PORTABLE NMR PROBE AND NMR APPARATUS

Abstract

A portable NMR probe for the analysis of dispersions, the portable NMR probe comprising: a base part; a detachable probe assembly detachably mounted on the base part and electrically connected to the base part, the detachable probe assembly comprising: a housing; and a radio-frequency coil assembly received in the housing, the radio-frequency coil assembly comprising an RF coil support that has a channel for receiving an NMR sample, and an RF coil wound around the RF coil support for transmitting radio-frequency pulses to the NMR sample and for detecting magnetic resonance responses from the NMR sample; and a field magnet arranged to generate a magnetic field in the detachable probe assembly.

Claims

1. A portable NMR probe for the analysis of dispersions, the portable NMR probe comprising: a base part; a detachable probe assembly detachably mounted on the base part and electrically connected to the base part, the detachable probe assembly comprising: a housing; and a radio-frequency coil assembly received in the housing, the radio-frequency coil assembly comprising an RF coil support that has a channel for receiving an NMR sample, and an RF coil wound around the RF coil support for transmitting radio-frequency pulses to the NMR sample and for detecting magnetic resonance responses from the NMR sample; and a field magnet arranged to generate a magnetic field in the detachable probe assembly.

2. The portable NMR probe according to claim 1, wherein the detachable probe assembly is detachably mounted on the base part by one or more detachable connectors.

3. The portable NMR probe according to claim 1, wherein the detachable probe assembly is detachably mounted on the base part by one or more mated male and female connectors.

4. The portable NMR probe according to claim 1, wherein: the detachable probe assembly has two protruding connectors on a surface thereof; the base part has two corresponding recessed connectors on a surface thereof; and the two protruding connectors of the detachable probe assembly are received in the corresponding recessed connectors of the base part, so as to detachably mount the detachable probe assembly on the base part and to electrically connect the detachable probe assembly to the base part.

5. The portable NMR probe according to claim 1, wherein the detachable probe assembly is detachably mounted on the base part through two coaxial RF connectors.

6. The portable NMR probe according to claim 1, wherein the RF coil support is a cylindrical tube having a portion with a reduced external diameter, and wherein the RF coil is wound around the portion with the reduced external diameter.

7. The portable NMR probe according to claim 1, wherein the detachable probe assembly comprises a gradient coil for generating a magnetic field gradient across the sample.

8. The portable NMR probe according to claim 7, wherein the gradient coil is a quadruple gradient coil.

9. The portable NMR probe according to claim 7, wherein the gradient coil is a five-segment quadruple gradient coil.

10. The portable NMR probe according to claim 7, wherein the gradient coil is formed on a sheet and wrapped around the RF coil wound around the RF coil support.

11. The portable NMR probe according to claim 1, wherein the detachable probe assembly comprises three gradient coils for providing x-, y- and z-magnetic field gradients.

12. The portable NMR probe according to claim 1, wherein: the field magnet has a channel there-through, the field magnet being arranged to generate a magnetic field in the channel; and the detachable probe assembly is inserted into the channel of the field magnet.

13. The portable NMR probe according to claim 1, wherein the field magnet is a cylindrical magnet assembly.

14. The portable NMR probe according to claim 1, wherein the detachable probe assembly is not connected to the field magnet.

15. The portable NMR probe according to claim 1, wherein the portable NMR probe has temperature control means for controlling a temperature of the portable NMR probe.

16. A portable NMR probe for the analysis of dispersions, the portable NMR probe comprising: a field magnet arranged to generate a magnetic field in a measurement space; an RF coil located in the measurement space for transmitting radio-frequency pulses to a sample in the measurement space, and for detecting magnetic resonance responses from the sample; and temperature control means for controlling a temperature of the portable NMR probe.

17. The portable NMR probe according to claim 15, wherein the temperature control means comprises a Peltier device.

18. The portable NMR probe according to claim 15, wherein the temperature control means has a programmable temperature.

19. An NMR apparatus comprising the portable NMR probe according to claim 1 and a Software Defined Radio device connected to the NMR probe and arranged to generate radio-frequency signals for the RF coil and to detect magnetic resonance responses detected by the RF coil.

20. An NMR apparatus comprising: a portable NMR probe for the analysis of dispersions, the portable NMR probe comprising: a field magnet arranged to generate a magnetic field in a measurement space; and an RF coil located in the measurement space for transmitting radio-frequency pulses to a sample in the measurement space, and for detecting magnetic resonance responses from the sample; and a Software Defined Radio device connected to the NMR probe and arranged to generate radio-frequency signals for the RF coil and to detect magnetic resonance responses detected by the RF coil.

21. The NMR apparatus according to claim 19, wherein the apparatus comprises a power amplifier connected between the Software Defined Radio device and the portable NMR probe for delivering the radio-frequency signals to the portable NMR probe.

22. The NMR apparatus according to claim 10, wherein the apparatus comprises a preamplifier connected between the portable NMR probe and the Software Defined Radio device for amplifying magnetic resonance responses detected by the portable NMR probe.

23. The NMR apparatus according to claim 19, further comprising a computer connected to the Software Defined Radio device for controlling the Software Defined Radio device.

24. An NMR apparatus comprising the portable NMR probe according to claim 1 and separate electronics for powering and controlling the portable NMR probe.

25. The NMR apparatus according to claim 19, wherein the NMR apparatus comprises a plurality of the portable NMR probes of any one of claims 1 to 18, wherein the plurality of the portable NMR probes are controlled by a single controller.

26. The NMR apparatus according to claim 19, wherein: the portable NMR probe comprises a gradient coil for generating a magnetic field gradient across the sample; and the NMR apparatus is configured to control the gradient coil to apply a bipolar magnetic field gradient across the sample.

27. The NMR apparatus according to claim 19, wherein: the NMR apparatus is configured to monitor the frequency of radio-frequency pulses that need to be applied to a sample to generate a magnetic resonance response from the sample.

28. The NMR apparatus according to claim 27, wherein the monitoring is continuous.

29. The NMR apparatus according to claim 27, wherein the NMR apparatus is configured to automatically re-set the frequency of radio-frequency pulses applied to the sample based on the results of the monitoring.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0137] Embodiments of the present invention will now be discussed, by way of example only, with reference to the accompanying FIGS., in which:

[0138] FIG. 1 is a schematic view of a portable NMR probe according to embodiments of the present invention;

[0139] FIG. 2 is a photograph of a portable NMR probe according to embodiments of the present invention with the magnet removed;

[0140] FIG. 3 is a photograph of a portable NMR probe according to embodiments of the present invention;

[0141] FIG. 4 is a photograph of a portable NMR probe and control console according to embodiments of the present invention;

[0142] FIG. 5 is a schematic view of a radio-frequency coil assembly used in embodiments of the present invention;

[0143] FIG. 6 is a photograph of a detachable probe assembly used in embodiments of the present invention;

[0144] FIG. 7(a) is an illustration of a gradient coil used in embodiments of the present invention;

[0145] FIG. 7(b) is an illustration of coil arrangements in embodiments of the present invention;

[0146] FIG. 7(c) is a partial x-y projection of FIG. 7(a) for all 4 segments of the quadrupolar coil;

[0147] FIG. 8 shows experimental results of the T.sub.2 relaxation time for a sample of water obtained with an embodiment of the present invention in a single scan—showing high stability, reproducibility and superior signal to noise;

[0148] FIG. 9 is an illustration of the control system for the NMR probe in embodiments of the present invention;

[0149] FIGS. 10 and 11 show a prior art NMR probe and control system.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS AND FURTHER OPTIONAL FEATURES OF THE INVENTION

[0150] As shown in FIGS. 1 to 4, a compact and portable NMR probe 7 in an embodiment of the present invention comprises a base part 8, a detachable probe assembly 9 detachably mounted on the base part 8 and a permanent field magnet 10 for generating a magnetic field in the detachable probe assembly 9.

[0151] The base part 8 contains an impedance matching circuit (not shown) for matching an impedance of the portable NMR probe 7 to an impedance of a control device or control circuit such as a computer, or intermediate control electronics such as a console. The base part 8 may also or alternatively contain other electronics, for example a preamplifier.

[0152] The base part 8 is typically an aluminum box.

[0153] The base part 8 has input and output connectors 11 for electrically connecting a control device or control circuit or intermediate electronics such as a console to the base part 8.

[0154] The detachable probe assembly 9 is detachably mounted on the base part 8 through two connectors 12. Typically the connectors 12 are RF coaxial connectors, for example two 50 ohm RF connectors.

[0155] In more detail, the detachable probe assembly 9 has two protruding connectors, and the base part 8 has two corresponding recessed connectors. The detachable probe assembly 9 is detachably mounted on the base part 8 by pushing the detachable probe assembly 9 towards the base part 8 so that the protruding connectors of the detachable probe assembly 9 are received in the corresponding recessed connectors of the base part 8. The detachable probe assembly 9 can be detached from the base part 8 by pulling the detachable probe assembly 9 away from the base part 8 to decouple the connectors 12.

[0156] The connectors 12 also form an electrical connection between the base part 8 (circuitry in the base part 8) and the detachable probe assembly 9. This is discussed in more detail below.

[0157] The permanent field magnet 10 is provided to generate a magnetic field across the detachable probe assembly 9.

[0158] As shown in FIG. 3, in one embodiment the permanent field magnet 10 is a cylindrical magnet 10 having a slot 13 formed there-through perpendicular to the axis of the cylindrical magnet 10. The slot 13 and the detachable probe assembly 9 have corresponding rectangular shapes, so that the detachable probe assembly 9 can be slotted inside the slot 13 as shown in FIG. 3.

[0159] The cylindrical magnet 10 comprises two magnetic pole pieces held in a cylindrical yoke.

[0160] The slot 13 is positioned in the space between the two magnetic pole pieces.

[0161] The magnetic pole pieces typically have parallel main surfaces and are typically axially aligned.

[0162] The cylindrical magnet 10 is bolted to the base part 8 but is not connected to the detachable probe assembly 9.

[0163] Therefore, the detachable probe assembly 9 can be detached from the portable NMR probe 7 by pulling the detachable probe assembly 9 away from the base part 8 through the slot 13. Thus, the detachable probe assembly 9 can be easily removed, for example for repair or for replacement with a different detachable probe assembly 9, without having to remove the cylindrical magnet 10 or otherwise disassemble the portable NMR probe 7.

[0164] Furthermore, the cylindrical magnet 10 can easily be removed from the portable NMR probe 7 by undoing the bolts. Therefore, different magnets having different field strengths which therefore generate different resonant frequencies can easily be interchanged in the present invention. For example, magnets providing field strengths that give resonant frequencies in the range of 10-50 MHz may be used.

[0165] The configuration of the detachable probe assembly 9 will now be discussed in more detail with reference to FIGS. 5 and 6.

[0166] As shown in FIGS. 5 and 6, the detachable probe assembly 9 comprises a housing 14 which has the form of a box. In FIG. 6 the top of the housing 14 (which is visible in FIG. 2) has been removed so that the inside of the housing 14 can be seen.

[0167] The housing is typically made of aluminum.

[0168] the housing 14 has a rectangular shape, and is hollow.

[0169] Inside the housing 14 is an RF coil support 15. Part of the RF coil support 15 protrudes from the housing through an opening at the top of the housing (through a side of the housing, the side being the short side of the rectangle). The RF coil support insert 15 is typically made of machined glass. As shown in FIG. 5, the RF coil support may have a length of approximately 11 mm and a maximum outer diameter of approximately 7 mm.

[0170] The RF coil support 15 is cylindrical and has an axial channel along its entire length, so that the RF coil support 15 has the form of a cylindrical tube. In one example the diameter of the axial channel may be approximately 5.05 mm. The axial channel is for receiving an NMR sample in an appropriate NMR sample holder (for example a glass tube).

[0171] Since the RF coil support 15 protrudes outside of the housing 14, an NMR sample can be inserted into the channel of the RF coil support 15 from outside of the housing 14.

[0172] The RF coil support 15 has a recessed collar portion 16, over which the outer diameter of the RF coil support is uniformly reduced.

[0173] As shown in FIG. 6, an RF coil 17 is wound around the recessed collar portion 16 of the RF coil support 15, so as to surround part of the channel in the RF coil support 15. The RF coil 17 is therefore appropriately positioned to apply a radio-frequency signal to a sample in the channel of the RF coil support 15 and to detect a magnetic resonance response from the sample.

[0174] The RF coil 17 is electrically connected to electrical connectors of the detachable probe assembly 9, so that an electrical connection can be made to the RF coil 17 to supply appropriate radio-frequency signals and to receive the detected magnetic resonance responses.

[0175] As is apparent from FIG. 6, different sizes of RF coil support 15 can be housed in the same size and shape of housing 14 by varying the size of the opening of the housing 14, or by providing different sizes of sealing members such as O-rings or rubber seals or supports for supporting the RF coil support 15 in the opening of the housing 14. Thus, different detachable probe assemblies 9 having the same size and shape housing 14 but having RF coil supports 15 with different diameter channels can be provided, and the different detachable probe assemblies 9 can easily be switched as needed to match a sample container size by quickly detaching a detachable probe assembly 9 and attaching a different detachable probe assembly 9.

[0176] As shown in FIG. 4, in embodiments the portable NMR probe 7 may have an outer housing to cover the components of the portable NMR probe 7. In addition, separate electronics provided in a separate console 18 can be connected to the portable NMR probe by a cable of any length, for example 10 m. These separate electronics are discussed below.

[0177] The NMR probe assembly 7 when fully assembled may have a circular base and a domed top.

[0178] As shown in FIGS. 7(a), 7(b) and 7(c), in embodiments of the present invention a 5 segment quadruple gradient coil 19 may be provided. As shown in FIG. 7(a), the 5 segment quadruple gradient coil comprises 5 different coils printed onto a sheet, for example a Mylar sheet, to form a flexible printed circuit board. The pattern is repeated for each of the four poles of the quadruple. The sheet is then wrapped around the RF coil support 15 over the RF coil 17 to provide a gradient coil 19 around the channel in the RF coil support 15. Electrical connections are then formed between the gradient coil 19 and the base part 8 through a plug and socket, to provide appropriate gradient coil signals to the gradient coil 19 and to also be detachable.

[0179] Each of the 5 segments of the gradient coil 19 may have a different thickness. For example, the middle of the 5 segments may have the greatest thickness.

[0180] The arrangement of the gradient coil 19 around the RF coil support 15 is illustrated schematically in FIG. 7(b). However, only the vertical section of the segment of the gradient coil 19 having the greatest thickness is shown in FIG. 7(b) for clarity, and is labeled as “20”.

[0181] FIG. 7(c) schematically shows an x-y projection of the 5 segments of the gradient coil 19. The size of the dot corresponds to the thickness of the segment.

[0182] The configuration of the portable NMR probe 7 in the present invention can substantially improve the signal-to-noise ratio relative to previous devices. FIG. 8 is a graph showing results of measurements performed with the portable NMR probe 7 of the present invention to measure the T2 relaxation time for a sample of water. The graph shows that the single exponential line perfectly fits the raw data, which allows for a very precise determination of the relaxation time. In the illustrated example, the measured value for water was 2443 ms with an error of only 0.43 ms. The data shown is for a single scan.

[0183] FIG. 9 illustrates how the portable NMR probe is controlled in some embodiments of the present invention.

[0184] As shown in FIG. 9, embodiments of the present invention include a Software Defined Radio Device for controlling the portable NMR probe 7. Typically the Software Defined Radio Device will be provided in the console 18 shown in FIG. 4, which is connected to the portable NMR probe 7 by a cable.

[0185] Software Defined Radio is a radio communication system where components that have been traditionally implemented in hardware (e.g. mixers, filters, amplifiers, modulators/demodulators, detectors, etc.) are instead implemented by means of software. The Software Defined Radio implements Direct Digital Syntheses, in which analogue waveforms, such as a sine wave, are generated digitally by generating a time-varying signal in digital form and then performing a digital-t-analogue conversion.

[0186] Such an arrangement is significantly simpler, more efficient, and has a lower operating power demand than analogue circuit configurations.

[0187] The Software Defined Radio may be implemented using a processor and memory in the console 18. For example, programming code stored in the memory may be executed by the processor to produce desired radio-frequency excitations required for the RF coil 17 and to detect the detected magnetic resonance response picked up by the RF coil 17.

[0188] A power amplifier PA is connected between the Software Defined Radio device and the portable NMR probe for delivering the radio-frequency signals to the portable NMR probe.

[0189] A preamplifier is connected between the portable NMR probe and the Software Defined Radio device for amplifying magnetic resonance responses detected by the portable NMR probe.

[0190] Alternatively, one or both of the power amplifier or preamplifier may be located in the base part 8 of the portable NMR probe 7.

[0191] A computer is connected to the Software Defined Radio device for controlling the Software Defined Radio device.

[0192] The computer is connected to the Software Defined Radio device via a fast Ethernet connection, making remote control possible and providing fast data connections. Because of the real-time fast Ethernet connection, data length is virtually unlimited.

[0193] Although not illustrated, embodiments of the present invention may comprise temperature control means for controlling a temperature of the portable NMR probe. For example, the temperature control means may be a Peltier device.

[0194] The temperature control means may control a temperature of the field magnet 10, or of the air in the portable NMR probe 7.

[0195] The portable NMR probe may have more than one, for example two, independent, frequency channels that can be used for measurements of more than one, for example two, different types of nuclei, for example Li and H, at the same time and also for decoupling.

[0196] In embodiments of the present invention the pulse length resolution may be 8 ns. This proves both a more accurate setting of instrument parameters as well as much improved accuracy in measurement of relaxation times, for example when compared the device disclosed in U.S. Pat. No. 7,417,426.

[0197] The RF coil support 15 may have a diameter between 2 to 12 mm, for example. Of course, in other embodiments the RF coil support may have a diameter different to this. Different detachable probe assemblies 9 may be provided having RF coil supports 15 with different diameter channels, so that different size samples can easily be measured using the same device.

[0198] The transmitter may be optimized to give a pulse length of less than 3 μs, for example.

[0199] The apparatus of the present invention may incorporate two 14 bit, 8 ns analogue-to-digital converters to give superior time resolution; RF pulses up to 1 ms at 8 ns resolution; any phase shift from 0-360 degrees; and dual frequency generation.

[0200] In one specific example the portable NMR probe 7 of the present invention may have dimensions of 220 mm diameter and 200 mm height, and a weight of 1.5 kg.

[0201] In another specific example the probe (FIG. 4) may be miniaturized to 60×50×30 mm and weigh 600 g, for example.

[0202] In one specific example, the console of the present invention may have dimensions of 125 mm height, 360 mm length and 250 mm width, and a weight of 6.3 kg.

[0203] In embodiments of the present invention, the field magnet comprises magnetic pole pieces held in place by a cylindrical yoke. The design in U.S. Pat. No. 7,417,426 provides only limited mechanical alignment of the magnet pole pieces, providing some coarse shimming. This directly impacts field homogeneity—a critical parameter as it directly influences sensitivity and signal-to-noise ratio. Further, replacement of the magnet pole pieces is not possible.

[0204] The simpler design in embodiments of the present invention (see FIGS. 7(a)-7(c)) is much easier to set up, requires no alignment of the magnetic pole pieces which have an optimized shim design, gives superior field homogeneity over the sample volume and signal-to noise ratio is substantially improved. In addition, the more accessible space makes it possible to generate multiple field gradients. Further, magnets of different designs can be easily exchanged to provide different field strengths (10-50 MHz) and sample volumes.

[0205] The present invention may alternatively be described as set out below.

[0206] The present invention seeks substantial improvements over the disclosure of U.S. Pat. No. 7,417,426.

[0207] 1. The NMR device of U.S. Pat. No. 7,417,426 consists of a single small footprint enclosure integrated within which are both the magnet assembly and the associated electronics. This necessitates temperature control of the enclosure because of the heat generated by the power supply, etc. However, U.S. Pat. No. 7,417,426 makes no mention of this. The typical temperature rise depends upon the ambient temperature of the environment where the device resides but can easily be more than 5° C. above ambient. Characterization of dispersion properties need to be made at constant temperature. Modification of the enclosure to allow for temperature control is not a trivial exercise. This limits the utility to controlled environment laboratories and precludes use in plants. Importantly, any change in temperature results in a shift in the resonant frequency which must be constantly manually re-set.

[0208] Embodiments of the present invention separate the magnet assembly from the electronics.

[0209] The small probe head/pod assembly (see FIG. 1) has direct, programmable temperature control by means of a small Peltier device. The resonant frequency is continuously monitored and, if necessary, automatically re-set. High temperatures up to 80° C. can be achieved. This is simply not feasible with the design of the device of U.S. Pat. No. 7,417,426.

[0210] The separate pod assembly also allows for remote operation, for example in hazardous environments (e.g. radioactive and infectious disease applications).

[0211] It also makes replacement of a broken NMR tube straightforward. In the U.S. patent device, this necessitates removal of the yoke/magnet assembly from inside the enclosure.

[0212] Conversion of the probe head to a flow-through version for use in manufacturing process operation is simple. This is a very important practical advantage. For example, it makes sampling of heterogeneous materials much more reproducible. No mention of such a flow-option is made in U.S. Pat. No. 7,417,426 but it would be very difficult to modify that device.

[0213] Exchanging probe heads or using multiple heads is now enabled. This significantly extends the utility of the device for particle characterization. It also allows for different probe nuclei to be used.

[0214] Multiple heads can be driven by one controller.

[0215] 2. The probe assembly in embodiments of the present invention (see FIG. 2) provides much more flexibility in terms of the sample volume that can be measured, as well as measurement sensitivity. The NMR device of U.S. Pat. No. 7,417,426 is limited to a single fixed diameter NMR tube (4 mm ID) that is custom made.

[0216] A variety of different diameter standard supply NMR tubes can be used in embodiments of the present invention. For example, a larger 10 mm diameter tube allows for measurement of viscous liquids, gels and semi-solid formulations.

[0217] Embodiments of the present invention employ a 5 segment quadrapolar coil for larger and more uniform field gradients. The US Pat. No. 7,417,426 device uses only a single segment coil.

[0218] Embodiments of the present invention utilize three gradient coils for 3D imaging, flow measurements and anisotropic diffusion. This is not possible with the U.S. Pat. No. 7,417,426 design and functionality is limited by the electronic design.

[0219] Embodiments of the present invention also use bipolar gradients and can employ unlimited pulse sequences and digital control of peripherals—to provide more precise measurements of diffusion (and all other experiments)—in conjunction with phase cycling and coherent noise reduction. None of this is possible with the device in U.S. Pat. No. 7,417,426.

[0220] 3. The Yoke holds the magnets in place. The design in U.S. Pat. No. 7,417,426 provides only limited mechanical alignment of the magnet pole pieces, no shimming is possible. This directly impacts field homogeneity—a critical parameter as it directly influences sensitivity and signal-to-noise ratio. Further, replacement of the magnet pole pieces is not possible.

[0221] The simpler design in embodiments of the present invention (see FIGS. 7(a)-7(c)) is much easier to set up. It provides maximum mechanical alignment of the magnetic pole pieces and the optimized shim design gives superior field homogeneity over a larger volume.

[0222] In addition, the extra space makes it possible to generate multiple field gradients

[0223] Signal-to noise ratio is substantially improved.

[0224] Further, magnets of different designs can be easily exchanged to provide different field strengths (10-50 MHz).

[0225] 4. The electronic layout in the U.S. Pat. No. 7,417,426 device is based on that employed in conventional, traditional NMR devices.

[0226] In contrast (see FIG. 9), embodiments of the present invention have a much simpler and straightforward electronic layout based on the new technique of Direct Digital Synthesis (DDS) which incorporates a software defined radio (SDR) device. This design is much more efficient with a lower operating power demand.

[0227] Here all RF generation and detection is done digitally; there are no analogue steps in detecting the NMR signal.

[0228] All filtering and phase detection is done digitally.

[0229] Embodiments of the present invention incorporate two 14 bit, 8 ns analogue-digital-converters (ADCs) giving superior time resolution; RF pulses up to 1 ms at 8 ns resolution; any phase shift from 0-360 degrees; dual frequency generation.

[0230] The SDR device provides better control of RF generation (using composite pulses).

[0231] A very large pulse sequence library is possible.

[0232] Some additional advantage of embodiments of the present invention are set out below:

[0233] The design of embodiments of the present invention provides many measurement advantages that cannot be performed using the U.S. Pat. No. 7,417,426 device.

[0234] 1. There is a significant enhancement in the speed of data processing. This reduces the measurement time permitting the study of kinetic processes, settling, sedimentation, etc.

[0235] 2. The vast improvement in measurement sensitivity allows study of highly paramagnetic materials and a broader range of dispersion concentrations and composition.

[0236] 3. Robust self-diffusion measurement from water to viscous liquids 10.sup.−9 to 10.sup.−12 m.sup.2s.sup.−1.

[0237] 4. Droplet sizing analysis of O/W and W/O emulsions; nano- and micro-emulsions.

[0238] 5. Polymer characterization in solution and also in melts.

[0239] 6. 1D, 2D and 3D imaging.

[0240] 7. Measurement of solid materials.

[0241] 8. Direct measurement of the solid/liquid ratio. This is an important and useful parameter and there is no other direct measurement available.