Patent Description:
Nuclear magnetic resonance (NMR) spectroscopy is an established and very powerful technique for chemical characterisation of substances, including structures of large and small biomolecules, and chemical products. It accurately reflects and reports on the in situ composition of samples, and therefore can be used to monitor the progress of chemical reactions, and conformational changes. Recently, it has been widely recognised that many chemical and enzymatic reactions are modulated with light. Sample illumination during NMR experiments can also dramatically increase the sensitivity of such experiments. Therefore, the combination of illumination and high-resolution NMR spectroscopy has been recently recognised as an exciting emerging technique.

Existing NMR spectrometers with illumination capability include systems that utilise optical fibre to guide light (from a laser or light-emitting diode (LED)) into an area just above the sample to be studied. This leads to significantly non-uniform light intensity distribution about the sample (e.g. one side is illuminated whilst the other is not). In some known arrangements, the optical fibre extends into the sample itself, but this leads to magnetic field distortion and difficulties in sample shimming and solvent signal suppression, as well as possible sample contamination, and, again, non-uniform light distribution. In some prior art devices, a combination of optical fibers and glass coaxial inserts are used, wherein the glass coaxial insert extends into the sample to be studied. Arrangements such as these result in field inhomogeneity, and for cryoprobes, a reduction in experimental sensitivity (i.e., a reduction in signal-to-noise ratio). In general, the use of optical fibre dramatically reduces the intensity of light which can reach the sample. Additionally, it is challenging to use optical fibre with sealed or pre-sealed samples (e.g. oxygen sensitive samples).

Due to the geometry of NMR spectrometers (and the bores of NMR spectrometers that samples are usually loaded into), it is often difficult to provide light to a sample in a manner that doesn't adversely affect the magnetic field within the NMR spectrometer.

Furthermore, certain known arrangements are difficult to make optical adjustments to in situ, and do not lend themselves to providing convenient selection of different irradiation frequencies or combinations thereof.

One known prior art system is described in <CIT> in which an insert device is provided that comprises a non-magnetic carrying structure that includes a cavity for hosting radiofrequency coils and a sample. Light sources are arranged within corresponding openings of the carrying structure facing the sample to provide illumination. Reflective material is arranged on the inside of the carrying structure to reflect light towards the sample.

<NPL>) describes an LED based illumination device in which LEDs are coupled to a core optical fiber guiding the light into the spectrometer. The tip of the fiber is roughened.

<NPL>) describes an arrangement in which optical fibres and a light-scattering quartz rod are positioned in a standard NMR tube.

<NPL>) describes an arrangement in which a sandblasted illumination fiber is positioned in an NMR tube.

<NPL>) describes an arrangement in which a glass fiber is introduced into an NMR tube. The glass fiber is connected to an LED illumination source and a bottom portion of the glass fiber is sandblasted to provide uniform illumination.

It is an object of certain embodiments of the present invention to overcome certain disadvantages associated with the prior art.

In accordance with an aspect of the present invention there is provided an illumination insert for an NMR spectrometer, the illumination insert being shaped to receive a sample and comprising:.

In certain embodiments, the illumination insert comprises a main body, wherein the main body comprises the light guide portion and the diffuser portion. The main body may be a unitary component. The main body may be a tube having an open end, a closed end and a bore in which the sample may be received. The illumination insert may comprise a cap which seals the open end of the tube, wherein optionally the cap is transparent.

In certain embodiments, the illumination insert may be shaped to receive a sample holder, wherein the sample holder may contain a sample. The main body may be a tube having a first open end, a second open end and a through bore therethrough, wherein the sample holder may be received within the through bore. In certain embodiments, the diffuser portion may be positionable proximate to radiofrequency coils of an NMR spectrometer. In certain embodiments, the radiofrequency coils may be disposed radially outward of the tube, proximate the diffuser portion.

In certain embodiments, the illumination insert may comprise a housing that houses at least part of the light guide portion or the diffuser portion. The housing may comprise a non-magnetic material, optionally wherein the non-magnetic material is aluminium or copper. In certain embodiments, the housing may be configured to locate the illumination insert in the NMR spectrometer.

In certain embodiments, the main body may comprise a reflective coating for improving internal reflection in the main body.

In certain embodiments, the illumination insert may further comprise one or more light sources for providing light to the light guide portion. The one or more light sources may comprise one or more of a light emitting diode, a laser, or a laser diode.

In certain embodiments, the illumination insert may comprise an auxiliary light guide for guiding light from a remote light source towards the light guide portion.

The illumination insert may comprise one or more intermediate light transmission components for facilitating transmission of light to the light guide portion. The one or more intermediate light transmission components may focus light towards the light guide portion.

The illumination insert may comprise one or more reflectors for reflecting light towards the light guide portion.

In certain embodiments, the diffuser portion may comprise a plurality of light scattering centres that scatter light so as to collectively diffuse light received from the light guide portion towards a sample received in the illumination insert. The plurality of light scattering centres may be provided within the diffuser portion or on a surface of the diffuser portion. In certain embodiments, the plurality of light scattering centres may comprise a plurality of defects, optionally wherein the plurality of defects comprise a plurality of grooves, indents and/or scratches. In certain embodiments, the plurality of light scattering centres may be distributed non-uniformly in and/or on the diffuser portion.

In certain embodiments, the illumination insert may comprise a heat sink for facilitating the transfer of heat away from the light source. The heat sink may be a dedicated component, or for example, another component having multiple functions (e.g. the housing may act as a heat sink). The heat sink may serve to facilitate the transfer of heat out of the illumination insert, e.g. into the magnet bore of the NMR spectrometer that the illumination insert is inserted into. The airflow in the magnet bore may assist in transferring the heat away from the illumination insert. Additionally or alternatively, additional airflow means may be provided for providing an airflow that facilitates the removal of heat from the illumination insert.

In accordance with another aspect of the present invention, there is provided an NMR probehead housing comprising an illumination insert, the illumination insert comprising a main body in the form of a tube having a first open end, a second open end and a through bore therethrough, wherein a sample holder may be received within the through bore, and the main body comprises:.

The NMR probehead housing may comprise radiofrequency coils disposed radially outward of the tube. In certain embodiments, the radiofrequency coils may be disposed proximate to the diffuser portion.

In certain embodiments, the NMR probehead housing may comprise a sample holder received within the through bore and radiofrequency coils disposed between the tube and the sample holder, proximate the diffuser portion.

In accordance with another aspect of the present invention, there is provided an NMR spectrometer comprising an illumination insert as described above or an NMR probehead housing as described above.

An illumination insert <NUM> in accordance with an embodiment of the present invention is shown in <FIG>. The illumination insert <NUM> is configured for insertion in a nuclear magnetic resonance (NMR) spectrometer (not shown in <FIG>). The illumination insert <NUM> serves to provide illumination to a sample contained within the illumination insert <NUM>, when the illumination insert <NUM> is received in an NMR spectrometer. The sample may therefore be illuminated whilst being subjected to a magnetic field and radio waves produced by radiofrequency coils within the NMR spectrometer. The illumination may serve to increase the sensitivity of NMR characterization of the sample, and/or trigger chemical, structural or physical changes in the sample.

The illumination insert <NUM> comprises a main body <NUM> in the form of an elongate tube. The tube has an open end 12a, a closed end 12b and a (blind) bore 12c formed therein defining a volume for containing a sample <NUM> to be analysed by NMR spectroscopy. In certain embodiments, the sample <NUM> is a liquid.

The main body <NUM> has a light guide portion <NUM> and a diffuser portion <NUM>. The light guide portion <NUM> is configured to guide light received from a light source <NUM> towards the diffuser portion <NUM>. Whilst a single light source <NUM> is shown in the embodiment of <FIG>, it will be appreciated that any embodiment may include any number of light sources, and the illustrated embodiments are not limiting in this respect. In certain embodiments, multiple light sources <NUM> may be provided in order to provide illumination of different wavelengths. In the embodiment shown in <FIG>, light is guided from the light source <NUM> towards the diffuser portion <NUM> by total internal reflection of the light along walls of the tube <NUM> in the light guide portion <NUM>. The walls of the tube <NUM> should be sufficiently thick and made of a suitably transparent material to enable such transmission therethrough and internal reflection therein. In certain embodiments, the tube <NUM> comprises glass, at least along the light guide portion <NUM>.

The diffuser portion <NUM> is positioned towards the closed end 12b of the tube <NUM> such that it surrounds the sample <NUM> contained in the bore 12c (when the tube <NUM> is orientated such that the sample is disposed towards the closed end 12b of the tube <NUM> due to gravity). Throughout the Figures, example light paths are indicated by dotted arrows.

In the non-limiting embodiment shown in <FIG>, the main body <NUM> is a unitary component. In alternative embodiments, the main body <NUM> may comprise more than one components, e.g. that are connected to one another, affixed to one another, or positioned relative to one another. However, the use of a unitary component will simplify the manufacture and assembly of the illumination insert <NUM>, and will reduce optical losses between the light guide portion <NUM> and the diffuser portion <NUM>.

The illumination insert <NUM> is positionable in an NMR spectrometer so that the sample <NUM> contained therein is located within an NMR detection region (indicated by reference numeral <NUM> in <FIG>) of the NMR spectrometer, in proximity to radiofrequency coil or coils. The active volume <NUM> of the NMR spectrometer is the volume in which a magnetic field is present so that a sample <NUM> in the active volume <NUM> may be subjected to the magnetic field and radio waves and therefore studied using NMR spectroscopy. The radio waves may be created by one or more radiofrequency coils. The diffuser portion <NUM> is configured to diffuse light received from the light guide portion <NUM> towards the sample <NUM> received in the bore 12c. In doing so, the sample may be substantially uniformly illuminated by the light source <NUM> whilst being disposed within the NMR spectrometer. In preferable embodiments, the diffuser portion <NUM> is positioned within the coils of the NMR spectrometer (i.e. between the coils and the sample <NUM>).

The diffuser portion <NUM> may be made of any suitable material and/or have a suitable geometry that permits light to be diffused towards the sample <NUM>. In certain embodiments, this may be achieved by a plurality of light scattering centres <NUM> that scatter light so as to collectively diffuse light received from the light guide portion <NUM> towards a sample <NUM>. For example, the plurality of light scattering centres <NUM> may be formed on an outer surface of the tube <NUM> along the diffuser portion <NUM> or within the material of the tube <NUM> itself. The plurality of light scattering centres <NUM> may comprise defects or imperfections, that may include one or more of indents, scratches, notches, surface roughening or any other suitable surface modification that gives rise to diffusion of light in that portion of the tube <NUM>. The plurality of light scattering centres <NUM> may be non-uniformly distributed along the diffuser portion <NUM>. In certain embodiments, the light guide portion <NUM> is substantially free of the light scattering centres that are provided on or in the diffuser portion <NUM>.

The illumination insert <NUM> may be provided with a main body cap <NUM> which may close the open end 12a of the tube (main body) <NUM>. The main body cap <NUM> may provide an air-tight seal on the tube <NUM> so as to seal the sample <NUM> in the bore 12c of the tube <NUM>. The main body cap <NUM> may be sufficiently transparent to permit the transmission of light from the light source <NUM> to the light guide portion <NUM> of the tube <NUM>. In certain embodiments, the main body cap <NUM> may be shaped so as to provide a degree of focussing to the light transmitting therethrough.

The light source <NUM> may be any suitable source of light. In certain embodiments, the light source <NUM> may provide a single or multiple wavelengths of light. In certain embodiments, the light source <NUM> may comprise a light emitting diode (LED), a laser diode or a laser. In certain embodiments, the light source <NUM> is made of substantially non-magnetic materials, such as non-magnetic LEDs that are currently commercially available. Such embodiments reduce the effect on the magnetic field produced by the NMR spectrometer. In certain embodiments, more than one light source <NUM> may be provided, and the multiple light sources <NUM> may not necessarily be identical to one another. In certain embodiments, multiple light sources <NUM> may be provided where each light source <NUM> is capable of providing a different frequency and/or intensity of light. The light sources <NUM> may be selectively controlled to provide the required duration, frequency and/or intensity of light. The light source <NUM> may be removable so as to facilitate swapping of light sources <NUM> as desired. In certain embodiments, the light sources <NUM> may be controlled (e.g. synchronised) with respect to the radiofrequency pulses of the NMR spectrometer.

In the embodiment shown in <FIG>, the light source <NUM> is connected to a pair of electrical connectors <NUM> for providing electrical power to the light source <NUM>. A reflector <NUM> is provided around the light source <NUM> and is configured to reflect light from the light source <NUM> towards the light guide portion <NUM>, thus increasing the intensity of light transmitted through the light guide portion <NUM>. Certain embodiments may not include a reflector <NUM>.

In the non-limiting embodiment of <FIG>, an intermediate light transmission component <NUM> is provided between the light source <NUM> and the light guide portion <NUM>. The intermediate light transmission component <NUM> may serve to facilitate transmission of the light from the light source <NUM> to the light guide portion <NUM>. In certain embodiments, the intermediate light transmission component <NUM> may provide some degree of focussing to the light passing from the light source <NUM> to the light guide portion <NUM>. In certain embodiments, the intermediate light transmission component <NUM> may comprise one or more of a flat protective glass component, a lens, an axicon, an optical guide, a light tunnel or an optical fibre. In certain embodiments, the intermediate light transmission component <NUM> may additionally or alternatively provide a protective or barrier function. For example, the intermediate light transmission component <NUM> may protect the light source <NUM> from surrounding components, e.g. the main body cap <NUM>, or, in embodiments where no main body cap <NUM> is present, the open end of the main body <NUM>. In embodiments where no main body cap <NUM> is present, the intermediate light transmission component <NUM> may serve to cover and/or seal the open end of the main body <NUM>. The intermediate light transmission component <NUM> may serve to prevent contamination or damage of the light source <NUM>. In such embodiments, the intermediate light transmission component <NUM> may comprise a glass window (e.g. made of quartz glass).

The illumination insert <NUM> is provided with a housing <NUM> that houses part of the tube <NUM>. In the embodiment shown in <FIG>, the housing <NUM> houses a part of the light guide portion <NUM> and the main housing cap <NUM>. Additionally, the housing <NUM> houses the light source <NUM>, the reflector <NUM> and the intermediate light transmission component <NUM>. In alternative embodiments, some or all of these components may be disposed outside of the housing <NUM>. The housing of the embodiment of <FIG> comprises a first housing part 20a and a second housing part 20b. The first housing part 20a and the second housing part 20b may be parts of a unitary component. In other embodiments, they may be distinct components that are assembled together. The housing <NUM> has a generally cylindrical profile with the first housing part 20a having a larger diameter than the second housing part 20b (in alternative embodiments, the first housing part 20a and the second housing part 20b may have the same diameter, i.e. forming one cylindrical part). The first housing part 20a houses a part of the light guide portion <NUM>, the main housing cap <NUM>, the light source <NUM>, the reflector <NUM> and the intermediate light transmission component <NUM>. The second housing part 20b houses only part of the light guide portion <NUM>. In alternative embodiments, other combinations of components may be contained by the first housing part 20a and/or the second housing part 20b. The housing <NUM> is axially-symmetric about its longitudinal axis such that the illumination insert <NUM> may be inserted into a bore of an NMR spectrometer in any rotational orientation (about the longitudinal axis). However, in certain embodiments, a specific rotational orientation may be desired, and the shape of the housing <NUM> may facilitate or provide a guide towards the correct orientation during insertion. In certain embodiments, the tube <NUM> may be moveable relative to the housing <NUM>. The second housing part 20b may further serve to locate the illumination insert <NUM> in the NMR spectrometer and reduce lateral movement of the illumination insert <NUM> when inserted. The housing <NUM> may be releasably attachable to the tube <NUM> and/or light source <NUM>, e.g. by a pair of cooperating screw threads, or a push-in fitting. In certain alternative embodiments, the housing <NUM> may not be cylindrical and/or axially-symmetric about its longitudinal axis.

The housing <NUM> may comprise a non-magnetic material such as aluminium, copper or a non-magnetic alloy. Such embodiments reduce the effect of the housing on the magnetic field produced by the NMR spectrometer, and may help to dissipate heat generated by the light source <NUM>. That is, in some embodiments, the housing <NUM> may provide a heat sink for dissipating heat from the light source <NUM>. In certain other embodiments, a separate heat sink may be provided. In certain embodiments, cooling of the illumination insert <NUM> and/or cooling of the heat sink may be achieved by using existing airflow in the magnet bore of the NMR spectrometer in which the illumination insert <NUM> is inserted. In certain embodiments an additional airflow means for cooling may be provided. In certain embodiments, the illumination insert <NUM> may include or be provided with means for measuring temperature (e.g. a thermistor or thermocouple) of the illumination insert <NUM> components, light source or heat sink.

In some embodiments, a housing may not be provided, at all. In such embodiments, the various components of the illumination insert <NUM> may be otherwise arranged relative to one another (and the NMR spectrometer).

The electrical connectors <NUM> may comprise wires or other elongate conductors that are connectable to a power source so as provide power to the light source <NUM>. In certain embodiments, the electrical connectors <NUM> may comprise terminals to which wires or other conductors may connect to so as to connect the light source <NUM> to a power source. For example, the light source <NUM> may only be connected or connectable to a power source when the illumination insert <NUM> is inserted into the NMR spectrometer.

The energising of the electrical connectors <NUM> may be controlled by a control system. The control system may be the control system of the NMR spectrometer (or at least be communicably coupled thereto). For example, the light source <NUM> may be switched on and off in synchronisation with radiofrequency pulses of the NMR spectrometer.

Certain principles associated with embodiments of the present invention are described below with reference to <FIG>. In particular, uniform illumination of a sample <NUM> may be achieved by non-uniform positioning of scattering centres (imperfections <NUM>) inside the wall of the tube <NUM> or on the outer surface of the tube <NUM> around the sample <NUM>. Light travels along the wall of the light guide portion <NUM> of the tube <NUM> without significant scattering until it enters the diffuser portion <NUM>. To illustrate the principle, the sample area (i.e. the area adjacent the sample <NUM>) can be divided, for convenience, into a number of short segments <NUM>. <FIG> shows, as an example, ten segments <NUM>, but this number can be larger or smaller, however the same principles will apply. For the ten segments <NUM> shown in <FIG>, only <NUM>/10th of light that enters the sample area along the walls of the tube <NUM> is scattered in the 1st segment, with <NUM>/10th of light passing to further segments. The quantity and arrangement of scattering centres <NUM> present in the 1st segment should ensure that only this proportion of light is scattered there. Similarly, only a proportion (<NUM>/<NUM>th) of remaining light should be scattered in the 2nd segment, with <NUM>/8th of the remaining light being scattered in the <NUM>rd segment, <NUM>/<NUM>th of the remaining light being scattered in the <NUM>th segment, <NUM>/<NUM>th of the remaining light being scattered in the <NUM>th segment, <NUM>/5th of the remaining light being scattered in the 6th segment, <NUM>/<NUM>th of the remaining light being scattered in the <NUM>th segment, <NUM>/<NUM>rd of the remaining light being scattered in the <NUM>th segment, <NUM>/<NUM> of the remaining light being scattered in the <NUM>th segment, whereas the rest of light should be scattered by the last, 10th segment. The positioning and arrangement of these scattering centres <NUM>, which is needed to obtain such a result, depends on a combination of factors, such as refraction index of glass used for the tube <NUM>, the wall thickness of the tube <NUM>, the angle at which light enters the tube <NUM>, the optical properties of the sample <NUM> and the nature of the scattering centres <NUM> themselves. Therefore, those skilled in art can use the principles described above to optimise the positioning of the scattering centres <NUM> to match the chosen geometry of the tube <NUM>, optical focussing system, and the light source <NUM>. For example, for a given tube <NUM>, circular grooves or scratches can be created on the outside surface of the tube <NUM>, with non-uniform spacing between them. While manufacturing the tube <NUM>, the positioning of such grooves or scratches may be guided by the measurement of the actual amount of the scattered light along the longitudinal axis of the tube <NUM> in the sample area, for example using photodetectors outside the sample <NUM>, or by observing uniformity of fluorescence of the test sample <NUM> inside the tube <NUM>, or by any other means available to those skilled in art.

An illumination insert <NUM> in accordance with an alternative embodiment of the present invention is shown in <FIG>. The illumination insert <NUM> of <FIG> shares many features with the illumination insert <NUM> described above with reference to <FIG> and <FIG>. Like features are indicated using reference numerals transposed by <NUM>.

The tube <NUM> of the illumination insert <NUM> of <FIG> extends entirely through the housing <NUM> so that each of the open end 112a and the closed end 112b are not housed within the housing <NUM>.

The illumination insert <NUM> comprises two light sources <NUM> positioned around the tube <NUM>. Thus, light enters the walls of the tube <NUM> through the outer surface of the tube <NUM> (as opposed to through the main body cap <NUM> and the top open end <NUM> of the tube <NUM> of <FIG>). As such, a cap <NUM> covering the open end 112a does not need to be transparent. To facilitate the transmission of light into the walls of the tube <NUM> an intermediate light transmission component <NUM> is provided. In the non-limiting embodiment of <FIG>, the intermediate light transmission component <NUM> comprises a funnel-shaped component. The funnel-shaped component is made of a transparent material with a refraction index matched to that of the tube <NUM>. The funnel-shaped component is shaped so as to collect light from the light sources <NUM> and guide it to the walls of the tube <NUM> so that it may be transmitted in the walls of the tube <NUM>. Optionally, the outer surface of the intermediate light transmission component <NUM> may comprise a reflective layer to improve the light-containing properties of the intermediate transmission component <NUM> and assist the internal reflection. In certain other embodiments, an independent reflector may be provided.

An illumination insert <NUM> in accordance with an alternative embodiment of the present invention is shown in <FIG>. The illumination insert <NUM> of <FIG> shares many features with the illumination insert <NUM> described above with reference to <FIG> and <FIG> and the illumination insert <NUM> described above with reference to <FIG>. Like features are indicated using reference numerals transposed by <NUM> relative to the embodiments of <FIG> and <FIG>.

The main body <NUM> of the embodiment of <FIG> is formed as a tube having a first open end 212a and a second open end 212d. That is, the tube <NUM> is a hollow cylinder having a through bore 212c (as opposed to the blind bore of the tubes of the embodiments described above). As such, whilst the bore 212c provides a volume that may receive the sample <NUM>, the sample <NUM> cannot be solely contained by the tube <NUM>. Rather, the bore 212c of the tube <NUM> may receive a sample holder <NUM> that contains the sample <NUM> therein. A sample holder cap <NUM> may be provided to seal the sample <NUM> within the sample holder <NUM>. The sample holder cap <NUM> may be non-transparent in embodiments in which light transmission therethrough is not required (such as the embodiment shown in <FIG>).

The tube <NUM> comprises a light guide portion <NUM> and a diffuser portion <NUM>, consistent with the embodiments described above. The diffuser portion <NUM> is positioned on the tube <NUM> such that when the sample holder <NUM> is received in the bore 212c of the tube <NUM>, the sample is proximate to the diffuser portion <NUM>. Moreover, the tube <NUM> and sample holder <NUM> are positionable in an NMR probehead housing <NUM>, with the sample holder <NUM> being inserted in a channel 238a such that the diffuser portion <NUM> and the sample <NUM> are disposed proximate radiofrequency coils <NUM> of the NMR probehead housing <NUM>. In the embodiment illustrated in <FIG>, the coils <NUM> are disposed outside of the tube <NUM>. In certain other embodiments, the tube <NUM> may be arranged relative to the sample holder <NUM> such that the coils <NUM> may reside between the tube <NUM> and the sample holder <NUM> in use.

A pair of light sources <NUM> are provided below the tube <NUM> so that light is transmitted into the walls of the tube <NUM> through the second open end 212d. An intermediate light transmission component <NUM> may direct the light to the desired optical entry point of the tube <NUM>.

In certain embodiments, the tube <NUM> is provided with a reflective outer coating that serves to improve the light-containing properties of the tube <NUM> and assist internal reflection. Alternatively or additionally, the top surfaces of the walls at the first open end 212a may be provided with a reflective coating so that any light reaching this part of the tube <NUM> is reflected back towards the sample <NUM>.

The illumination insert <NUM> may remain within the NMR probehead housing <NUM> once it is assembled (e.g. embedded) therein.

As is shown in <FIG>, the illumination insert <NUM> does not comprise a housing. Indeed, in certain embodiments (such as the one shown in <FIG>), a housing may not be provided. In the embodiment of <FIG>, the various components on the illumination insert <NUM> are arranged relative to one another by virtue of them being embedded in the NMR probehead housing <NUM>.

An illumination insert <NUM> in accordance with an alternative embodiment of the present invention is shown in <FIG>. The illumination insert <NUM> of <FIG> shares many features with the illumination insert <NUM> described above with reference to <FIG> and <FIG>, and the illumination insert <NUM> described above with reference to <FIG>. Like features are indicated using reference numerals transposed by <NUM> relative to the embodiments of <FIG> and <FIG>.

The illumination insert <NUM> of <FIG> is largely identical to the illumination insert <NUM> of <FIG>, but for the fact that the illumination insert <NUM> does not include a light source. Rather, an auxiliary light guide <NUM> is provided to channel light from a remote light source to the tube <NUM>. The auxiliary light guide <NUM> may comprise an optical fibre or other means for transmitting light from a remote light source to the tube <NUM>. The remote light source may be one or more LEDs, laser diodes or lasers, for example. In embodiments having a remote light source, the light source may be positioned far away from the magnet of the NMR spectrometer so as to reduce any effect the light source may have on the magnetic field produced by the magnet, allowing use of light sources containing magnetic materials, such as specialised or stationary lasers.

The skilled reader will appreciate that any of the above described features are not necessarily exclusive to the particular embodiment described. Indeed, the above described features may be combined in any suitable combination in order to form alternative embodiments within the scope of the present invention.

Claim 1:
An illumination insert (<NUM>, <NUM>, <NUM>, <NUM>) for an NMR spectrometer, the illumination insert (<NUM>, <NUM>, <NUM>, <NUM>) comprising a main body (<NUM>, <NUM>, <NUM>, <NUM>) in the form of a tube shaped to receive a sample, the main body (<NUM>, <NUM>, <NUM>, <NUM>) comprising:
a light guide portion (<NUM>, <NUM>, <NUM>, <NUM>) for guiding light from a light source (<NUM>, <NUM>, <NUM>); and
a diffuser portion (<NUM>, <NUM>, <NUM>, <NUM>) for diffusing light received from the light guide portion (<NUM>, <NUM>, <NUM>, <NUM>) towards the sample received in the tube.