Abstract:
The apparatus disclosed herein features: (a) a handheld, portable spectrometer that includes a radiation source configured to direct incident radiation to a sample, a detector configured to receive signal radiation from the sample, and a housing enclosing the radiation source and the detector; (b) an extended member attachable to the housing and having an interior channel to define a path for directing radiation from the source to the sample and for receiving radiation from the sample at the detector; (c) and a vial receptacle configured to hold a different sample and positioned to receive radiation from the source, where the detector is positioned to receive radiation from the different sample and the housing is configured to support the vial receptacle and attach to the extended member at the same time.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of, and claims priority under 35 U.S.C. §120 to, U.S. patent application Ser. No. 11/117,940, filed on Apr. 29, 2005 now U.S. Pat. No. 7,636,157 and published as U.S. Patent Application Publication No. US 2005/0248759, which claims priority under 35 U.S.C. §119(e) to the following applications: U.S. Provisional Patent Application Ser. No. 60/566,713, filed on Apr. 30, 2004; and U.S. Provisional Patent Application Ser. No. 60/607,735, filed on Sep. 7, 2004. The entire contents of each of the foregoing applications are 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 both the scientific and commercial areas. By way of example but not limitation, commercial areas of use currently include medicine, biotechnology, pharmaceuticals, security and geology. In addition, 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 out-of-lab uses such as the measurement and identification of powders, pills, liquids, etc. 
     Unfortunately, a number of problems exist with respect to current Raman spectroscopy systems. For example, a persistent problem in existing Raman spectroscopy systems is the delivery of laser light to the specimen and the collection of the Raman signature from the specimen. Among other things, these problems include space limitations in portable Raman systems, signal distortions introduced into the system due to Amplified Spontaneous Emission (ASE) from the laser sources, etc. 
     Also, for Raman spectroscopy of specimens which are located remotely from the light sources and light detectors, optical fibers are commonly used to deliver the excitation light and to collect the Raman signals. However, the use of these optical fibers can introduce fluorescence and Raleigh and Raman scatterings generated through interactions in the optical fibers. 
     Accordingly, a primary object of the present invention is to provide an improved Raman spectroscopy system which overcomes the shortcomings of currently available systems. 
     SUMMARY OF THE INVENTION 
     In one preferred embodiment of the present invention, there is provided an improved Raman spectroscopy system (sometimes hereinafter referred to as a Raman probe) in which a set of optical elements is used to separate the pump source from the Raman signal and to direct the Raman signal to a remote spectrometer or detector. The Raman probe is preferably also configured so as to be able to filter ASE background from the laser sources, as well as to filter fluorescence and Raleigh and Raman scatterings generated through interactions in the optical fibers. 
     In another form of the present invention, there is provided a Raman probe comprising: 
     a first optical fiber for receiving laser excitation light from a light source and transmitting the same; 
     a first filter for receiving light from the first optical fiber and adapted to pass the laser excitation light and to block spurious signals associated with the light; 
     a second filter for receiving light from the first filter and adapted to direct the light toward a specimen; 
     focusing apparatus for receiving the light from the second filter, focusing the light on the specimen so as to generate the Raman signal, and returning the Raman signal to the second filter; 
     wherein the second filter is further configured so that when the second filter receives the Raman signal from the focusing apparatus, the second filter filters out unwanted laser excitation light before directing the Raman signal to a second optical fiber; and 
     a second optical fiber for receiving the Raman signal from the second filter and transmitting the same to a light analyzer. 
     And in one preferred embodiment of the invention, a novel optical probe delivery system is provided which offers three unique modes of use for exciting and collecting light from the specimen under test, all encompassed with one optical probe design. In a first mode of use, the Raman probe allows the user to maintain distance from the specimen by using a conical standoff, which provides both distance control and laser safety by limiting the exposed beams. The second mode of use allows the user to remove the conical standoff so as to maintain distance control by hand or other means. The third mode of use allows a specimen vial to be inserted directly within the probe optics assembly. 
     In another form of the present invention, there is provided a Raman probe comprising: 
     a light source for generating laser excitation light; 
     focusing apparatus for receiving the laser excitation light from the light source, focusing the laser excitation light on a specimen so as to generate the Raman signal, and returning the Raman signal to a light analyzer; and 
     a light analyzer for analyzing the Raman signature of the specimen, whereby to identify the specimen; 
     wherein the focusing apparatus is configured to permit the specimen to reside in a vial receptacle or at a target location remote from the vial receptacle. 
     In another form of the present invention, there is provided a method for conducting Raman spectroscopy of a specimen, comprising: 
     generating laser excitation light using a light source; 
     passing the laser excitation light through a first filter so as to block spurious signals associated with the light; 
     directing the laser excitation light to a second filter so as to direct the laser excitation light toward the specimen; 
     receiving the light from the second filter, focusing the light on the specimen so as to generate the Raman signal, and returning the Raman signal to the second filter; 
     wherein the second filter is further configured so that when the second filter receives the Raman signal from the specimen, the second filter filters out unwanted laser excitation light; 
     passing the filtered light received from the second filter to a light analyzer; and 
     analyzing the Raman signature of the specimen so as to identify the specimen. 
     In another form of the present invention, there is provided a Raman probe comprising: 
     a housing; 
     a light source disposed within the housing for generating laser excitation light; 
     focusing apparatus disposed within the housing for receiving the laser excitation light from the light source, focusing the laser excitation light on a specimen so as to generate the Raman signal, and returning the Raman signal to a light analyzer; and 
     a light analyzer disposed within the housing for analyzing the Raman signature of the specimen, whereby to identify the specimen; 
     wherein the focusing apparatus is configured to permit the specimen to reside at a target location remote from the housing; 
     and further comprising an optical shield mounted to the housing so as to be disposed between the specimen and the user, whereby to optically shield the user from the light source. 
     In another form of the present invention, there is provided a Raman probe comprising: 
     a housing; 
     a light source disposed within the housing for generating laser excitation light; 
     focusing apparatus disposed within the housing for receiving the laser excitation light from the light source, focusing the laser excitation light on a specimen so as to generate the Raman signal, and returning the Raman signal to a light analyzer; and 
     a light analyzer disposed within the housing for analyzing the Raman signature of the specimen, whereby to identify the specimen; 
     wherein the focusing apparatus is configured to permit the specimen to reside at a target location remote from the housing; 
     and further comprising a camera mounted to the housing so that its field of view encompasses the target location, and a display mounted to the housing for displaying the image captured by the camera, whereby to permit the user to position the probe relative to the specimen while watching the display. 
    
    
     
       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  illustrates a novel Raman optical probe; 
         FIG. 1A  illustrates the overall Raman spectroscopy system in schematic form; 
         FIG. 2  illustrates a thin film design to filter out the ASE, fluorescence and Raleigh and Raman scattering from the fibers; 
         FIG. 3  illustrates thin films designed for reflective (blocking) laser lines and transmitting Raman signals; 
         FIG. 4  illustrates an additional broadband reflector to direct Raman signals and blocking the laser lines; 
         FIG. 5  illustrates another Raman probe layout where the broadband reflector is omitted through the rearrangement of collecting fibers; 
         FIG. 6  illustrates another embodiment of the present invention, wherein the fibers and signal collecting optics are collinear (as opposed to being perpendicular to each other); 
         FIG. 7  illustrates another embodiment which is similar to that of  FIG. 1 , except using a 5 degree of Angle Of Incidence (AOI) for the filters; 
         FIG. 8  illustrates another embodiment which is similar to that of  FIG. 5 , except using a 5 degree of Angle Of Incidence (AOI) for the filters; 
         FIG. 9  illustrates another embodiment which is a variation of  FIG. 6 , except using a 10 degree AOI for the filters; 
         FIG. 10  illustrates another embodiment of Raman probe which is designed to be more compact through the use of two prisms with various coatings on the surface; 
         FIG. 11  illustrates a portable Raman probe which is configured to allow three different methods of use; 
         FIGS. 12 and 13  illustrate the portable Raman probe of  FIG. 11  configured to allow the user to maintain distance from the specimen using a conical standoff; 
         FIG. 14  illustrates the portable Raman probe of  FIG. 11  configured to allow the user to remove the conical standoff so as to maintain distance control by hand or other means; 
         FIG. 14A  illustrates a novel portable Raman probe with another form of conical standoff; 
         FIGS. 15-17  illustrate the portable Raman probe of  FIG. 11  configured to allow the user to insert a specimen vial directly within the probe optics assembly; 
         FIG. 18  is a schematic view showing a specimen vial inserted directly within the probe optics assembly, wherein the specimen vial incorporates a shutter to prevent stray backlight from entering the vial receptacle; and 
         FIG. 19  is a schematic view showing a camera mounted to the front of the Raman probe. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Novel Raman Spectroscope 
     Looking first at  FIG. 1 , there is shown a novel Raman probe  5 . The excitation light source LS in this arrangement may be, for example, one or more 785 nm semiconductor lasers with limited linewidths. However, the Raman probe  5  may also use any other laser source as the excitation light source LS as long as the laser source is compatible with Raman spectroscopy detection techniques. The output of excitation light source LS is delivered through optical fiber  10  and collimated through lens  15 . A bandpass filter  20  (or multiple combination of bandpass filters  20 A,  20 B) is used to pass the laser excitation light and to block spurious signals associated with the laser, the fiber, and/or both. The spurious signals associated with the laser generally comprise ASE from the laser, and the spurious signals associated with the fiber generally comprise fluorescence and Raleigh and Raman scatterings generated inside the fiber  10 . Preferably bandpass filter  20  is adapted to block spurious signals associated with both the laser and the fiber. The laser excitation light is then reflected by filters  25  (at a 22.5 degree Angle of Optical Incidence, AOI) and  30  (at a 22.5 degree AOI), and then it is focused through lens  35  to excite specimen  40 . In this respect it should be appreciated that, for the purposes of the present disclosure, certain AOI values are used, however, in accordance with the present invention, the AOI may vary from one embodiment to another. Moreover, since the geometry of the input fiber and output fiber does not need to be parallel or perpendicular, AOI values may vary with the particular geometry employed, e.g., the AOI values may be anywhere from 5 degree AOI to 50 degree AOI. In one preferred embodiment of the present invention, filters  25  and  30  are preferably long-pass filters. In this respect it should also be appreciated that filter  25  may be replaced by a simple reflector to reflect the laser light. After the laser excitation light has been projected on the specimen, the Raman signal is re-collimated through lens  35  and passed through filter  30 . Alternatively, the Raman signal may pass through multiple filters (i.e., in addition to passing through filter  30 , the Raman signal may pass through additional filter  45 , at a 22.5 degree AOI). In one preferred embodiment of the present invention, additional filter  45  is preferably also a long-pass filter. When the Raman signal from the specimen is passed though filter  30 , filter  30  serves a second purpose at this time, i.e., it blocks the laser line. Filters  30  and  45  can provide up to &gt;OD10 filtration of the laser line before the light is redirected through broadband reflector  50  (at a 45 degree AOI) and focus lens  55  into collecting optical fibers  60 . Optical fibers  60  transmit the Raman signal to a light analyzer LA which analyzes the Raman signature of the specimen, whereby to identify the specimen. The light analyzer LA may comprise a spectrometer with associated analysis apparatus of the sort well known in the art. See, for example,  FIG. 1A , which shows the overall Raman spectroscopy system in schematic form. In addition to reflecting the Raman signal, broadband reflector  50  also filters out laser excitation light (OD1). 
     Dielectric Thin Film Filters 
     The various filtering described above may be accomplished by the following dielectric thin film filters. In this respect, for the purposes of the present disclosure, it will be assumed that the Raman signal of interest is &gt;300 cm-1. Raman signal that is close to the excitation source (i.e., about 100 cm-1 to about 300 cm-1) can also be detected through another set of filters. 
     (1) Passband Filter Design. 
     As noted above, one or more passband filters  20 A,  20 B can be used to pass the laser light and block spurious signals associated with the laser, the fiber, and/or both. A passband filter can be constructed using a dielectric thin film construction. See, for example,  FIG. 2 , which illustrates the transmission characteristics of a thin film design configured to filter out laser ASE, and the fluorescence and Raleigh and Raman scattering in the fibers. 
     (2) Filter Design. 
     As also noted above, filters  25 ,  30  and/or  45  (in one embodiment of the invention, preferably long-pass filters) can be used to reflect or block the laser line and to pass the Raman signals. Such filters can be constructed using dielectric thin film constructions. The design is preferably configured for the range of 800 nm-1100 nm; the CCD detector is generally not sensitive beyond this range. See, for example,  FIG. 3 , which illustrates the transmission characteristics of a filter thin film design for reflecting (and/or blocking) laser lines and for transmitting Raman signals. 
     (3) Additional Broadband Reflector. 
     The additional broadband reflector  50  is used to redirect the Raman signal to the collecting fibers. In addition, the additional broadband reflector  50  further filters the laser excitation light (OD&gt;1) before passing the light to the collecting fibers. The broadband reflector  50  can also be constructed using dielectric thin film constructions. See, for example,  FIG. 4 , which illustrates the transmission characteristics of an additional broadband reflector  50  configured to direct Raman signals and block the laser lines. 
     Additional Novel Constructions 
     Looking now at  FIG. 5 , there is shown another novel Raman probe layout  105  which is generally similar in construction to that shown in  FIG. 1 , except that the broadband reflector  50  is omitted through the rearrangement of the collecting fibers. Thus, in the construction shown in  FIG. 5 , the output of excitation light source LS is delivered through optical fiber  110  and collimated through lens  115 . A bandpass filter  120  (or multiple combination of bandpass filters  120 A,  120 B) is used to pass the laser excitation light and to block spurious signals associated with the laser, the fiber, and/or both. The spurious signals associated with the laser generally comprise ASE from the laser, and the spurious signals associated with the fiber generally comprise fluorescence and Raleigh and Raman scatterings generated inside the fiber  110 . Preferably bandpass filter  120  is adapted to block spurious signals associated with both the laser and the fiber. The laser excitation light is then reflected by filters  125  (at a 22.5 degree AOI) and  130  (at a 22.5 degree AOI), and then it is focused through lens  135  to excite specimen  140 . In this respect it should be appreciated that, for the purposes of the present disclosure, certain AOI values are used, however, in accordance with the present invention, the AOI may vary from one embodiment to another. Moreover, since the geometry of the input fiber and output fiber does not need to be parallel or perpendicular, AOI values may vary with the particular geometry employed, e.g., the AOI values may be anywhere from 5 degree AOI to 50 degree AOI. In one preferred embodiment of the present invention, filters  125  and  130  are preferably long-pass filters. In this respect it should also be appreciated that filter  125  may be replaced by a simple reflector to reflect the laser light. After the laser excitation light has been projected on the specimen, the Raman signal is re-collimated through lens  135  and passed through filter  130 . Alternatively, the Raman signal may pass through multiple filters (i.e., in addition to passing through filter  130 , the Raman signal may pass through additional filter  145 , at a 22.5 degree AOI). In one preferred embodiment of the present invention, additional filter  145  is preferably also a long-pass filter. When the Raman signal from the specimen is passed though filter  130 , filter  130  serves a second purpose at this time, i.e., it blocks the laser line. Filters  130  and  145  can provide up to &gt;OD10 filtration of the laser line before the light is redirected by focus lens  155  into collecting optical fibers  160 . Optical fibers  160  transmit the Raman signal to a light analyzer LA which analyzes the Raman signature of the specimen, whereby to identify the specimen. The light analyzer LA may comprise a spectrometer with associated analysis apparatus of the sort well known in the art. See, for example,  FIG. 1A , which shows the overall Raman spectroscopy system in schematic form. 
     Looking next at  FIG. 6 , there is shown another novel Raman probe layout  205  which is generally similar to the construction shown in  FIG. 5 ; however, with this novel arrangement, the fibers and signal collecting optics are collinear with one another (rather than being perpendicular to one another). Thus, in the construction shown in  FIG. 6 , the output of excitation light source LS is delivered through optical fiber  210  and collimated through lens  215 . A bandpass filter  220  (or multiple combination of bandpass filters  220 A,  220 B) is used to pass the laser excitation light and to block spurious signals associated with the laser, the fiber, and/or both. The spurious signals associated with the laser generally comprise ASE from the laser, and the spurious signals associated with the fiber generally comprise fluorescence and Raleigh and Raman scatterings generated inside the fiber  210 . Preferably bandpass filter  220  is adapted to block spurious signals associated with both the laser and the fiber. The laser excitation light is then reflected by filters  225  (at a 22.5 degree AOI) and  230  (at a 22.5 degree AOI), and then it is focused through lens  235  to excite specimen  240 . In this respect it should be appreciated that, for the purposes of the present disclosure, certain AOI values are used, however, in accordance with the present invention, the AOI may vary from one embodiment to another. Moreover, since the geometry of the input fiber and output fiber does not need to be parallel or perpendicular, AOI values may vary with the particular geometry employed, e.g., the AOI values may be anywhere from 5 degree AOI to 50 degree AOI. In one preferred embodiment of the present invention, filters  225  and  230  are preferably long-pass filters. In this respect it should also be appreciated that filter  225  may be replaced by a simple reflector to reflect the laser light. After the laser excitation light has been projected on the specimen, the Raman signal is re-collimated through lens  235  and passed through filter  230 . Alternatively, the Raman signal may pass through multiple filters (i.e., in addition to passing through filter  230 , the Raman signal may pass through additional filter  245 , at a 22.5 degree AOI). In one preferred embodiment of the present invention, additional filter  245  is preferably also a long-pass filter. When the Raman signal from the specimen is passed through filter  230 , filter  230  serves a second purpose at this time, i.e., it blocks the laser line. Filters  230  and  245  can provide up to &gt;OD10 filtration of the laser line before the light is redirected by focus lens  255  into collecting optical fibers  260 . Optical fibers  260  transmit the Raman signal to a light analyzer LA which analyzes the Raman signature of the specimen, whereby to identify the specimen. The light analyzer LA may comprise a spectrometer with associated analysis apparatus of the sort well known in the art. See, for example,  FIG. 1A , which shows the overall Raman spectroscopy system in schematic form. 
     It should be appreciated that with the constructions shows in  FIGS. 1-6 , the configurations preferably utilize a 22.5 degree Angle of Optical Incidence (AOI) for filters  25 ,  30  and/or  45  (or  125 ,  130  and/or  145 , etc.). However, as noted above, any other AOI can also be configured to take advantage of certain manufacturing tolerances. 
     For example, and looking now at  FIG. 7 , there is shown another novel Raman probe configuration  305  which uses a different AOI for the filters. With this construction, the output of excitation light source LS is delivered through optical fiber  310  and collimated through lens  315 . A bandpass filter  320  (or multiple combination of bandpass filters  320 A,  320 B) is used to pass the laser excitation light and to block spurious signals associated with the laser, the fiber, and/or both. The spurious signals associated with the laser generally comprise ASE from the laser, and the spurious signals associated with the fiber generally comprise fluorescence and Raleigh and Raman scatterings generated inside the fiber  310 . Preferably bandpass filter  320  is adapted to block spurious signals associated with both the laser and the fiber. The laser excitation light is then reflected by a filter  325 , which in this configuration may be a laser line reflector (at a 40 degree Angle of Optical Incidence, AOI) and a filter  330  (at a 5 degree AOI), and then it is focused through lens  335  to excite specimen  340 . In this respect it should be appreciated that, for the purposes of the present disclosure, certain AOI values are used, however, in accordance with the present invention, the AOI may vary from one embodiment to another. Moreover, since the geometry of the input fiber and output fiber does not need to be parallel or perpendicular, AOI values may vary with the particular geometry employed, e.g., the AOI values may be anywhere from 5 degree AOI to 50 degree AOI. In one preferred embodiment of the present invention, filter  330  is preferably a long-pass filter. In this embodiment, laser line reflector  325  is preferably a simple reflector to reflect the laser light. After the laser excitation light has been projected on the specimen, the Raman signal is re-collimated through lens  335  and passed through filter  330 . Alternatively, the Raman signal may pass through multiple filters (i.e., in addition to passing through filter  330 , the Raman signal may pass through additional filter  345 , at a 5 degree AOI). In one preferred embodiment of the present invention, additional filter  345  is preferably also a long-pass filter. When the Raman signal from the specimen is passed though filter  330 , filter  330  serves a second purpose at this time, i.e., it blocks the laser line. Filters  330  and  345  can provide up to &gt;OD10 filtration of the laser line before the light is redirected through broadband reflector  350  (at a 45 degree AOI) and focus lens  355  into collecting optical fibers  360 . Optical fibers  360  transmit the Raman signal to a light analyzer LA which analyzes the Raman signature of the specimen, whereby to identify the specimen. The light analyzer LA may comprise a spectrometer with associated analysis apparatus of the sort well known in the art. See, for example,  FIG. 1A , which shows the overall Raman spectroscopy system in schematic form. In addition to reflecting the Raman signal, broadband reflector  350  also filters out laser excitation light (OD1). 
     As noted above, Raman probe configuration  305  uses a 5 degree AOI for filters  330  and  345 . Such a small AOI can reduce the s and p polarization differences which are associated with a large angle of AOI. By using a smaller AOI value, the Raman signal at around ˜300 cm-1 (or smaller) can be readily resolved. In this configuration, laser line reflector (or filter)  325  is designed for a 40 degree AOI. The laser line reflector  325  may be a simple laser line Distributed Bragg Reflector (DBR). 
     It should be appreciated that with a much narrower bandpass filter and a filter with a much smaller AOI, Raman signals as close as 100 cm-1 can also be readily utilized. 
     Looking now at  FIG. 8 , there is shown another novel Raman probe configuration  405  which also uses a smaller AOI for the filters (which are preferably long-pass filters). More particularly, with this construction, the output of excitation light source LS is delivered through optical fiber  410  and collimated through lens  415 . A bandpass filter  420  (or multiple combination of bandpass filters  420 A,  420 B) is used to pass the laser excitation light and to block spurious signals associated with the laser, the fiber, and/or both. The spurious signals associated with the laser generally comprise ASE from the laser, and the spurious signals associated with the fiber generally comprise fluorescence and Raleigh and Raman scatterings generated inside the fiber  410 . Preferably bandpass filter  420  is adapted to block spurious signals associated with both the laser and the fiber. The laser excitation light is then reflected by a laser line reflector  425  (at a 40 degree Angle of Optical Incidence, AOI) and a filter  430  (at a 5 degree AOI), and then it is focused through lens  435  to excite specimen  440 . In this embodiment, laser line reflector  425  is preferably a simple reflector to reflect the laser light. In this respect it should be appreciated that, for the purposes of the present disclosure, certain AOI values are used, however, in accordance with the present invention, the AOI may vary from one embodiment to another. Moreover, since the geometry of the input fiber and output fiber does not need to be parallel or perpendicular, AOI values may vary with the particular geometry employed, e.g., the AOI values may be anywhere from 5 degree AOI to 50 degree AOI. In one preferred embodiment of the present invention, filter  430  is preferably a long-pass filter. After the laser excitation light has been projected on the specimen, the Raman signal is re-collimated through lens  435  and passed through filter  430 . Alternatively, the Raman signal may pass through multiple filters (i.e., in addition to passing through filter  430 , the Raman signal may pass through additional filter  445 , at a 5 degree AOI). In one preferred embodiment of the present invention, additional filter  445  is preferably also a long-pass filter. When the Raman signal from the specimen is passed a through filter  430 , filter  430  serves a second purpose at this time, i.e., it blocks the laser line. Filters  430  and  445  can provide up to &gt;OD10 filtration of the laser line before the light is redirected by focus lens  455  into collecting optical fibers  460 . Optical fibers  460  transmit the Raman signal to a light analyzer LA which analyzes the Raman signature of the specimen, whereby to identify the specimen. The light analyzer LA may comprise a spectrometer with associated analysis apparatus of the sort well known in the art. See, for example,  FIG. 1A , which shows the overall Raman spectroscopy system in schematic form. 
     As noted above, any other angles in the filters can also be used to configure the Raman probe wherein the fibers and signal collecting optics are collinear with one another. Thus, in the construction shown in  FIG. 9 , the output of excitation light source LS is delivered through optical fiber  510  and collimated through lens  515 . A bandpass filter  520  (or multiple combination of bandpass filters  520 A,  520 B) is used to pass the laser excitation light and to block spurious signals associated with the laser, the fiber, and/or both. The spurious signals associated with the laser generally comprise ASE from the laser, and the spurious signals associated with the fiber generally comprise fluorescence and Raleigh and Raman scatterings generated inside the fiber  510 . Preferably bandpass filter  520  is adapted to block spurious signals associated with both the laser and the fiber. The laser excitation light is then reflected by filters  525  (at a 10 degree AOI) and  530  (at a 10 degree AOI), and then it is focused through lens  535  to excite specimen  540 . In this respect it should be appreciated that, for the purposes of the present disclosure, certain AOI values are used, however, in accordance with the present invention, the AOI may vary from one embodiment to another. Moreover, since the geometry of the input fiber and output fiber does not need to be parallel or perpendicular, AOI values may vary with the particular geometry employed, e.g., the AOI values may be anywhere from 5 degree AOI to 50 degree AOI. In one preferred embodiment of the present invention, filters  525  and  530  are preferably long-pass filters. In this respect it should also be appreciated that filter  525  may be replaced by a simple reflector to reflect the laser light. After the laser excitation light has been projected on the specimen, the Raman signal is re-collimated through lens  535  and passed through filter  530 . Alternatively, the Raman signal may pass through multiple filters (i.e., in addition to passing through filter  530 , the Raman signal may pass through additional filter  545 , at a 10 degree AOI). In one preferred embodiment of the present invention, additional filter  545  is preferably also a long-pass filter. When the Raman signal from the specimen is passed through filter  530 , filter  530  serves a second purpose at this time, i.e., it blocks the laser line. Filters  530  and  545  can provide up to &gt;OD10 filtration of the laser line before the light is redirected by focus lens  555  into collecting optical fibers  560 . Optical fibers  560  transmit the Raman signal to a light analyzer LA which analyzes the Raman signature of the specimen, whereby to identify the specimen. The light analyzer LA may comprise a spectrometer with associated analysis apparatus of the sort well known in the art. See, for example,  FIG. 1A , which shows the overall Raman spectroscopy system in schematic form. 
     The Raman probe can also be made significantly more compact by utilizing two prisms with various coatings on their surfaces. One such embodiment is illustrated in  FIG. 10 . In this configuration, the functions of the various coatings are the same as discussed above. More particularly, in  FIG. 10  there is shown a Raman probe configuration  605 . The output of excitation light source LS is delivered through optical fiber  610  and collimated through lens  615 . A bandpass filter coating  665  on a first prism  675  is used to pass the laser excitation light and to block spurious signals associated with the laser, the fiber, and/or both. The spurious signals associated with the laser generally comprise ASE from the laser, and the spurious signals associated with the fiber generally comprise fluorescence and Raleigh and Raman scatterings generated inside the fiber  610 . Preferably bandpass filter  620  is adapted to block spurious signals associated with both the laser and the fiber. The laser excitation light is then reflected by a dichroic beamsplitter coating  680 , at a 45 degree AOI, through a broadband AntiReflection (AR) coating  670  and then it is focused through lens  635  to excite specimen  640 . In this respect it should be appreciated that, for the purposes of the present disclosure, certain AOI values are used, however, in accordance with the present invention, the AOI may vary from one embodiment to another. Moreover, since the geometry of the input fiber and output fiber does not need to be parallel or perpendicular, AOI values may vary with the particular geometry employed, e.g., the AOI values may be anywhere from 5 degree AOI to 50 degree AOI. After the laser excitation light has been projected on the specimen, the Raman signal is re-collimated through lens  635  and passed through broadband AR coating  670 . When the Raman signal from the specimen is passed though broadband AR coating  670 , broadband AR coating  670  serves a second purpose at this time, i.e., it blocks the laser line. The light passes through second prism  685 , and then through filter coating  690  before being redirected by focus lens  655  into collecting optical fibers  660 . Optical fibers  660  transmit the Raman signal to a light analyzer LA which analyzes the Raman signature of the specimen, whereby to identify the specimen. The light analyzer LA may comprise a spectrometer with associated analysis apparatus of the sort well known in the art. See, for example,  FIG. 1A , which shows the overall Raman spectroscopy system in schematic form. 
     Portable Raman Probe with Inline Vial Capability 
     Raman optical probes of the type shown in  FIGS. 1-10  may be used for delivery and collection of light to and from the specimen in a variety of settings. However, usability challenges can arise when trying to utilize such a Raman optical probe in portable field applications. 
     By way of example, with the construction shown in  FIG. 1 , the distance from delivery/collection lens  35  and the specimen  40  must generally be kept to within approximately +/−0.5 mm of the focal length of lens  35  so as to maximize the signal strength. 
     In addition, many users may desire to maintain the specimen  40  close to the lens  35 , while not actually touching the specimen, so as to avoid contaminating the Raman probe instrument with the specimen. 
     Also, some users may prefer to have their specimens placed in a glass vial during measurement. This can be awkward with prior art Raman probes. 
     To address these and other concerns, the present invention provides a novel Raman probe which may be used in three different modes of use. In a first mode of use, the Raman probe allows the user to maintain distance from the specimen using a conical standoff, which provides both distance control and laser safety by limiting the exposed beams. The second mode of use allows the user to remove the conical standoff so as to maintain distance control by hand or other means. The third mode of use allows a specimen vial to be inserted directly within the probe optics assembly. 
     More particularly, and looking now at  FIG. 11 , there is shown a novel Raman probe configuration  705  which provides the three aforementioned modes of use. With this construction, the output of excitation light source LS is delivered through optical fiber  710  and collimated through lens  715 . A bandpass filter  720  (or multiple combination of bandpass filters  720 A,  720 B) is used to pass the laser excitation light and to block spurious signals associated with the laser, the fiber, and/or both. The spurious signals associated with the laser generally comprise ASE from the laser, and the spurious signals associated with the fiber generally comprise fluorescence and Raleigh and Raman scatterings generated inside the fiber  710 . Preferably bandpass filter  720  is adapted to block spurious signals associated with both the laser and the fiber. The laser excitation light is then reflected by a laser line reflector  725  (e.g., at a 22.5 degree Angle of Optical Incidence, AOI) and a filter  730  (e.g., at a 22.5 degree AOI), and then it is focused through lens  735  on specimen vial receptacle  805 , or passed through the specimen vial receptacle  805  and through a focus lens  800 , and then through another focus lens  795 , to a specimen location  740 . In this respect it should be appreciated that, for the purposes of the present disclosure, certain AOI values are used, however, in accordance with the present invention, the AOI may vary from one embodiment to another. Moreover, since the geometry of the input fiber and output fiber does not need to be parallel or perpendicular, AOI values may vary with the particular geometry employed, e.g., the AOI values may be anywhere from 5 degree AOI to 50 degree AOI. In one preferred embodiment of the present invention, filter  730  is preferably a long-pass filter. In this embodiment, laser line reflector  725  is preferably a simple reflector to reflect the laser light. After the laser excitation light has been projected on the specimen, the Raman signal is re-collimated through lens  735  (where the specimen is located in vial receptacle  805 ), or lenses  795 ,  800  and  735  (where the specimen is located at specimen location  740 ) and passed through filter  730 . Alternatively, the Raman signal may pass through multiple filters (i.e., in addition to passing through filter  730 , the Raman signal may pass through additional filter  745  (e.g., at a 22.5 degree AOI). In one preferred embodiment of the present invention, additional filter  45  is preferably also a long-pass filter. When the Raman signal from the specimen is passed through filter  730 , filter  730  serves a second purpose at this time, i.e., it blocks the laser line. Filters  730  and  745  can provide up to &gt;OD10 filtration of the laser line before the light is redirected by focus lens  755  into collecting optical fibers  760 . Optical fibers  760  transmit the Raman signal to a light analyzer LA which analyzes the Raman signature of the specimen, whereby to identify the specimen. The light analyzer LA may comprise a spectrometer with associated analysis apparatus of the sort well known in the art. See, for example,  FIG. 1A , which shows the overall Raman spectroscopy system in schematic form. In one preferred embodiment of the invention, filters  730  and/or  745  may comprise long-pass filters. 
     The novel Raman probe  705  may be implemented and used as follows. 
     Looking first at  FIGS. 12 ,  13 ,  14  and  14 A, in the first mode of use, the novel Raman probe  705  allows the user to maintain distance to the specimen using a conical standoff  810  which mounts to the housing  815  of the Raman probe adjacent to output fiber  760 . The conical standoff  810  is designed to provide both distance control and laser safety (by limiting beam exposure). Conical standoff  810  can be manufactured as a disposable element so as to alleviate contamination concerns, or it can be a more permanent element of the Raman probe. In one preferred construction, the probe and conical standoff include a mechanism for attaching and removing a permanent or disposable conical standoff to and from a portable Raman unit. Among other things, the conical standoff may be snap fit to the remainder of the probe (see  FIG. 14 ), or the conical standoff may be pivotally attached to the remainder of the probe so that it may be swung into and out of position as desired. 
     The conical standoff  810  may comprise a variety of configurations, e.g., such as those shown in  FIGS. 12-14  and  14 A. In one preferred form of the invention, conical standoff  810  comprises an outer cone  810 A ( FIG. 13 ) which serves as the distance standoff and an inner cone  810 B which provides eye safety. Preferably, the inner cone  810 B is backpainted to conceal laser light. The conical standoff can be made from plastic or metal or a combination of the two materials. A glass window  810 C ( FIG. 12 ) may be provided at the point of laser emission to prevent the specimen from penetrating into the cone. Optionally, a switch (not shown) in conical standoff  810  may be provided to trigger laser emission on contact with the sample. If desired, conical standoff  810  may comprise a half-moon filter  810 D ( FIG. 14A ) surrounding the outer perimeter of outer cone  810 A, where the filter elements  810 E are configured to filter out the operative wavelength of the laser so as to prevent direct viewing of the laser beam and thereby provide operator safety. 
     The second mode of use allows the user to remove the conical standoff  810  so as to maintain the desired distance manually or with other means. This mode also allows the user to avoid having to touch the specimen which, again, can help alleviate contamination concerns. In this second mode, it is also possible to couple the use of an electronic/optical method to provide a feedback signal which is proportional to the distance between the specimen and the lens in order to optimize the Raman signal. 
     In the third mode of use, and looking now at  FIGS. 15-17 , a vial  820  may be inserted in vial receptacle  805  so that the vial  820  sits within the probe optics assembly. The additional optics permit the light to be focused on a vial  820  in the receptacle  805  (if one is present) or deliver the light to a standoff specimen at  740  (if the vial is not present). The receptacle  805  preferably incorporates a water tight barrier between the interior of the receptacle and the working elements of the probe. Windows  822  ( FIG. 18 ) permit light to pass into and out of receptacle  805 . 
     If desired, vial  820  can include a “shutter”  825  to close off the window  822  adjacent to lens  800  so as to prevent stray backlight from entering receptacle  805  when the specimen is retained in receptacle  805 . 
     Looking next at  FIG. 19 , a camera  830  may be added to the front of the probe, with the image from the camera being displayed on the probe&#39;s screen  835  ( FIG. 14A ). With this construction, the operator can position the probe relative to a specimen at a standoff location  740  while looking at screen  835 . This feature can enhance eye safety and, additionally, by providing camera magnification, can assist in positioning the Raman pump beam at the correct location. Furthermore, the data from camera  830  can be stored, along with date and time information, etc., in a removable memory chip (e.g., a CompactFlash card) so as to permit easy documentation of a probe test. 
     Further Constructions 
     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.