Abstract:
A Raman probe assembly comprises: a light source for generating laser excitation light; a camera for capturing an image; a light analyzer for analyzing a Raman signature; and a light path for (i) delivering the laser excitation light from the light source to the specimen so as to produce the Raman signature for the specimen, (ii) capturing an image of the specimen and directing that image to the camera, and (iii) directing the Raman signature of the specimen to the light analyzer. A method includes providing a Raman probe assembly carried by a remote controlled robot; navigating the remote control robot to a position adjacent to a specimen; opening a shutter/wiper disposed adjacent to a window of the Raman analyzer; using a camera to aim the probe body at the specimen; energizing a light source; and analyzing the return light passed to the light analyzer.

Description:
REFERENCE TO PENDING PRIOR PATENT APPLICATIONS 
   This patent application: 
   (i) is a continuation-in-part of pending prior U.S. patent application Ser. No. 11/117,940, filed Apr. 29, 2005 by Peidong Wang et al. for METHOD AND APPARATUS FOR CONDUCTING RAMAN SPECTROSCOPY ; and 
   (ii) claims benefit of pending prior U.S. Provisional Patent Application Ser. No. 60/694,385, filed Jun. 27, 2005 by Kevin J. Knopp et al. for RAMAN IDENTIFICATION SYSTEM . 
   The two above-identified patent applications are hereby incorporated herein by reference. 

   FIELD OF THE INVENTION 
   This invention relates to methods and apparatus for identifying and characterizing substances in general, and more particularly to methods and apparatus for identifying and characterizing substances using Raman spectroscopy. 
   BACKGROUND OF THE INVENTION 
   Raman spectroscopy is a viable technique for identifying and characterizing a vast array of substances. Raman spectroscopy is widely used in the scientific, commercial and public safety areas. 
   Recent technological advances are making it possible to increase the range of applications using Raman spectroscopy through a reduction in cost and size. For example, portable units have recently become available for field uses such as the on-site identification of potentially hazardous substances. 
   Unfortunately, with Raman spectroscopy, it is generally desirable to bring the optical probe to a position adjacent to the specimen when conducting the Raman spectroscopy. However, this can be a problem in view of the potentially hazardous materials which are to be analyzed, e.g., explosives, chemical agents, toxic industrial chemicals, etc. 
   Accordingly, a primary object of the present invention is to provide an improved Raman spectroscopy system which overcomes the aforementioned shortcomings of currently available systems. 
   SUMMARY OF THE INVENTION 
   In one preferred embodiment of the present invention, there is provided an improved Raman probe system in which a remote Raman probe assembly is mounted to a remote control robot for unmanned delivery to a remote specimen. The remote Raman probe assembly includes a wireless communication feature for transmitting information from the remote Raman probe assembly to a base unit. If desired, the wireless communication feature can take the form of a wireless Web link, so as to simplify communication transmission. Furthermore, the remote Raman probe assembly may comprise a Raman probe which may be attached to a robot arm, with the remainder of the remote Raman probe assembly being mounted to the body of the robot, such that the Raman probe can be selectively positioned vis-à-vis the specimen. 
   In another form of the present invention, there is provided a Raman probe assembly for analyzing a specimen, comprising: 
   a light source for generating laser excitation light; 
   a camera for capturing an image; 
   a light analyzer for analyzing a Raman signature; and 
   a light path for (i) delivering the laser excitation light from the light source to the specimen so as to produce the Raman signature for the specimen, (ii) capturing an image of the specimen and directing that image to the camera, and (iii) directing the Raman signature of the specimen to the light analyzer. 
   In another form of the present invention, there is provided a Raman probe assembly for analyzing a specimen, comprising: 
   a light source for generating laser excitation light; 
   a camera for capturing an image; 
   a light analyzer for analyzing a Raman signature; 
   a first light path for delivering the laser excitation light from the light source to the specimen so as to produce the Raman signature for the specimen; 
   a second light path for capturing an image of the specimen and directing that image to the camera; 
   a third light path for directing the Raman signature of the specimen to the light analyzer; 
   wherein the a least a portion of the first light path, the second light path and the third light path are coaxial with one another. 
   In another form of the present invention, there is provided a Raman probe assembly for analyzing a specimen, comprising: 
   a light source for generating laser excitation light; 
   a light analyzer for analyzing a Raman signature; 
   a light path for (i) delivering the laser excitation light from the light source to the specimen so as to produce the Raman signature for the specimen, and (ii) directing the Raman signature of the specimen to the light analyzer; 
   wherein the assembly further comprises a probe body for housing the at least a portion of the light path, and a window, with the light path extending through the window; 
   and further wherein the probe body further comprises a shutter/wiper disposed adjacent to the window. 
   In another form of the present invention, there is provided a Raman probe assembly for analyzing a specimen, comprising: 
   a light source for generating laser excitation light; 
   a light analyzer for analyzing a Raman signature; 
   a light path for (i) delivering the laser excitation light from the light source to the specimen so as to produce the Raman signature for the specimen, and (ii) directing the Raman signature of the specimen to the light analyzer; and 
   wherein the light analyzer comprises a transmitter for transmitting information using an Internet Web protocol. 
   In another form of the present invention, there is provided a method for identifying the nature of a specimen, the method comprising: 
   providing a Raman probe assembly comprising:
         a light source for generating laser excitation light;   a camera for capturing an image;   a light analyzer for analyzing a Raman signature;   a light path for (i) delivering the laser excitation light from the light source to the specimen so as to produce the Raman signature for the specimen, (ii) capturing an image of the specimen and directing that image to the camera, and (iii) directing the Raman signature of the specimen to the light analyzer   wherein the assembly further comprises a probe body for housing the at least a portion of the light path, and a window, with the light path extending through the window;   wherein the probe body further comprises a shutter/wiper disposed adjacent to the window;   wherein the assembly is carried by a remote controlled robot;       

   providing a base station for receiving the image, and for remotely controlling the robot, and for receiving information from the light analyzer; 
   navigating the remote control robot from the base station to a position adjacent to the specimen; 
   opening the shutter/wiper; 
   using the camera to aim the probe body at the specimen; 
   energizing the light source so that the laser excitation light is directed at the specimen; and 
   analyzing the return light passed to the light analyzer so as to determine of the nature of the specimen. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     These and other objects and features of the present invention will be more fully disclosed or rendered obvious by the following detailed description of the preferred embodiments of the invention, which is to be considered together with the accompanying drawings wherein like numbers refer to like parts and further wherein: 
       FIG. 1  is a schematic view of a novel Raman probe system formed in accordance with the present invention; 
       FIG. 2  is a schematic view of selected elements of the Raman probe system; 
       FIG. 3  is a schematic view of the Raman probe system&#39;s laser subsystem, optical probe subsystem and spectrometer subsystem; 
       FIGS. 4-7  are schematic views of the optical control unit of the present invention; 
       FIGS. 8-11  are schematic view of the Raman probe of the present invention; 
       FIG. 12  is a schematic view showing the specimen being targeted through the probe; 
       FIG. 13  is a schematic view of the system controller; and 
       FIGS. 14 and 15  are schematic views showing a standoff cone used in conjunction with the optical probe assembly. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Looking first at  FIG. 1 , there is shown a novel Raman probe system  5  for conducting remote sensing of a specimen  10 . Novel Raman probe system  5  generally comprises a remote control robot  15  for piloting a remote Raman probe assembly  20  to a position adjacent to specimen  10 , and a base station  25  for controlling operation of remote control robot  15  and for receiving specimen analysis information from remote Raman probe assembly  20 . 
   Remote control robot  15  may be any remote control robot of the sort well known in the art of remote transport, remote sensing, remote bomb disposal, etc. By way of example but not limitation, remote control robot  15  may be a tracked vehicle remotely controlled by base station  25 , e.g., by radio control of the sort well known in the art. 
   Looking now at  FIGS. 1-3 , remote Raman probe assembly  20  generally comprises a laser subsystem  30  ( FIGS. 2 and 3 ) for generating the Raman pump signal, an optical probe subsystem  35  ( FIG. 3 ) for delivering the Raman pump signal to the specimen and for gathering the Raman signature from the specimen, and a spectrometer subsystem  40  ( FIGS. 2 and 3 ) for analyzing the Raman signature of the specimen so as to determine the nature of the specimen, and for transmitting analysis data to base station  25 . 
   For convenience, laser subsystem  30  and spectrometer subsystem  40  may be packaged into an optical control unit  45  (see  FIGS. 4-7 ) which is mounted onto remote control robot  15  so as to be carried thereby. Optical control unit  45  may also house an onboard power supply (e.g., a battery) for powering remote control robot  15  and its payload. Furthermore, optical control unit  45  is preferably provided with a communication subsystem  47  for permitting remote control robot  15 , and its payload, to communicate with base station  25 . 
   Optical probe subsystem  35  is also mounted to remote control robot  15 . Preferably optical probe subsystem  35  is mounted to an articulating arm  50  ( FIG. 1 ) on remote control robot  15 . Articulating arm  50  may be remotely controlled by base station  25 , such that the working end of optical probe subsystem  35  may be appropriately positioned adjacent to the specimen  10 , as will hereinafter be discussed. 
   Laser subsystem  30  may comprise any laser suitable for use in Raman spectroscopy. By way of example but not limitation, laser subsystem  30  may comprise one or more &gt;300 mW, 785 nm semiconductor lasers with limited linewidths (e.g., ˜2 cm −1 ). The output of laser subsystem  30  is delivered into the excitation fiber (see below) of optical probe subsystem  35  for delivery to the specimen. 
   Optical probe subsystem  35  is shown in FIGS.  3  and  8 - 11 . Optical probe subsystem  35  comprises an excitation fiber  53  (e.g., 100 micrometer core diameter, Low OH) which delivers the excitation light through a flat polished excitation fiber ferrule  54  (e.g., a 100 micrometer Core multimode fiber) and then through a laser collimating lens  54 A (e.g., PCX, f=3 mm, D=3 mm) to a reflector  55  (e.g., for a 785 nm laser) and then to a notch filter  60  (e.g., OD&gt;6) which also aligns the excitation light with the longitudinal axis of the Raman probe  65 . The excitation light is then focused using focusing lens  70  (e.g., PCX, f=6 mm, D=3 mm) and then passed through a first pair of telescopic lenses  75 ,  80  (e.g., Achromat, f=19 mm, D=12.7 mm), a second pair of telescopic lenses  85 ,  90  (e.g., Achromat, f=45 mm, D=25 mm), and a window  95  for permitting the excitation light to pass out of the distal end of Raman probe  65  and onto specimen  10 . 
   A shutter/wiper assembly  100  is disposed adjacent to window  95 . Shutter/wiper assembly  100  is adapted to (i) selectively close off window  95  so as to protect the window (e.g., during storage and selected transit); and/or (ii) wiper off window  95  so as to keep it free of debris (e.g., during scanning in a dusty and/or debris-laden environment). Furthermore, shutter/wiper assembly  90  can be used to wiper away any of specimen  10  which might unintentionally stick to window  95 , so as to help ensure that the specimen is not inadvertently carried away from the remote site by Raman probe system  5  at the conclusion of the analysis. 
   The excitation light from optical probe subsystem  35  engages specimen  10  and interacts with specimen  10  so as to produce the Raman signature of the specimen. 
   The light returning from specimen  10  (including but not limited to the Raman signature of the specimen) passes back through window  95 , through lenses  90 ,  85  and then through lens  80 . A beam splitter  105  (e.g., gold coated glass, 1.5×3.8 mm, 1 mm thick) then directs some of the returning light through an imaging lens  105 A, through a CCD imaging lens aperture  106  (e.g., D=0.9 mm), through an infra red blocking filter  107  (e.g., to block 785 nm laser light and pass visible spectrum, OD&gt;3) to CCD chip  108  on CCD active die  109  of CCD camera  110  driven by CCD electronics  115 ; and the remainder of the returning light (including the Raman signature of the specimen) is directed through lens  75 , through focusing lens  70 , through notch filters  60 ,  116  (e.g., OD&gt;6), through a collection collimator lens  118  (e.g., PCX, f=4 mm, D=6 mm), through a flat polished collection fiber ferrule  119  (e.g., a 200 micrometer Core multimode fiber) and into collection fiber  120  (e.g., 200 micrometer core diameter, Low OH) for delivery to spectrometer subsystem  40 . A shield  119 A may be provided around CCD camera  110  for stray and laser light blocking. 
   Preferably, CCD camera  110  and CCD electronics  115  are constructed so as to provide streaming digital video output to base station  25 . Preferably, CCD electronics  115  are contained in Raman probe  65  or, alternatively, some or all of CCD electronics  115  may be contained within optical control unit  45 . In any case, CCD electronics  115  are carried by remote control robot  15 . 
   The output from CCD camera  110  is relayed to base station  25 , whereby to permit a user at base station  25  to aim the Raman pump light on specimen  10 . More particularly, and looking now at  FIG. 12 , CCD camera  110  and base station  25  can be configured to overlay cross-hairs  125  on the image provided by CCD camera  110 , whereby to permit the user to maneuver articulating arm  50  so that the Raman pump light is directed onto specimen  10 . 
   Spectrometer subsystem  40  generally comprises a spectrometer  130  for identifying the wavelength characteristics of the Raman signature of specimen  10 . Spectrometer subsystem  40  sends the wavelength characteristics of the Raman signature of specimen  10  to analysis apparatus  135 , which determines the nature of specimen  10  using the wavelength characteristics of the Raman signature. If desired, spectrometer  130  may comprise a dispersive spectrometer having a resolution of 7-10.5 cm −1 , a spectral range of 250-2800 cm −1 , and 2048 pixels. 
   Thus it will be appreciated that specimen analysis is conducted completely onboard remote control robot  15 , and only the analysis results need be communicated to base station  25 . However, in one preferred form of the invention, it is preferred that remote control robot  15  be configured to send base station  25  the Raman signature spectra, as well as the analysis results. 
   Base station  25  preferably comprises a system controller  140 , preferably including a computer having appropriate user interface controls (e.g., a joystick, touch pad, etc.) for (i) controlling the operation of remote control robot  15 , including its articulating arm  50 ; (ii) receiving the output from CCD camera  110 , whereby to permit remote aiming of Raman probe  65 ; and (iii) receiving the analysis results from analysis apparatus  135 . 
   If desired, Raman probe assembly  20  and base station  25  may also be provided with a Raman feedback loop, whereby to use the relative intensity of the Raman signature being obtained by the system so as to further improve alignment of Raman probe  65  with specimen  10 . More particularly, base station  25  is configured so as to measure (either continuously or on a periodic basis) how much useful Raman signal is being collected by the system. Then, using a feedback loop, the intensity of the Raman signal can be used, in conjunction with cross-hairs  125 , to help guarantee that Raman probe  65  is properly aimed at specimen  10 . 
   In one preferred form of the invention, some or all of the communication links between (i) remote controlled robot  15  and/or its payload (i.e., Raman probe assembly  20 , including CCD camera  110  and CCD electronics  115 ) and (ii) base station  25 , may be effected via Internet Web-based protocols, e.g., the IEEE 802.11b wireless network standard. 
   If desired, remote control robot  15  can communicate analysis results, Raman spectra or any other information (e.g., CCD camera pictures) to a location other than, or in addition to, base station  25 . 
   Use 
   Raman probe system  5  is preferably used as follows. 
   First, the user interface controls at base station  25  are used to navigate remote control robot  15 , including its articulating arm  50 , to position Raman probe  65  adjacent to specimen  10 , e.g., within approximately 1 to 2 inches. 
   Then, shutter/wiper  100  is opened, and CCD camera  110  and CCD electronics  115  are used, in conjunction with the cross-hairs  125 , to move articulating arm  50  so that Raman probe  65  is aimed at specimen  10  and positioned approximately 30 mm away from the specimen. 
   Then the Raman signature feedback system is used to optimize positioning of Raman probe  65  relative to specimen  10 . This is done by energizing laser subsystem  30  so that Raman pump light is directed at specimen  10  and reading the intensity of the Raman signature returned from specimen  10 , with a feedback loop driving the positioning of articulating arm  50 , so as to optimize the position of Raman probe  65  relative to the specimen, whereby to provide the best possible Raman signature for the specimen. 
   Then, laser subsystem  30  is energized so that the Raman pump light is directed at specimen  10 . The return light is passed to spectrometer  130 , so as to determine the Raman signature of the specimen, and then the Raman signature is fed to analysis apparatus  135  for determination of the nature of the specimen. Analysis apparatus  135  then sends information regarding the nature of specimen  10  (optionally including the Raman spectra for specimen  10  as well) to base station  25 . 
   Further Constructions 
   If desired, various modifications can be made to the foregoing construction without departing from the scope of the present invention. 
   Thus, for example, and looking now at  FIGS. 14 and 15 , the shutter/wiper  100  may be replaced by a standoff cone  145 . The standoff cone  145  can have various lengths, depending on whether specimen  10  is a solid or a liquid. More particularly, for solid specimens, standoff cone  145  is constructed so that when the distal tip of the standoff cone is positioned against the specimen, the focal point of the Raman laser will be located on the surface of the specimen. However, for liquid specimens, standoff cone  145  is constructed so that when the distal tip of the standoff cone is positioned against the specimen, the focal point of the Raman laser will be located on the within the body of the specimen. 
   It is to be understood that the present invention is by no means limited to the particular constructions herein disclosed and/or shown in the drawings, but also comprises any modifications or equivalents within the scope of the invention.