GB2583071A

GB2583071A - Attenuated total reflection spectrometer

Info

Publication number: GB2583071A
Application number: GB1903989.0A
Authority: GB
Inventors: Singh Maneesh
Original assignee: Biocel Instruments Ltd
Current assignee: Biocel Instruments Ltd
Priority date: 2019-03-22
Filing date: 2019-03-22
Publication date: 2020-10-21
Anticipated expiration: 2039-03-22
Also published as: GB201903989D0; GB2583071B

Abstract

Attenuated Total Reflectance (ATR) spectrometer 100 comprises a sampling region 62 configured to receive infra-red light from an IR source, which may be provided by a smart phone or smart device. Region 62 comprises an ATR crystal 73, arranged to receive light from the source, fixed focussing mirror 75, analysing region 63 having a fixed diffraction element 82 and a detector 51. The fixed mirror and diffraction element may be held in a fixed position with relation to each other e.g. by moulded supports. The spectrometer may be portable or hand-held, or may comprise an optical probe (112, figure 6) comprising a tip (113, figure 6), wherein the attenuated total reflection crystal is on the tip of the optical probe. Also disclosed is a spectrometer coupled to a smart device (60, figure 5), from which the spectrometer may receive power.

Description

Intellectual Property Office Application No. GII1903989.0 RTM Date:23 September 2019 The following terms are registered trade marks and should be read as such wherever they occur in this document: Bluetooth HotKnot Intellectual Property Office is an operating name of the Patent Office www.gov.uk /ipo Attenuated total reflection spectrometer

Field

The present disclosure relates to an attenuated total reflection spectrometer and more particularly to a portable and/or hand-held attenuated total reflection spectrometer that is

suitable for use in the field.

Background

The use of spectroscopy for qualitative and quantitative analysis of chemical and biochemical materials is known. More particularly, spectroscopy may be used to provide a chemical signature of a material being analysed according to an interaction between electromagnetic radiation at specific frequencies and the molecules present in the material. Electromagnetic radiation comprises a range of frequencies, from long radio waves (from around 3 Hz) to gamma rays (>30 EHz). One form of spectroscopy is infrared (IR) spectroscopy based on interactions between matter and IR radiation. IR region of the electromagnetic spectrum comprises frequencies between 430 THz and 300 GHz (1.7 eV to 1.24 meV), which in wavelength is 700 nm to 1 mm.

In IR spectroscopy, the absorption of IR radiation by molecules causes vibrational and rotational transitions, but not electronic transitions. At temperatures above absolute zero (T > OK), all molecular bonds, including covalent bonds, vibrate. There are two types of molecular vibration movements affected by IR radiation: stretching (axial deformation) and bending (angular deformation). Stretching vibrations can be either symmetric or asymmetric; while bending vibrations can be in-plane (symmetric or asymmetric) or out-ofplane (symmetric or asymmetric).

A bond vibration can be approximately explained by a mechanical model composed by two masses connected by a spring (harmonic oscillator model). Thus, a diatomic molecule can be compared to an ideal harmonic oscillator, defined by Hooke's law. In an equilibrium position, the potential energy is zero; therefore, when the chemical bond is compressed or stretched, the potential energy will vary according to the work needed to move the atoms, resulting in a parabolic potential energy curve of a simple harmonic oscillator. However, real molecules do not follow an ideal model, therefore a more accurate potential energy curve for diatomic molecules resembles a harmonic oscillator, where vibrational levels are within the same electronic level.

A vibrating covalent bond creates an electromagnetic field proportional to the variation of the dipole moment of the molecule. Incident IR radiation having the same oscillating frequency is absorbed, in a form of constructive interference (or resonance). Accordingly, a molecule which has a dipole moment which is non-zero (PR # 0) can be analysed using IR radiation. Molecules with no resultant dipole moment, including homonuclear species such as 02, N2, 012 and 12, do not absorb IR radiation in this way.

As a result of the above, when a molecule is exposed to IR radiation with a frequency equal to that of a fundamental vibration frequency of one of its bonds, the bond absorbs the radiation. By investigating a sample with IR radiation, the resultant absorption spectra can be used to identify or otherwise analyse the sample being tested.

Known infrared spectrometers include laboratory-based, benchtop systems which are large, complex, and bulky. Such systems are highly sensitive and require careful calibration. Accordingly, in view of their size and sensitivity, such systems may not be readily moved, so are not suitable for use in the field. It would therefore be desirable to provide an infrared spectrometer which offers an alternative or improvement to one or more the above considerations.

Summary

In one embodiment a spectrometer for attenuated total reflection spectroscopy is provided. The spectrometer comprises a sampling region configured to receive light from an infrared light source. The sampling region comprises an attenuated total reflection crystal arranged to receive light from the light source; and a fixed focusing mirror for focusing light from the attenuated total reflection crystal. The spectrometer also comprises an analysis region configured to receive light from the sampling region. The analysis region comprises a fixed diffraction element configured to separate the received light by wavenumber. The spectrometer also comprises a detector configured to receive light from the analysis region.

As described above, the focusing mirror and the diffraction element are fixed. This means that the focusing mirror and the diffraction mirror are fixed or otherwise held in a respective single position such that they cannot, and do not need to, be adjusted. The focusing mirror and the diffraction element can be fixed using any known means; for example they could be glued in place, stapled in place, screwed in place, welded into place or held in place using any other means. They could also be held in place using nails, tape or any other known attachment means. In one example they could also be held in place by being mounted into fixed supports, or seats or fittings, provided in the sampling region and analysis region. Fixing the focusing mirror and diffraction element in place means that their position is not adjustable after the apparatus has been assembled. In particular, the focusing mirror and the diffraction element do not move with respect to each other and the detector. With these components fixed in place -in fixed relation to one another -use of the spectrometer in the field, including transporting the device, may be readily undertaken without concern that subsequent recalibration (requiring a skilled practitioner and being a time-consuming procedure) will be needed. Embodiments of the spectrometer may therefore be more rugged or robust than known devices. Furthermore, by providing a fixed configuration of the above components in the spectrometer, the need for bulky, weighty, potentially fragile mechanical or electromechanical adjustment or calibration mechanisms may be removed. The spectrometer may therefore be provided in a relatively small assembly, and assume a smaller footprint than known spectrometers; in particular, the spectrometer may be portable and/or handheld.

In some examples, the attenuated total reflection (ATR) crystal can also be fixed in place. In these examples the focusing mirror, the diffraction element and the ATR crystal do not move with respect to each other or the detector. In one example, the diffraction element is a transmission grating although other suitable diffraction elements can be used.

Attenuated total reflection (ATR) IR spectroscopy uses mid-infrared radiation for reflection based spectroscopy. Mid-infrared radiation is advantageous since the wavelength of mid-infrared radiation (3 -50pm) means the frequency of the radiation corresponds to the fundamental vibration frequency of vibrational modes of bonds that give rise to a less convoluted spectral output than with near infrared radiation techniques. At the same time, the frequency range of mid-infrared radiation covers the fundamental vibrational frequency of modes for most covalent bonds. As such, it may provide a more useful range of results than far infrared radiation techniques while allowing easier analysis than near infrared radiation techniques.

The use of reflection-based spectroscopy, and in particular, ATR allows a wider range of samples to be analysed than transmission mode spectroscopy which is typically only suitable for analysing liquids in relatively large volumes (e.g. > 2 mL) or thin materials. Therefore, using mid-infrared ATR spectroscopy allows a wide range of samples to be conveniently analysed.

Known ATR IR spectrometers are bulky and require re-calibrations and adjustments that make them unsuitable for use in in-field environments. Embodiments of the device described herein may address, improve on, or overcome these difficulties with ATR mid-IR spectroscopy and provide a portable spectrometer that can be used in an in-field environment. This may be partially achieved by fixing the focusing mirror and the fixed diffraction element. By fixing the focusing mirror and the diffraction element the spectrometer may be resistant to movement and not require regular mechanical re-calibrations. This may allow the size of the spectrometer to be reduced and may allow the spectrometer to be used in in-field environments where the spectrometer may be subject to relatively rough treatment that would otherwise require mechanical realignment of the components. By dispensing of moving parts in the spectrometer, faster spectrum acquisition may be achieved. The use of spectroscopy for in the field measurements is advantageous since it allows the user to quickly assess the quality of the materials or quantification of chemical parameters.

The spectrometer can further comprise a housing wherein the housing comprises a moulded mirror support configured to hold the fixed focusing mirror in a fixed position within the housing and/or a moulded diffraction element support configured to hold the fixed diffraction element in a fixed position within the housing.

The housing can take any suitable form and in one example can be a casing; for example a plastic casing, a rigid plastic casing, or a black plastic casing. The housing may also be made of other suitable materials such as metal or wood, or other non-transparent and/or non-reflective rigid materials.

The moulded mirror support and/or the moulded diffraction element support can comprise a seat, a mount, a fixture, a fitting or any other form of moulded support that holds the mirror and/or diffraction element, respectively, in place. The or each support may be moulded into, or to, a base of the housing thus holding the mirror/diffraction element from the base of the mirror/diffraction element. The or each support may also or alternatively be moulded into, or to, a ceiling of the housing thus holding the mirror/diffraction element from the top of the mirror/diffraction element.

Having the focusing mirror and/or the diffraction element held in place using a moulded support allows the position of the focusing mirror and/or diffraction element to be pre-set or preconfigured before the mirror and/or diffraction element is placed in the housing. This ensures the focusing mirror and/or diffraction element are held in the correct position when they are placed in the housing. It also ensures the focusing mirror and/or diffraction element are fixed or held in place even when the spectrometer is subject to movement.

In some embodiments, all components in the sampling region and all components in the analysis region of the spectrometer can be fixed with respect to each other.

The sampling region and the analysis region may comprise further components such as a collimating mirror in the sampling region and a collimating mirror and a focusing mirror in the analysis region. When present, these components may also be fixed in place in any of the manners described above; for example they may be glued in place, stapled in place, screwed in place, welded into place or held in place using any other means. They may also be held in place using nails, tape or any other known attachment means. In one example they may be held in place by being mounted into fixed supports, or seats, or fittings provided in the sampling region and/or analysis region.

In some embodiments, the attenuated total reflection crystal may also be fixed in place. In such cases, the attenuated total reflection crystal may be fixed in place such that the crystal is only partially contained within any housing of the sampling region. This allows a sample to be applied to the attenuated total reflection crystal without needing to access the housing. However, the attenuated total reflection crystal may also be fixed in place entirely within the sampling region. The attenuated total reflection crystal may be fixed in place using any of the methods described above.

The attenuated total reflection crystal may also be attached to, or otherwise part of, a probe connected to the sampling region. The probe may be moveable relative to the sampling region. In such a scenario, while the attenuated total reflection crystal may be fixed relative to the probe, it may be moveable with respect to the mirror(s) and other components within the sampling region.

Fixing all components in the sampling region and analysis region in place may increase the robustness of the device against movement and may prevent the need for regular mechanical calibration. This in turn may allow the size of the spectrometer to be reduced and may increase the robustness of the spectrometer, allowing it to be used in the

field.

The attenuated total reflection crystal of the spectrometer may comprise an entrance slit. The sampling region may further comprise a chamber, the chamber comprising a chamber entrance slit and at least the entrance slit of the attenuated total reflection crystal.

The chamber may further comprise one or more walls comprising a reflective material to reflect light received from the chamber entrance slit into the entrance slit of the attenuated total reflection crystal.

The chamber may take the form of a housing. Alternatively, the sampling region may comprise a housing and the chamber may be a portion of the housing that is separated from the rest of the sampling region by a wall. The chamber may also be open to the rest of the sampling region. The fixed focusing mirror may be outside the chamber. The attenuated total reflection crystal may comprise an exit slit which is also outside of the chamber. This ensures that any light entering the chamber and being reflected in the chamber does not interact with the fixed focusing mirror while enabling the fixed focusing mirror to receive light from the attenuated total reflection crystal.

The reflective material may be a metallic coating on the walls of the chamber. The metallic coating may be an aluminium coating. The aluminium coating may be polished to ensure the surface is reflective.

The use of walls comprising a reflective material may aid with the convergence of light into the attenuated total reflection crystal. An aluminium coating may also enhance the infrared signal. The use of walls with a coating allows light to be converged into the attenuated total reflection crystal without the use of a collimating mirror. This reduces the number of components in the spectrometer and thus may allow further reductions in size of the spectrometer. Removal of a collimating mirror also reduces the number of components in the spectrometer so simplifies the spectrometer and removes a possible cause of errors.

The spectrometer may further comprise an infrared light source. In some embodiments, the light source is provided by a smart phone or smart device. Using a smartphone or smart device as a light source removes the need for the spectrometer to include an integrated light source. This simplifies the form of the spectrometer and allows the overall size of the spectrometer to be reduced, enhancing portability. Removing an internal light source also enhances the robustness of the spectrometer since it removes the need for a black body light source such as a SiC light source that may need replacing or otherwise adjusting.

When a smart phone or smart device is used as a light source, the smart phone or smart device may be placed in a housing where the internal walls of the housing may be coated in a reflective material. An exit to the housing allows light to exit the housing and enter the sampling region. The light may exit the housing through a filter such as a BaF2 window to ensure only the relevant wavelengths/frequencies of light enter the sampling region.

The spectrometer may be configured to receive power from a smart phone or smart device. A smartphone or smart device may therefore be used as a power source for the spectrometer.

The smartphone or smart device may be used to power the detector of the spectrometer. If the spectrometer is provided with an internal light source, the smart phone or smart device may also be used to power the internal light source of the spectrometer.

The smartphone or smart device may be used to power both the internal light source and the detector.

If the spectrometer has a microcontroller connected to the detector, the smartphone or smart device may be used to power the microcontroller. The smartphone or smart device may be used to power both the detector and the microcontroller; both an internal light source and the microcontroller or all three.

Using a smartphone or smart device as a source of power for the spectrometer means the spectrometer does not require its own power source or, at least, reduces the size of the internal power source required by the spectrometer. This allows the size of the spectrometer to be reduced and enhances portability of the spectrometer.

The spectrometer may further comprise a data processing system for processing data from the detector wherein the data processing system is provided by a smartphone or smart device.

The data processing system may be used to process data received from the detector.

The detector may be controlled by a microcontroller that converts the voltage signal from each pixel into a reading for pixel intensity. The smart phone or smart device may then receive the data from the microcontroller. Alternatively, the smart phone or smart device data processing system may receive data directly from the detector.

Using a smart phone or smart device as a data processing system may reduce the need for data processing at the spectrometer. This may allow a simplified spectrometer to be produced, reducing the size and weight of the spectrometer hence enhancing portability.

The spectrometer may further comprise a data processing system wherein the data processing system is configured to adjust a sample output signal based upon a comparison between a reference output signal obtained from analysing a reference sample and a stored reference output signal for the reference sample.

The reference sample may be a gold material. For example, the reference material may be a gold-coated reference slide. The reference material may also be a gold material applied in any other way. Other reference materials may also be used; for example other stable materials such as synthetic polymers and reflective standards may be used as a reference material.

The data processing system may be a smart phone or smart device that can be connected to the spectrometer. Alternatively, the data processing system may be built into and form part of the spectrometer. Any suitable data processing system can be used.

The data processing system may receive a reading from a reference material that has a known absorbance spectrum. As mentioned above, the reference material may be gold or another stable material. The data processing system may then compare this reading to a stored reference for the reference material. If the reading differs from the reference then subsequent output readings may be adjusted based upon this difference.

If the difference between the reference output signal (the reading) and the stored reference output signal (the stored reference) is large, then in some circumstance the processing device may produce an output indicating that calibration is unlikely to be successful and that the spectrometer should not be used. This may occur when the difference between the reference output signal and the stored reference output signal is greater than 30% of the stored reference output signal.

Known spectrometers use mechanical calibration where optical components in the spectrometer are adjusted to maintain the accuracy of a signal. However, this requires adjustment of the optical components such as mirrors. This means the sampling region and analysis region need to be accessible and the components cannot be fixed. Using computer calibration, or calibration by software, such as the method described above means that the spectrometer can still be calibrated while allowing the use of fixed components. This allows the size of the spectrometer to be reduced and also increases the robustness of the spectrometer.

The spectrometer may further comprise an optical probe comprising a tip and wherein the attenuated total reflection crystal is on the tip of the optical probe.

The optical probe may be a fibre optics probe. Light may enter the optical probe through a first fibre optic cable and exit the probe through a second fibre optic cable. The attenuated total reflection crystal may be aligned with the first and second fibre optic cables such that light leaving the first fibre optic cable enters the attenuated total reflection crystal and light leaving the attenuated total reflection crystal enters the second fibre optic cable. Alternatively, the light may pass along a single fibre optic cable to and from the ATR crystal.

The optical probe may be connected to the sampling region. The sampling region may contain a connector configured to receive light entering the sampling region. This connector could be any type of optical window screwed, glued, taped, or attached to the device by any other means. The connector holds and aligns the optical probe with the sampling region. Light entering the connector may travel down the optical probe until it reaches the attenuated total reflection crystal where it may enter the crystal. Light leaving the attenuated total reflection crystal may then travel back down the probe and back into the sampling region.

When an optical probe is used, the sampling region may comprise a housing. The walls of the housing may be coated with a reflective material which may be a metal material and which may be polished aluminium.

The use of the probe allows the spectrometer to be used to analyse less portable samples and also allows use of the spectrometer in procedures such as surgery including laparoscopic or keyhole surgery. The use of a probe may also allow the analysis of samples in otherwise hard to reach areas or samples that cannot be moved for environmental and/or other reasons.

In another embodiment a spectrometer for attenuated total reflection spectroscopy is defined. The spectrometer is configured to couple to a smart phone or a smart device. The spectrometer comprises a sampling region configured to receive light from an infrared light source wherein the sampling region comprises an attenuated total reflection crystal arranged to receive light from the light source, and a focusing mirror for focusing light from the attenuated total reflection crystal. The spectrometer also comprises an analysis region configured to receive light from the sampling region, the analysis region comprise a diffraction element configured to separate the received light by wavenumber. The spectrometer also comprises a detector configured to receive light from the analysis region.

The spectrometer may couple to the smart phone or smart device in any suitable way; for example the spectrometer may couple to a smartphone or smart device by a USB connection. Alternatively, the spectrometer may connect to the smart phone or smart device using Bluetooth, electromagnetic induction, near-field communication (NFC), HotKnot, wireless internet or any other suitable wired or wireless connection. In some cases, the coupling may also or alternatively be a mechanical coupling where the smart phone or smart device is aligned with the spectrometer. The spectrometer may be configured to couple to the smart phone by having any suitable adaptor. For example the spectrometer may comprise a USB port to allow connection of a smart phone via USB. Alternatively or in addition, the smart phone or smart device may have an adaptor to allow any suitable form of connection such as a Bluetooth, electromagnetic induction, NFC, HotKnot, wireless internet or any other suitable wired or wireless connection.

The smart phone or smart device may be any suitable smart phone or smart device that has sufficient processing power and/or battery power to interact with the device. Having the spectrometer configured to connect to a smart phone or smart device means that functionality of the spectrometer can be outsourced to the smart phone or smart device, reducing the complexity and size of the spectrometer.

The spectrometer may be configured to couple to the smart phone or smart device to enable the smart phone or smart device to provide electrical power to the spectrometer. The coupling may be enabled by having the spectrometer comprise a connector to allow attachment/coupling of the smart phone or smart device. For example, the -10 -spectrometer may have a USB connector to allow the spectrometer to receive power. Alternatively, the spectrometer may receive power from the smart phone or smart device wirelessly.

The spectrometer may use the electrical power from the smart phone or smart device to power the detector of the spectrometer. Alternatively or in addition, when the spectrometer has a built in light source, the power from the smart phone or smart device may be used to power this light source. Similarly, when the spectrometer has a built in microcontroller, the power from the smart phone or smart device may be used to power the microcontroller.

Having the spectrometer receive power from a smart phone or smart device reduces or removes the need for the spectrometer to have its own power source thus allowing the size of the spectrometer to be reduced thus making the spectrometer more portable.

The spectrometer can be configured to couple to the smart phone or smart device to enable the smart phone or smart device to provide an infrared light source for the spectrometer.

The smart phone or smart device may provide an infrared light source using a light source built into the phone or device; for example the infrared illuminator built into some phones or devices for depth sensing or in some cases, where appropriate, the light provided in the smart phone or device for the camera flash and/or illuminating the environment.

The spectrometer may comprise a guide or some form of seat or support to align the smart phone or smart device correctly so that that the smart phone or smart device light source can act as a light source for the spectrometer. Therefore, the coupling does not necessarily have to allow transmission of data/power between the smart phone or smart device and spectrometer.

Using a smart phone or smart device as a light source means the spectrometer does not need to comprise a built in light source. This reduces the complexity of the spectrometer and also allows the size of the spectrometer to be reduced.

The spectrometer may be configured to couple to the smart phone or smart device to enable the smart phone or smart device to provide a processing device for signals received from the detector.

When a smart phone or smart device is used as a processing device it may be used to perform all analysis of the signals received by the detector. Alternatively, the detector may be controlled by a microcontroller which performs some initial signal processing and only then will the smart phone or smart device be used for processing.

The spectrometer may be configured to couple to the smart phone or smart device in any suitable fashion to allow data to be transferred to the smart phone or smart device. For example the spectrometer may be configured to couple to the smart phone via a USB connection and to this end the spectrometer may comprise a USB port. Alternatively or in addition, the spectrometer may be configured to couple to the smart phone or smart device via Bluetooth, Hotknot, NFC, wireless internet or another wireless connection. To this end, the spectrometer may comprise an adaptor, or port, or connector that allows such a connection to be formed. In some arrangements, spectral data may be sent to the smartphone or smart device, and also to a central, remote server or database that may periodically be used to update the smartphone or smart device database, in particular to ensure proper functioning of the processing algorithms.

Having the spectrometer configured to couple to a smart phone or smart device to allow use of the smartphone or smart device as a processing device means that the spectrometer does not need to be provided with a built in processing device. This simplifies the spectrometer and allows reductions in the size of the spectrometer.

The spectrometer can be calibrated using a computer implemented method wherein the method comprises analysing a reference sample to obtain a reference sample output signal; comparing the reference sample output signal with a stored reference sample output signal for the reference sample; and adjusting sample output signals based on the comparison.

To analyse the reference sample, the reference sample may first be applied to the attenuated total reflection crystal. A reading may then be taken for the reference sample using infrared light to obtain the reference sample output. This reading may then be compared to stored reference sample output signal. The stored reference sample output signal may be a known absorbance spectrum for the reference sample that is stored by the computer performing the method or at an external memory. As a result of the comparison subsequent output sample signals may be adjusted. This adjustment may be given by the equation: -12 -signal of re f encemeasured signal p"l= signalmeasured signal of re ferencestored The above method may be performed by a computing device that is part of the spectrometer or a computing device external to the spectrometer e.g. a smart phone.

Using the above method of calibration reduces or removes the need for mechanical calibration through, for example, the adjustment of mirrors and/or the diffraction element. This ensures accurate readings can be obtained even when fixed components are used and also provides an improved and simplified calibration process.

Brief description of the drawings

Exemplary apparatus, systems and methods may be put into practice in a number of ways and some non-limiting examples will now be described with reference to the accompanying figures in which: Figure 1 shows a spectrometer with fixed components according to an embodiment; Figure 2 shows a spectrometer in accordance with another embodiment, in accordance with, or supplementary to, or separate from other arrangements described herein; Figure 3 shows a spectrometer in accordance with another embodiment, in accordance with, or supplementary to, or separate from other arrangements described herein; Figure 4 shows a spectrometer in accordance with another embodiment, in accordance with, or supplementary to, or separate from other arrangements described herein; Figure 5 shows a spectrometer with a connector for connecting the spectrometer to a smart phone or smart device, in accordance with, or supplementary to, or separate from other arrangements described herein; Figure 6 shows a spectrometer with a probe to allow analysis of samples at a distance, in accordance with, or supplementary to, or separate from other arrangements described herein; Figure 7 shows the tip of a probe such as the one connected to the spectrometer in Figure 6 above; Figure 8 shows a light source region that can be used in conjunction with any of the spectrometers described herein; -13 -Figure 9 shows a detector region that can be used in conjunction with any of the spectrometers described herein; Figure 10 shows a method of calibrating a spectrometer in accordance with the example spectrometers described herein; Figure 11 shows a spectrometer coupled to a smartphone or smart device in accordance with one or more embodiments described herein; Figure 12 shows a light source configuration in accordance with one or more embodiments described herein; Figure 13 shows a sampling region in accordance with one or more embodiments described herein; Figure 14 shows an analysis region in accordance with one or more embodiments described herein; Figure 15 shows a spectrometer coupled to a smartphone or smart device in accordance with one or more embodiments described herein; Figure 16 shows a sampling region in accordance with one or more embodiments described herein; Figure 17 shows an analysis region in accordance with one or more embodiments described herein; Figure 18 shows a spectrometer configured for coupling to an optical probe in accordance with one or more embodiments described herein; Figure 19 shows a sampling region and probe coupling for the spectrometer of figure 18 in accordance with one or more embodiments described herein; and Figure 20 shows an optical probe for coupling to the spectrometer of figure 18 or the probe coupling of figure 19 in accordance with one or more embodiments described herein.

Detailed description

The IR region of the electromagnetic spectrum may be divided into three sub-regions: near infrared (NIR), 0.7 -3 pm; mid-infrared (MIR), 3 -50 pm; and far-infrared (FIR), 50 -1000 pm. When using NIR radiation for spectroscopy, the vibrational transitions happen in regions of high energy, where the absorptions are called overtones or combination bands.

This generates a very superposed signal of chemical features (in comparison with MIR), though it can be used to assess relevant chemical information. On the other hand, FIR analysis works in low frequencies (< 200 cm-1, > 50 pm), being particularly useful for studies involving bonds containing metallic atoms.

Experimental measurements using MIR spectroscopy are made using bench-top instruments, composed basically of five parts: (1) light source, (2) sampling region, (3) analysis region, (4) detector, and (5) computer module. The light source generates infrared light/radiation; the sampling region contains, holds, or allows access to the sample to be irradiated with IR light; the analysis region contains a diffraction grating or prism for diffraction of the incident IR light; the detector captures the diffracted IR light, generating an electric potential response; and the computer module process the information transforming it into an interferogram and, by using a Fourier transform (FT), into a spectrum.

MIR spectrometers can work in two modes: transmission or reflection. In transmission mode, the infrared light passes through a sample and reaches a detector.

The final recorded IR signal is given by:

P

T = -n ro where T is the transmission (with a value between 0 and 1), P is the signal potential through the sample, and Po is the signal potential through a blank, i.e., background signal (e.g., reference material, air, or sample matrix without substance of interest). The transmission of IR radiation does not have a linear relationship with concentration of a particular analyte in a sample. For this reason, a mathematical transformation using Beer-Lambert's law is applied: A = -log T where A is the absorbance, which is linearly proportional to the chemical concentration. A disadvantage of the transmission mode is that it is generally only effective for analysing liquid samples in relatively large volumes (e.g. > 2 mL) or relatively thin materials.

In reflection mode, the absorption properties of a sample can be determined from IR light reflected from the sample. For example, the IR light may reach the material surface and bounce in the material through a phenomenon called reflectance, where the incident light after a certain degree of depth penetration reflects back to the spectrometer in an angle close to 180° from the incident direction. One technique for reflection is the attenuated total reflection (ATR) mode, where a crystal, such as diamond, is placed between the light source and sample to generate an evanescent wave that attenuates the signal intensity. The penetration depth of ATR using a diamond crystal varies according to -15 -the incident radiation frequency and material properties, but it usually varies from 0.5 to 2 pm. Thus, in contrast to transmission mode, reflectance by means of an ATR technique is readily suitable for analysing solid or thick samples, or small volumes of liquid.

Figure 1 shows a spectrometer 100 in accordance with an embodiment of the disclosure. The spectrometer 100 is for attenuated total reflection spectroscopy of a sample. The embodiment shown in Figure 1 comprises a sampling region 62, an analysis region 63 and a detector 51.

The sampling region 62 includes an attenuated total reflection crystal 73 and a fixed focusing mirror 75. The analysis region 63 includes a fixed diffraction element 82. The sampling region 62 is configured to receive light from an infrared light source (not shown).

The attenuated total reflection (ATR) crystal 73 is arranged to receive light from the light source. The fixed focusing mirror 75 is arranged for focusing light from the ATR crystal 73. The analysis region 63 is configured to receive light from the sampling region 62. The fixed diffraction element 82 is configured to separate the received light by wavenumber. The detector 51 is configured to receive light from the analysis region 63.

In use, a sample (not shown) may be provided on a sample analysis portion of the ATR crystal 73. The sample analysis portion of the ATR crystal 73 may be an externally facing portion of the ATR crystal 73; for example, a portion of the ATR crystal 73 which is accessible externally of the spectrometer 100. The sample may be applied directly to the ATR crystal 73. A light source (not shown) may be configured to provide infrared light in the MIR region to the sampling region 62. The infrared light is received by the ATR crystal 73. The infrared light passes into the ATR crystal 72 and travels towards the sample analysis portion of the crystal, to the boundary or interface between the ATR crystal and the sample. At the interface, the infrared light undergoes at least one reflection back into the crystal. Based on the vibrational modes of the sample which may be excited by the infrared radiation, an evanescent wave may pass into the sample at the relevant frequency or frequencies, thereby attenuating the infrared light intensity at the relevant frequency or frequencies. Frequencies of the infrared light which do not excite vibrational modes of the sample are not attenuated in this way. As such, an infrared light signal, with specific wavenumbers attenuated in a characteristic manner based on the sample under investigation, may be output from the ATR crystal after the one or more reflections from the crystal-sample interface. The ATR crystal 73 may be cleaned, wiped, and/or sterilised before another sample is applied.

Light output from the ATR crystal 73 is received by the fixed focusing mirror 75. The focusing mirror 75 focuses the received light towards the analysis region 63. The analysis -16 -region 63 thereby receives light from the sampling region 62. The received light is received by the fixed diffraction element 82. The diffraction element 82 separates the received light according to wavenumber to provide a detectable light signal for receipt by the detector 51. The detector 51 receives the light signal and generates a detected signal output. The detected signal output is representative of infrared light intensity according to wavenumber in the received light signal. In this way, a measure of the infrared frequencies which have been absorbed or attenuated by the sample, and/or a measure of the extent or degree to which such frequencies have been attenuated, may be provided by the detector.

The sampling region 62 is arranged to receive light from an infrared light source (not shown). The infrared light source can be any form of light source and may be an external light source that is not part of the spectrometer 100. Alternatively, the light source may be provided with the spectrometer 100.

The MR crystal 73 is arranged to receive light that enters the sampling region 62 from the light source (not shown). In one example, the ATR crystal 73 is formed of Ge or diamond although other suitable ATR crystals can also be used. The crystal may take the form of a prism, in particular, a trapezoidal prism. The ATR crystal can have outer dimensions of between 10mm x lOmm x 1mm and 50mm x 20mm x 2mm, although other sizes of crystal are also possible. In one example, the outer dimensions of the ATR crystal are 50mm x 20mm x 2mm and the crystal is a trapezoidal prism. The entrance and exit slopes of the ATR crystal can be at 45° to the base or largest surface of the prism.

The fixed focusing mirror 75 is arranged to receive light after the light has left the ATR crystal 73 and to reflect the light into the analysis region 63. The length and width of the fixed focusing mirror 75 can be between 20mm x 20mm and 60mm x 60mm and the thickness of the mirror can be between 0.5mm and 2mm. The mirrors can be either rectangular or square. In one example, the fixed focusing mirror 75 can have length and width of 40mm x 40mm and can have a thickness of 1mm. However, other sized mirrors can also be used. In one example the mirror has a slope of 135° relative to a virtual horizontal axis parallel to the ATR crystal (for example, parallel to a sample analysis portion surface of the crystal).

The analysis region 63 is arranged to receive light from the sampling region 62. The analysis region includes a diffraction element 82 which is arranged to receive the light from the sampling region 62. The diffraction element 82 splits the light by wavenumber. In one example, the diffraction element 82 is a fixed transmission grating. In one example, the fixed transmission grating can split the incident IR light into wavenumbers in the region 900 to 1800cm-1. However, other diffraction elements 82 could also be used and the diffraction -17 -element could split IR light in a different region to the wavenumbers given above. The fixed diffraction element 82 is arranged such that light leaving the diffraction element 82 is received by detector 51.

To use the above spectrometer, a sample may be applied to one surface of the ATR crystal 73. A light source is aligned with the sampling region 62 such that light from the light source enters the sampling region 62 and the ATR crystal 73. The light reflects off the surface of the ATR crystal 73 which is in contact with the sample. This reflection forms an evanescent wave which can extend into the sample; in some example to between 0.52pm and 2pm. The reflected light may leave the ATR crystal in a direction generally opposite to the incident direction; for example, at an angle close to 180° to the angle of incident light; from the downstream end of the ATR crystal. The light may undergo a single reflection or it may be reflected multiple times, reflecting off the surface of the ATR crystal 73 in contact with the sample and a second, opposing surface. The number of rounds of reflection depends upon the size and dimensions of the crystal. After undergoing the above-mentioned reflection(s), the light leaves the ATR crystal 73.

After leaving the ATR crystal 73, the light reaches the fixed focusing mirror 75. The fixed focusing mirror 75 reflects and focuses the light onto the fixed diffraction element 82 in the analysis region 63. The fixed diffraction element 82 splits the received light by wavenumber. Light leaving the fixed diffraction element 82 leaves the analysis region 63 and is received by the detector 51. The detector 51 can be an IR charge-coupled device (CCD) which may have a 256 or 512 pixels size. All processing of the signal generated by the detector may be performed externally to the detector, with the detector merely forwarding the signal on for further processing. Alternatively, the detector can include a processor and some or all processing of the signal can be performed at the detector 51.

The use of a fixed focusing mirror and a fixed diffraction element can ensure the device is robust to movement and thus can reduce the need for any servicing. The fixing of the focusing mirror and the diffraction element also allows for the size of the device to be reduced since there is no need for extra space required by adjustable components. Furthermore, other savings in space may be possible as the reduced need for servicing means the sampling region 62 and the analysis region 63 do not need to be readily accessible.

Furthermore, unlike known IR spectrometers, the embodiment described above has only a single mirror in the sampling region 62 and no mirrors in the analysis region 63. This may allow the size of the sampling region 72 and the analysis region 63 to be reduced further, thus further reducing the size of the spectrometer.

-18 -The above-mentioned reductions in size and increases in robustness may make the spectrometer more suitable for use in the field than known IR spectrometers.

As mentioned above, the focusing mirror 75 and the diffraction element 82 are fixed in place. When other optical components are present, such as discussed with respect to Figure 3, these can also be fixed in place. In some examples, the attenuated total reflection crystal 73 is also fixed in place. However, in other examples, the attenuated total reflection crystal 73 may be connected to a probe 112 and hence is moveable with respect to the other optical components.

Having the optical components such as focusing mirror 75 and diffraction element 82 fixed in place means that these elements cannot move or be moved with respect to each other. Accordingly, these components are configured not to be adjustable, and their position cannot be, and does not need to be, changed or adjusted; for example to set up and/or calibrate the spectrometer 100, whether before or after the spectrometer 100 has been shipped.

The focusing mirror 75, diffraction element 82 and other fixed components can be fixed in place using any suitable method. They may be glued in place, taped in place, screwed in place, welded in place, nailed in place etc. In one example the spectrometer 100 may comprise a housing. This housing may be a single housing or each region of the spectrometer may comprise a housing for that region. The housing may be made of plastic; for example a rigid plastic, including a rigid black plastic.

When the spectrometer 100 comprises a housing, the focusing mirror 75, diffraction element 82 and other fixed components may be fixed in place using moulded supports provided in the housing. A moulded support may be provided for just one of the focusing mirror 75 and the diffraction element 82 or for both of these components. In addition, moulded supports may be provided for other fixed components.

The moulded support may take the form of a seat, fitting, fixture, stand or any other suitable feature that enables the focusing mirror 75 and/or diffraction element 82 to be held in place. In some examples, the moulded supports may each comprise an element on the base of the housing that supports or otherwise holds the focusing mirror 75 or diffraction element 82 in place. Alternatively the moulded supports may each comprise an element on the top or lid or ceiling of the housing that supports or otherwise holds the focusing mirror or diffraction element 82 in place. In some examples the moulded supports are provided on both the base and the top of the housing to hold the relevant optical component in place.

-19 -The moulded supports may be formed such that the respective orientation and/or angle of the focusing mirror 75 and diffraction element 82 are pre-set or pre-determined before the focusing mirror 75 and/or diffraction element are put into place. This makes manufacture of the spectrometer 100 easier and more reliable.

Figure 2 shows a spectrometer 200 in accordance with another embodiment of the disclosure. The spectrometer 200 includes the features described above with respect to the spectrometer 100 and reference numerals used in relation to spectrometer 200 represent the same or similar components as used with respect to spectrometer 100.

In addition to the features described above, the sampling region 62 of spectrometer 200 further comprises a housing 72 and a wall 74. In one example, the housing 72 can be made of a black plastic that can be a hard black plastic. Similarly, in addition or as an alternative, the wall 74 can be made of a black plastic which may be hard black plastic. The fixed focusing mirror 75 and the wall 74 are contained within the housing 72 of the sampling region 62. In one example, the ATR crystal 73 is contained in the housing 72. In another example the ATR crystal 73 is partially contained within the housing 72 such that a sample can be applied to one surface of the ATR crystal 73 without opening the housing 72. In another example, the ATR crystal 73 is not positioned in the housing 72 and is instead separated from the housing 72 by, for example, an optical probe or fibre optic cable.

The wall 74 divides the sampling region such that light entering the ATR crystal 73 is separated from light exiting the ATR crystal 73. To this end, the wall 74 divides the sampling region 62 at a location along the length of the ATR crystal 73 such that light enters the ATR crystal 73 in a first section 77 of the sampling region 62 and light exits the ATR crystal 73 and is reflected by the fixed focusing mirror 75 in a second section 78 of the sampling region 62. When the ATR crystal 73 is not contained in housing 72, such as in the case of a fibre optical cable or probe arrangement, then the wall 74 may divide the sampling region 62 at a location along the length of a connector to the probe and ATR crystal 73 such that light enters the connector in the first section 77 and exits the connector in the second section 78.

The surface of the wall 74 that faces the first section 77 is internally coated with a metallic material such as an aluminium material. Similarly the internal walls of the housing 72 in the first section 77 of the sampling region 62 are coated in a metallic material such as an aluminium material. This material is reflective and amplifies the infrared signal so causes convergence of light to the ATR crystal 73. To prevent light entering the ATR crystal 73 at multiple angles, the ATR crystal may be provided with an entrance slit so only -20 -light converging at this point on the ATR crystal 73 enters the crystal 73 and is subsequently used for analysis. The entrance slit may be made by coating the entrance surface of the ATR crystal with a reflective material, such as aluminium, and leaving an uncoated portion to serve as an entrance slit.

The metallic, or metal coated, wall 74 and housing 72 can be used to increase the amount of light that reaches the ATR crystal 73 and hence increase the signal strength. In known spectrometers, a collimating mirror has been used for this purpose. However, the wall 74 can take up less space than a collimating mirror thus allowing the size of the spectrometer 200 to be reduced while still giving a strong signal. Furthermore, the wall 74 can be more robust than a mirror thus providing for a more robust spectrometer 200 and

potentially better for use in the field.

In combination, the wall 74 and housing 72 form a cavity which contains the light entering the sampling region 62 and the entrance slit to the ATR crystal 73. Light may enter this cavity and hence the sampling region 62 through an entrance slit to the cavity.

While the above describes the cavity formed from a housing 74 divided by a wall, the cavity could itself be a single housing containing the cavity entrance slit and the ATR crystal 73 entrance slit. Any other suitable form of cavity could also be used.

Figure 3 shows a spectrometer 300 in accordance with another embodiment of the disclosure. The spectrometer 300 includes the features described above with respect to the spectrometer 100 and reference numerals used in relation to spectrometer 300 represent the same or similar components as used with respect to spectrometer 100. In addition, while not shown, the spectrometer 300 could be used with the additional features of spectrometer 200 described above.

In addition to the features described above, spectrometer 300 contains a filter window 79 for filtering light from the light source to ensure only desired or relevant frequencies of light are received in the sampling region 62. The filter can be a BaF2 window 79. In Figure 3, filter window 79 is shown as being in the sampling region 62. However, light could pass through filter window 79 before entering the sampling region 62. Therefore, filter window 79 could be situated in the same region as the light source. In Figure 3, filter window is illustrated as being in sampling region 62 for convenience since the light source is not shown. The filter window may be BaF2 window which may have outer length/width of between 1cm x 1cm and 4cm x 4cm and may be between 0.25cm and 1cm thick. In one example, the outer length/width of the window may be 2cm x 2cm and it may be 0.5cm thick. However, other sizes of window are also suitable.

-21 -In use, light passes through filter window 79 after it leaves the light source but before it enters ATR crystal 73. Filter window 79 acts as a filter for the light source filtering out unwanted frequencies of light so that only frequencies in the range used for analysis at 400-4000 cm-1 are transmitted through filter window 79. BaF2 is particularly suited since it is infrared transparent, allowing transmission of mid-infrared frequencies [400-4000 cm-1].

The use of a filter window allows a wider range of light sources to be used in relation to spectrometer 300.

Figure 4 shows a spectrometer 400 in accordance with another embodiment of the disclosure. The spectrometer 400 includes the features described above with respect to the spectrometer 100 and reference numerals used in relation to spectrometer 400 represent the same or similar components as used with respect to spectrometer 100. In addition, while not shown, the spectrometer 400 could be used with the additional features of spectrometer 200 and/or spectrometer 300 described above.

In addition to the features described above, the spectrometer 400 contains additional fixed components in the sampling region 62 and analysis region 63. In particular, in the embodiment shown in Figure 4, the sampling region contains an additional fixed collimating mirror 32 and the analysis region 63 contains an additional fixed collimating mirror 42 and an additional fixed focusing mirror 44.

The fixed collimating mirror 32 in sampling region 62 is positioned before the ATR crystal 73 such that light entering the sampling region 62 reaches fixed collimating mirror 32 and is reflected off fixed collimating mirror 32 and into ATR crystal 73. The fixed collimating mirror 32 may have a length and width of between 20mm x 20mm and 60mm x 60mm and may be between around 0.5mm to 5mm thick. In one example, the fixed collimating mirror 32 may have a length and width of 40mm x 40mm and may be 2mm thick. The fixed collimating mirror 32 can have a 45° slope relative to a virtual horizontal axis parallel to the ATR crystal. Other sized mirrors can also be used. Similarly, mirrors with a different angle of slope may also be suitable.

The fixed collimating mirror 42 in analysis region 63 is positioned before the diffraction element 82 such that light entering the analysis region 63 is received by collimating mirror 42 and reflected onto the diffraction element 82. The fixed collimating mirror 42 may have a length and width of between 20mm x 20mm and 60mm x 60mm and a thickness of 0.5mm to 2mm. In one example the fixed collimating mirror 42 may have a length and width of 40mm x 40mm and a thickness of 2mm. The mirror can have a 135° slope relative to a virtual horizontal axis parallel to the ATR crystal. Other sized mirrors can also be used. Similarly, mirrors with a different angle of slope may be suitable.

-22 -The fixed focusing mirror 44 in analysis region 63 is positioned after the diffraction element 82 such that light is received by fixed focusing mirror 44 from the diffraction element 82 and is reflected out of the analysis region 63 and to detector 51. In one example, the fixed focusing mirror 44 reduces the signal resolution to around 16cm-1.

As with spectrometer 100, when spectrometer 400 is in use a sample is applied to one surface of ATR crystal 73. Light enters the sampling region 62 from a light source (not shown) and reaches fixed collimating mirror 32. The light is reflected off fixed collimating mirror 32 and into the ATR crystal 73. The light reflects off the surface of the ATR crystal 73 which is in contact with the sample. This reflection forms an evanescent wave which can extend into the sample, typically to between 0.52pm and 2pm. The light then reflects back at an angle which can be close to 180°. The light can undergo a single reflection or it can be reflected multiple times, reflecting off the surface of the ATR crystal 73 in contact with the sample and a second surface. The number of rounds of reflection depends upon the size and dimensions of the crystal. After undergoing the above-mentioned reflection(s), the light leaves the ATR crystal 73.

The light from ATR crystal 73 is received by focusing mirror 75 and is reflected into sampling region 63 where it is received by fixed collimating mirror 42 which reflects the light onto diffraction element 82. The fixed diffraction element 82 splits the received light by wavenumber. Light leaving diffraction element 82 is received by fixed focusing mirror 44.

The fixed focusing mirror 44 reflects light out of the analysis region 63 and onto detector 51 for further analysis.

The spectrometer may be arranged in an L shape. The total size, or outer dimensions, of the spectrometer may be 28cm x 20cm x 10cm.

Another example of the sampling region is shown in figure 13. Here, the sampling region includes an entrance slit 31; a fixed collimating mirror 32; an ATR crystal prism 33; a fixed focusing mirror 34; and an exit slit 35. The sampling region may be housed in a casing or housing 36, such as a black plastic case. The angle 9 of the collimating mirror 32, relative to a horizontal parallel to the sample analysis or receiving surface of the ATR crystal 33, here is e = 45°. The angle cp of the focusing mirror 34, relative to the same horizontal, here is p = 135°.

Figure 5 shows a spectrometer 500 in accordance with another embodiment of the disclosure. The spectrometer 500 may include the features described above with respect to the spectrometer 100 and reference numerals used in relation to spectrometer 500 represent the same or similar components as used with respect to spectrometer 100. In -23 -addition, while not shown, the spectrometer 500 could be used with the additional features of spectrometers 200, 300 and/or 400 described above.

In addition to the features described above, Figure 5 shows an adaptor or connector 69 configured to connect the spectrometer to a smart phone or smart device 60. In one example, the smart phone 60 may be aligned with the spectrometer 500 and held in position such that a light source of the smart phone or smart device 60, such as an IR light source for distance measurement, can be used as a light source for the spectrometer. The smart phone or smart device 60 can be held in place using a clip, support, seat, holder or any other suitable device. This may be attached to the spectrometer using a screw or other connecting means.

The adaptor or connector 69 may be an adaptor/connector to allow power from the smart phone or smart device 60 to be provided to the spectrometer 500. Alternatively, or in addition, the adapter or connector 69 may be an adaptor/connector to allow data to be transferred from the spectrometer 500 and to/from the smart phone or smart device or remote central database or server. In one example, the adaptor or connector 69 may be a USB port such as USB 2.0 port. However, in other examples, other adaptors/connectors may be used such as a Bluetooth, HotKnot, NFC or any other suitable wired or wireless connector.

In use, a user couples the smart phone 60 to the spectrometer by connecting the smart phone or smart device 60 to the adaptor or connector 69 and/or placing the smart phone or smart device 60 in the support. This allows the smart phone or smart device 60 to be used to provide various aspects of functionality for the spectrometer 500 as detailed herein.

The smart phone or smart device 60 may be used as the infrared light source for the spectrometer 500. In this example, the smart phone or smart device 60 may be placed in a support or holder such that a light source from the smart phone or smart device 60 aligns with the spectrometer 500 to provide light to the sampling region 62. The amount of light entering the sampling region 62 may be controlled by an entrance slit to the sampling region which may be between 1mm to 2mm wide and 4mm to 6mm high. Once light has entered the sampling region 62, the spectrometer can be used as described above.

When a smart phone is used as a light source, the smart phone or smart device may be placed in a housing. The support or holder may be in the housing or external from the housing. If the support or holder is external to the housing, it may align the smart phone or smart device light source such that light enters the housing through an entrance slit. The internal walls of the housing may be formed of, or coated in, a reflective material. This -24 -material may be a metal material and may be aluminium. An exit to the housing allows light to exit the housing and enter the sampling region. The light may exit the housing through a filter such as a BaF2 window to ensure only the relevant wavelengths/frequencies of light enter the sampling region.

In addition, or as an alternative, the smart phone or smart device 60 may be used to provide processing power to the spectrometer 500. In such a case, the spectrometer 500 is coupled to the smart phone or smart device 60 via the adaptor or connector 69. Once connected, the smart phone or smart device 60 can be used to perform data processing of signals received from detector 51.

When the spectrometer 500 is connected to smart phone or smart device 60 via the adaptor or connector 69 then the smart phone or smart device 60 may also provide electrical power to the spectrometer 500 as an alternative or in addition to processing power. This electrical power can be used to power the detector 51 of the spectrometer 500. If an internal light source is provided with the spectrometer 500 then the electrical power can also be used to power the internal light source. In some cases the detector 51 is controlled by a microcontroller and in these cases the smart phone or smart device 60 may also be used to power the microcontroller.

While the connection of a smart phone or smart phone 60 to a spectrometer 500 has been discussed in combination with the spectrometers above, a smart phone or smart device 60 may alternatively be connected or coupled to a spectrometer 500 which has moveable rather than fixed optical components. As such, in some examples where spectrometer 500 is configured to connect to a smart phone or smart device 60, focusing mirror 75 and diffraction element 82 may not be fixed and may instead be adjustable relative to each other. Similarly when collimating mirror 32, collimating mirror 42, and focusing mirror 44 are used, these may also be adjustable components.

By configuring a spectrometer 500 to connect to a smart phone or smart device 60, parts of the spectrometer's 500 operation can be outsourced to the smart phone or smart device 60. For example, the smart phone or smart device 60 can serve as one or more of a power supply, a processing device, and a light source. This means these components do not have to be built into the spectrometer 500, allowing the size and complexity of the spectrometer 500 to be reduced.

Figure 11 shows an embodiment of a spectrometer configured for coupling to a smart device, such as a smart phone. The spectrometer includes a light source module 11; a sampling region/area module 12 (similar to that discussed in relation to figure 4); an analysis region including a diffraction element, such as a transmission grating 13; and a -25 -detector 14, in this example placed in a vertical orientation, or in a substantially perpendicular orientation relative, for example, to the ATR crystal. The spectrometer also includes electrical wires 15 for power supply from the smart device to the detector, and/or data communication between the detector and the smart device. The spectrometer also includes foam material 16 to prevent internal damage; a hard plastic case or housing 17; a universal smart device clip 18, attached to the spectrometer by, for example, a conventional screw; a USB cable 19; and a coupleable smart device, such as a smart cell/mobile phone 10. The spectrometer shown in figure 11 may be configured and operate in accordance with some or all of the features of the spectrometers described herein; in particular with reference to any of the spectrometers of figures 1 to 5.

Figure 15 shows another embodiment of a spectrometer configured for coupling to a smart device, such as a smart phone. The spectrometer of figure 15 is similar to that in figure 11 but has a configuration with fewer components, allowing the device to be reduced in size. The spectrometer includes a light source module 61; a sampling region/area module 62 (similar to that discussed in relation to figure 2); an analysis region including a diffraction element, such as a transmission grating 63; and a detector 64, in this example placed in a vertical orientation, or in a substantially perpendicular orientation relative, for example, to the ATR crystal. The spectrometer also includes electrical wires 65 for power supply from the smart device to the detector, and/or data communication between the detector and the smart device. The spectrometer also includes foam material 66 to prevent internal damage; a hard plastic case or housing 67; a universal smart device clip 68, attached to the spectrometer by, for example, a conventional screw; a USB cable 69; and a coupleable smart device, such as a smart cell/mobile phone 60. The spectrometer shown in figure 15 may be configured and operate in accordance with some or all of the features of the spectrometers described herein; in particular with reference to any of the spectrometers of figures 1 to 5.

Figure 6 shows a spectrometer 600 in accordance with another embodiment of the disclosure. The spectrometer 600 includes the features described above with respect to the spectrometer 100 or 500 and reference numerals used in relation to spectrometer 600 represent the same or similar components as used with respect to spectrometer 100. In addition, while not shown, the spectrometer 600 could be used with the additional features of spectrometers 200, 300 and/or 400 described above.

In addition to the features described above, Figure 6 shows an optical probe 112. One end of optical probe 112 is connected to the sampling region 62 via an optical adaptor 102. At the other end of optical probe 112, the tip 113 is connected or coupled to the -26 -attenuated total reflection crystal 73. The optical probe 112 is configured such that light travels in the optical probe 112 from sampling region 62 to ATR crystal 73 and is then returned by the optical probe 112 to the sampling region 62.

In one example, the optical probe 112 may be a fibre optic probe and the optical adaptor 102 may be a fibre optics attachment. The optical probe 112 may be a laparoscopic probe and the optical adaptor 102 may be an adaptor for a laparoscopic probe. In some embodiments, the optical probe 112 may be removably coupled to the spectrometer. In other embodiments, the optical probe 112 may be permanently coupled to the spectrometer. An example of an optical probe 112 is shown in figure 20.

In use, light enters the sampling region 62 from a light source. The light then enters the optical adaptor 102 and passes into the optical probe 112. The light then travels down optical probe 112 where it reaches the ATR crystal 73 which is positioned at the tip 113 of the optical probe 112. The light interacts with the ATR crystal 73 and any sample, as described previously, before re-entering optical probe 112. The light then travels back along the optical probe 112 to the sampling region 62. The light exits the optical probe through the optical adapter 102 and is received by the fixed focusing mirror 75. The light then continues to travel through the spectrometer 600 as described with respect to the spectrometers above.

When an optical probe 112 is used, the sampling region 62 may comprise a housing 105 containing an entrance to the optical probe adaptor 102 and the fixed focusing mirror 75, 103. An entrance slit 101 to the housing 105 may allow light to enter the housing from the light source. The walls of the housing may be coated with a reflective material which may be a metal, which may be aluminium, to reflect light into the optical probe adaptor 102. An example of this is shown in figure 19.

Figure 7 shows a more detailed view of the tip 113 of an example optical probe 112.

In this example, the optical probe 112 comprises an input optical fibre 114 and an output optical fibre 115. Light entering the probe travels through the input optical fibre 114 until it reaches the ATR crystal 73. The light undergoes reflection in the ATR crystal 73 as has been described previously and exits the ATR crystal into the output optical fibre 115. Light then travels through the output optical fibre 115 back to the sampling region 62.

The provision of an optical probe 112 allows the spectrometer to be used in a wider variety of settings and allows readings to be taken where samples cannot readily be moved or collected. In one instance, an optical probe 112 would allow use of the spectrometer in laparoscopy.

-27 -Figure 18 shows an embodiment of a spectrometer configured for coupling to an optical probe and a smart device, such as a smart phone. The spectrometer here is a portable MIR device, with a surgical configuration. The spectrometer includes a light source module 91; a fibre optics sampling region module 92; a spectrographic analysis region 93; a detector 94, placed in a vertical position; electrical wires 95; foam material 96 to prevent internal damage; a hard plastic case 97; a universal cell phone clip 98, attached to the device, optionally by a conventional screw; a USB cable 99; and a coupleable smart device, such as a smart cell/mobile phone 90.

While the spectrometers 100, 200, 300, 400, 500 and 600 described above can be used with a light source provided by a smart phone or smart device 60, in other examples the light source may be an internal light source 23 provided in a light source region 11.

The light source 23 may be a black body light source. The light source may be made of SiC. The light source may emit in the wavelength range of 2 pm to 14 pm.

Figure 8 shows a specific example of a light source region 11 that can be used in conjunction with any of the spectrometers 100, 200, 300, 400, 500 and 600 described herein. In the example shown in Figure 8, the light source 23, which may be a black body SiC light source as discussed above, is connected into an electrical circuit which receives power from either a smart phone or any other suitable power source 21. The power source may be a smart phone or smart device connected via a USB connection. The incoming current from the power source may be 86mA. A diode 24 ensures current flows from the power source 21 to the light source 23. A resistor 22 prevents the circuit malfunctioning in the case of any short circuits. The resistor may be 3300. The components described above can be provided on a printed electronic plate or board 25. However, in other embodiments the components described above can be provided in any other form of electric circuit. Figure 12 shows another light source arrangement which may be used with the spectrometers described herein.

The light source region 11 may have slits 26, 27 and 29 to allow for wires which control the above mentioned components to enter the light source region 11 and allow power to leave the light source region 11 so that it can be used to power other components of the spectrometer 100, 200, 300, 400, 500. Slit 26 may be used for connections that allow data to enter/exit the light source region; slit 27 may be used to allow power to exit the light source region 11; while slit 29 may be used to allow a connection or access to ground.

-28 -Light can exit the light source region 11 through a filter, such as a BaF2 window 28, which may be the filter window 79 described above. After exiting the light source region 11 light enters the sampling region 62 and is processed as described above.

Spectrometers 100, 200, 300, 400, 500 and 600 comprise a detector 51. Figure 9 shows a detection region 50 which may be used to provide detector 51 for any of the spectrometers 100, 200, 300, 400, 500, 600.

Detection region 50 comprises a detector 51 and a microcontroller 52 which may be provided on an electronic plate or other form of electronic circuit 53. Detection region 50 may also comprise a slit 55 to allow wires to leave the detection region 50, and a housing 54.

The detector 51 is a light detector, which may be in the form of IR charge-coupled device (CCD) with a 256 or 512 pixels size. The microcontroller 52 can be a PIC (programmable intelligent computer) microcontroller, such as a PIC 16F microcontroller.

The voltage signal for each pixel of the light detector 51 may be converted into pixel intensity by the microcontroller 52 according to a linear transformation function defined by v = ax + b, where v is the potential response, x is the pixel intensity ranging from 0 to 1, and a and b are regression coefficients. The absorbance signal is calculated across the middle horizontal position of the CCD as: a = -log-Po where a is a vector array containing the absorbance spectrum across the CCD horizontal pixels; p is the potential signal obtained as the pixel intensity across the CCD horizontal position by the IR light from the sample; and po is the potential signal obtained as the pixel intensity across the CCD horizontal position by the IR light from a blank. A blank can be a reading taken from the air with no sample in place or any other blank reading, such as a reflective reference material, a solvent, or a real mixture of substances without the analyte of interest.

The resultant absorbance spectrum a can then be stored, processed at the spectrometer and/or sent to a smart phone or other mobile computing device attached to the spectrometer. In one embodiment, the resultant absorbance spectrum a may be sent via USB connection, or any other suitable form of connection, in a TXT text file to a user smart phone or smart device for further processing.

-29 -Any of the spectrometers 100, 200, 300, 400, 500 and 600 described herein may be provided with, or in addition comprise, a reference sample that can be used for calibrating the spectrometer 100, 200, 300, 400, 500, 600. The calibration may be a software/computer calibration that does not require any physical or optical components of the spectrometer 100, 200, 300, 400, 500, 600 to be adjusted.

The reference sample mentioned above may be a gold reference sample. When a gold reference sample is used, it may be provided on a glass slide in the form of a gold-coated glass slide. This slide may be 60mm x 30mm x 2mm. However, other suitable ways of providing the gold reference sample may also be used. The reference sample may also be any other suitable stable material such as a suitable synthetic polymer as a reflective standard.

Figure 10 shows an example method 1000 for using a reference sample to calibrate the spectrometer 100, 200, 300, 400, 500, 600. In one example, the spectrometer 100, 200, 300, 400, 500, 600 may be calibrated every day before use.

The method comprises analysing a reference sample to obtain a reference sample output, such as in stage 1100; comparing the reference sample output signal to a stored reference sample output signal, such as in stage 1200; and adjusting the sample output signal based on the comparison, such as in stage 1300.

To obtain a reference sample output 1100 using the spectrometer 100, 200, 300, 400, 500, 600, a reading of the air may be taken as a blank in step 1101. The reference sample may then be applied to, or positioned on, the ATR crystal 73 and a reading may be taken with the reference sample in place in step 1102. The reading taken with the reference sample in place and the reading taken as a blank may then be used to obtain a reading for the absorbance spectrum of the reference sample in step 1103. This may be done by adjusting the signal according to the formula: a = -log-Po where a is the absorbance spectrum; p is the pixel intensity obtained from the reference sample; and Po is the pixel intensity returned from a blank. This reading of absorbance can form reference sample output signal.

Once the reference sample output signal has been obtained, it is compared to a stored reference sample output signal. The stored signal may be stored at the spectrometer 100, 200, 300, 400, 500, 600 itself or at any other connected computing -30 -device including smart phone 60. In some cases, if the comparison 1200 reveals that the reference sample output signal differs from the stored reference sample output signal by more than a set amount, a warning is provided in step 1201 to indicate that readings from the spectrometer 100, 200, 300, 400, 500, 600 may not be reliable and that the spectrometer 100, 200, 300, 400, 500, 600 may need repair or other servicing. The set amount may be 30%. In some examples, the spectrometer may be replaced if the warning is provided.

Once a reading has been taken using the reference sample, the spectrometer 100, 200, 300, 400, 500, 600 can be used for analysing samples. When a sample is analysed, the output signal from the sample may be adjusted based on the comparison in step 1200.

The output signal may be adjusted in step 1300 using the formula: signalfinat = signalmeasured (signal of reference sample",,"red) k signal of reference samplestored This calibrates the spectrometer 100, 200, 300, 400, 500, 600 and ensures any output readings are accurate. In some examples, the spectrometer 100, 200, 300, 400, 500, 600 may only have its readings adjusted if the warning above was not provided.

The use of computer-based calibration removes or reduces the need for mechanical calibration of the optical components. The above mentioned calibration procedure can also be used to ensure the accuracy of the spectrometer 100, 200, 300, 400, 500, 600. This increases the accuracy of the results from the spectrometer 100, 200, 300, 400, 500 and 600 while allowing non-moving components to be used.

It will be appreciated that the method described has been shown as individual steps carried out in a specific order. However, the skilled person will appreciate that these steps may be combined or carried out in a different order whilst still achieving the desired result.

The spectrometers 100, 200, 300, 400, 500 and 600 described above comprise various regions including a sampling region 62, an analysis region 63, and in some examples a light source region 11 and/or a detection region 50.

In some examples, these regions are all provided in separate housings. This leads to a modular design where different sampling regions can be used with different analysis regions 63 etc. The housing of one or all of the regions can be formed of plastic; for example, rigid or hard plastic, including rigid or hard black plastic.

When the regions 11, 62, 63 and 50 are provided in housings, entrance and exit slits can allow light to pass between the regions. In some examples, foam material 66, 96 may be provided to protect some of the components. For example, a foam material 66, 96 -31 -might be provided around the detector 51 or otherwise in detection region 50 to protect and/or buffer the detector 51. This is shown with the spectrometers shown in figures 15 and 18.

The sampling region 62 may have an entrance slit which allows light to enter the sampling region 62 from a light source such as light source region 11. The entrance slit may be between 1mm to 2mm wide and 4mm to 6mm high. In one example, it may be 1mm wide and 4mm high. The sampling region may also have an exit slit 76 to allow light to exit the sampling region 62 and enter the analysis region 63. The exit slit of the sampling region may be roughly 10mm x 10mm.

The analysis region 63 may have an entrance slit to allow light to enter the analysis region 63 from the sampling region 62. The entrance slit of the analysis region 63 may be between 1mm to 2mm wide and 4mm to 6mm high. In one example, it may be 1mm wide and 4mm high. The analysis region 63 may have an exit slit to allow light to exit the analysis region 63 and be received by detector 51 or detection region 50. The exit slit of the analysis region 63 may be 10mm x 10mm.

In one specific example, a portable or hand-held MIR spectrometer which may be coupled or attached to a mobile phone is provided. The spectrometer comprises the following miniaturized components: (1) light source 23, (2) sampling region/area 62, (3) analysis region/area 63, (4) detector 51 and computer module 52, and optionally (5) reference material. The instrument can be set in a standard or reduced configuration. The following components may be assembled to produce the device.

The light source 23 may be a compact, black body light source made of SiC. The emission wavelength range may be 2 to 14 pm. The light source 23 may be connected in an electronic circuit 25 composed of a power source 21 via USB connection to a smart phone, and a resistor 22 to prevent a short circuit malfunction. The IR light source 23 may be actioned by the incoming current, and the IR beam may pass through a BaF2 window 28 (of dimensions 1 x 1 cm to 4 x 4 cm, 0.25 to 1 cm mm thick) to the sampling area 62. All the light source components may be within a black, hard plastic case to prevent interferences. A diode 22 may be placed in the printed electronic circuit 25 to prevent incoming current from going in a different direction than the power source. The light source may alternatively be generated by the smart phone, whereby module 11 may be substituted by a suitable window, such as a BaF2 window 28, and an internally reflective material; thus, using the smart phone light element as the light source.

The sampling region/area 62 may comprise one or a combination of the following features: a black, hard plastic case 36; an entrance slit 31 (1-2 mm wide, 4-6 mm high); a -32 -fixed collimating mirror 32 for the entrance IR light (20 x 20 mm to 60 x 60 mm, -0.5 to 4 mm thick, 45° slope); an ATR Ge or diamond crystal 33, 73 prism (10 x 10 x 1 mm to 50 x 20 x 2 mm, 45° entrance and exit slopes); a fixed focusing mirror 34, 75 for the IR light coming out of the ATR crystal (20 x 20 mm to 60 x 60 mm, 0.5-2 mm thick, 135° slope); and/or an exit slit 35 (HO x 10 mm). An example of this is shown in figure 13.

The sampling area 62 may have a reduced size configuration by eliminating one of the mirrors 32. An example of this is shown in figure 16. Here, the sampling region includes an entrance slit 71; black plastic case 72, internally coated with aluminium; an ATR crystal prism 73; black plastic wall 74, internally coated with aluminium; a fixed focusing mirror 75; and an exit slit 76.

The convergence of light to the ATR crystal 73 may be obtained through an internally aluminium coated material. The incident angle in the ATR crystal may be set by a slit in the crystal (entrance slit), so only light converging at this point is used. For measurements using fibre optics, the ATR crystal may be substituted by a regular fibre optics probe 112 removably coupled to the device, where an ATR crystal 73 is attached to the end of the probe where the radiation is emitted. In surgical procedures, this can also include a laparoscopic probe.

The IR light coming from the sampling area 62 may be directed into an entrance slit 41 (1-2 mm wide, 4-6 mm high) of the analysis area 63, where it may reach a fixed collimating mirror 42 (20 x 20 mm to 60 x 60 mm, 0.5-2 mm thick, 135° slope), and then pass through a fixed transmission grating 43, 82 to split the incident IR light into wavenumbers; for example, in the region from 900 to 1800 cm-1. The light may then be reflected by a fixed focusing mirror 44. This may reduce the signal resolution to H6 cm* The light may pass out of the analysis area 63 through an exit slit 45 of approximately 10 x 10 mm, reaching the detector 51. An example of this is shown in figure 14.

A reduced analysis area 62 configuration may be obtained by removing mirrors 42, 44, and only employing a fixed transmission grating 82, with entrance slit 81 and exit slit 83. The analysis region may be provided in a black plastic case 84. In this configuration, the signal-to-noise ratio may be reduced, but is still fit for analysis. An example of this is shown in figure 17.

The detector area 50 may comprise an IR charge-coupled device (CCD) 51 with a 256 or 512 pixels size. The voltage signal for each pixel may be converted into pixel intensity by a microcontroller 52 according to a linear transformation function defined by v=ax+b, where v is the potential response, x is the pixel intensity ranging from 0 to 1, and a -33 -and b are regression coefficients. The absorbance signal may be calculated across the middle horizontal position of the CCD 51 as: a = -log-Po where a is a vector array containing the absorbance spectrum across the CCD 51 horizontal pixels; p is the potential signal obtained as the pixel intensity across the CCD 51 horizontal position by the IR light from the sample; and Po is the potential signal obtained as the pixel intensity across the CCD 51 horizontal position by the IR light from a blank. The resultant absorbance spectrum a may then be stored or processed, for example via USB connection in a.TXT text file, in the mobile phone or smart device attached to the device.

A reference gold-coated glass slide (e.g., 60 mm x 30 mm x 2 mm) may be used for assessing the instrument performance. The reference material may be analysed once a day before using the instrument. For this, the gold-coated slide may be measured by the instrument as a sample using an air signal as a blank, and if the average absorbance from this measurement is >30% different from the stored reference value (IR signal 900-1800 cm-1), the user may replace the instrument. If the signal difference is 30°/,,, the instrument baseline may be adjusted to the gold reference value, reducing signal interferences caused by environmental conditions. The adjustment may be made by: (signal of goldmeasu"d signal final = signalmeasurcd signal of goldre erence From an economic point of view, the use of MIR spectroscopy, in particular ATR Fourier transform infrared spectroscopy (ATR-FTIR), has great advantages. This is because the instrumentation has a relatively low-cost, requires low-cost maintenance, does not require laborious or wet-chemistry sample preparation procedures, has a fast data acquisition, and is non-destructive; that is, the sample can be reused after analysis. Thus, applications of this technique in chemical and biochemical areas are of great importance as substitute or auxiliary methods to reference analysis usually employed using electrochemical, chromatographic, mass spectrometric, and thermogravimetric techniques, or a combination of these. The spectrometers described herein can be used to obtain these advantages.

-34 -The spectrometers discussed herein can have many uses, including qualitative or quantitative applications. For example, the spectrometers could be used to analyse and/or segregate a variety of acute and/or chronic medical conditions and in testing biofluids including saliva, urine, blood, cerebrospinal fluid, breast milk, and infective exudate such as pus. They can also be used for cytology, tissues and skin surface analysis or diagnosis.

The spectrometers can also be used in the diagnosis/characterisation/identification of: bacterial, viral, and mycobacterial infections, including demonstrating strains with antibiotic resistance and diagnosing the exact strain of an infective agent; endometriosis; preterm labour; intrauterine growth restriction and stillbirth; pre-eclampsia; Parkinson's or Alzheimer's disease; multiple sclerosis; myocardial infarction; and malaria, dengue, and Ross River fever. The spectrometers can also be used to differentiate different skin cancers including basal cell carcinoma, squamous cell carcinoma, and malignant melanoma; differentiate and diagnose meningitis/other infections through interrogation of cerebrospinal fluid; differentiate and diagnose neurodegenerative disorders including Alzheimer's disease and Lewy body dementia; and differentiate and screen for all cancers including prostate, ovarian, uterine, leukaemia, breast, maxilla-oral, cervical, skin, and bowel cancers.

Further potential medical uses of the above mentioned spectrometers for human and veterinary medicine include providing accurate blood sugar measurements; diagnosing the presence of micro-and nano-plastics in human fluids/tissues and the environment inclusive of medical prostheses; detecting epigenetic changes in human and animal DNA; determining hormone levels in biofluids such as blood or urine to determine conditions such as pregnancy; testing cancer cells obtained at surgery allowing interrogation of these cells leading to tailored therapies for individual patients thus optimizing treatment regimes; identifying methicillin resistant staphylococcus infections on human skin, infected exudate and surfaces of equipment; screening implantable devices for colonization of infective pathogens reducing the risk of infection after transplantation allowing quality control; distinguishing between different subgroups of stem cells and viability of cells in cell culture and mediums; non-destructively interrogating ex vivo material being grown for transplantation to ascertain its quality; in situ diagnostics of oral infection and disease such as lichen planus and oral cancers; in forensics for the identification of blood and other human fluids allowing rapid diagnostics in criminal investigations; analysing of endometrial tissue in pre-implantation IVF and embryo transfer; and diagnosing cancer margins in real time during surgical excision of cancers by using a laparoscopic attachment.

-35 -The spectrometers described above may also have potential uses in industry, agriculture and in relation to the environment where they may be used for interrogating any fluids, surfaces and solids; interrogating paints and the surface of materials prior to application of paints; differentiating between infected and non-infected milk and in the quality control of milk; aging the ripeness of fruit on farms and also at retail outlets allowing timely use of these foods; testing the quality of fresh poultry, meat and fish and detecting contaminants; detecting infection on foliage and fruit in the farming industry; testing the quality of soil samples allowing efficient production choices; checking for environmental changes in soil and water supplies; testing environmental contamination of oceans and habitats such as reefs; and detecting the presence of plastics, micro-plastics and nano-plastics throughout the environment.

The spectrometers may also be used when exploring new planets including currently undiscovered planets where they may be used for identifying new life in the form viruses, bacteria and other life forms both at a macroscopic and microscopic level; identifying the presence and qualities of soil to include the detection of water; and identifying the presence of DNA or DNA-like substances present in samples.

While specific spectrometers have been described above, the skilled person would understand that the features from one or more of the spectrometers described herein may be used with the features from any or all of the other spectrometers.

When a processing device is part of the spectrometer then the processing device may be any data processing unit suitable for executing one or more computer programs (such as those stored on a storage medium and/or in a memory), some of which may be computer programs according to embodiments or computer programs that, when executed by the processor, cause the processor to carry out a method according to an embodiment and configure the system to be a system according to an embodiment. The processing device may comprise a single data processing unit or multiple data processing units operating in parallel or in cooperation with each other. The processing device, in carrying out data processing operations for embodiments, may store data to and/or read data from a storage medium and/or the memory.

In some embodiments, the spectrometer may be coupled to a smart device, such as a smart phone, and the smart device may be configured to operate as a processing device for the spectrometer. The smart device may store one or more processing algorithms for one or more of a diagnostic analysis, screening analysis, and/or predictive analysis. The output from the analysis may then be provided or relayed to a user of the smart device, substantially immediately, in substantially real time. In one example, the output may be -36 -provided in the form of one or more of a traffic light system, an acoustic output, and/or a numerical output, which may facilitate ready appreciation or understanding of the output. In some embodiments, the data processing system may include a library spectral dataset, one or more spectral pre-processing methods, and one or more computational algorithms configured for classification, feature extraction, and/or predictive analysis.

In the description above and in the figures, certain embodiments have been described. However, it will be appreciated that the disclosure is not limited to the embodiments that are described and that some embodiments may not include all of the features described. It will be evident, however, that various modifications and changes may be made in keeping with the breadth and scope of the disclosure.

Claims

-37 -CLAIMS: 1. A spectrometer for attenuated total reflection spectroscopy comprising: a sampling region configured to receive light from an infrared light source, the sampling region comprising: an attenuated total reflection crystal arranged to receive light from the light source; and a fixed focusing mirror for focusing light from the attenuated total reflection crystal; an analysis region configured to receive light from the sampling region, the analysis region comprising: a fixed diffraction element configured to separate the received light by wavenumber; and a detector configured to receive light from the analysis region.
2. The spectrometer of claim 1 further comprising a housing wherein the housing comprises: a moulded mirror support configured to hold the fixed focusing mirror in a fixed position within the housing; and/or a moulded diffraction element support configured to hold the fixed diffraction element in a fixed position within the housing.
3. The spectrometer of any preceding claim wherein all components in the sampling region and all components in the analysis region are fixed with respect to each other, or wherein all components in the sampling region, apart from the attenuated total reflection crystal, and all components in the analysis region are fixed with respect to each other.
4. The spectrometer of any preceding claim wherein: the attenuated total reflection crystal comprises an entrance slit, and the sampling region further comprises a chamber, the chamber comprising: a chamber entrance slit; and at least the entrance of the attenuated total reflection crystal; the chamber further comprising: -38 -one or more walls comprising a reflective material to reflect light received from the chamber entrance slit into the entrance slit of the attenuated total reflection crystal.
5. The spectrometer of any preceding claim further comprising an infrared light source wherein the light source is provided by a smart phone or smart device.
6. The spectrometer of any preceding claim wherein the spectrometer is configured to receive power from a smart phone or smart device.
7. The spectrometer of any preceding claim further comprising a data processing system for processing data from the detector wherein the data processing system is provided by a smart phone or smart device.
8. The spectrometer of any preceding claim further comprising: a data processing system wherein the data processing system is configured to adjust a sample output signal based upon a comparison between a reference output signal obtained from analysing a reference sample and a stored reference output signal for the reference sample.
9. The spectrometer of any preceding claim further comprising an optical probe comprising a tip and wherein the attenuated total reflection crystal is on the tip of the optical probe.
10. A spectrometer for attenuated total reflection spectroscopy wherein the spectrometer is configured to couple to a smart phone or smart device and the spectrometer comprises: a sampling region configured to receive light from an infrared light source, the sampling region comprising: an attenuated total reflection crystal arranged to receive light from the light source; and a focusing mirror for focusing light from the attenuated total reflection crystal; an analysis region configured to receive light from the sampling region, the analysis region comprising: -39 -a diffraction element configured to separate the received light by wavenumber; and a detector configured to receive light from the analysis region.
11. The spectrometer of claim 10 wherein the spectrometer is configured to couple to the smart phone or smart device to enable the smart phone or smart device to provide electrical power to the spectrometer.
12. The spectrometer of claim 10 or claim 11 wherein the spectrometer is configured to couple to the smart phone or smart device to enable the smart phone or smart device to provide an infrared light source for the spectrometer.
13. The spectrometer of any of claims 10 to 12 wherein the spectrometer is configured to couple to the smart phone or smart device to enable the smart phone or smart device to provide a processing device for signals received from the detector.
14. The spectrometer of any of claims 10 to 13 further comprising the features of any of claims 1 to 9.
15. A computer implemented method for calibrating the spectrometer of any preceding claim, the method comprising: analysing a reference sample to obtain a reference sample output signal; comparing the reference sample output signal with a stored reference sample output signal for the reference sample; and adjusting sample output signals based on the comparison.