Spatially offset raman probe with coaxial excitation and collection apertures

Abstract

The present invention relates to a spatially offset Raman probe with coaxial excitation and collection apertures. An optical measurement probe for capturing a spectral response through an intervening material that emits unwanted background radiation, comprising: a first lens configured to receive light and collimate the light into a collimated excitation beam defining a first aperture; an objective element for focusing the collimated excitation beam through the intervening material to a point or region in a sample, wherein the objective element also receives light scattered by the sample and the intervening material and collimates the scattered light into a collimated collection beam defining a second aperture; and, a blocking element within the collimated collection beam for removing light scattered by the intervening material from the collimated collection beam received by the sample, wherein the second aperture defined by the collimated collection beam is at least twice the first aperture defined by the collimated excitation beam.

Description

Technical Field

[0001] This disclosure generally relates to remote optical measurement probes, and more specifically, to probes capable of achieving the benefits of spatially offset excitation and collection in a compact configuration. Background Technology

[0002] Induced radiation effects such as Raman scattering and fluorescence have become extremely valuable tools associated with the non-destructive determination of molecular composition. In fact, Raman spectroscopy has become an established and practical method for chemical and structural analysis and characterization, applicable to many different chemical species.

[0003] Raman spectroscopy is based on the principle that monochromatic excitations are reflected, absorbed, and scattered according to the specific molecules receiving the radiation. Most of the energy is elastically scattered at the same wavelength, a process called Rayleigh scattering. A much smaller amount is scattered at different wavelengths, called inelastic or Raman scattering, in which the scattered photons retain some of their energy in the form of vibrations between bound atoms in the molecule that scattered the photon. In Raman spectroscopy analysis, these wavelength shifts in the scattered radiation are analyzed to determine the characteristics of the sample.

[0004] Raman spectroscopy has become increasingly popular for online process monitoring, largely due to advancements in instrumentation and related component technologies. For many process applications, Raman analyzers have proven to offer significant advantages over alternative techniques such as gas chromatography, infrared spectroscopy, and near-infrared spectroscopy. As a non-destructive, real-time technique, Raman spectroscopy is compatible with a wide variety of samples, including opaque solids, aqueous solutions, emulsions, and gases, without the need for sample preparation.

[0005] Traditional Raman systems have three main components: an excitation source, a sampling device, and a detector. While these three components have evolved over the years, modern Raman instruments use a laser as the excitation source, a spectrometer as the detector, and a fiber optic probe as the sampling device. The probe illuminates the sample with a laser and collects the scattered light from the sample using an optical fiber, lens, or both. A complete system typically also includes a computer processor that runs analytical software suitable for the application.

[0006] To characterize the composition of samples in remote or harsh environments, optical fibers can be used to transfer excitation energy to a probe tip and transmit scattered radiation from the sample back to the instrument used for spectroscopic analysis. An excitation laser emitting radiation at an appropriate wavelength is coupled to the input fiber as the excitation path, and a complementary collection path typically includes a second collection fiber that carries the returned spectral information, including the scattered radiation, to the spectrometer.

[0007] In some instances, fiber optic Raman probes may be located far from other facilities, including the spectrometer. This type of installation is increasingly used in industrial applications for materials handling, process monitoring, and process control. As an example, industrial Raman spectrometers used for chemical process monitoring and control can utilize laser energy from a laser source installed in an instrument in a central control room. This instrument couples the laser radiation into fiber optic cables routed to remote probes. The remote probe heads can be mounted on pipes, process vessels, and other locations that may be significantly remote from the laser source.

[0008] Figure 1 A simplified, conventional, fiber-coupled remote Raman probe 100 is schematically illustrated. In summary, laser-excited radiation is transmitted via fiber 102, collimated at 104, reoriented at 118, and combined at 109 into path 110, which may also carry scattered light (i.e., collected light) collected from sample 112. A common objective 114 is used to focus the laser radiation and collimate the collected light. A bandpass filter 116 and a notch filter 111 pass through and reject the laser wavelength, respectively. The collected light is focused at 113 and transmitted via fiber 122 to a spectrometer. Other exemplary configurations are described in U.S. Patent No. 5,377,004 entitled *Remote Optical Measurement Probe*, which is incorporated herein by reference and elsewhere in the literature.

[0009] Notice Figure 1 The probe 100 is capable of penetrating certain barriers 126 (e.g., walls or windows) to analyze samples in dishes, containers, tubing, etc. In fact, this capability enables Raman spectroscopy to be used in harsh or sterile environments without contaminating biological processes or impairing workflows. However, barriers 126 typically introduce unwanted scattering, background Raman, and / or fluorescence features 120 that may overlap with the Raman collection path, creating analytical challenges such as noise. To a lesser extent, background features 120 from the objective 114 may also affect signal processing based on the specific material chosen for the objective 114—e.g., UV-grade fused silica or sapphire.

[0010] Raman probe construction techniques have been developed to mitigate the background feature problem just described. One approach is to use spatially shifted Raman spectroscopy, or SORS. SORS is an established technique for obtaining the Raman spectra of samples inside a container or behind a window, while reducing interference or contamination from the fluorescence and / or Raman spectra of the container or window material transmitted to the sample spectrum, and focusing on the target—i.e., background features. Figure 2A simplified conventional schematic diagram of the SORS arrangement 200 is shown. The conventional SORS concept involves focusing an excitation laser beam 202 through a spatial region 204 of a container or window 126 and collecting Raman scattering 206 from a sample 212 through different spatial regions 208 of the container or window 126.

[0011] While effective, the angle between the excitation and collection paths reduces the efficiency of probe construction and implementation. These problems can be addressed by using methods such as... Figure 3 The example of the prior art arrangement shows a reduction to some extent in the use of the common objective lens 314. Figure 2 Similar to the configuration, the laser irradiation portion 304 of the window / container 126 is separated from the portion 308 of the window / container 126 through which the collection path 310 passes. While this arrangement allows the excitation and collection paths to be parallel, the geometry is still not optimal in terms of product size and overall efficiency.

[0012] Therefore, there is a great need for a remote optical measurement probe configuration that can achieve SORS-like excitation / collection separation to reduce container / window interference in narrower, more compact probe designs. Summary of the Invention

[0013] The probes and systems according to this disclosure achieve the desired window / container background feature suppression advantages of prior art spatial shift spectroscopy techniques, while further preserving most of the signal collection advantages of conventional coaxial excitation and collection paths. These advantages can be significant in optically transparent samples, as found in many process monitoring and control applications—such as bioprocessing and biopharmaceutical applications, alcoholic fermentation, and other applications known to those skilled in the art.

[0014] In one aspect of this disclosure, an optical measurement probe for capturing a spectral response by means of an intervening material emitting unwanted background radiation comprises: a first lens configured to receive light and collimate the light into a collimated excitation beam defining a first aperture; and an objective element adapted to focus the collimated excitation beam through the intervening material onto a point or region in a sample, wherein the objective element is also adapted to receive light scattered by the sample and the intervening material and collimate the scattered light into a collimated collection beam defining a second aperture; and a blocking element disposed within the collimated collection beam and configured to remove light scattered by the intervening material from at least a portion of the collimated collection beam received by the sample, wherein the second aperture defined by the collimated collection beam is at least twice as large as the first aperture defined by the collimated excitation beam.

[0015] In at least one embodiment, the probe further includes a mirror disposed in the collimated collection beam, wherein the mirror is operable to redirect the collimated excitation beam to the objective element, and wherein the mirror is a blocking element. In such an embodiment, the redirected collimated excitation beam and the collimated collection beam may be coaxial. In another embodiment, the probe includes: a beam combiner disposed in the collimated collection beam, wherein the beam combiner is adapted to redirect the collimated excitation beam to the objective element; and a bandpass filter disposed in the collimated excitation beam between the beam combiner and the objective element, wherein the bandpass filter is a blocking element. In such an embodiment, the redirected collimated excitation beam and the collimated collection beam may be coaxial. Furthermore, in such an embodiment, the objective element and the bandpass filter are part of a removable, replaceable module.

[0016] In at least one embodiment, the first lens is configured to receive and collimate light from the optical fiber. In another embodiment, the probe includes a second lens configured to focus a collimated collected beam onto a collecting optical fiber for transmission to a spectrometer. In yet another embodiment, the probe includes a second lens configured to focus a collimated collected beam onto a collecting optical fiber for transmission to a spectrometer, wherein the first lens is configured to receive laser light from the optical fiber. In such embodiments, the first lens has a first focal length; the second lens has a second focal length; the second focal length may be more than twice the length of the first focal length. Furthermore, in such embodiments, the first optical fiber defines a first core diameter; the second optical fiber defines a second core diameter; the second core diameter may be larger than the first core diameter. In such embodiments, the first optical fiber may be a single multimode optical fiber; the second optical fiber may comprise a bundle of single optical fibers.

[0017] In another aspect of this disclosure, an optical analysis apparatus includes: a first optical fiber configured to transmit light from a light source; a second optical fiber configured to transmit light to a detector; and a probe configured to capture a spectral response by an intervening material that emits unwanted background radiation when irradiated, the probe comprising: a first lens configured to receive light from the first optical fiber and collimate the light into a collimated excitation beam defining a first aperture; an objective element adapted to focus the collimated excitation beam through the intervening material onto a point or region in a sample, wherein the objective element is further adapted to receive light scattered by the sample and the intervening material and collimate the scattered light into a collimated collection beam defining a second aperture; a blocking element disposed within the collimated collection beam and configured to block at least a portion of the light scattered by the intervening material from the collimated collection beam, wherein the second aperture defined by the collimated collection beam is at least twice the size of the first aperture defined by the collimated excitation beam; and a second lens configured to focus the collimated collection beam onto the second optical fiber to transmit the collimated collection beam to the detector.

[0018] In at least one embodiment, the device further includes one or more connectors configured to secure a first optical fiber and / or a second optical fiber in optical communication with a probe. In one embodiment, the device further includes a spectrometer comprising a detector, wherein the probe communicates optically with the spectrometer via a second optical fiber, thereby collimating and collecting a light beam that is transmitted to the detector. In another embodiment, the first optical fiber defines a first core diameter; the second optical fiber defines a second core diameter; the second core diameter may be larger than the first core diameter. In yet another embodiment, the first optical fiber is a single multimode optical fiber; the second optical fiber comprises a bundle of single optical fibers. In still another embodiment, the first lens has a first focal length; the second lens has a second focal length; the second focal length is more than twice the length of the first focal length.

[0019] In at least one embodiment, the device further includes a mirror disposed in the collimating collected beam, wherein the mirror is adapted to redirect the collimated excitation beam to the objective element, and wherein the mirror is a blocking element. In another embodiment, the device further includes: a beam combiner disposed in the collimating collected beam, wherein the beam combiner is configured to redirect the collimated excitation beam to the objective element; and a bandpass filter disposed in the collimated excitation beam between the beam combiner and the objective element, wherein the bandpass filter is a blocking element. Attached Figure Description

[0020] The described embodiments and other features, advantages, and disclosures contained herein, as well as ways of implementing them, will become apparent and better understood by reference to the following description of various embodiments of this disclosure taken in conjunction with the accompanying drawings, wherein:

[0021] Figure 1 A simplified fiber-coupled remote Raman probe head of the prior art is schematically shown;

[0022] Figure 2 This is a simplified schematic diagram of existing SORS arrangements;

[0023] Figure 3 It includes existing technology devices such as public objective lenses;

[0024] Figure 4 This is a schematic diagram of the probe configuration disclosed herein;

[0025] Figure 5 It is the existing technology PhAT TM A simplified diagram of the probe head design;

[0026] Figure 6 The following is a modification made in accordance with this disclosure. Figure 5 The probe head;

[0027] Figure 7This is a schematic diagram of an alternative embodiment of the present disclosure, including a second bandpass filter mounted near the common objective lens; and

[0028] Figure 8 The optical analysis apparatus of this disclosure is shown. Detailed Implementation

[0029] The probes and systems according to this disclosure achieve the advantages of spatially shifted Raman spectroscopy, while in some embodiments, coaxial excitation and collection apertures are realized. Broadly speaking, these advantages are achieved by: a) introducing a relatively small collimated laser beam into a large collimated collection beam; and b) fabricating the optical components of the probes of this disclosure such that light emitted from the sample is prevented from entering the collection path of the spectrometer. Although the aperture loss due to the cross-section of the excitation beam may reduce collection efficiency to some extent, the large collection-to-excitation signal ratio and the purity of the resulting collected signal outweigh the loss, for example in advanced biological processes where the probe may need to penetrate multilayer container materials, such as for single-use plastic bioreactors.

[0030] As used herein, “probe” and “probe head” are used interchangeably to describe components of an optical assembly configured to illuminate a sample with excitation light, collect scattered light from the sample, and interface with a light source and a detector.

[0031] According to at least one embodiment of this disclosure, probe 400 can be configured as follows: Figure 4 As schematically illustrated, probe 400 may include excitation fiber 402 electromagnetically coupled to a radiation source (not shown) configured to emit excitation radiation of a selected wavelength (e.g., light), such as a laser, and excitation optics 404 adapted to collimate the excitation radiation transmitted through excitation fiber 402. Probe 400 may also include a bandpass filter 416 selected to remove unwanted wavelengths caused by fiber 402, such as wavelengths that do not include the selected wavelength of the radiation source. The excitation radiation transmitted through bandpass filter 416 is routed to sample 412 via excitation beam 406 formed by downstream optics of probe 400, which may include a first mirror 418, a second mirror 409, and an objective lens 414 (e.g., an objective lens). The excitation radiation from the radiation source via excitation fiber 402 is collimated by excitation optics 404, redirected by the first mirror 418, and again redirected by the second mirror 409 into the backpropagation space 410 to form excitation beam 406. Objective lens 414 focuses the excitation beam 406 onto sample 412 at the focal point or region.

[0032] The probe 400 may include a collecting fiber 422 electromagnetically coupled to a spectrometer (not shown) configured to spectrally separate and detect a collecting beam 426 composed of light scattered from the sample 412 generated by the incident excitation beam 406. The collecting beam 426 travels through a backpropagation space 410 via an objective lens 414. In at least one embodiment, the objective lens 414 both focuses the collimated excitation radiation to form the excitation beam 406 and collimates the collecting beam 426 of light collected from the sample 412. The probe 400 may also include a notch filter 411 adapted to reject (e.g., filter out) scattered light at a selected radiation wavelength (e.g., the wavelength of the radiation source), thereby rejecting elastic Rayleigh scattering from the sample 412. The probe 400 may further include a collecting optics 424 adapted to transmit and input the collecting beam 426 into the collecting fiber 422. In some embodiments of the probes disclosed herein (e.g., probe 400), the excitation fiber 402 and / or the collection fiber 422 may comprise a bundle of multiple fibers. As a non-limiting example, the excitation fiber 402 and / or the collection fiber 422 may comprise multimode or single-mode fibers.

[0033] and Figure 1 In contrast to probe 100, in at least one embodiment of probe 400 according to this disclosure, the cross-section of the collimated collecting beam 426 is significantly larger than the cross-section of the collimated excitation beam 406 in the backpropagation space 410. In a further embodiment, instead of beam combiner 109 of probe 100, mirror 409 may be included in probe 400.

[0034] The probe 400 can be employed when the sample 412 is located within a container—such as a vessel or bioreactor, for example a single-use plastic bioreactor, or, as a further non-limiting example, a pipe or measuring unit for conveying process flow. Therefore, both the excitation beam 406 and the light scattered from the sample 412 must be transmitted through the container wall or window 126. In some embodiments of the probe 400, the window 126 may be a specific portion of the container that is at least partially transparent to both excitation and scattered radiation. In further embodiments where the container material is at least partially transparent to both excitation and scattered radiation, the window 126 may be any suitable portion of the container wall that is at least partially transparent to both excitation and scattered radiation. While the window 126 enables real-time monitoring of the process within the container or pipe, such a window may introduce inference noise.

[0035] As described, objective lens 414 focuses the collimated excitation beam 406 and collimates the collection beam 426 to the sample 412 and the collection beam 426 from the sample 412, respectively. Figure 4As shown, region 408 of window 126 and a portion 415 of objective lens 414 can each generate parasitic, unwanted signals. As described herein, such unwanted signals can include fluorescence and unwanted Raman features from window 126 and objective lens 414. However, due to the configuration of the components of probe 400, region 408 and portion 415 are smaller than prior art probes—for example, as... Figure 1 The probe 100 shown represents a similar region. Not only is the area in probe 400 where parasitic, unwanted signals may potentially be generated smaller, but the second mirror 409 also prevents at least a portion of these unwanted signals from entering the collecting fiber 422. The second mirror 409 projects a shadow 421, which effectively blocks fluorescence and unwanted Raman features from window 126 and objective lens 414 from reaching the spectrometer. In prior art probes, such as probe 100, beam combiner 109 allows such signals to transmit through fiber 122.

[0036] One aspect of this disclosure includes the significant asymmetric amplification between the excitation beam and the collection beam. In prior art probe designs, such as Figure 1 The probe designs shown, if not substantially identical (e.g., close to 1:1), have an excitation image to collection image ratio at the target (e.g., the sample) that is less than 2:1. However, probes according to this disclosure, including probe 400, are implemented to produce a ratio of 2:1 or greater, and in some embodiments up to 6:1 or higher. To achieve such a ratio, the focal length of the collection optics 424 can be two to six times greater than the focal length of the excitation optics 404 suitable for collimating the excitation beam 406, thereby obtaining a highly magnified excitation image. Simultaneously, the ratio of the focal length of the collection optics 424 to the focal length of the excitation optics 404 can preferably match or at least nearly match the ratio of the diameter of the excitation fiber to the diameter of the collection fiber, such that the image diameters of the excitation fiber 402 and the collection fiber 422 (i.e., the excitation image and the collection image) are substantially the same at the sample.

[0037] Because the focal length of the excitation optics 404 is smaller than that of the collection optics 424, the image of the excitation fiber generated by the optical components of the probe 400 is highly magnified. However, the focal length of the collection optics 424 is comparable to or the same as that of the objective lens 414, so even if it is magnified, it is only slightly magnified. Furthermore, since in some embodiments the ratio of the focal lengths of the collection optics 424 to the excitation optics 404 can match the ratio of the diameters of the excitation fiber 402 and the collection fiber 422, the image diameters of the two fibers 402, 422 are approximately the same at the sample 412, thereby optimizing the signal generation capability of the probe 400.

[0038] While single or multiple optical fibers can be used for excitation fiber 402 or collection fiber 422, in at least one embodiment of this disclosure, excitation fiber 402 may comprise a single fiber, and collection fiber 422 may comprise a bundle of fibers, for example, 50, or more, or fewer. The diameter of excitation fiber 402 can be selected to define the desired ratio of magnification of the excitation image to the collection image. In at least one embodiment, the diameter of excitation fiber 402 may range from approximately 200 micrometers to 1 mm. In such embodiments, the core diameter of collection fiber (e.g., the diameter of the fiber excluding cladding and coating) must therefore be correspondingly larger than the core diameter of excitation fiber. In some embodiments, the desired magnification can be achieved using a larger circular bundle of fibers of similar size to effectively collect Raman scattering from a fully illuminated sample region.

[0039] The probe implementation according to this disclosure is well-suited to existing probe head designs, known as PhAT. TM The probe is manufactured and marketed by Kaiser Optical Systems Inc., a subsidiary of Endress+Hauser Group, located in Ann Arbor, Michigan. PhAT TM The probe is already equipped with many of the properties just described. PhAT TM Details of the probe can be found in U.S. Patent No. 7,148,963, the entire contents of which are incorporated herein by reference. Figure 5 It is a traditional PhAT TM A simplified schematic diagram of probe head 500. In view of the benefits of this disclosure, those skilled in the art will understand that while a probe according to this disclosure is described herein in conjunction with this particular probe design, the advantages made possible by this disclosure also apply to other configurations, provided that the operating principles of the apparatus and methods described herein are implemented.

[0040] The Probe 500 features the efficiency of a more conventional 2-fiber coaxial excitation / collection probe, but with a significantly larger excitation / collection spot size, thus reducing the risk of laser power density and sample damage. A circular collection fiber bundle is rearranged at the spectrometer entrance slit to form a linear array to maintain spectral resolution, and the collected signal is integrated over a large volume to provide accurate readings for suspensions or solid mixtures (e.g., tablets).

[0041] Although Figure 5 The probe head schematic may look similar to Figure 4 The arrangement of probes 400, however, is shown below as an example of at least some non-exclusivity between them. For example, with Figure 1Compared to the conventional probe 100, the combiner 509 of the probe head 500 is a transmission wavelength selective combiner that reflects laser excitation radiation in one direction while transmitting it through the combiner 509 in another direction. This ensures that background radiation from window 126 and common objective 514 is not blocked and is thus allowed to reach the spectrometer via path 512. Additionally, as an option, the distal portion of the assembly may include a protective window 510 (e.g., UV sapphire) and a threaded objective slide 511 to accommodate different focal lengths and spot sizes. For non-limiting exemplary lenses, objectives 514 and 516 may be 25 mm diameter achromatic lenses and aspherical lenses with focal lengths in the range of 18-250 mm, while the laser collimating lens 504 may have a 5 mm diameter and a 7.5 mm focal length. The collecting focusing lens 516 may also be an achromatic lens, for example, with a 25 mm diameter and a 35 mm focal length.

[0042] Therefore, the probe head 500 includes a lens 516 for focusing the collection beam 526 from the sample into the collection fiber with a relatively, significantly larger focal length, instead of the lens 504 for collimating the laser emitted from the excitation fiber. Thus, the excitation and collection path scales are correspondingly different in diameter. However, instead of the wavelength selection combiner 509, the SORS probe 600 according to this disclosure includes a second reflector 613, as... Figure 6 As shown. The second mirror 613 can be supported on an on-axis "spider-like" slide and centered on the collimated collecting beam 626. As described with respect to probe 400, the second mirror 613 creates a central shield in the collection path, slightly reducing the Raman signal collected from the sample using the collecting beam 626, but greatly or completely reducing the Raman / fluorescence background spectrum from the sample focusing objective 514 and the window or container wall 126. The configuration is the same as that of probe 400, as... Figure 4 As shown by the dashed line 518, unwanted wavelengths generated by window 126 and / or objective lens 514 are blocked (e.g., masked) and cannot reach the spectrograph.

[0043] Figure 7 This is a simplified schematic diagram of an alternative embodiment of the probe 700 according to the present disclosure, wherein a second bandpass filter 702 is mounted near the common objective 514, optionally within a removable, replaceable module 706. The second bandpass filter 702 is adapted to filter light from the excitation beam that is not in the wavelength of the radiation source, thereby allowing light at or near the wavelength of the radiation source to pass through the common objective 514 and reach the sample. Such an embodiment facilitates modifications to existing PhAT... TMThe probe tip can be inserted without structural changes to the body and contents of the existing probe tip assembly behind the protective window 510. Bandpass filter 702 provides similar functionality to bandpass filter 506. Collimated excitation light reflected from mirror 518 is redirected by selective wavelength combiner 509 and passes through filter 702 and common objective 514 to reach the sample. However, in the opposite direction, filter 702 transmits only the laser wavelength and rejects all other wavelengths, including at least a portion of the Raman and fluorescence generated in container / window 126 and in objective 514. Like beam combiner 109 (or combiner 509), bandpass filter 702 can be suspended on a spider slide in the optical path.

[0044] In another embodiment, a conceptually similar non-coaxial method can utilize similar advantages of a larger collection focal length and aperture relative to the excitation focal length and aperture, but as... Figure 3 As shown in the prior art arrangement, the feed to the common objective—specifically, the smaller excitation beam—is deflected to the side rather than the center of the collection path. This non-coaxial approach should result in better rejection of the container / window background, but reduces the cost of sample Raman collection due to less overlap between the non-coaxial excitation and collection paths within the sample, leading to a reduced depth of focus.

[0045] In yet another alternative embodiment, embodiments of this disclosure are suitable for non-fiber-coupled excitation and / or collection of the beam—specifically, the laser and / or spectrometer are located close to the probe, thereby realizing free-space optics. Furthermore, embodiments of this disclosure are not limited to the “container” or “window” to be penetrated, which may include one or more layers of polymer or other materials capable of introducing background noise into the collected signal stream. Embodiments of the invention are also not limited to the phase of the sample, which may include, but is not limited to, gases, liquids, slurries, and solids.

[0046] In at least one embodiment according to this disclosure, such as Figure 8As shown, the probe according to this disclosure can be implemented in an optical analysis apparatus 800. The optical analysis apparatus 800 may include any embodiment of the probe of this disclosure, including but not limited to probe 400, probe 600, and probe 700. The optical analysis apparatus 800 may include a first optical fiber, such as excitation fiber 402, for transmitting excitation light from a radiation (e.g., a light source) source such as a laser to probe 400. The optical analysis apparatus 800 may also include a second optical fiber, such as collection fiber 422, for transmitting a collected beam collected by probe 400 to detector 812 of spectrometer 810. To secure excitation fiber 402 and collection fiber 422 to probe 400, the optical analysis apparatus 800 may include one or more connectors 820 configured to secure the first and / or second optical fibers for optical communication with probe 400. Such connectors may be complementary connectors between the housing of probe 400 and each of the corresponding optical fibers 402, 422.

[0047] Although various embodiments of the optical measurement probe and methods of using and constructing the probe have been described in considerable detail herein, these embodiments are provided only as non-limiting examples of the present disclosure described herein. Therefore, it should be understood that various changes and modifications can be made without departing from the scope of this disclosure, and elements therein can be substituted with equivalents. This disclosure is not intended to be exhaustive or to limit the scope of its subject matter.

[0048] Furthermore, in describing representative embodiments, this disclosure may have presented methods and / or processes as a specific sequence of steps. However, the method or process should not be limited to the specific sequence of steps described herein, provided that the method or process does not depend on the specific sequence of steps described herein. Other sequences of steps may be possible and therefore remain within the scope of this disclosure.

Claims

1. An optical measurement probe (400, 600, 700) for capturing a spectral response by emitting unwanted background radiation through an intervening material, said probe (400, 600, 700) comprising: First lens (404, 504), the first lens is configured to receive light and collimate the light into a collimated excitation beam (406) defining a first aperture. Objective elements (414, 514) are adapted to focus the collimated excitation beam (406) through the interventional material onto a point or region in the sample (412), wherein the objective elements (414, 514) are also adapted to receive light scattered by the sample (412) and the interventional material and collimate the scattered light into a collimated collection beam (426) defining a second aperture, wherein the second aperture defined by the collimated collection beam (426) is at least twice as large as the first aperture defined by the collimated excitation beam (406); A beam combiner (509) is disposed in the collimated collecting beam (426), wherein the beam combiner (509) is adapted to redirect the collimated excitation beam (406) to the objective elements (414, 514). A blocking element (702) is disposed within the collimated collecting beam (426) and configured to remove light scattered by the intervening material from at least a portion of the collimated collecting beam (426) received by the sample (412); as well as A bandpass filter is disposed in the collimated excitation beam (406) between the beam combiner (509) and the objective element (414), wherein the bandpass filter is the blocking element (702) that transmits only the laser wavelength and rejects all other wavelengths.

2. The probe (400, 600, 700) according to claim 1, wherein, The objective lens element (414) and the bandpass filter are removable, replaceable modules.

3. The probe (400, 600, 700) according to claim 1, wherein, The reoriented collimated excitation beam (406) and the collimated collection beam (426) are coaxial.

4. The probe (400, 600, 700) according to claim 2, wherein, The reoriented collimated excitation beam (406) and the collimated collection beam (426) are coaxial.

5. The probe (400, 600, 700) according to any one of claims 1 to 4, wherein, The first lens (404, 504) is configured to receive and collimate light from the optical fiber.

6. The probe (400, 600, 700) according to any one of claims 1 to 4 further comprises a second lens (424, 516) configured to focus the collimated collected beam (426) onto the collecting fiber for transmission to the spectrometer.

7. The probe (400, 600, 700) according to any one of claims 1 to 4 further comprises a second lens (424, 516) configured to focus the collimated collecting beam (426) onto the collecting fiber (422) for transmission to the spectrometer, wherein the first lens (404, 504) is configured to receive and collimate the light from the fiber (402).

8. The probe (400, 600, 700) according to claim 6, wherein: The first lens (404, 504) has a first focal length; The second lens (424, 516) has a second focal length; and The second focal length is more than twice as long as the first focal length.

9. The probe (400, 600, 700) according to claim 7, wherein: The first lens (404, 504) has a first focal length; The second lens (424, 516) has a second focal length; and The second focal length is more than twice as long as the first focal length.

10. An optical analysis device (800), comprising: A first optical fiber (402) is configured to transmit light from a light source; A second optical fiber (422) is configured to transmit light to a detector; as well as Probes (400, 600, 700), configured to capture a spectral response by an intervening material that emits unwanted background radiation upon irradiation, the probes (400, 600, 700) comprising: A first lens (404, 504) is configured to receive light from the first optical fiber and collimate the light into a collimated excitation beam (406) defining a first aperture. Objective element (414), the objective element being adapted to focus the collimated excitation beam (406) through the intervening material onto a point or region in the sample (412), wherein the objective element (414) is also adapted to receive light scattered by the sample (412) and the intervening material, and to collimate the scattered light into a collimated collection beam (426) defining a second aperture. A beam combiner (509) is disposed in the collimated collecting beam, wherein the beam combiner (509) is adapted to redirect the collimated excitation beam (406) to the objective element (414). A blocking element (702) is disposed within the collimated collecting beam (426) and configured to block at least a portion of the light scattered by the intervening material from the collimated collecting beam (426), wherein the second aperture defined by the collimated collecting beam (426) is at least twice as large as the first aperture defined by the collimated excitation beam (406); A bandpass filter is disposed in the collimated excitation beam (406) between the beam combiner (509) and the objective element (414), wherein the bandpass filter is the blocking element (702), and the bandpass filter transmits only the laser wavelength and rejects all other wavelengths; and A second lens (424, 516) is configured to focus the collimated collected beam (426) onto the second optical fiber so as to transmit the collimated collected beam (426) to the detector.

11. The apparatus (800) of claim 10 further includes a spectrometer comprising the detector, wherein the probes (400, 600, 700) optically communicate with the spectrometer via the second optical fiber (422) to transmit the collimated collected beam (426) to the detector.

12. The apparatus (800) according to claim 10 or 11, wherein: The first optical fiber (402) defines the diameter of the first core; The second optical fiber (422) defines the second core diameter; and The diameter of the second core is larger than the diameter of the first core.

13. The apparatus (800) according to claim 10 or 11, wherein: The first optical fiber (402) is a single multimode optical fiber; and The second optical fiber (422) comprises a bundle of single optical fibers.

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