U.S. patent application number 12/112401 was filed with the patent office on 2009-08-27 for analyzer system and optical filtering.
Invention is credited to Dirk Appel, Gaston E. Marzoratti, Robert F. Mouradian, Shrikrishna H. Nabar.
Application Number | 20090213381 12/112401 |
Document ID | / |
Family ID | 40997979 |
Filed Date | 2009-08-27 |
United States Patent
Application |
20090213381 |
Kind Code |
A1 |
Appel; Dirk ; et
al. |
August 27, 2009 |
ANALYZER SYSTEM AND OPTICAL FILTERING
Abstract
A gas analyzer system includes an optical source, an optical
filter assembly, a controller, and an analyzer. The optical source
generates an optical signal. The optical filter assembly includes
different optical filters in which to filter the optical signal.
During operation, the controller selects sequential application of
each of the different optical filters in a path of the optical
signal to modulate the optical signal using different frequency
bands of optical energy. The modulated optical signal passes
through an unknown sample. The optical analyzer analyzes the
modulated optical signal after passing through the sample to detect
which types of multiple different gases are present in the
sample.
Inventors: |
Appel; Dirk; (Salem, MA)
; Marzoratti; Gaston E.; (Franklin, MA) ; Nabar;
Shrikrishna H.; (Shrewsbury, MA) ; Mouradian; Robert
F.; (Canton, MA) |
Correspondence
Address: |
BARRY W. CHAPIN, ESQ.;CHAPIN INTELLECTUAL PROPERTY LAW, LLC
WESTBOROUGH OFFICE PARK, 1700 WEST PARK DRIVE, SUITE 280
WESTBOROUGH
MA
01581
US
|
Family ID: |
40997979 |
Appl. No.: |
12/112401 |
Filed: |
April 30, 2008 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61030475 |
Feb 21, 2008 |
|
|
|
Current U.S.
Class: |
356/438 |
Current CPC
Class: |
G01N 21/3504 20130101;
G01N 21/031 20130101; G01N 2021/3133 20130101; G01N 2021/3174
20130101; G01N 21/274 20130101; G01N 2201/1215 20130101 |
Class at
Publication: |
356/438 |
International
Class: |
G01N 21/59 20060101
G01N021/59 |
Claims
1. A system comprising: an optical source to generate an optical
signal; an optical filter assembly including different optical
filters in which to filter the optical signal; a controller
configured to select sequential application of each of the
different optical filters in a path of the optical signal to
modulate the optical signal; and an optical analyzer to analyze the
modulated optical signal passing through a sample to detect which
of multiple gases are present in the sample.
2. The system as in claim 1, wherein the optical analyzer is
configured to determine a concentration of multiple gases present
in the sample based on how much of the modulated optical signal is
absorbed by the sample at different optical energies, at least two
of the multiple gases present in the sample absorbing optical
energy in a common frequency band of the modulated optical
signal.
3. The system as in claim 2, wherein the optical filter assembly
includes an optical filter to pass optical energy of the optical
signal in the common frequency band through the sample to the
optical analyzer.
4. The system as in claim 1, wherein the optical assembly is an
optical filter wheel including the different optical filters, the
different optical filters of the optical filter wheel separated by
opaque partitions that block the optical signal from passing
through the sample.
5. The system as in claim 4, wherein the controller is configured
to rotate the optical wheel to each of multiple successive
positions including a first position, a second position, and a
third position; the first position of the optical filter wheel
aligning a first filter of the optical filter wheel with a path of
the optical signal enabling the optical signal to pass through the
first optical filter and the sample to the analyzer; the second
position of the optical filter wheel placing an opaque partition of
the optical wheel in a path of the optical signal such that the
optical signal does not pass through the sample to the analyzer;
and the third position of the optical filter wheel aligning a
second filter of the optical filter wheel with the path of the
optical signal enabling the optical signal to pass through the
second optical filter and the sample to the analyzer.
6. The system as in claim 1, wherein the multiple filters include a
first optical filter and a second optical filter; the first optical
filter configured to pass a first optical frequency energy band of
the optical signal through the sample to the analyzer; and the
second optical filter configured to pass a second optical frequency
energy band of the optical signal through the sample to the
analyzer, the first optical frequency band being different than the
second optical frequency band.
7. The system as in claim 6, wherein the controller is configured
to generate the modulated optical signal based on positioning the
first optical filter in a path of the optical signal generated by
the optical source and thereafter positioning the second optical
filter in the path of the optical signal generated by the optical
source.
8. The system as in claim 1, wherein the sample is a flue sample at
least partially derived based on burning of fossil fuels; and
wherein the optical analyzer is configured to analyze the modulated
optical signal passing through the flue sample to detect which of
the multiple gases are present in the flue sample.
9. The system as in claim 1, wherein the optical source generates
the optical signal in an infrared frequency range.
10. The system as in claim 1, wherein at least one of the multiple
optical filters is a reference filter in which none of the multiple
gases in the sample absorb optical energy.
11. The system as in claim 1, wherein the optical analyzer is
configured to detect a relative peak optical energy of the
modulated optical signal that passes through the sample for each of
the filters in the optical filter assembly.
12. A method comprising: generating an optical signal to pass
through a sample; selecting application of each of different
optical filters in a path of the optical signal to modulate the
optical signal; and analyzing the modulated optical signal after
passing of the modulated optical signal through the sample to
detect which of multiple gases are present in the sample.
13. The method as in claim 12 further comprising: determining a
concentration of multiple gases present in the sample based on how
much of the modulated optical signal is absorbed by the sample at
different optical energies.
14. The method as in claim 12 further comprising: producing the
modulated optical signal based on positioning of different optical
filters and opaque partitions in the path of the optical signal,
each of the different optical filters passing different optical
frequency bands of the optical signal through the sample.
15. The method as in claim 12 further comprising: producing the
modulated signal by rotating an optical filter wheel to each of
multiple successive positions including a first position, a second
position, and a third position: the first position of the optical
filter wheel aligning a first filter of the optical filter wheel in
the path of the optical signal to enable the optical signal to pass
through the first optical filter and the sample to an analyzer that
analyzes the optical signal; the second position of the optical
filter wheel aligning an opaque partition of the optical wheel in a
path of the optical signal such that the optical signal does not
pass through the sample; and the third position of the optical
filter wheel aligning a second filter of the optical filter wheel
in the path of the optical signal enabling the optical signal to
pass through the second optical filter and the sample to the
analyzer.
16. The method as in claim 12, wherein selecting application of
each of the different optical filters in the path of the optical
signal to modulate the optical signal includes: disposing a first
optical filter in the path of the optical signal for a first
duration of time, the first optical filter configured to pass a
first optical frequency energy band of the optical signal through
the sample; and subsequent to the first duration of time, disposing
a second optical filter in the path of the optical signal for a
second duration of time, the second optical filter configured to
pass a second optical frequency energy band of the optical signal
through the sample.
17. The method as in claim 12, wherein generating the optical
signal includes generating the optical signal in an infrared
frequency range.
18. The method as in claim 12, wherein analyzing the modulated
optical signal after passing of the modulated optical signal
through the sample includes, for each of multiple filters,
detecting an amount of optical energy in the modulated optical
signal after passing of the optical energy through the sample for
each of the multiple filters.
19. A computer readable medium having computer code thereon, the
medium comprising: instructions for generating an optical signal to
pass through a sample; instructions for selecting application of
each of different optical filters in a path of the optical signal
to modulate the optical signal; and instructions for analyzing the
modulated optical signal after passing of the modulated optical
signal through the sample to detect which of multiple gases are
present in the sample.
20. The computer readable medium as in claim 19 further comprising:
instructions for producing the modulated optical signal based on
positioning of different optical filters and opaque partitions in
the path of the optical signal, each of the different optical
filters passing different optical frequency bands of the optical
signal through the sample.
Description
RELATED APPLICATION
[0001] This application claims priority to United States
Provisional patent application entitled "FLUID ANALYZER SYSTEM"
(Attorney Docket No. TEC07-04(TEI)p) having assigned Ser. No.
61/030,475, filed on Feb. 21, 2008, the entire teachings of which
are incorporated herein by this reference.
[0002] This application is related to United States patent
application entitled "GAS ANALYZER SYSTEM" (Attorney Docket No.
TEC07-05(TEI)) filed on the same day as the present application,
the entire teachings of which are incorporated herein by this
reference.
BACKGROUND
[0003] Emissions from fossil fuel combustion facilities, such as
flue gases of coal-fired utilities and municipal solid waste
incinerators, typically include multiple types of gases. For
example, emissions can include gases such as CO.sub.2, NO.sub.2,
SO.sub.2, etc.
[0004] Many countries regulate emissions of the different types of
waste gases because of potential environmental hazards posed by
such harmful emissions. Accordingly, many facilities that generate
or potentially generate harmful gas emissions need to employ
multiple gas analyzers systems to ensure that emitted gases are
compliant with corresponding regulations. Operating and maintaining
each of the different gas analyzer systems can be expensive.
[0005] Each of the different types of gases has unique optical
absorption characteristics. These unique characteristics enable a
corresponding gas analyzer system to positively identify whether a
particular type of gas is present in a gas sample.
[0006] One way to quantify a type of gas present in an unknown gas
sample is the application of Beer's law. In general, Beer's law
defines an empirical relationship that relates the absorption of
light to properties of the material through which the light is
traveling. In other words, different materials absorb different
frequencies of light energy. By passing of optical energy through a
gas sample and detecting which frequencies of optical energy are
absorbed by the gas sample, it is possible to determine what type
of gas is present in the gas sample. The amount of absorption can
indicate a concentration of a respective gas.
[0007] One conventional gas analyzer system includes an optical
source that generates an optical signal for passing through a
sample gas. Such an analyzer also includes a so-called optical
filter wheel and a so-called chopper wheel. The optical filter
wheel and the chopper are both disposed in a path of the optical
signal.
[0008] The optical filter wheel includes a number of different
optical filters, each of which passes only a single frequency band
of light energy. Depending on which filter is disposed in a path of
the optical signal, it is known what frequency band of light is
being passed through the sample. An optical detector measures how
much optical energy passes though the sample.
[0009] The chopper wheel includes multiple windows or cut-outs
separated by opaque regions that block light. The chopper wheel is
also placed in a path of the optical signal such that a position of
the chopper wheel dictates whether any of the optical signal passes
through the gas sample or is blocked by an opaque region. As the
chopper wheel spins, it blocks and passes optical energy through
the sample to a detector.
[0010] During operation, a conventional gas analyzer system
produces modulated light by setting the filter wheel in a position
so that the optical signal passes through a selected filter in the
optical wheel. When the selected filter is in such a position, a
controller spins the chopper wheel to repeatedly block and pass the
optical signal through the gas sample as discussed above.
Application of the chopper wheel results in modulation of a single
frequency band of optical energy depending on which filter on the
filter wheel has been chosen to be "chopped" or modulated.
Accordingly, a controller can produce a modulated optical signal
using a two-wheel assembly including a chopper wheel and filter
wheel.
SUMMARY
[0011] Conventional ways of generating a modulated optical signal
suffer from a number of deficiencies. For example, the conventional
two-wheel assembly as discussed above is prone to failure because
it includes many moving parts. In particular, such an assembly
includes a filter wheel and a chopper wheel that operate
independently of each other and, thus, require separate driver
control logic and motors.
[0012] Embodiments herein include a unique way to produce a
modulated optical signal and collect data for detecting a presence
of different types of matter in a sample chamber.
[0013] More specifically, in one embodiment, a gas analyzer system
includes an optical source, an optical filter, a controller, and an
analyzer. The optical source generates an optical signal. The
optical filter assembly includes different optical filters in which
to filter the optical signal. The controller is configured to
select sequential application of each of the different optical
filters in a path of the optical signal to modulate the optical
signal. The optical analyzer analyzes the modulated optical signal
passing through a sample to detect which of one or more types of
matter are present in the sample.
[0014] By way of a non-limiting example, the matter can include
different types of gases, liquids, or solids present in the
sample.
[0015] In addition to having an ability to detect different types
of gases present in the sample, an example analyzer system as
described herein can determine a concentration of multiple gases
present in the sample based on how much of the modulated optical
signal is absorbed by the sample at different optical energies.
[0016] It is possible that two or more of the different gases
present in the sample may absorb optical energy in a common
frequency band of the modulated optical signal due to interference.
This complicates the task of detecting which types of gases may be
present in the sample. Thus, merely knowing that a gas sample
absorbs a single frequency of light energy may not be enough
information to determine which gas is present in the sample. To
discern between different gases, the optical filter assembly can
include multiple filters in which to measure absorption of optical
energy. Depending on how much energy is absorbed in different
optical frequency bands, the gas analyzer system according to
embodiments herein can identify concentrations of different types
of gases in a sample even though there happens to be absorbance
interference amongst the gases.
[0017] In further embodiments, the optical filter assembly can be
an optical filter wheel including the different optical filters,
each of which is separated by opaque partitions that block the
optical signal from passing through the sample.
[0018] When disposed in a path of the optical signal, the
controller can initiate spinning the wheel to produce a modulated
signal of different optical energy frequency bands. For example, a
filter wheel according to embodiments herein can include a first
filter, a second filter, a third filter, etc. In accordance with
embodiments as discussed above, between each filter pair is an
opaque region that blocks the optical energy. Each filter passes
different frequency bands of optical energy. The controller can be
configured to rotate the optical wheel to each of multiple
successive positions including a first position, a second position,
a third position, a fourth position, a fifth position, etc. to
produce the modulated optical signal.
[0019] When in the first position, the first filter is disposed in
a path of the optical signal enabling the optical signal to pass
through the first optical filter and the sample to the
analyzer.
[0020] When in the second position, an opaque region of the optical
filter wheel is disposed in a path of the optical signal to block
the optical signal from passing through the sample.
[0021] When in the third position, the second filter is disposed in
a path of the optical signal enabling the optical signal to pass
through the second optical filter and the sample to the
analyzer.
[0022] When in the fourth position, another opaque region of the
optical filter wheel is disposed in a path of the optical signal to
block the optical signal from passing through the sample.
[0023] When in the fifth position, the third filter is disposed in
a path of the optical signal enabling the optical signal to pass
through the first optical filter and the sample to the analyzer.
Sequentially setting the optical filter wheel in these positions as
discussed herein produces the modulated optical signal for passing
through the sample to detect the presence of different gases.
[0024] This process can be repeated for any number of filters on
the optical filter wheel such that the controller generates the
modulated optical signal based on positioning different optical
filters in a path of the optical signal. As each different filter
is sequentially disposed in the optical path, the analyzer collects
absorption information for the frequency band. The transition from
one filter to a next filter serves as a way of modulating the
optical signal.
[0025] Modulating the optical signal as described herein enables
the analyzer to collect absorption data in a different manner than
as discussed above for the conventional two-wheel assembly
including a chopper wheel. For example, the conventional two-wheel
assembly lends itself to repeated sampling of the optical signal
for a single filter of the filter wheel assembly based on use of
the chopper wheel. In contradistinction to the conventional
two-wheel assembly, embodiments herein enable more efficient serial
collection of absorption data in a serial manner via modulation
without use of a chopper wheel.
[0026] Techniques herein are well suited for use in applications
such as those supporting detection of different types of gases in a
gas sample. However, it should be noted that configurations herein
are not limited to such use and thus configurations herein and
deviations thereof are well suited for use in other environments as
well.
[0027] Note that each of the different features, techniques,
configurations, etc. discussed herein can be executed independently
or in combination. Accordingly, the present invention can be
embodied and viewed in many different ways.
[0028] Also, note that this summary section herein does not specify
every embodiment and/or incrementally novel aspect of the present
disclosure or claimed invention. Instead, this summary only
provides a preliminary discussion of different embodiments and
corresponding points of novelty over conventional techniques. For
additional details and/or possible perspectives or permutations of
the invention, the reader is directed to the Detailed Description
section and corresponding figures of the present disclosure as
further discussed below.
BRIEF DESCRIPTION OF THE DRAWINGS
[0029] The foregoing and other objects, features, and advantages of
the invention will be apparent from the following more particular
description of preferred embodiments herein as illustrated in the
accompanying drawings in which like reference characters refer to
the same parts throughout the different views. The drawings are not
necessarily to scale, with emphasis instead being placed upon
illustrating the embodiments, principles and concepts.
[0030] FIG. 1 is an example diagram of an analyzer system according
to embodiments herein.
[0031] FIG. 2 is an example diagram illustrating an optical filter
assembly according to embodiments herein.
[0032] FIG. 3 is an example diagram illustrating detected
intensities of light for different frequency bands according to
embodiments herein.
[0033] FIG. 4 is an example diagram illustrating collected sample
data according to embodiments herein.
[0034] FIG. 5 is an example graph illustrating absorption of energy
associated with carbon dioxide over a range of wavelengths.
[0035] FIG. 6 is an example graph illustrating absorption of energy
associated with carbon monoxide over a range of wavelengths.
[0036] FIG. 7 is an example graph illustrating energy absorption at
different wavelengths for multiple different gas samples.
[0037] FIG. 8 is an example block diagram of a computer system
configured with a processor and related storage to execute
different methods according to embodiments herein.
[0038] FIGS. 9 and 10 are example flowcharts illustrating methods
according to embodiments herein.
DETAILED DESCRIPTION
[0039] Now, more specifically, FIG. 1 is an example diagram of an
analyzer system 100 according to embodiments herein. As shown,
analyzer system 100 includes a user 108, an optical source 110,
optical signal 115, optical filter assembly 120, modulated optical
signal 125, chamber 129, detector assembly 135, repository 180,
sample data processor 142, and display screen 130. Optical filter
assembly 120 includes multiple filters 122 such as filter 122-1,
filter 122-2, filter 122-3, filter 122-4, filter 122-5, filter
122-6, filter 122-7, filter 122-8, filter 122-9, filter 122-10,
etc. Chamber 129 includes inlet 127, outlet 128, and reflectors
131-1 and 131-2. Display screen 130 displays report 145 for viewing
by user 108. Detector assembly 135 includes detector 136 and
monitor circuit 137.
[0040] In general, analyzer system 100 analyzes absorption
characteristics of sample 126 as it passes from inlet 127 through
chamber 129 to outlet 128. The analyzer system 100 passes the
modulated optical signal 125 through the sample 126 to identify a
presence and/or concentrations of multiple different target gases
such as H.sub.2O (water), CO (carbon monoxide), CO.sub.2 (carbon
dioxide), NO (nitric oxide), NO.sub.2 (nitrogen dioxide), SO.sub.2
(sulfur dioxide), N.sub.2O (nitrous oxide), CH.sub.4 (methane), HC
(hydrocarbons), etc.
[0041] By way of a non-limiting example, the inlet 127 of chamber
128 can be configured to receive gas sample 126 from a smokestack.
In such an embodiment, the analyzer system 100 measures combustion
by-products in sample 126 using a unique method employing
non-dispersive infrared (IR) absorbance spectroscopy.
[0042] The basis of analyzing sample 126 according to one
embodiment is use of Beer-Lambert's Law. As mentioned above, this
law defines a linear relationship between the concentration of a
gas of interest and the amount of energy it absorbs. Via this
technique, the gas analyzer 140 determines the presence and/or
concentration of matter such as individual pollutants in the sample
126 based on the capacity of the compounds to absorb infrared
energy of a specific wavelength.
[0043] During operation, optical source 110 generates optical
signal 115. In one embodiment, and by way on a non-limiting
example, the optical source generates optical signal 115 in an
infrared spectrum such as a broad range of optical wavelengths
between 1.5 and 7.5 micrometers. The optical source 115 can be a
device such as semiconductor device, a glowing metal filament
heated to a temperature of several hundred degrees C., etc.
[0044] In one embodiment, the optical detector 136 is a
pyroelectric detector device such as the Selex detector Type #5482
(available from SELEX S&AS, PO Box 217, Millbrook Industrial
Estate, Southampton, Hampshire, UK).
[0045] In accordance with another embodiment, the detector device
is a lead-selenide device such as the SensArray detector, part
number SA-432-386T (available from SensArray Infrared, Burlington,
Mass. 01803).
[0046] As its name suggests, filter controller 155 changes which of
multiple optical filters 122 is aligned in a path of the optical
signal 115 for passing of a limited frequency band of the optical
signal 115 through sample 126 to detector 136. The filter
controller 155 produces the modulated optical signal 125 by
rotating an optical filter assembly 120 to each of multiple
successive positions in which the optical filters 122 pass
different frequency bands of optical energy through the sample
126.
[0047] As an example, optical filter assembly 120 can be a filter
wheel that spins in response to input by the filter controller
155.
[0048] More specifically, the filter controller 155 rotates optical
filter assembly 120 so that optical filter 122-1 of the optical
filter assembly 120 initially lies in the path of the optical
signal 115. When in such a position, the filter 122-1 absorbs
certain frequencies in the optical signal 115 and passes other
frequencies of the optical signal 115 to sample 126 in chamber
129.
[0049] As the optical filter assembly 120 rotates further, filter
122-1 moves out of the path of optical signal 115. The opaque
partition of the optical filter assembly 120 between filter 122-1
and filter 122-2 then temporarily blocks the optical signal 115 so
that substantially little or no optical energy passes through the
sample 126 in chamber 129 to detector 126.
[0050] The filter controller 155 continues to rotate optical filter
assembly 120 so that optical filter 122-2 aligns in the path of the
optical signal 115. When in such a position, the filter 122-2
absorbs certain frequencies in the optical signal 115 and passes
other frequencies of the optical signal 115 to sample 126 in
chamber 129.
[0051] As the optical filter assembly 120 rotates further, filter
122-2 moves out of the path of optical signal 115. The opaque
partition of the optical filter assembly 120 between filter 122-2
and filter 122-3 then temporarily blocks the optical signal 115 so
that substantially little or no optical energy passes through the
sample 126 in chamber 129.
[0052] The filter controller 155 continues to rotate optical filter
assembly 120 so that optical filter 122-3 of the optical filter
assembly 120 lies in the path of the optical signal 115. When in
such a position, the filter 122-3 absorbs certain frequencies in
the optical signal 115 and passes other frequencies of the optical
signal 115 to sample 126 in chamber 129.
[0053] Based on repeating the above sequence of blocking and
filtering different portions of the optical signal 115 over time,
analyzer system 100 produces modulated optical signal 125 by
multiplexing different frequency bands of the optical signal 115
through the sample. Each filter 122 can pass one or more frequency
bands or channels of optical energy to the optical detector
136.
[0054] As mentioned above, the analyzer system 100 passes the
(multi-frequency) modulated optical signal 125 through sample 126.
Depending on how much energy in the different energy bands is
absorbed by the sample, the analyzer 140 detects types of gas
present in the chamber 126 as well as a concentration of the
detected gases.
[0055] By way of a non-limiting example, the filter controller 155
can initiate spinning the optical filter assembly 120 at a rate
such as thirty rotations per second. In such an embodiment,
assuming there are twelve filters on the optical filter assembly
120, the detector 136 and sampling circuit 137 collects three
hundred sixty intensity samples or thirty samples per each filter
for each second.
[0056] A rate of rotating the optical filter assembly 120 to
collect data can vary depending on such factors as how many filters
are presenting the optical filter assembly 120, the ability of the
detector 136 to take a reading, etc.
[0057] The chamber 129 can include reflector 131-1 and reflector
131-2 to increase the optical path length of the modulated optical
signal 125 as it passes through the sample 126. Increasing the
effective optical path length of the modulated optical signal 125
in the chamber 129 enables greater absorption of the modulated
optical signal 125 when a target gas happens to be present in the
chamber 129. This results in more accurate gas type determinations
and/or more accurate gas concentration readings.
[0058] By way of a non-limiting example, the reflectors 131 can be
configured as a multi-pass cell in which the optical signal
repeatedly reflects off reflector 131-1 and 131-2 prior to striking
detector 136.
[0059] After passing through chamber 129, a portion of the
modulated optical signal 132 not absorbed by the sample 126 strikes
detector assembly 136. By way of non-limiting example, an output
signal 305 such as on output voltage of the detector 136 varies
depending on how much energy is present in the optical signal 132.
Monitor circuit 137 can include an amplifier and A/D circuit (e.g.,
analog to digital converter circuit) to measure a strength of the
received optical signal 132. For example the monitor circuit 137
samples the intensity of the detector 136 to produce sample data
138. For example, detector assembly 135 then stores intensity
readings associated with optical signal 132 as sample data 138 in
repository 180.
[0060] By way of a non-limiting example, an output signal 305 such
as the output voltage of the detector 136 varies depending on how
much energy is present in the optical signal 132. Monitor circuit
137 can include an amplifier and A/D circuit (e.g., analog to
digital converter circuit) to measure a strength of the received
optical signal 132.
[0061] In an example embodiment, the detector assembly 135 can be
configured to detect peak values and trough values associated with
the optical signal 132 as illustrated in FIG. 3. As will be
discussed later in this specification, peaks and troughs provide a
relative measure of how much of the optical energy at the different
frequency bands has been absorbed by the sample 126.
[0062] The sample data processor 142 of analyzer 140 processes the
sample data 138 such as peak and trough information at the
different frequency bands to identify which, if any, types of gases
are present in the chamber 129 as well as concentrations of the
gases. Via report 145 on display screen 130, the analyzer 140 can
indicate the different types of gases and concentrations in the
sample 126 for viewing by user 108.
[0063] A benefit of sequentially collecting data in the different
frequency bands is the ability to more accurately detect a presence
of fast moving gases in chamber 126. For example, conventional
methods include setting a filter in a path of an optical signal and
chopping the frequency with a so-called chopper wheel as discussed
above. In such an embodiment, a fast moving gas of a particular
type may not be detected because the conventional analyzer did not
sample the appropriate frequency bands while the fast passing gas
was present in a sample chamber. Embodiments herein include
sequentially collecting data from different frequency bands. In
such embodiments, a fast passing gas in the chamber 129 is more
likely to be detected by the analyzer 140 because the frequency
bands are changed more frequently.
[0064] FIG. 2 is a diagram illustrating an example filter assembly
120 for filtering optical signal 115 and producing modulated
optical signal 125 according to embodiments herein. As shown,
optical filter assembly 120 includes multiple filters 122 including
reference filter 122-1, reference filter 122-2, filter 122-3,
filter 122-4, filter 122-5, filter 122-6, filter 122-7, filter
122-8, filter 122-9, filter 122-10, filter 122-11, and filter
122-12. Opaque regions 220 such as opaque region 220-1, opaque
region 220-2, opaque region 220-3, block optical energy from
passing through sample 126.
[0065] Note that use of twelve filters is shown by way of example
only and that optical filter assembly 120 can include any practical
number of filters.
[0066] Each of the filters 122 can be chosen so that it is possible
for the analyzer 140 to identify which, if any, types of the target
type gases are present in the sample 126 passing through the
chamber 129. As previously discussed, the target gases can include
gases such as H.sub.2O (water), CO (carbon monoxide), CO.sub.2
(carbon dioxide), NO (nitric oxide), NO.sub.2 (nitrogen dioxide),
SO.sub.2 (sulfur dioxide), N.sub.2O (nitrous oxide), CH.sub.4
(methane), HC (hydrocarbons), etc.
[0067] By way of a non-limiting example, the filters 122 can be
configured as follows:
[0068] Each of reference filter 122-1 and reference filter 122-2
can be configured to have a center wavelength of approximately
3.731 micrometers +/-2 percent. The filter 122-1 can have an FWHM
(Full Width at Half Maximum) of 0.08 micrometers. Of course, these
are examples only and the actual filters can vary depending on a
respective application.
[0069] Assuming that the center wavelength of filter 122-1 is 3.731
micrometers, when the filter 122-1 is positioned in a path of the
optical signal 115, the filter 122-1 passes a wavelength band or
range of energy centered around 3.731 micrometers.
[0070] In one embodiment, the center wavelength value of filter
122-1 such as 3.731 micrometers is chosen such that the filter
passes a range of energy wavelengths that are not absorbed by any
of the target gases except water, which tends to absorb energy in
every channel. Use of such reference channels (i.e., filter 122-1
and filter 122-2) serve as a way to correct for drift associated
with other channels in the analyzer system 100. Drift can be caused
by factors such as changes in the intensity of the optical signal
115 produced by 115 over time, changes in the detector and its
ability to detect optical signal 132 over time, etc. If used for
correction of drift, the readings produced by the analyzer system
100 typically will be more accurate.
[0071] Disposing of the reference filters 122-1 and 122-2, one
after the other in a sampling sequence, enables the analyzer system
100 to obtain a more accurate reference reading because the first
reference filter 122-1 establishes a good pre-sample for taking a
following reading with filter 122-2.
[0072] Filter 122-3 can be configured to have a center wavelength
of approximately 2.594 micrometers +/-2 percent. The filter 122-2
can also have an FWHM (Full Width at Half Maximum) of +/-15 percent
of the center wavelength.
[0073] Assuming that the center wavelength of filter 122-3 is 2.594
micrometers, when the filter 122-3 is positioned in a path of the
optical signal 115, the filter 122-3 passes a wavelength band or
range of energy centered around 2.594 micrometers. This frequency
band is at least partially absorbed by H.sub.2O when present in the
sample 126. Other gases that absorb energy in this range, and which
are possibly present in sample 126, include: CO (carbon monoxide),
CO.sub.2 (carbon dioxide), and N.sub.2O (nitrous oxide).
[0074] Filter 122-4 can be configured to have a center wavelength
of approximately 4.630 micrometers +/-2 percent. The filter 122-4
can also have an FWHM (Full Width at Half Maximum) of +/-15
percent.
[0075] Assuming that the center wavelength of filter 122-4 is 4.630
micrometers, when the filter 122-4 is positioned in a path of the
optical signal 115, the filter 122-4 passes a wavelength band or
range of energy centered around 4.630 micrometers. This frequency
band is at least partially absorbed by CO (carbon monoxide) when
present in the sample 126. Other gases that absorb energy in this
range, and which are possibly present in sample 126, include:
H.sub.2O (water) and N.sub.2O (nitrous oxide).
[0076] Filter 122-5 can be configured to have a center wavelength
of approximately 4.843 micrometers +/-2 percent. The filter 122-5
can also have an FWHM (Full Width at Half Maximum) of +/-15 percent
of the center wavelength.
[0077] Assuming that the center wavelength of filter 122-5 is 4.843
micrometers, when the filter 122-5 is positioned in a path of the
optical signal 115, the filter 122-5 passes a wavelength band or
range of energy centered around 4.843 micrometers. This frequency
band is at least partially absorbed by CO.sub.2 (carbon dioxide)
when present in the sample 126. Other gases that absorb energy in
this range, and which are possibly present in sample 126, include:
CO (carbon monoxide), NO (nitric oxide), and SO.sub.2 (sulfur
dioxide).
[0078] Filter 122-6 can be configured to have a center wavelength
of approximately 5.25 micrometers +/-2 percent. The filter 122-6
can also have an FWHM (Full Width at Half Maximum) of +/-15 percent
of the center wavelength.
[0079] Assuming that the center wavelength of filter 122-6 is 5.25
micrometers, when the filter 122-6 is positioned in a path of the
optical signal 115, the filter 122-6 passes a wavelength band or
range of energy centered around 5.25 micrometers. This frequency
band is at least partially absorbed by NO (nitric oxide) when
present in the sample 126. Other gases that absorb energy in this
range, and which are possibly present in sample 126, include:
H.sub.2O (water), CO.sub.2 (carbon dioxide), and NO.sub.2 (nitrogen
dioxide).
[0080] Filter 122-7 can be configured to have a center wavelength
of approximately 6.211 micrometers +/-2 percent. The filter 122-7
can also have an FWHM (Full Width at Half Maximum) of +/-15 percent
of the center wavelength.
[0081] Assuming that the center wavelength of filter 122-7 is 6.211
micrometers, when the filter 122-7 is positioned in a path of the
optical signal 115, the filter 122-7 passes a wavelength band or
range of energy centered around 6.211 micrometers. This frequency
band is at least partially absorbed by NO.sub.2 (nitrogen dioxide)
when present in the sample 126. Other gases that absorb energy in
this range, and which are possibly present in sample 126, include:
H.sub.2O (water), CO (carbon monoxide), NO (nitric oxide), SO.sub.2
(sulfur dioxide), and N.sub.2O (nitrous oxide).
[0082] Filter 122-8 can be configured to have a center wavelength
of approximately 8.696 micrometers +/-2 percent. The filter 122-8
can also have an FWHM (Full Width at Half Maximum) of +/-15 percent
of the center wavelength.
[0083] Assuming that the center wavelength of filter 122-8 is 8.696
micrometers, when the filter 122-8 is positioned in a path of the
optical signal 115, the filter 122-8 passes a wavelength band or
range of energy centered around 8.696 micrometers. This frequency
band is at least partially absorbed by SO.sub.2 (sulfur dioxide)
when present in the sample 126. Other gases that absorb energy in
this range, and which are possibly present in sample 126, include:
CO (carbon monoxide), NO.sub.2 (nitrogen dioxide), and N.sub.2O
(nitrous oxide).
[0084] Filter 122-9 can be configured to have a center wavelength
of approximately 7.831 micrometers +/-2 percent. The filter 122-9
can also have an FWHM (Full Width at Half Maximum) of +/-15 percent
of the center wavelength.
[0085] Assuming that the center wavelength of filter 122-9 is 7.831
micrometers, when the filter 122-9 is positioned in a path of the
optical signal 115, the filter 122-9 passes a wavelength band or
range of energy centered around 7.831 micrometers. This frequency
band is at least partially absorbed by N.sub.2O (nitrous oxide)
when present in the sample 126. Other gases that absorb energy in
this range, and which are possibly present in sample 126, include:
SO.sub.2 (sulfur dioxide).
[0086] Filter 122-10 can be configured to have a center wavelength
of approximately 3.236 micrometers +/-2 percent. The filter 122-10
can also have an FWHM (Full Width at Half Maximum) of +/-15 percent
of the center wavelength.
[0087] Assuming that the center wavelength of filter 122-10 is
3.236 micrometers, when the filter 122-10 is positioned in a path
of the optical signal 115, the filter 122-10 passes a wavelength
band or range of energy centered around 3.236 micrometers. This
frequency band is at least partially absorbed by CH.sub.4 (methane)
when present in the sample 126. Other gases that absorb energy in
this range, and which are possibly present in sample 126, include:
H.sub.2O (water), SO.sub.2 (sulfur dioxide), and N.sub.2O (nitrous
oxide).
[0088] Filter 122-11 can be configured to have a center wavelength
of approximately 3.367 micrometers +/-2 percent. The filter 122-11
can also have an FWHM (Full Width at Half Maximum) of +/-15 percent
of the center wavelength.
[0089] Assuming that the center wavelength of filter 122-11 is
3.367 micrometers, when the filter 122-11 is positioned in a path
of the optical signal 115, the filter 122-11 passes a wavelength
band or range of energy centered around 3.367 micrometers. This
frequency band is at least partially absorbed by HC (hydrocarbons)
when present in the sample 126. Other gases that absorb energy in
this range, and which are possibly present in sample 126, include:
H.sub.2O (water), NO.sub.2 (nitrogen dioxide), SO.sub.2 (sulfur
dioxide), and N.sub.2O (nitrous oxide).
[0090] Filter 122-12 can be configured to have a center wavelength
of approximately 3.896 micrometers +/-2 percent. The filter 122-12
can also have an FWHM (Full Width at Half Maximum) of +/-15 percent
of the center wavelength.
[0091] Assuming that the center wavelength of filter 122-12 is
3.896 micrometers, when the filter 122-12 is positioned in a path
of the optical signal 115, the filter 122-12 passes a wavelength
band or range of energy centered around 3.896 micrometers. This
frequency band is at least partially absorbed by N.sub.2O when
present in the sample 126. Other gases that absorb energy in this
range, and which are possibly present in sample 126, include:
H.sub.2O (water), NO.sub.2 (nitrogen dioxide) and SO.sub.2 (sulfur
dioxide).
[0092] Note again that the center frequencies and frequency bands
as discussed above for each of the filters 122 is presented as an
example only and that these values can vary depending on the
embodiment or which types of gases are to be detected in sample 126
passing through chamber 129. Generally, filters 122 can be any
values that allow passing of bands of optical energy that can be
absorbed by sample 126 and aid in discerning which of multiple
gases are present in the sample 126.
[0093] FIG. 3 is an example diagram illustrating intensities of
optical energy for different frequency bands according to
embodiments herein. As shown, detector 136 senses a magnitude of
light energy in a respective frequency band depending on which
filter is in the path of optical signal 115. Signal 305 such as an
output voltage of the detector 136 represents a measure of how much
optical energy is detected by detector 136. As previously
discussed, sample 126 absorbs a certain portion of optical energy
passed by a respective filter depending on which of one or more
types of gases are present in sample 126.
[0094] Between time T0 and time T1, the light-blocking region of
optical filter assembly 120 between filter 122-12 and filter 122-1
passes the path of optical signal 115. Because the signal is being
blocked during such time, the intensity of signal 305
decreases.
[0095] Between time T1 and time T2, the reference filter 122-1
passes the path of optical signal 115. Because a respective
frequency band of optical signal 115 passes though filter 122-1
during such time, the intensity of signal 305 increases. As
previously discussed, the amount of optical energy detected by
detector 136 will vary depending on drift or other undefined
fluctuations in the system hardware. In one embodiment, one or more
reference filters of the optical filter assembly have a center
wavelength selected to minimize absorbance due to flue
gas/sample.
[0096] Between time T2 and time T3, the light-blocking region or
opaque region of optical filter assembly 120 between filter 122-1
and filter 122-2 passes the path associated with optical signal
115. Because the optical signal 115 is being blocked during such
time, the intensity of signal 305 decreases.
[0097] Between time T3 and time T4, the reference filter 122-2
passes the path of optical signal 115. Because a respective
frequency band of optical signal 115 passes though filter 122-2
during such time, the intensity of signal 305 increases.
[0098] Between time T4 and time T5, the light-blocking region or
opaque region of optical filter assembly 120 between filter 122-2
and filter 122-3 passes the path of optical signal 115. Because the
optical signal 115 is blocked during such time, the intensity of
signal 305 decreases.
[0099] Between time T5 and time T6, filter 122-3 passes the path of
optical signal 115. Because a respective frequency band of optical
signal 115 passes though filter 122-3 during such time, the
intensity of signal 305 increases. As previously discussed, the
amount of optical energy detected by detector 136 will vary
depending on how much of the optical signal is absorbed by sample
126.
[0100] Eventually, the analyzer 140 repeats the same sequence of
filtering for each following cycle 2, 3 and so on. In one
embodiment, during this process of repeatedly blocking and passing
of the optical signal 115 over time, the monitor circuit 137
samples signal 305 to produce sample data 138 as in FIG. 4. An
intensity reading for a given filter 122 can be a measure between a
peak and subsequent valley or between a valley and subsequent peak
of signal 305. Or alternately, the intensity can be measured by
tracking the rate at which the signal changes when optical filters
and opaque areas sequentially pass in front of the source.
[0101] For example, as previously discussed and as shown in FIG. 3,
signal 305 increases between time T1 and time T2. The monitor
circuit 137 can be configured to measure the optical energy in a
frame such as when filter 122-1 passes in a path of optical signal
115 by repeated sampling of signal 305 to identify the lowest value
of the signal 305, which occurs around time T1. The identified low
value represents a valley and relative "zero" of the detector 136
for filter 122-1. The monitor circuit 137 also monitors signal 305
in the frame to identify a subsequent highest value of the signal
305, which occurs at around time T2. The high value represents a
peak for filter 122-1. A difference in the signal 305 values
between this peak and the valley pair represents a measure of how
much optical energy is detected by the detector 136 for the given
filter.
[0102] Signal 305 increases between time T3 and time T4. The
monitor circuit 137 can be configured to measure the optical energy
in a frame such as when filter 122-2 passes in a path of optical
signal 115 by repeated sampling of signal 305 to identify the
lowest value of the signal 305, which occurs around time T3. The
identified low value represents a valley and relative "zero" of the
detector 136 for filter 122-2. The monitor circuit 137 also
monitors signal 305 to identify a subsequent highest value of the
signal 305, which occurs at around time T2. The high value
represents a peak for filter 122-2. A difference in the signal 305
between this peak and the valley pair represents a measure of how
much optical energy is detected by the detector 136 for filter
122-2.
[0103] This monitor circuit 137 can be configured to repeat
sampling of signal 305 for each of the different filters 122 on a
continuous basis so that the analyzer system 100 continuously
monitors the presence of different gases in sample 126 as it passes
from inlet 127 through chamber 129 to outlet 128. Note again that
measuring the optical energy between peak-valley pairs or
valley-peak pairs to determine an absorbance of optical energy is
shown by way of a non-limiting example only and that the signal 305
can be processed in a number of different ways to detect how much
of the optical signal 115 passes through the sample 126 and/or how
much is absorbed by the sample 126.
[0104] FIG. 4 is an example diagram illustrating sample data 138
according to embodiments herein. As shown, sample data 138-1
includes intensity readings associated with signal 305 for each of
the filters 122 for cycle #1, sample data 138-2 includes intensity
readings associated with signal 305 for each of the filters 122 for
cycle #2, and so on. Sample data such as data 11, data 12, etc. for
each successive filter 122 represents data collected by monitor
circuit 137.
[0105] In one embodiment, data sample 138-1 can include sample
information collected during cycle #1. For example, data 11 can
include a pair of peak-valley readings for reference filter 122-1
in cycle #1, data 12 can include a pair of peak-valley readings for
reference filter 122-2 in cycle #1, data 13 can include a pair of
peak-valley readings for filter 122-3 in cycle #1, and so on.
[0106] In furtherance of such an embodiment, data sample 138-2 can
include sample information collected during cycle #2. For example,
data 21 can include a pair of peak-valley readings for reference
filter 122-1 in cycle #2, data 22 can include a pair of peak-valley
readings for reference filter 122-2 in cycle #2, data 23 can
include a pair of peak-valley readings for filter 122-3 in cycle
#2, and so on.
[0107] In this way, the monitor circuit 137 can store sample data
for each of the cycles.
[0108] To reduce the amount of data stored in repository 180, the
monitor circuit 137 can store sample data 138 in any of multiple
different ways. For example, in one embodiment, the monitor circuit
137 collects the peak and valley values for each of the different
filters 122 for cycle #1 and stores the sample data in repository
180. In following cycle #2, the monitor circuit 137 collects peak
and valley values for each of the different filters 122 for cycle
#2 and adds the collected peak and valley values for cycle #2 to
those for cycle #1. The monitor circuit 137 repeats this process of
collecting and summing the sample data such that, after K cycles,
the sample data 138 in repository 180 includes a summation of K
peak samples and a summation of K valley samples for filter 122-1,
a summation of K peak samples and a summation of K valley samples
for filter 122-2, a summation of K peak samples and a summation of
K valley samples for filter 122-3, a summation of K peak samples
and a summation of K valley samples for filter 122-4, and so
on.
[0109] As previously discussed, after collection of the sample data
138, the analyzer 140 (FIG. 1) uses the collected sample data 138
to identify which type of matter such as gases are present in
sample 126 and/or a concentration of the gases.
[0110] FIG. 5 is an example graph 500 illustrating absorption of
energy associated with carbon monoxide over a range of wavelengths.
As shown, carbon monoxide absorbs optical energy in the range of
optical wavelengths approximately between 4.4 and 4.8
micrometers.
[0111] FIG. 6 is an example graph 600 illustrating absorption of
energy associated with carbon dioxide over a range of wavelengths.
As shown, carbon dioxide absorbs optical energy in the range of
optical wavelengths approximately between 4.2 and 4.5
micrometers.
[0112] FIG. 7 is an example graph 700 illustrating energy
absorption at different wavelengths for multiple different gases
such as gas X, gas Y, and gas Z, potentially present in sample 126
passing through chamber 129. Note that this is only an example
illustration of different gases and how they can absorb optical
energy in the same wavelengths and thus "interfere" with each
other.
[0113] As illustrated, certain gases can absorb optical energy at
around the same wavelengths. For example, gas Y and gas Z both
absorb optical energy in a range of wavelength values around
wavelength W2. Also, gas Y and gas Z both absorb optical energy in
a range of wavelength values around wavelength W3.
[0114] The following discussion presents an example of how to
convert detected optical intensity values such as those in sample
data 138 to one or more corresponding concentration measurements of
gases present in sample 126. The first step is to determine the
amount of energy that was absorbed by the gas sample. This is
called the Absorbance, and it is defined as the log of the ratio of
the intensity measured when there is no sample present (the Zero
Intensity) divided by the intensity measured when the sample is
present (Sample Intensity).
A=In(I.sub.o/I.sub.s), (Equation 1)
[0115] where A is the absorbance, I.sub.o is the intensity measured
while sampling high purity zero air, and I.sub.s the intensity
measured while sampling the gas of interest.
[0116] As long as you hold other parameters constant, the
absorbance is a direct measure of concentration. Also, absorbance
values are additive, so if two different gases both cause some
attenuation or absorbance of the modulated optical signal 125 for a
given filter 122, the total absorbance at that wavelength is the
sum of the individual absorbance for each of the gases. This is
referred to as interference. Analyzer 140 corrects for cross
interferences between channels as discussed below.
[0117] To more accurately measure absorbance of the modulated
optical signal 125, the analyzer 140 can be calibrated in
accordance with a calibration procedure that establishes the
relationship between the measured absorbance and the concentration
of the target compound in the sample 126.
[0118] In one embodiment, the calibration procedure includes
filling the chamber 129 with clean, so-called "zero" air that does
not contain the target compound (Absorbance=0). The analyzer 140
records the detected signal for such a gas. In one embodiment,
calibration includes calibrating the analyzer 140 at each of
multiple different concentrations for each gas of interest that may
be present in sample 126.
[0119] According to Beer's Law:
A=.epsilon.bC, (equation 2)
[0120] where A is absorbance, .epsilon. is the absorptivity of the
gas of interest, b is the sample pathlength as a result of
reflections between reflectors 131, and C is the concentration of
the gas of interest.
[0121] Absorbance readings increase proportionally for increased
concentrations of the target compound. In practice, some deviation
from linearity may be observed.
[0122] As mentioned above, the analyzer 140 can be calibrated using
multipoint calibration, using high purity zero air and a series of
different concentration of span gases in a factory setting.
[0123] In the field, it may be difficult for an average user to
perform this type of calibration. Thus, field calibration
procedures may be different than factory calibration procedures. A
so-called field zero procedure or calibration performed in the
field can be similar to the factory zero as discussed above, except
there is no assumption that the so-called "zero" air will be free
of water. Also, instead of calibrating the analyzer 140 via testing
of multiple span concentrations for each target gas, the
calibration procedure can include measuring a single target sample
at a known concentration as the non-linearity detected during the
factory calibration is repeatable.
[0124] As previously discussed, the reference wavelength for filter
122-1 and filter 122-2 is selected at a point in the optical
spectrum where none of the possible target gases in the sample 126
is expected to cause absorbance. Changes in the intensity of the
modulated optical signal 125 measured at the reference wavelength
are assumed to occur because of fluctuations in behavior of the
hardware such as the source 110 and detector 136 and are assumed to
occur to the same degree in both the reference channels and sample
channels. Reference channels refer to sampling of the modulated
optical signal 125 via use of filter 122-1 and filter 122-2. Sample
channels refer to sampling of the modulated optical signal 125 via
use of filter 122-3, filter 122-4, etc. By recording the ratio of
sample signal to reference signal (S/R), the impact of instrument
drift or random interferences can be reduced.
[0125] FIG. 8 is a block diagram of an example architecture of a
respective computer system 810 such as one or more computers,
processes, etc., for implementing analyzer 140 according to
embodiments herein. Computer system 810 can include one or more
computerized devices such as personal computers, workstations,
portable computing devices, consoles, network terminals, networks,
processing devices, etc.
[0126] Note that the following discussion provides a basic example
embodiment indicating how to carry out all or portions of the
functionality associated with the analyzer 140 as discussed above
and below. However, it should be noted again that the actual
configuration for carrying out the analyzer 140 can vary depending
on a respective application. For example, as previously discussed,
computer system 810 can include one or multiple computers that
carry out the processing as described herein.
[0127] As shown, computer system 810 of the present example
includes an interconnect 811 coupling memory system 812, a
processor 813, I/O interface 814, and a communications interface
817.
[0128] I/O interface 814 provides connectivity to peripheral
devices such as repository 180 and other devices 816 (if such
devices are present) such as a keyboard, mouse (e.g., selection
tool to move a cursor), display screen 130, etc.
[0129] Communications interface 817 enables the analyzer
application 140-1 of computer system 810 to communicate over
network 190 and, if necessary, retrieve data, update information,
etc., from different sources.
[0130] As shown, memory system 812 can be encoded with instructions
associated with analyzer application 140-1. The instructions
support functionality as discussed above and as discussed further
below. The analyzer application 140-1 (and/or other resources as
described herein) can be embodied as software code such as data
and/or logic instructions on a tangible and/or intangible computer
readable medium, media, etc. such as memory or on another computer
readable medium that supports processing functionality according to
different embodiments described herein.
[0131] During operation of one embodiment, processor 813 accesses
memory system 812 via the use of interconnect 811 in order to
launch, run, execute, interpret or otherwise perform the logic
instructions of the analyzer application 140-1. Execution of the
analyzer application 140-1 produces processing functionality in
analyzer process 140-2. In other words, the analyzer process 140-2
represents one or more portions of the analyzer 140 performing
within or upon the processor 813 in the computer system 810.
[0132] It should be noted that, in addition to the analyzer process
140-2 that carries out method operations as discussed herein, other
embodiments herein include the analyzer application 140-1 itself
such as the un-executed or non-performing logic instructions and/or
data, etc. The analyzer application 140-1 may be stored on a
computer readable medium such as a floppy disk, hard disk or in an
optical medium. According to other embodiments, the analyzer
application 140-1 can also be stored in a memory type system such
as in firmware, read only memory (ROM), or, as in this example, as
executable code within the memory system 812 (e.g., within Random
Access Memory or RAM).
[0133] Functionality supported by analyzer 140 and, more
particularly, functionality associated with analyzer 140 will now
be discussed via flowcharts in FIGS. 9 through 10.
[0134] More particularly, FIG. 9 is an example flowchart 900
illustrating operations associated with analyzer 140 according to
embodiments herein. Note that flowchart 900 of FIG. 9 and
corresponding text below may overlap with and refer to some of the
matter previously discussed with respect to FIGS. 1-8. Also, note
that the steps in the below flowcharts need not always be executed
in the order shown.
[0135] In step 910, the analyzer 140 generates an optical signal
115 to pass through a sample 126.
[0136] In step 915, the analyzer 140 selects application of each of
different optical filters 122 in a path of the optical signal 125
to produce modulated optical signal 125.
[0137] In step 920, the analyzer 140 analyzes the modulated optical
signal 125 after passing of the modulated optical signal 125
through the sample 126 to detect which of multiple possible target
gases are present in the sample 126.
[0138] FIG. 10 is an example flowchart 1000 illustrating operations
associated with analyzer 140 according to embodiments herein. Note
that flowchart 1000 of FIG. 10 and corresponding text below may
overlap with and refer to some of the matter previously discussed
with respect to FIGS. 1-9. Also, note that the steps in the below
flowcharts need not always be executed in the order shown.
[0139] In step 1010, the analyzer 140 generates an optical signal
115 in an infrared frequency range.
[0140] In step 1015, the analyzer 140 selects application of each
of different optical filters 122 in a path of the optical signal
115 to produce modulated optical signal 125. Selecting the
different filters 122 can include successive positioning of
different optical filters 122 and opaque partitions 220 in the path
of the optical signal 115. As previously discussed, each of the
different optical filters 122 can be configured to pass a different
optical frequency band of the optical signal 115 through the sample
126.
[0141] For example, in sub-step 1020, the analyzer 140 disposes a
first optical filter such as filter 122-2 in the path of the
optical signal 115 for a duration of time. The optical filter 122-2
is configured to pass a first optical frequency energy band of the
optical signal 115 through the sample 126.
[0142] In sub-step 1030, subsequent to the first duration of time,
the analyzer 140 disposes a second optical filter such as filter
122-3 in the path of the optical signal for a duration of time. The
second optical filter can be configured to pass a second optical
frequency energy band of the optical signal through the sample
126.
[0143] In step 1040, subsequent to the second duration of time, the
analyzer 100 can dispose a third optical filter such as filter
122-4 in the path of the optical signal 115 for a duration of time.
The third optical filter can be configured to pass a third optical
frequency energy band of the optical signal through the sample
126.
[0144] Based on repeatedly passing the filter 122 in a path of the
optical signal 115, the analyzer 140 produce modulated optical
signal 125.
[0145] In step 1050, the analyzer 140 analyzes the modulated
optical signal 125 after passing of the modulated optical signal
125 through the sample 126 to detect which of multiple gases are
present in the sample 126.
[0146] In step 1060, for each of multiple filters, the analyzer 100
detects an amount of optical energy in the modulated optical signal
125 after passing of the optical energy through the sample 126 for
each of the multiple filters 122.
[0147] In step 1070, the analyzer 140 determines a concentration of
one or more gases present in the sample based on how much of the
modulated optical signal 125 is absorbed by the sample 126 at
different optical energies.
[0148] Those skilled in the art will understand that there can be
many variations made to the operations of the user interface
explained above while still achieving the same objectives of the
invention. Such variations are intended to be covered by the scope
of this invention. As such, the foregoing description of
embodiments of the invention are not intended to be limiting.
Rather, any limitations to embodiments of the invention are
presented in the following claims.
* * * * *