect the zero-angle line 20 corresponding to
the collection region 26.
[0044] In the particular implementation shown in FIG. 5, for
example, the excitation beam enters the first layer of the sample
and excites the first layer at an excitation region offset a
distance from a collection region of the sample. The excitation
beam also excites the second layer of the sample at or closer to
the collection region of the sample than the excitation region of
the first layer of the sample. A spatial filter of a spectrometer
is configured to spatially filter all or a portion of a
spectrometer signal corresponding to the first layer of the sample
at point 28 and to spatially accept or passed to a detector of the
spectrometer all or a portion of the spectrometer signal
corresponding to the second layer of the sample at point 30.
[0045] Further, depending on the angle of the excitation beam with
respect to the zero-axis line, more or less relative contributions
of the first and second layers may be achieved. In the particular
example shown in FIG. 5 where the excitation beam is directed
toward the collection region 26 and zero-axis line 20, for example,
a relatively lesser angle of the excitation beam with respect to
the zero-axis line 20 corresponds to an excitation of the first
layer at a relatively closer distance to the collection region
while a relatively larger angle of the excitation beam with respect
to the zero-axis line 20 corresponds to an excitation of the first
layer at a relatively further distance to the collection region.
Where the excitation of the first layer is closer to the collection
region (lesser angle in this example), the relative contribution of
the first layer to the signal collected by the spectrometer via the
spatial filter is greater than where the excitation of the first
layer is further to the collection region (greater angle in this
example).
[0046] FIG. 6 shows an example implementation of a spectrometer 50
configured to reduce interference caused by a material 86 disposed
adjacent (directly or indirectly) to a sample 88 of interest. In
one implementation, for example, the material 86 may correspond to
the first layer and the sample 88 may correspond to the second
layer of the sample shown in FIG. 5. Although the particular
example shows a Raman spectrometer, other types of spectrometers,
such as a luminescence spectrometer, could readily be designed
based on the description herein. As shown in FIG. 6, the
spectrometer 50 comprises an excitation source 52 configured to
generate an excitation incident beam 56. In a Raman spectrometer,
for example, the excitation source 52 typically comprises a laser
light source. In one implementation, for example, the excitation
source 52 comprises a diode laser. A diode laser, for example, is
capable of providing a plurality of wavelengths from the excitation
source 52. The spectrometer 50 further comprises a filter 54. The
filter 54 filters the output of the excitation source 52, such as
removing spurious emissions from the excitation source 52.
[0047] The spectrometer 50 further comprises an optical system 55.
The optical system 55 directs the incident beam 56 toward a sample
58 and receives a spectroscopy signal from the sample 58. In the
implementation shown in FIG. 6, for example, the optical system 55
comprises a dichroic beam-splitter mirror 60. However, the incident
beam 56 may be directed at sample 58 without any intervening
instrument components located in the path of incident beam 56. The
incident beam 56 also may be directed at a mirror, a holographic
transmissive element, a mirror formed with a hole in the mirror or
any other means for directing an incident beam known in the
art.
[0048] In this particular implementation, the optical system 55
further comprises one or more optical elements configured to
deliver the incident beam to the sample 58 and direct/move the beam
with respect to a surface of the sample 58. In the particular
implementation shown in FIG. 6, for example, the optical system 55
further comprises an actuator 61 (e.g., an actuator motor) and a
movable mirror 62 or other optical element to reflect or otherwise
direct and move the incident beam 56 across a surface of the sample
58. Various implementations of optical systems and methods for
moving an incident beam relative to a surface of a sample are shown
and described in U.S. Pat. No. 8,988,678 entitled "Spectrometer,"
filed on Aug. 31, 2011 and issued on Mar. 24, 2015 and U.S. patent
application Ser. No. 13/907,812 entitled "Spectrometer" and filed
on May 31, 2013, each of which is incorporated by reference as if
fully set forth herein. In one implementation, for example, an
actuator assembly 61 moves (e.g., displaces and/or angles) one or
more element of the optical system 25 (e.g., a moveable mirror 62)
to move the beam with respect to a surface of the sample 58 (e.g.,
move the beam across a surface of the sample 58). The actuator
assembly 61, for example, may control a displacement and/or angle
of the moveable mirror 62 to direct the incident beam in toward the
sample 58.
[0049] The incident beam 56 may further be directed through a lens
64. In one implementation, the lens 64 comprises a focusing lens in
the path of the incident beam 56. The focusing lens couples the
incident beam 56 with the sample 58 and collects a spectroscopy
signal (e.g., Raman scattered light) from the sample. In another
implementation, more than one lens 64 may be located in the path of
the incident beam 56 before the incident beam 56 is directed toward
the sample 58 from the moveable mirror. In various implementations,
the spectrometer 50 may include other optical elements for
directing an incident beam 56 toward a sample and collecting a
spectroscopy signal from the sample. The optical system of the
spectrometer 50, for example, may include elements such as a
collimated beam tube or a fiber optic waveguide. See, e.g., U.S.
Pat. No. 7,403,281 for examples of collimated beam tubes or fiber
optic waveguides that may be used in optical systems of various
spectrometers.
[0050] In the particular implementation shown in FIG. 6, for
example, an offset excitation source 90 generates an offset
excitation incident beam 92. The offset excitation source 90, for
example, may also comprise a laser light source, diode laser light
source or other spectrometer light source. A focusing lens 94, for
example, focuses the excitation incident beam 92 and directs the
beam 92 towards an offset mirror 96. The offset mirror 96 (or other
optical element configured to direct the incident beam) may be
fixed to deliver the incident beam 92 at an angle (e.g., a
predetermined angle) toward the sample 58 from an offset direction.
In another implementation, for example, the offset mirror 96 (or
other optical element configured to direct the incident beam) may
be movable so that the incident beam 92 may be directed toward the
sample 58 at one or more different angles and/or may be movable so
as to move the beam relative to a surface of the sample 58 as
described above with respect to mirror 62. An actuator 98, such as
a motor, may be configured to move the mirror 62 (or other optical
element).
[0051] In one implementation, for example, the mirror 96 and/or the
actuator 98 may be configured to direct the excitation incident
beam 92 towards the sample 58 at one or more non-zero angles
relative to a collection axis (generally coincident with
spectroscopy signal 66 shown in FIG. 6 and as further described and
shown with respect to FIG. 5 above). The actuator assembly 98, for
example, may control a displacement and/or angle of the moveable
mirror 96 (or other optical element) to direct the incident beam 92
toward the sample 58.
[0052] The incident beams 56, 92 induce or generate on contact with
the sample 58 a spectroscopy signal to be detected by the
spectrometer 50. In Raman spectroscopy, for example, the incident
beam 56 induces or generates on contact with the sample 58
scattered radiation having an energy differential different from,
and one or more wavelengths different than, the incident radiation
56, 92, or the Raman shift that, for convenience, may be described
as a Raman beam. As stated above, and as shown in FIG. 6, in one
implementation, the spectrometer 50 comprises a beam-splitter, such
as a dichroic beam-splitter mirror 60. The spectroscopy signal 66
(e.g., Raman beam) is directed back through the lens 64 and the
dichroic beam-splitter mirror 60. Neither the incident beams 56, 92
nor the spectroscopy signal 66 need be co-linear. In the
implementation shown in FIG. 6, however, the spectroscopy signal 66
passes back through the dichroic beam-splitter mirror 60 and then
through a filter element 68. In one implementation, the filter
element 68 comprises a long pass filter that removes extraneous
radiation (e.g., from the light source 52 or another source) prior
to dispersing the spectroscopy signal 66 into a spectrum.
Alternatively, the filter element 68 may comprise a notch filter,
or any other filter that is capable of rejecting elastically
scattered radiation.
[0053] The spectroscopy signal 66 may further pass through an input
focusing lens 70 that focuses the spectroscopy signal 66 to a point
at a spatial filter 71. In one implementation, for example, the
spatial filter 71 comprises an aperture, slit or notch and is
located at the focal point of the input focusing lens 70. The
spatial filter 71 spatially filters the beam at the focal point of
the input focusing lens.
[0054] The spectrometer 50 shown in FIG. 6 further comprises a
collimating lens 72 that collimates the diverging spectroscopy
signal 66 after it has passed through an aperture of the spatial
filter 71 (e.g., an aperture, slit or notch). The collimating lens
72 further directs the re-collimated Raman beam toward a
diffraction grating 74. The diffraction grating 74 comprises an
optical element that divides a Raman beam into spatial separated
wavelengths. The diffraction grating 74 further directs a divided
Raman beam 76 toward a detector 78. The divided Raman beam 76
passes through a detector focusing lens 80 that focuses the
spatially separated wavelengths of the divided Raman beam 76 onto
the detector 78.
[0055] The detector 78 comprises a transducer that converts optical
energy into an electrical signal. In one implementation, for
example, the detector 78 comprises an array of individual
transducers that create an electrical pattern representing the
spatially separated wavelengths of the Raman spectrum. A
charge-coupled device (CCD) array, for example, may be used as the
detector 48 in one implementation of the invention. In another
implementation, an Indium-Gallium-Arsenide (InGaAs) detector 78.
Other detectors known in the art may also be used within a
spectrometer of the present invention.
[0056] The spectrometer 50 further comprises control electronics 82
for controlling the operation of the spectrometer 50. The control
electronics 82, for example, may control the operation of the light
sources 52, 90, the actuator assemblies 61, 98 the detector 78,
temperature control elements (e.g., for the light source or
detector), and data transfer to and/or from the spectrometer. In
one implementation, the control electronics 82 may be integrated
onto a single PC board within a housing of the spectrometer. The
control electronics 82 may also comprise one or more discrete
component(s) and/or one or more integrated circuit
component(s).
[0057] In one implementation, the control electronics 82 may
comprise a means for communicating with an external device. The
means for communicating, for example, the means form communicating
may comprise a wired or wireless communication port for
communicating with an external computer, personal data assistant
(PDA), network or the like. A wired communication port, for
example, may comprise a parallel, serial, universal serial bus
(USB), FireWire..TM.., IEEE 1394, Ethernet, modem, cable modem or
other wired communication port known in the art. A wireless
communication port, for example, may comprise an antenna for
wireless communicating with an external device, such as via and
infrared, Bluetooth, IEEE 802.11a/b/g, IrDA, a wireless modem or
other wireless communication port known in the art. The control
electronics 82 may be powered from a battery for a portable device
or may include a power input for receiving power from an external
supply as known in the art. A battery or power supply circuit
(e.g., a rectifier) may be located within a housing of the
spectrometer 50.
[0058] In Raman spectroscopy, the spectrometer 50 operates to
detect a Raman spectrum of a sample 58. In order to detect the
Raman spectrum, the light source 52, 90 is activated to generate an
incident beam 56, 92 of excitation radiation, such as generating a
laser incident beam in a laser light source. In one implementation,
for example, the temperature of the light source 52, 90 is
controlled to control the output frequency of the incident beam 56
generated by the light source 52, 90. The incident beam 56, 92 of
excitation radiation may pass through the filter 54, which removes
spurious emissions from the incident beam. The incident beam 56 is
reflected off the beam-splitter mirror 60 toward the sample 58. The
incident beam 56 is focused onto the sample 58 by the output
focusing lens 64.
[0059] The incident beam 56 generates Raman scattered light from
the sample 58. The Raman scattered light is received by the output
focusing lens 64 and transmitted back through the beam-splitter
mirror 60. In this implementation, the beam-splitter mirror 60
passes the Raman scattered light through the mirror 60 to the
filter 68. From the filter 68, the Raman scattered light passes
through the input focusing lens 70 and is focused onto a spatial
filter 71 such as an aperture, slit or notch. The Raman scattered
light is spatially filtered and diverges toward the collimating
lens 72. The collimating lens 72 collimates the diverging Raman
scattered light and transmits the light to the diffraction grating
74, which divides the Raman scattered light into spatial separated
wavelengths and directs the wavelengths towards the detector
element 78. The spatially separated wavelengths of the Raman
scattered light pass through the detector focusing lens 80 and are
focused into a focused band of radiation that represents the
spatially separated wavelengths of the Raman scattered light. The
focused band of radiation is further directed by the detector
focusing lens 80 onto the detector 78.
[0060] In this particular implementation, the detector 78 comprises
an array of individual transducers that each generate an electrical
signal corresponding to intensity of the radiation received at each
of the individual transducers. The electrical signals generated at
the individual transducers of the detector represent the spatially
separated wavelengths of the Raman spectrum of the sample 58. The
electrical signals are read from the detector by the control
electronics 82. In one implementation, for example, the
spectrometer 50 may then present the Raman spectrum detected to a
user such as via a display or indicator on the spectrometer itself.
In another implementation, the control electronics of the
spectrometer 50 may comprise a look-up table stored in a data
storage element (e.g., memory, tape or disk drive, memory stick or
the like). In this implementation, the control electronics 82
compares the signal from the detector with the values stored in the
look-up table to determine a result of the Raman scan. The
spectrometer 50 then presents the result to a user such as via a
display or indicator on the spectrometer. The result, for example,
may indicate the presence or absence of one or more chemicals or
substances in the sample and may further indicate an amount or
concentration of a chemical or substance detected by the
spectrometer.
[0061] In other implementations, the detector 78 may comprise one
or more individual transducers that rapidly scan for one or more
anticipated spectral features (e.g., Raman features). An example
such system is disclosed in U.S. patent application Ser. no.
13/161,485 entitled "Spectrometer" and filed by Carron et al. on
Jun. 15, 2011, which is hereby incorporated herein by reference in
its entirety for all that it teaches and suggests.
[0062] FIG. 7 illustrates an experimental design which examines to
layers of a sample (e.g., Delrin and Teflon of a plastic material).
In this example implementation, a first system emits laser
excitation incident beam while the other collects Raman scattered
light with a spatially filter collection. In this case, a
delineation between a first layer (e.g., Teflon) and a second layer
(e.g., Delrin) is continuous and even at a fairly large angle the
spectrum contains signals from both layers. If a spectral library
of material is searched then it is possible to remove the
interference through spectral subtraction or other mathematical
approaches such as, but not limited to, principal component
analysis.
[0063] An example of a spectral subtraction for a mixture matching
approach for the system shown in FIG. 7 is illustrated in FIG. 8.
This example method, for example, is also useful in the field of
Raman spectroscopy for analysis of mixtures where the spectrum of a
mixture is resolved in it individual components by library
searching and subtraction. In FIG. 8, a sample taken with a 7 mm
offset is shown as the top spectrum corresponding to
"Delrin+Teflon." A representation of a spectrum for Teflon is
stored in a library (e.g., in the device or accessible by the
device). The library spectrum representation for Teflon may be
subtracted from the combined spectrum (Delrin+Teflon) to obtain a
difference spectral representation as shown in FIG. 8 as the
resulting Delrin spectrum.
[0064] FIGS. 9, 10 and 11 illustrate the same method using multiple
data points at different angles where a multispectral method of
Principle Component Analysis or Independent Component Analysis was
used to extract the signal from the two layers.
[0065] FIGS. 12A and 12B illustrate two example implementations of
a spectrometer 100 in which an optical system 102 of the
spectrometer 100 comprises a beam splitter 104 that directs an
incident beam 106 toward one or more moveable mirrors 108. The one
or more moveable mirrors 108, in turn, reflect the incident beam
106 toward a sample. In the implementation shown in FIG. 12A, for
example, one or more moveable mirrors 108 are displaceable
laterally along a translation axis 110 but are configured to
reflect the incident beam at a common angle toward the sample from
one or more displaced locations along the translation axis 110. In
this particular implementation, by directing the incident beam 106
at a common angle toward the sample from different laterally
displaced locations, the incident beam enters the sample (and/or a
container or other material adjacent the sample) at laterally
displaced locations 112 and reach a point in front of a collection
lens at different depths of the sample/material. The incident beam
is passed through a spatial filter to a spectrometer.
[0066] In the implementation shown in FIG. 12A, for example, a
moveable lens 114 of the spectrometer 100 can also be moved along
an axis 116 toward or away from the sample to collect a
spectroscopy signal. In this implementation, the collection lens
114 may be moved closer to receive the spectroscopy signal from an
illumination of the sample and/or material deeper within the sample
and retracted to receive a signal from an illumination of the
sample and/or material shallower within the sample or at an outer
boundary of the sample. In other implementations, however, the
collection lens may be fixed.
[0067] In the implementation shown in FIG. 12B, for example, the
sample includes a multi-layer sample (e.g., a sample container wall
and a sample disposed within the container) indicated in FIG. 12B
as layers 1 and 2, although any number of layers and/or materials
may be included. In this implementation, the mirror receives an
excitation signal (e.g., directly from an excitation source such as
a laser or via one or more optical elements such as a beam splitter
shown in FIG. 12A) and reflects it toward the sample at a common
angle from translated locations 1, 2, 3 along a translation axis as
described above with reference to FIG. 12A. In this implementation,
as the reflected excitation beam is translated, the resulting
spectroscopy signal includes varying contributions from the
different layers. The spectroscopy signal, in this example, may
include varying contributions correspond to different depths 1, 2,
3 within the sample at a collection axis as the excitation beam
disperses through the sample. A collection lens receives a
spectroscopy signal from the sample along the collection axis and
focuses the signal at a filter (e.g., the spatial filter shown).
Depending on the position of the translating mirror, the signal at
the filter and in turn the spectrometer correspond to varying
layer(s) of the sample. In the particular example shown in FIG.
12B, for example, Layer 1 at position 1, Layer 1 plus a portion of
the signal corresponding to Layer 2 at position 2, Layer 1 and a
greater portion of the signal corresponding to Layer 2 at position
3, etc.
[0068] FIG. 13 shows another example implementation of a
spectrometer in which the optical system of the spectrometer
includes separate excitation and collection optical paths. In this
particular example implementation, one or more mirrors (1,2,3) are
positioned in an arrangement in which the mirrors reflect an
incident beam at different angles from different lateral positions
toward the sample. In this example, each of the incident beams from
the different mirrors (1,2,3) are directed toward a common location
on the sample and/or material (in this case the translucent
material layer (e.g., a container) positioned adjacent the sample
layer. Each of the incident beams pass through the same position
(A) on the external surface being illuminated with the incident
beam. As the beams pass through the layers, the directions of the
individual incident beams intersect with an axis (B) of a
collection optical path at varying distances from the collection
optics of the spectrometer. In this manner, spectroscopy signals
returned from the individual incident beams represent signals
corresponding to different depths being sampled.
[0069] The mirrors (1,2,3) may represent individual fixed mirrors
located at different lateral positions and configured at the
different angles, or may include one or more moveable mirrors that
are positioned at different lateral locations at different angles
to reflect the incident beam to a common position (A).
[0070] FIG. 14 illustrates yet another example implementation of a
spectrometer in which the optical system of the spectrometer
includes a light source (e.g., a laser) or reflective optical
element (e.g., a mirror) positioned such that the light source is
moveable along an arc so that an incident beam is directed at
varying angles through a common location at the surface of a sample
and/or material adjacent to the sample similar to the incident
beams described with reference to FIG. 13. Although FIG. 14 shows
the light source being moveable, a light source may also direct an
incident beam onto one or more reflective optical elements (e.g.,
mirrors) that can move in a similar manner to the light source
shown in FIG. 14.
[0071] FIG. 15 shows another implementation of a spectrometer. In
this implementation, a mirror is adapted to be rotated or turned to
change an angle of an excitation beam (e.g., laser) directed toward
a multi-layer sample. In the particular implementation shown in
FIG. 15, the excitation beam is shown directed toward the sample at
three different angles such that the beam disperse generally toward
the second layer at points 1, 2, 3 beyond a collection axis, at a
collection axis and before a collection axis. Although the
collection angle is shown as being generally orthogonal to a
surface of the first layer of the sample, the collection angle may
be angled at another angle from the surface of the first layer of
the sample. A collection lens collects the spectroscopy signal
(e.g., a Raman spectroscopy signal) and focuses the spectroscopy
signal on a spatial filter. The spatial filter removes at least a
portion of an interference corresponding to the first layer as will
be described in further detail with respect to FIG. 16. The
spatially filtered spectroscopy signal is then directed by an
optical system of the spectrometer to a detector of the
spectrometer.
[0072] FIG. 16 shows an example graph of a method for determining
one or more spectra corresponding to the second layer of the sample
shown in FIG. 15. In this implementation, the structure of the data
illustrated in FIG. 16 provides insight into methods of
distinguishing different layers. Layer 1 represents an external
(first layer) of the material and Layer 2 is a second layer
disposed internally to layer 1. A spectra from Layer 1 decreases
very rapidly, at a much faster rate, than the subsequent layers. If
there is only one subsequent layer the signal of that layer is
relatively consistent.
[0073] Mathematically different rates of decay can be used to
separate components of the data set into the different components.
For example, a Least Squares analysis of the data along each
spectral point shows that the second layer is mostly contained in
the first component of the Least Squares polynomial and the rapidly
decaying spectral information is contained in the second component.
Likewise, statistically the average of the data along the spectral
data points is largely composed of the second layer and the
standard deviation of the along the spectral data points represents
the variance in the data and largely is composed of the first layer
of the sample. A subtraction of the normalized standard deviation
from the average produces a pure spectrum of the second layer. This
method is illustrated in FIGS. 17 and 18.
[0074] FIG. 19 shows another example of extracting spectra for an
external container layer and an internal content layer disposed
within the external container layer. In this particular
implementation, the container comprises a white cardboard layer.
Spectra of the container and contents of a carton of Epsom salts
(Magnesium Sulfate) are shown in FIG. 19. In this example, spectra
were collected at multiple angles. A least squares analysis of the
spectra was carried out at each wavenumber element. A comparison of
the extracted signal from the least squares algorithm and contents
are illustrated. As shown in FIG. 16, the intensity of spectral
features of the container decrease in a nonlinear relationship with
respect to the off-axis angle. When a quadratic equation is formed
with the least squares analysis, the equation a+bx+cx.sup.2 relates
more container content in the b value than in the a value.
Subtraction of the a normalized b value from a leads to separation
of the content spectrum from the container spectrum.
[0075] FIGS. 20 and 21 show other implementations of systems for
sampling a material disposed within/behind an outer layer. The
material, for example, may comprise a material disposed within a
container (e.g., within a plastic or paper container). In this
implementation, an excitation beam is first directed into the
external layer at a first location (1) where the internal material
is not disposed adjacent to/behind the external layer. In this
implementation, the spectroscopy signal is collected along a first
collection axis and a spectrum corresponding to the first outer
layer is determined. An excitation beam is then directed at an
angle through the external layer at a second location (2) and into
a second layer that is disposed adjacent to/behind the first layer
at the second location. Although FIGS. 20 and 21 show example in
which a first location is sampled first, the order of sampling the
first and second layers may be reversed or performed simultaneously
in various implementations.
[0076] As discussed further herein, the second spectra collected
from the second location corresponding to a combination of the
first and second layers can be normalized (e.g., by a normalization
factor n) and the normalized second spectrum may be subtracted from
the first spectrum (2-n1).
[0077] The spectra shown in the example of FIG. 20 correspond to
contents in a container including a relatively strong Raman
scattering material (bicarbonate), and the spectra in the example
of FIG. 21 correspond to contents in a container including a
relatively weak Raman scattering material (citric acid). As can be
seen in the Figures, the method was successful in both
examples.
[0078] FIG. 22 shows three examples of spectroscopically sampling a
surface with an incident spectroscopy beam, such as a laser beam of
a Raman spectrometer. In the first example, a single focused beam
illuminates a spot on the surface. While the focused beam allows
for a relatively high resolution sample of the spot illuminated by
the focused beam on the surface, where the surface is not
homogeneous, the illuminated spot may miss a particle or region of
interest where the single illuminated spot does not illuminate the
particle or region of interest on the sample surface. In this
example, the particle or region of interest is not illuminated by
the focused excitation beam and, thus, the spectrometer does not
detect one or more particles in the identified region of interest
that falls outside the focused beam.
[0079] In a second example, a larger excitation beam (e.g., a laser
beam of a Raman spectrometer) illuminates a relatively larger
region of the surface of the sample than in the first example. In
this second example, the excitation beam is not as relatively
tightly focused as the excitation beam in the first example and the
spectrometer has a lower resolution than the spectrometer in the
first example with the focused excitation beam. Thus, the
spectrometer may have an insufficient resolution to detect one or
more particles of interest in a region of the sample surface even
where the excitation beam overlaps all or a portion of the region
including the one or more particle of interest.
[0080] In the third example, a focused excitation beam is moved
across the surface of the sample. The focused excitation beam may
be moved (e.g., scanned, rotated or otherwise moved) in a pattern
and/or randomly across the surface of the sample, including the
region of interest that includes the one or more particles to be
detected. The focused excitation beam, in this third example, is
likely to intersect the region of interest and maintains a
relatively high resolution as the excitation beam is moved across
the surface of the sample. Thus, the spectrometer is able to detect
the one or more particles of interest in the region. Examples of
devices that are adapted to move an excitation beam across the
surface of the sample, such as shown in the third example of FIG.
15, are described in U.S. Pat. No. 8,867,033 and patent application
nos. Ser. No. 13/161,485 filed on Jun. 15, 2011, Ser. No.
12/268,419 filed Nov. 10, 2008 and Ser. No. 13/907, 812 filed May
31, 2013, each of which is hereby incorporated by reference in
their entirety for all they teach and suggest.
[0081] FIG. 23 shows an example graph that can be used to
illustrate an example of a statistical method to isolate signals of
trace discrete materials from an overwhelming matrix background. In
the relatively large excitation beam of the second example shown in
FIG. 22, for example, a small signal corresponding to the target
particle(s) of interest that is present in a spectrum taken from
the entire region of the sample illuminated by the relatively large
excitation beam that primarily corresponds to the material of the
sample surrounding target particle(s) of interest. Where the
resolution of the spectrometer due to the size of the beam is too
low to distinguish the spectral features of the particle(s) of
interest from the remainder of the sample, the particle(s) are
likely to not be detected.
[0082] Where multiple, discrete spectra are collected during the
movement of a focused excitation beam across a surface of the
sample as shown in the third example of FIG. 22, an array of
spectra data may be generated. A majority of the array will
correspond to the material (matrix) of the sample and a minority of
the array data will include primarily the target(s) and secondarily
the material (matrix) of the sample. In this implementation, the
target spectrum can be separated from the majority signal of the
matrix sample material. Since the majority of the spectra originate
from the matrix sample material, the spectra are typically very
similar. A standard deviation of the signal at each wavenumber
element will be small. On the other hand, the target
spectrum/spectra may be present in a minority (e.g., one or more)
of the spectra of the array and those signals will deviate strongly
from the average matrix sample material signals.
[0083] In the example shown in FIG. 23, for example, a sample of a
small 100 nm gold nanoparticle with a trace of a target
material/particle(s) was used with an ethanol for the sample
material. In this example, algorithm and data from a DRS analysis
of particles floating in a solution are shown. A normalized average
(mean) spectrum (.mu.) contains mostly the predominant solution or
surface material. A standard deviation spectrum (.sigma.) contains
a large amount of the weaker particles in the solution or on the
surface. If the mean spectrum is normalized to its equivalent
intensities in the standard deviation spectrum and subtracted from
the standard deviation the resultant spectrum is the of the
particles. Thus, the difference between a standard deviation
spectrum (.sigma.) and a normalized average spectrum (.mu.) produce
a pure spectrum of the target material. In this example, the
resultant target spectrum can be achieved autonomously without the
need of an operator to search for the target as would be required
with a Raman (or other spectroscopic) microscope and may thus be
achieved with a relatively lightweight and portable Raman (or other
spectroscopic) system.
[0084] FIG. 24 shows an example of a dynamic scattering system
(e.g., a dynamic Raman scattering system) including spatial
separation. In this example an excitation beam (e.g., a laser)
moves across a surface of a sample (e.g., using a stepper motor)
and a spectrometer takes multiple acquisitions across the surface.
The multiple acquisitions provide multiple unit spectral features
for individual components that may be distributed or otherwise
disposed on the surface of the sample. An extracted spectrum of a
target can be determined, such as using a statistical approach as
described above with reference to FIG. 23, a principle component
analysis or other statistical or mathematical approach.
[0085] Further each individual spectrum taken in the example shown
in FIG. 24 may be collected during the movement of a focused
excitation beam across a surface of the sample as shown in the
third example of FIG. 22. Thus, an array of spectra data may be
generated for each individual sample shown in the example of FIG.
24.
[0086] FIG. 25 shows another example, in which a residue present on
a fingerprint imprinted on a plastic (e.g., Delrin) background
material may be detected. In this example, a residue (e.g., a trace
residue) can be detected by separating the spectral features of the
background (e.g., Delrin) from the target residue (e.g., trace
residue), such as described above with respect to FIGS. 23 and
24.
[0087] FIG. 26 shows another example implementation of a
spectroscopic system in which an excitation beam is fixed at an
angle to a surface of a multi-layered sample (e.g., Layer 1 and
Layer 2). The first layer, for example, may be sampled such as
shown in FIGS. 24 and 25. The second layer (and/or any additional
layers) may be further sampled by changing the excitation angle and
then moving (e.g., rotating, angling or otherwise moving) a mirror
to move the excitation beam relative to the second layer (and/or
any additional layers). The excitation angle may then be changed
again, and then moved relative to the second layer (and/or any
additional layers) using the mirror (or another mirror) any number
of additional times.
[0088] Appendix B of United States provisional application
62/192,023 entitled Spectrometer and filed Jul. 13, 2015, which is
incorporated by reference in its entirety as if fully set forth
herein, provides additional example, implementations and methods
related to spectrometers utilizing an off-axis excitation.
[0089] In yet another alternative method to identify a material
inside a container (or through a barrier), a library of popular
container/barrier materials is used. In this particular
implementation, for example, the method has an advantage by
permitting the ingredients to be determined with a single
acquisition. In one implementation, the method may be associated
with longer integration times to maximize the signal to noise
(sensitivity) ratio of a measurement. The implementation may also
permit a very high quality with maximized signal to noise to be
used as the subtrahend in the analysis and again this may produce
an improved or optimal spectrum of ingredients.
[0090] An example implementation utilizing this concept of
measurement is illustrated in FIG. 27. In this particular
implementation, a single measurement is made with a laser
excitation that is at an angle, .THETA., between 90 and 180
degrees. The laser can also be adjusted to enter the container at a
point which is not within the cone of collected light accepted by
the spectrometer. This may produce a signal that contains both the
container's spectrum and the ingredient's spectrum. This spectrum
is illustrated in FIG. 28A. When a spectral library is searched
that contains a spectra of container materials the top hit may
correspond to the spectra of the container in some implementations.
In this implementation, this true even though a small amount of
ingredient spectra is contained within the spectrum in FIG. 28A. A
Pearson correlation may be used to maximize the correlation between
spectra which contain the largest amount of a common signal. In one
example, a container material may be found even when a minor signal
from an ingredient is present.
[0091] In this particular implementation, a library may contain a
pure spectrum of the container material. In this example, this is
illustrated in FIG. 28B. While not instantly apparent the spectrum
in FIG. 28A differs slightly from that in 28B. Peak shoulders and
small new peaks are present in FIG. 28A that are not in FIG. 28B. A
Pearson determination (r.sup.2) between the two, in this example,
is 0.98. If the spectrum from FIG. 28B is subtracted from the
spectrum in FIG. 28A the resultant is the ingredient. In this
example it matches to sodium bicarbonate which is the ingredient.
The sodium bicarbonate spectrum in FIG. 28C has a high signal to
noise level for two reasons: the acquisition time was maximized ion
this example since only one spectrum was required; and the library
container spectrum has a high signal to noise entry acquired
previously under not critical time constraints.
[0092] In one implementation, for example, this method could also
use common mixture analysis methods for Raman spectroscopy. One
such method is that described above. It also could be methods used
on more advanced methods such as Principal Component Analysis or
other methods.
[0093] Individual example implementations shown and described with
respect to one or more Figures in this application introduce
individual concepts that may be used in different implementations
as well. Thus, discrete implementations described herein are not
exclusive and different concepts described with respect to one or
more implementations shown in one or more Figures are done so
merely to simplify the description of individual concepts. Thus,
one or more features introduced in one example may also be used in
other examples that may be described with reference to different
figures or implementations herein. For example, the concept of
collecting a spectra during the movement of a focused excitation
beam across a surface of the sample as shown in the third example
of FIG. 22 to collect an array of spectra data may be used in
combination with any of the implementations in which a spectrometer
is configured to deliver an off-axis excitation incident beam to a
sample. Similarly, different methods of collecting a spectroscopy
signal may be used in combination with different methods of
directing a off-axis excitation incident beam to a sample.
[0094] Although implementations of this invention have been
described above with a certain degree of particularity, those
skilled in the art could make numerous alterations to the disclosed
implementations without departing from the spirit or scope of this
invention. All directional references (e.g., upper, lower, upward,
downward, left, right, leftward, rightward, top, bottom, above,
below, vertical, horizontal, clockwise, and counterclockwise) are
only used for identification purposes to aid the reader's
understanding of the present invention, and do not create
limitations, particularly as to the position, orientation, or use
of the invention. Joinder references (e.g., attached, coupled,
connected, and the like) are to be construed broadly and may
include intermediate members between a connection of elements and
relative movement between elements. As such, joinder references do
not necessarily infer that two elements are directly connected and
in fixed relation to each other. It is intended that all matter
contained in the above description or shown in the accompanying
drawings shall be interpreted as illustrative only and not
limiting. Changes in detail or structure may be made without
departing from the spirit of the invention as defined in the
appended claims.
* * * * *