1] n T169
Contents
1. 6 369 894 Bl 4 2002 Rasimas et al 6 490 030 Bl 12 2002 Gill et al 356 71 6 670 617 Bl 12 2003 Banks 6 685 840 B1 2 2004 Hatch 2002 0054288 Al 5 2002 Kim et al FOREIGN PATENT DOCUMENTS WO WO 03 060461 A2 7 2003 OTHER PUBLICATIONS SCUFA Submersible Fluorometer Performance Testing www turnerdesigns com t2 esci s_0039 11 pages Dec 1 2003 Continued Primary Examiner F L Evans 74 Attorney Agent or Firm Peter A DiMattia Thomas M Breininger 57 ABSTRACT Described and claimed is an interchangeable tip open cell fluorometer comprising a housing and a fluorometric probe tip interchangeably connected to the housing the probe tip including a probe tip housing defining an open cell and enclosing a probe optical arrangement the probe optical arrangement including an excitation source and a fluores cence detector wherein the excitation source is aimed directly into the fluorescence detector such that a sample can be fluorometrically detected Also claimed is a method of using this interchangeable tip open cell fluorometer for detecting fluorescent signals emitted by one or more fluo rophores from samples from a natural or industrial water system The fluorometer when coupled with a controller is capable of monitoring and optionally controlling an indus trial process or system 2 Claims 5 Drawing Sheets US 7 154 603 B2 Page 2 OTHER PUBLICATIONS SCUFA Submersible Fluorometer Perfo2. 11 measure a portion of the light from light source 108 to account for variations in light source 108 Example Four Interchangeable Probe Tip with Compound Angle Beam Configuration Turning to FIG 4 another embodiment illustrative of the interchangeable tip is provided In general this example provides another variation regarding the positioning with respect to a pair of light sources that can be used to enhance the fluorescent detection capabilities of the interchangeable probe tip The interchangeable probe tip 120 includes an excitation source 122 that includes a UV LED source This is used to measure fluorescence in a sample 124 within a measuring cell 126 In this regard the excitation light source 122 emits a collimated beam of light 128 into the sample 124 via a first filter 130 such that a fluorescence emission 131 is generated and then passes through the second filter 132 into a detector 134 via an aperture 136 The excitation light 128 passes through the first filter 130 at an angle offset from perpen dicular such as about 9 or less The excitation light 128 is effectively blocked out or at least a substantial portion thereof from passing into the detector 134 due to the optical features of the filters as discussed above Thus the fluores cent measurement can be taken with minimal if any effect due to the excitation light Further the probe tip 120 includes a second light source 137 The second light source 137 incl
3. 12 United States Patent Banks US007154603B2 10 Patent No US 7 154 603 B2 45 Date of Patent Dec 26 2006 54 75 73 21 22 65 63 51 52 58 56 INTERCHANGEABLE TIP OPEN CELL FLUOROMETER Inventor Rodney H Banks Aurora IL US Assignee Nalco Company Naperville IL US Notice Subject to any disclaimer the term of this patent is extended or adjusted under 35 U S C 154 b by 0 days Appl No 11 493 446 Filed Jul 26 2006 Prior Publication Data US 2006 0262309 A1 Nov 23 2006 Related U S Application Data Continuation of application No 10 769 631 filed on Jan 30 2004 now Pat No 7 095 500 Int Cl GOIN 21 64 2006 01 USS CL eerte 356 417 250 461 1 356 73 Field of Classification Search 356 317 356 318 417 73 250 458 1 459 1 461 1 250 461 2 See application file for complete search history References Cited U S PATENT DOCUMENTS 2 663 801 A 12 1953 Slavin et al we 250 365 4 084 905 A 4 1978 Schreiber et al 356 317 4 301 372 A 11 1981 Giering et al 4 577 110 A 3 1986 MacBride et al 250 46 1 2 4 783 314 A 11 1988 Hoots et al 4 804 850 A 2 1989 Norrish et al 250 459 1 4 992 380 A 2 1991 Moriarty et al 5 994 707 A 11 1999 Mendoza et al 6 060 318 A 5 2000 Moeggenborg et al 6 255 118 Bl 7 2001 Alfano et al 6 280 635 Bl 8 2001 Moriarty et al 6 329 165 B1 12 2001 Chattoraj et al
4. measure the temperature and or the status of the flowswitch may be included The fluorometer can be further connected to the controller by a communication cable that enables the controller to electronically communicate with the fluorometer to control the components of the fluorometer as previously discussed A suitable communication protocol must be selected in order to operate the fluorometer Suitable standard communication protocols include but are not limited to RS 232 FC CAN TCP IP and a standard RS 485 serial communication pro tocol The preferred communication protocol is a standard RS 485 serial communication protocol It is also possible to use a wireless communication protocol between the fluo rometer and controller One such suitable wireless commu nication protocol is Bluetooth The controller can include isolated multiple analog inputs These inputs provide information based on their signal magnitude via 4 20 mA connections The signals are read by the analog inputs for controlling logic of the controller to provide additional levels of control to for example an industrial water system In a preferred embodi ment the controller has twenty 20 discrete analog inputs As previously discussed the fluorometer of the present invention can be used to monitor and or detect the presence of one or more fluorophores in a sample derived from any suitable process or system including natural water systems industrial water systems
5. or other like sources Industrial 20 25 30 40 45 50 55 14 water systems include but are not limited to cooling tower water systems including open recirculating closed and once through systems petroleum wells downhole forma tions geothermal wells and other oil field applications boilers and boiler water systems mineral process waters including mineral washing flotation and benefaction paper mill digesters washers bleach plants and white water sys tems black liquor evaporators in the pulp industry gas scrubbers and air washers continuous casting processes in the metallurgical industry air conditioning and refrigeration systems industrial and petroleum process water indirect contact cooling and heating water such as pasteurization water water reclamation and purification systems mem brane filtration water systems food processing streams meat vegetable sugar beets sugar cane grain poultry fruit and soybean and waste treatment systems as well as in clarifiers liquid solid applications municipal sewage treatment and industrial or municipal water systems The fluorometer of the present invention can be used in a variety of different industrial water system applications as disclosed for example in the following U S patent appli cations The instant claimed fluorometer and controller are capable of functioning to control a cooling water system as described and claimed in U S Pat No 6 31
6. 5 909 B1 entitled USE OF CONTROL MATRIX FOR COOLING WATER SYSTEMS CONTROL issued Nov 13 2001 which is herein incorporated by reference in its entirety The instant claimed fluorometer and controller are capable of functioning to control a boiler as described and claimed in U S Pat No 6 336 058 B1 entitled USE OF CONTROL MATRIX FOR BOILER CONTROL issued U S Pat No 6 336 058 B1 issued Jan 1 2002 which is herein incorporated by reference in its entirety It should be understood that various changes and modi fications to the presently preferred embodiments described herein will be apparent to those skilled in the art Such changes and modifications can be made without departing from the spirit and scope of the present invention and without diminishing its attendant advantages It is therefore intended that such changes and modifications be covered by the appended claims What is claimed is 1 An interchangeable tip open cell fluorometer compris ing a housing and a fluorometric probe tip interchangeably connected to the housing the probe tip including a probe tip housing defining an open cell and enclosing a probe optical arrangement the probe optical arrange ment including an excitation source and a fluorescence detector wherein the excitation source is aimed at the fluorescence detector such that a sample in the open cell can be fluorometrically detected wherein said interchangeable tip fluorometer has an aperture that
7. cal features of the filters as discussed above Thus the fluorescent measurement can be taken with minimal if any effect due to the excitation light The probe tip further includes a reference detector 107 that detects a portion of the excitation light derived from the excitation source This can also enhance the detection capabilities of the probe tip as previously discussed Further the probe tip 90 includes a second light source 108 The second light source 108 includes an IR LED that generates a collimated beam of light 110 The light 110 passes through the first filter 98 at an angle offset from perpendicular to the first filter For example the angle is offset at about 12 or less from perpendicular or normal In this way the second source of light 110 passes through the sample through the second filter 102 and into the detector 104 via the aperture 106 along a path that corresponds in a sufficient amount to the path through which the excitation light and fluorescent emission has passed The detector then can measure the intensity of the second light source which can be used for corrective purposes as previously discussed This demonstrates that the second source of light does not necessarily have to pass along the same path as the source of excitation light and or emission therefrom in order to effectively act for corrective purposes due to fouling tur bidity and or the like Reference detector 107 can be used to US 7 154 603 B2
8. ctor 169 80 169 U S Patent Dec 26 2006 Sheet 3 of 5 US 7 154 603 B2 FIG 3 Ref Detector lined 9 169 U S Patent Dec 26 2006 Sheet 4 of 5 US 7 154 603 B2 FIG 4 US 7 154 603 B2 Sheet 5 of 5 Dec 26 2006 U S Patent BuisnoH zol EE aes 9S1 09 est a2 O5 hd dd col J0 08UU0D e9493 G Sls di 9goud J cL 10 98UU0 EIDO vol big 991 891 easy ajdwes US 7 154 603 B2 1 INTERCHANGEABLE TIP OPEN CELL FLUOROMETER CROSS REFERENCE TO RELATED APPLICATIONS This application is a continuation application of U S patent application Ser No 10 769 631 which was filed on Jan 30 2004 now U S Pat No 7 095 500 FIELD OF THE INVENTION The present invention relates generally to analytical devices and methods for monitoring and or controlling natu ral or industrial processes or systems More specifically the present invention relates to an interchangeable tip open cell fluorometer for detecting fluorescence emitted by a sample derived from a natural or an industrial process or system such that the process or system can be monitored and optionally controlled BACKGROUND OF THE INVENTION A fluorometer is an analytical device that essentially comprises a light source a means of selecting the desired excitation wavelength range a sample cell a means of selecting the desired emission wavelength range and a detector A spectrofluorometer is a spec
9. d for detection purposes in any suitable way such as for grab sampling purposes in line detection in process detection and or the like In general the fluorometer includes a fluorometric probe tip that is interchangeably connected to a housing The fluorometric probe tip includes an excitation light source The excitation source can include any suitable type of light source such as a monochromatic light source polychro matic light source and the like For example the excitation source can include a LED source a laser source and the like The LED source can emit light of varying wavelengths such as an IR LED a UV LED a blue LED and or the like The excitation source generates a collimated beam of excitation light The excitation light passes through a filter in the probe tip and into a measuring cell with an open cell configuration defined by the probe tip housing and the 20 25 30 35 40 45 50 55 60 65 6 surface of the excitation light filter and the surface of the emission light filter The sample is in direct contact with the filters as previously discussed This allows the excitation light to project into the sample within the measuring cell whereupon fluorescence is produced due to the presence of one or more fluorophores in the sample The emitted fluo rescence then passes through an additional filter and is directed to a fluorescence detector for detection purposes The additional filter also acts
10. e ready for use once one probe tip is inter changed with another probe tip Turning to FIG 5 the fluorometer 150 includes a housing 152 and a probe tip 154 The housing electronics not shown can be configured in any suitable way to power the fluorometer 150 In this regard the fluorometer can be battery operated In the 20 25 30 35 40 45 50 55 60 65 12 alternative the fluorometer can be operated by an external power source that is electrically connected to the fluorom eter such as through the housing The housing 152 can include a display 156 for monitoring the fluorescent mea surements At least a number of the functions of the fluo rometer can be automated such as through a switch For example the housing 152 can include an on off switch 158 and a calibration switch 160 for operation in calibration mode as shown in FIG 5 The wiring from the electronics of the housing 152 leads to an electrical connector 162 of any suitable type The interchangeable probe tip 154 has a housing 164 with an opening 166 that defines a measuring cell 168 within which a sample 170 can be fluorometrically measured as previously discussed The probe housing encloses the optics and electronics of the probe tip which can be configured in any suitable way such as illustrated above The wiring of the electronics such as the leads 169 to the detectors light sources and the like connect to the electrical connector 172 of the pr
11. ed fluorom eters have one channel with this channel containing an optically appropriate cell A light source and an optional excitation filter are posi tioned on one side of the optically appropriate cell and an emission detector and an emission filter are positioned on another side of the optically appropriate cell A reference detector may optionally be present Because fluorescence is isotropic in general fluorometers are configured to detect any fluorescent light emitted from the fluorophore at a 90 angle from the light source in order to minimize collection of any spurious excitation light The excitation filter permits light of the chosen excitation wavelength range to pass through the filter and into the cell When conducting off line batch testing a sample of for an 5 20 30 35 40 45 55 60 2 example water from a natural or an industrial water system is placed and held in the optically appropriate cell When conducting on line testing the sample of water can flow through the optically appropriate cell The light is absorbed by a fluorophore present in the water sample which in turn emits a fluorescent light hereinafter known as a fluorescent signal having the same or a longer wavelength than the excitation light The emission filter which is positioned between the emission detector and the optically appropriate cell is chosen so as to permit only the light emitted by the fluorophore the fluor
12. escent signal of the fluorophore to pass through the filter to the emission detector The use of fluorophores in industrial water systems or in hydrology in general is known The use of inert fluorescent tracers for determining the hydraulic losses in an industrial water system is known Furthermore using fluorescent tracers for controlling additive or product dosage to a recirculating or once through cooling water system is also known see U S Pat No 4 783 314 In this method a fluorescent tracer is combined with one or more additives in a known proportion of tracer to additive s and then the mixture is added to the water of a cooling system A fluorometer is then used to detect the presence and concen tration of the fluorescent tracer in the cooling water and therefore the presence and concentration of the amount of additive There will always be a continuing need for new and improved fluorometers to be available for use in the chal lenging area of monitoring and controlling industrial water processes SUMMARY OF THE INVENTION The first aspect of the instant claimed invention is an interchangeable tip open cell fluorometer comprising a housing and a fluorometric probe tip interchangeably connected to the housing the probe tip including a probe tip housing defining an open cell and enclosing a probe optical arrangement the probe optical arrangement including an excitation source and a fluorescence detector wherein the excitatio
13. ght scattering that can be detected and thus interfere with the fluorescent measurement As the aperture size is decreased this should minimize light scattering effects due to turbidity However the aperture size should not be too small such that the emitted fluorescence or sufficient portion thereof is pre vented from passing to the fluorescence detector In an embodiment the interchangeable probe tip includes two light sources an excitation light source and a second light source that does not induce fluorescence The second light source can be used to correct for effects on the fluorescent measurement due to fouling turbidity and or the like The excitation source is dedicated for direct fluores cence measurement This source emits a collimated beam of light into the sample whereupon fluorescence is emitted based on the amount of fluorophore in the sample The fluorescence emission then passes to the fluorescence detec tor via the filter where the excitation light is effectively blocked from passing to the fluorescence detector as previ ously discussed Once fluorescent detection has been made the excitation source is turned off and the second light source is turned on The light emitted from the second light source is a different wavelength than the light emitted from the excitation source so as not to induce fluorescence In an embodiment the excitation source includes a UV LED and the second light source includes an IR LED The sec
14. hat it can withstand general use such as cleaning brushing abrasive particles in the sample and the like This is an important quality due to the fact that the filters act to define the open cell configu ration of the measuring cell according to an embodiment of US 7 154 603 B2 7 the present invention In this regard the sample is in direct contact with the filters and thus must be able operate effectively under normal process conditions The filters are also effectively chemically inert In this way the filters should not be reactive such as with respect to the sample cleaning solutions and the like Having the filters define the measuring cell light scattering due to glass sample cells in conventional fluorometers is effectively eliminated The filters can also be used to adjust the sensitivity of the fluorescent detection In this regard the distance between the filters can be varied and thus effectively acts to adjust sensitivity This may be useful if the measured samples may require different levels of detection sensitivity For example a more concentrated sample of fluorophores may require a lower sensitivity to enhance detection capabilities In this regard the spacing between the filters can be decreased to create less volume of measured sample thus lowering the sensitivity with respect to the detection of same For less concentrated samples the spacing may be increased to increase sensitivity Thus the present inventio
15. he fluorometer housing and the US 7 154 603 B2 5 thermistor resistance is made known the specific optical and electronic arrangement with respect to the probe tip can be identified thus allowing the interchangeable tip open cell fluorometer to be ready for use As previously discussed the probe tip has an optical arrangement that provides a linear and slim profile for the fluorometer In this regard the excitation source of the probe tip is aimed at the fluorescence detector For example the excitation source and or the light that emits therefrom and the fluorescence detector can be configured in a 180 arrangement or acceptable deviations thereof This is differ ent from conventional one channel sample fluorometers where detection of the fluorescent light emitted from the fluorophore is at a 90 angle from the light source as previously discussed Based on these differences the inter changeable tip open cell fluorometer of the present inven tion can provide a number of advantages over conventional one channel sample fluorometers including for example a sleek and simple design selectable sensitivity accurate compensation for turbidity and window fouling and the like as described below The fluorometer of the present invention makes use of a specific type of optical filters such as a thin film optical filter with the requisite optical mechanical and chemical properties necessary to enhance the fluorescent detection capabili
16. ific type of fluorom eter where the means for selecting the excitation and or emission wavelength range is performed by a grating A grating acts to disperse a continuum of light into its com ponents Spectrofluorometers may be further subdivided into scanning spectrofluorometers those that use a mechanical means to scan the wavelength spectrum based on the posi tion of the grating relative to the excitation source and or emission this describes a standard laboratory model fluo rometer or fixed spectrofluorometers where the grating is fixed with respect to the emission The emission fluores cence is then directed to an array of detectors The array of detectors could be charge coupled devices usually abbre viated CCD or the array of detectors could be photo diodes The detectors are then calibrated in the appropriate wavelength units A commercial device such as this is available from Ocean Optics available from Drysdale and Associates Inc PO Box 44055 Cincinnati Ohio 45244 513 831 9625 This type of fixed spectrofluorometer still requires the appropriate excitation wavelength selection device which could be a grating or filter The fluorometers that are most suitable for use under field conditions are not grating spectrofluorometers rather they are filter based fluorometers A filter based fluorometer uses a filter to exclude all but the selected wavelength range In general currently available and known filter bas
17. is in communication with said fluorescence detector 2 The apparatus of claim 1 wherein said aperture is configured as a cylindrical tube shape
18. is a cut away sectional view of yet another interchangeable probe tip for a fluorometer made in accor dance with the present invention FIG 4 is a cut away sectional view of still yet another interchangeable probe tip for a fluorometer made in accor dance with the present invention FIG 5 is a sectional view of an interchangeable probe tip fluorometer made in accordance with the present invention DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENTS Throughout this patent application the following words have the indicated meanings A fluorophore is a molecule that upon absorption of a photon of energy hv that results in an electron being promoted from the molecular electronic ground state S to an electronic excited state S or S or S3 and subsequently relaxing to the lowest vibronic state of excited state S emits a photon of energy E hv that is lower in energy though longer in wavelength than was absorbed Note that this relationship can be illustrated with the equation B apsorprion gt Eymorescencey This emission of energy results in the molecular electronic state being returned to the ground state So The overall process results in emission of fluorescent photons in an isotropic distribution The fluorophores capable of being detected by the instant claimed fluorometer must be capable of absorbing excitation light in the wave lengths of from about 200 nm to about 1200 nm and emitting it at a longe
19. n can be readily adapted to adjust for varying levels of sensitivity depending on the application This sensitivity adjustment cannot be achieved with the conventional 90 optical arrangement Preferably the filter includes a layered structure In gen eral the filter provides a low pass filter layer and a high pass filter layer that are separated by a substrate layer such as a glass substrate This structure allows for the fluorescence emission to pass to the detector via the filter while the excitation light is effectively blocked from doing so The filters are commercially available as Brightline at Sem rock Incorporated 3625 Buffalo Road Suite 6 Rochester N Y 14624 585 594 7017 It should be appreciated that a commercially available filter material may be required to be modified and customized with respect to the optical mechanical and chemical properties of the filter depending on the application The interchangeable probe tip can include additional other and suitable components that can further enhance its detec tion capabilities For example the probe tip can include a reference detector This is used to measure a portion of the excitation light source during fluorescent detection In this regard the reference detector can be used to compensate for variations in the excitation light emission due to for example changes in current associated with the excitation light source temperature changes aging device to device va
20. n source is aimed at the fluorescence detector such that a sample can be fluorometrically detected The second aspect of the instant claimed invention is a method of fluorometrically detecting fluorophores present in a sample the method comprising the steps of a providing a fluorometer the fluorometer comprising a housing and a fluorometric probe tip interchangeably connected to the housing the probe tip including a probe tip housing defining an open cell and enclosing a probe optical arrangement the probe optical arrangement including an excitation source and a fluorescence detector wherein the excitation source is aimed at the fluorescence detector such that a sample can be fluorometrically detected b providing one or more samples derived from a natural or industrial process stream c using the fluorometer to detect the fluorescent signals of the fluorophores in the samples and d operating a controller in such a way that the fluorescent signals detected by the fluorometer are used by the controller to monitor and or control the natural or industrial process from which the samples are taken BRIEF DESCRIPTION OF THE DRAWINGS FIG 1 is a cut away sectional view of an interchangeable probe tip for a fluorometer made in accordance with the present invention US 7 154 603 B2 3 FIG 2 is a cut away sectional view of another inter changeable probe tip for a fluorometer made in accordance with the present invention FIG 3
21. nd colorimetric measurements can be taken with a probe tip that has been configured specific to that application Thus the present invention contemplates the interchangeability of probe tips that can separately measure fluorescence turbidity and colorimetry For example the turbidity probe tip can be configured in a similar way as the fluorometric probe tip as discussed above The difference between the two results in the type of light sources For the turbidity probe tip the light source must not cause fluorescence For highest sensitivity the aperture is removed Any suitable light source can be used such as a UV LED blue LED or the like With the turbidity probe tip a blue light source is preferable However the fluorometric probe tip can be interchanged with the turbidity probe tip and vice versa given the self identifying features as discussed above With respect to a colorimetric probe tip this design is similar to the fluorometric and or turbidity tip design except that only one filter is necessary The light source is chosen to correspond to an absorption band of the material in the sample to be detected In general a calorimetric amount US 7 154 603 B2 13 associated with the sample can be measured by passing an excitation light source such as a UV LED though a first filter and then into a detector constructed for that particular type of detection It should be appreciated that the mirrors filters detectors excitati
22. obe tip 154 This allows the probe tip 154 to be pluggable into the housing 152 via mating of the electrical connector 172 of the probe tip 154 and the electrical connector 162 of the housing 152 Once the probe tip is plugged into the housing the fluorometer is effectively ready for use The probe tip includes a thermistor not shown The optical and electronic arrangement of the probe tip is associated with a respective thermistor that has a specific resistance as previously dis cussed This allows the fluorometer to recognize what type of probe tip is being used once a probe tip has been interchanged with another probe tip thus enabling it ready for use It should be appreciated that the self identifying property of the interchangeable tip open cell fluorometer can be configured in any suitable way For example the self identifying features of the present invention can include the same or similar features with respect to the smart probe as disclosed in U S Pat No 6 556 027 that issued on Apr 29 2003 which is herein incorporated by reference in its entirety The interchangeable probe tip can include any suitable type of optical and electrical arrangement for purposes of fluorescent detection examples of which have been dis cussed above In addition to fluorescence the fluorometer can be adapted to take additional other measurements such as with respect to turbidity colorimetry and the like In this regard the turbidity a
23. on light sources and other suitable components can include a variety of different and suitable commercially available or known products For example the detectors are commercially available from Hamamatsu Corporation 360 Foothill Road Bridgewater N J 08807 Part No S2386 44K the UV LED source is commercially available from Nichia America Corporation 3000 Town Center Drive Southfield Mich 48075 Part No NSHU590A and the IR LED source is commercially available from Optek Technol ogy Inc 1215 W Crosby Road Carrollton Tex 75006 Part No OP265B The present invention can include a variety of different and additional components for optimizing process control monitoring and or automation In an embodiment the fluo rometer includes a printed circuit board assembly connected to a controller each of a suitable and known construction not shown For example the controller is available from Tecnova 1486 St Paul Ave Gurnee Ill 60031 847 662 6260 The printed circuit board PCB assemblies useful in this device must be fabricated to allow powering by the control ler or other device of the components of the fluorometer which include for example drivers for the excitation sources and amplifiers to perform current to voltage con version and signal amplification from the photodetectors Circuitry to manipulate the signals and communicate the magnitude of the signals is also integral to the PCB Addi tional circuitry to
24. ond light source emits light into the fluorescence detector via the filters and sample The second light emission is preferably directed along a path that corresponds to the same path along which the light from the excitation source was passed In an embodiment the first and second light emissions pass along the same or substan tially the same path This allows the second light once detected to provide an accurate indication that corresponds to the amount of fouling turbidity and or other effects on the fluorescent measurement In this way the fluorescent mea surement can be corrected in any suitable manner to account for such effects thus enhancing the fluorescent detection capabilities These corrections cannot be done with the conventional 90 optical arrangement Alternatively the first and second light emissions can deviate from an emission path that is the same or substan tially the same Thus the first and second light emissions can be configured to pass in sufficient portion along the same path such that correction with respect to fouling turbidity and or the like can be effectively though less accurately made It should be appreciated that the first and second light sources can be configured in a number of suitable and different ways some of which are described in greater detail below As previously discussed the interchangeable tip open cell fluorometer of the present invention can be configured in a number of suitable wa
25. ore in the sample The fluorescence emission 72 passes through a second filter 74 and into a fluorescence detector 76 for detection purposes The fluo rescence emission 72 passes through an aperture 78 to minimize the effects of turbidity on the detectable fluores cence The aperture 78 is sized such that all or a substantial portion of the fluorescence emission passes therethrough and into the detector The interchangeable probe tip further includes a reference detector 80 that can be used to measure a portion of the light derived from the excitation source As previously discussed this can be then used to account for variations in the excitation light source Example Three Interchangeable Probe Tip with Double Angle Beam Configuration Turning to FIG 3 another embodiment of the inter changeable probe tip is provided The interchangeable probe tip 90 includes an excitation source 92 that includes a UV LED source This is used to measure fluorescence in a sample 94 within a measuring cell 193 in a similar fashion as provided in EXAMPLE TWO In this regard the exci tation light source 92 emits a collimated beam of light 96 into the sample 94 via a first filter 98 such that a fluorescence emission 100 is generated and then passes through a second filter 102 into a detector 104 via an aperture 106 The excitation light 96 is effectively blocked out or at least a substantial portion thereof from passing into the detector 104 due to the opti
26. orophores tip damage and or the like Upon replacing one interchangeable tip for another interchangeable tip the fluorometer is ready for use with minimal or effectively no added effort required from the operator This is a huge practical advantage of the instant claimed invention especially when compared to the effort required to set up and use two different fluorometers In this regard the probe tip contains virtually all of the electronics and optics to perform the fluorescence measure ments For example proper gain can be built into the electronic configuration associated with the probe tip thus relieving the main unit from having to adjust gain settings Further noise interferences can be minimized by having the electronics inside of the probe tip The excitation source such as a light emitting diode LED source can be config ured to have its own series resistor so that the main unit does not have to regulate LED current The probe tip also optionally can include a thermistor It is preferred that the probe tip include a thermistor to measure sample temperature for correction of fluorescence intensity By choosing different thermistor resistances based on for example a temperature of 25 C the probe tips are effec tively self identifying without added cost or complexity In other words each probe tip can include a thermistor with a resistance that is specific to the respective probe tip Once the probe tip is plugged into t
27. r wavelength than the excitation light Inert refers to the fact that an inert fluorophore is not appreciably or significantly affected by any other chemistry in the cooling water system or by the other system param eters such as metallurgical composition microbiological activity biocide concentration heat changes or overall heat content To quantify what is meant by not appreciably or significantly affected this statement means that an inert fluorophore has no more than a 10 change in its fluorescent signal under conditions normally encountered in cooling water systems Conditions normally encountered in cooling water systems are known to people of ordinary skill in the art of cooling water systems Isotropic refers to the fact that if a moiety is considered a point source and excitation light is directed at the moiety fluorescent light is emitted equally in all directions creating in effect a sphere in 3 dimensions nm means nanometers which are 107 meters The present invention provides an interchangeable tip open cell fluorometer This interchangeable tip open cell fluorometer includes one or more probe tips that can be interchangeably used with respect to the same fluorometer At least one of the probe tips includes an optical arrange ment that allows for the fluorometric detection of a sample in a measuring cell associated with the fluorometer such as a measuring cell in an open or flow cell configu
28. ration In general the probe tip optical arrangement includes an exci tation source and a fluorescence detector such that excitation source is aimed at the fluorescence detector such as directly at the detector in a 180 arrangement or substantially approximate 180 arrangement This effectively provides a sleek and simple design that can be effectively used to detect monitor and or control industrial or natural streams based on a fluorometric measurement from a sample derived from same It should be appreciated that the present inven 20 25 30 35 40 45 50 55 60 65 4 tion contemplates an arrangement with respect to the exci tation source and the fluorescence detector that can deviate from a 180 arrangement as described below in greater detail The interchangeable tip open cell fluorometer of the present invention can provide a low cost alternative to conventional fluorometers In an embodiment the fluorom eter of the present invention is provided in a flashlight style that can be hand held and shaped in any suitable way such as a cylindrical tube shape In this regard a measurement can be taken by dipping the interchangeable tip of the fluorometer of the present invention into a process water sample for example cooling water treated with treatment chemicals and using fluorometers for detecting fluorophores pushing a button and reading the product level such as in parts per million ppm on a displa
29. rescence emission 32 passes through a second filter 34 and into a fluorescence detector 36 via an aperture 38 that has an opening 40 sized to receive the collimated beam of fluorescence emission 32 in at least a substantial amount The fluorescence detector 36 then acts to measure the amount of fluorescence which can be correlated in any suitable manner to a concentration of the target fluorophore or fluorophores in the sample for monitoring and or control purposes To enhance the detection capabilities of the fluorescent detection the interchangeable probe tip includes a reference detector 42 that receives a portion of the excitation light 18 via the reflective member 20 as previously discussed The reference detector 42 can be used to compensate for varia tions in the excitation light emission as discussed above The interchangeable probe tip 10 further includes a sec ond light source 14 that is used for corrective purposes with respect to fouling turbidity and or the like as discussed above The second light source 14 includes an IR LED source This generates a collimated beam of light 46 that is directed to the reflective member 20 A substantial amount of the beam 46 is transmitted through the reflective member 20 as light beam 48 along the same or substantially the same path as the reflected excitation light beam 22 In an embodiment about 98 or more of the light beam is transmitted through the reflective member 20 and into the meas
30. riability production tolerances and or the like This can be done in a number of suitable ways For example the fluorescent measurement associated with the fluorescence detector can be divided by the reference detector measure ment to provide a normalized fluorescent measurement This in essence subtracts outs the variation effects with respect to the excitation light source as discussed above In an embodiment the reference detector and the fluorescence detector include the same type of detector This effectively alleviates any variability in detection between the reference detector and the fluorescence detector that may be due differences in the type of detector that is used It should be appreciated that the reference detector can also be applied to effectively eliminate any variability in the second light source in any suitable way such as in a similar way as discussed above with respect to the excitation light source Further the interchangeable probe tip can include an aperture The aperture can be made of any suitable material and sized and configured in any suitable way including a cylindrical tube shape In an embodiment the fluorescence emission passes to the detector via the aperture In this way 20 25 30 35 40 45 50 55 60 65 8 the aperture can be effectively sized and shaped to minimize the effects of turbidity on the fluorescent detection capabili ties of the fluorometer Turbidity can cause li
31. rmance Testing www turnerdesigns com t2 esci s_ 0039 9 pages Jun 14 2004 SCUFA User s Manual Turner Designs 47 pages Apr 15 2002 K H Mittenzwey G Sinn R Hiersigk M Krause P Lenz L Pfeil J Rauchfuss G Streich A portable absorption fluorometer for detection of organic substances in fluids Fresenius Journal of Analytical Chemistry p 355 1996 Abstract only Robert F Chen A laser based fiber optic fluorometer for in situ seawater measurements Ocean Science and Technology pp 189 209 2000 Abstract only J Bloch B Johnson N Newbury J Germaine H Hemond J Sinfield Field test of a novel microlaser based probe for in situ fluorescence sensing of soil contamination Society for Applied Spectroscopy pp 1299 1304 1998 Abstract only T Vo Dinh Development of a DNA biochip principle and appli cations Sensors and Actuators B Chemical Ysensors Actuators B Chem vol B51 pp 52 59 Abstract only Maofan Qing The Design of a novel field portable fluorescence spectrophotometer Current Developments in Optical Design and Optical Engineering III pp 140 145 2000 Abstract only cited by examiner U S Patent Dec 26 2006 Sheet 1 of 5 US 7 154 603 B2 FIG 1 u S N ao s Oo eo ND Os 26 a SN 38 34 48 4 N 32 40 fi de o oo U S Patent Dec 26 2006 Sheet 2 of 5 US 7 154 603 B2 FIG 2 Ref Dete
32. terial In general the optical mechanical and chemical properties of the filter are provided and required as follows according to an embodiment With respect to optical properties the filters are required to have a high transmittance in pass band areas for the excitation light ie UV LED or the emitted fluorescence As mentioned above the first filter essentially allows all of the excitation light to pass therethrough and into the sample Then the emitted fluorescence from the sample can pass through the second filter all the while the excitation light is effectively blocked from passing through the second filter and inevitably to the detector Thus this ensures that the interference effects of the excitation light with respect to the fluorescent measurement are effectively eliminated or at least greatly reduced This effect can be further enhanced if the pass bands of the filters are sharp and deep cut If a second light source is used the optical properties of the filters allow the second light in a sufficient amount to pass through both filters and at a different wavelength than the light emitted from the excitation source In this way the second light source can be used to correct for fouling turbidity and or other like effects that can adversely impact the detection capabilities of the fluorometer as described in greater detail below With respect to mechanical properties the filter includes an exposed surface that is hard such t
33. ties The physical attributes of the filters can also enhance the detection sensitivity as compared to quartz glass sample cells cuvettes or the like that can contribute to unwanted light scattering such that the sensitivity and con centration range can be reduced In this regard the measured sample is in direct contact with the filters that define the measuring volume Thus the use of the term open cell as a descriptor of the fact that it is the filters themselves that form the outer boundaries of the sample cell and there is no other structure involved in the sample cell except for the outer walls of the housing itself The filters are required to be made from a material or combination of materials that are chemically inert and provide a hard surface such that chemical and brush cleaning of the cell can be performed when it becomes necessary By designing the optical filters for a water interface on the sample side and air interface on the internal side perfor mance of the filters can be optimized for analyzing low levels of fluorophores The fluorometer of the present invention can include a variety of different components fashioned in any suitable configuration depending on the application It can be con figured as a stand alone unit or it can be interfaced with one or more additional process components for monitoring and or control purposes in any known and suitable way The interchangeable tip open cell fluorometer can be adapte
34. to effectively block the exci tation light from passing to the fluorescence detector This allows the fluorescence of the sample to be measured with precision sensitivity and accuracy despite the fact that the excitation light is directed at the fluorescence detector such as directly at the fluorescence detector in a 180 optical arrangement As previously discussed this optical arrange ment provides a number of advantages as compared to fluorometers that use a conventional 90 optical arrange ment The sample can emit fluorescent light due to the presence of one or more fluorophores within the sample as discussed above Regarding the description of the fluorophores capable of being detected by the instant claimed fluorometer it is necessary to note that in order to be detectable by the instant claimed fluorometer the fluorophore must be capable of absorbing light in the wavelengths of from about 200 nm to about 1200 nm and emitting it at a slightly longer wavelength Preferably the fluorophores absorb light in the wavelengths of from about 350 nm to about 800 nm The fluorescence detector measures an amount of fluorescence that can be correlated to a concentration of the fluorophore in the sample In an embodiment the fluorescence detector can measure an intensity of the fluorescence that can be equated to a concentration of the fluorophore as generally understood to one of skill in the art The filters can be made of any suitable ma
35. udes an IR LED that generates a collimated beam of light 138 The light 138 passes through the first filter 130 at an angle offset from perpendicular such as about 9 or less with respect to the first filter 130 In this way the second source of light 138 passes through the sample 124 through the second filter 132 and into the detector 134 via the aperture 136 along a path that corresponds in a sufficient amount to the path through which the fluorescent emission passed The detector 134 then can measure the intensity of the second light source which can be used for corrective purposes as previously discussed This further demonstrates that the second source of light does not necessarily have to pass along the same path as the source of excitation light and or emission there from in order to effectively act for corrective purposes due to fouling turbidity and or the like The probe tip 120 further includes a reference detector 140 that detects a portion of the excitation light derived from the excitation source This can also enhance the detection capabilities of the probe tip as previously discussed Refer ence detector 140 can be used to measure a portion of the light from light source 137 to account for variations in light source 137 Example Five Self Identifying Interchangeable Tip Open Cell Fluorometer As previously discussed the fluorometer of the present invention has a self identifying feature that allows the fluorometer to b
36. uring cell 28 The remaining portion of light beam 50 associated with the second light source 14 is reflected via the reflective member 20 into the reference detector 42 to compensate for variations in the second light source emis sion similar to the excitation source emission as previously discussed The transmitted amount of light beam 48 from the second light source 14 passes through the sample 30 and further passes through the second filter 34 in at least a substantial amount along the same or substantially the same path that the fluorescent emission 32 passes through the second filter 34 The amount of transmitted light associated with the second light source is then detected by the fluorescence detector 36 This measurement can be used in any known way to correct for changes in the fluorescent measurement due to fouling turbidity and or the like as previously dis cussed 20 25 30 35 40 45 50 55 60 65 10 Example Two Interchangeable Probe Tip with Straight Through Beam Configuration Turning to FIG 2 another embodiment of the inter changeable probe tip according to the present invention is provided The interchangeable probe tip 60 includes a single light source 62 that includes a UV LED source The exci tation source 62 emits a collimated light beam 64 through a first filter 66 and into a measuring cell 68 where the sample 70 is located This causes fluorescence associated with an amount of fluoroph
37. y With this fluorometer the design emphasis is on minimal cost for small accounts and ease of use for unskilled opera tors The cylindrical tube shape has many desirable func tional features including battery operation numerical read out two point calibration compensation for sample temperature turbidity and fouling of the optical surfaces communications to Palm computer or the like for down loading of stored data a unique self identifying fluorometer probe tip and the like The fluorometer of the present invention can be made with a process control output and connector for controlling a chemical feed pump data log ging and or for performing other suitable process monitoring and or control activities For example the fluorometer of the present invention can be adapted to alert the user when cleaning of the tip is required An important aspect of the present invention is the interchangeable probe tip In general the probe tip provides a small self contained fluorometer with built in optics and circuitry such as for type identification detectors light sources temperature measurement and the like The probe tip is constructed such that it is readily pluggable into the fluorometer housing This makes it easily replaceable with another probe tip whenever a different probe tip with dif ferent optics is necessary to account for changes in the sampling environment such as for measuring the fluores cence derived from different flu
38. ys As detailed below a number of examples of the interchangeable probe tip are provided illustrative of the present invention EXAMPLES Example One Interchangeable Probe Tip with Normal Parallel Beam Configuration Turning to FIG 1 an embodiment of the present inven tion is illustrated The interchangeable probe tip 10 includes an excitation light source 12 and a second light source 14 US 7 154 603 B2 9 The excitation source 12 includes an ultraviolet light emit ting diode 16 UV LED The excitation source 12 emits a collimated excitation light beam 18 that is directed at a reflective member 20 such as a dichroic mirror or the like as shown in FIG 1 The reflective member 20 is reflective with respect to a substantial amount of the excitation light beam 18 such as about 98 reflective or less The reflective member 20 is also transmissive with respect to the remain ing portion of excitation light beam such as about 2 transmissive or greater The reflected portion 22 of excita tion light associated with the excitation light source 12 is directed to a first filter 24 at an angle that is perpendicular or substantially perpendicular with respect to the first filter 24 The excitation light beam 26 passes into a measuring cell 28 where the sample 30 is provided in an open cell arrange ment The projection of the excitation light 26 causes a fluorescence emission 32 based on an amount of fluorophore in the sample 30 The fluo
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