Light guide module and device for measuring optical properties of medium

Abstract

A light guide module (140) for a device for measuring optical properties of a medium in an animal body has a support member (140, 180), a first light guide (142) supported in the support member (140, 180), and a second light guide (150) supported in the support member (140, 180). One of the first light guide (142) and the second light guide (150) is a fixed light guide, and the other of the first light guide (142) and the second light guide (150) is a movable light guide. The second light guide (150) is arranged coaxially with the first light guide (142) such that light can pass between the first light guide (142) and the second light guide (150). At least one of the fixed light guide and the movable light guide is a hollow tube light guide having a hollow interior that receives the other light guide. The interior of the hollow tube light guide is reflective.

Description

Technical Field

[0001] The present disclosure relates to a light guide module for use with an apparatus for measuring an optical property of a medium, and the present disclosure relates to an apparatus for measuring an optical property of a medium. Background Art

[0002] In many applications it is very useful to be able to measure the optical properties of a medium. A specific example of an optical property is the change in the concentration of a chromophore in a biological medium. Other examples include the absorption coefficient and the decorrelation rate. Known devices are often bulky and, in the case of biological media, uncomfortable for the subject. Known devices also have a low signal-to-noise ratio level, specifically because the signal intensity is usually low, while the noise level may be high, which can mask the signal to be obtained.

[0003] This is a problem faced by devices that transmit light to or from a subject, and particularly if the device is used to transmit light into a (human) subject's head and detect the diffusely reflected light.

[0004] In WO2018 / 033751A1 (the entire contents of which are incorporated herein by reference), a measuring device is disclosed, which is used to fit onto an animal body to measure changes in chromophore concentration in the animal body. The measuring device has a plurality of devices, commonly known as "tiles". Each device or tile has at least one light source for emitting light to the animal body and at least one light detector for detecting light returning from the animal body. The device controller in the tile receives signals from and sends signals to a main controller via a connection arrangement structure, which may be or include a common bus. An optical guide in the form of an optical fiber helps to guide light from the light source to the tissue being measured, and then from the tissue being measured back to the light detector. Summary of the invention

[0005] According to a first aspect disclosed herein, there is provided a light guide module for use with a device fitted to an animal body for measuring optical properties of a medium within the animal body, the light guide module comprising:

[0006] Supporting members;

[0007] a first light guide supported in the supporting member; and

[0008] a second light guide supported in the support member;

[0009] wherein one of the first light guide and the second light guide is a fixed light guide, the fixed light guide being fixedly arranged relative to the support member, and wherein the other of the first light guide and the second light guide is a movable light guide, the movable light guide being arranged to be movable back and forth between an extended position and a retracted position relative to the support member;

[0010] wherein the second light guide is coaxially arranged with the first light guide so that light can pass between the first light guide and the second light guide;

[0011] wherein at least one of the fixed light guide and the movable light guide is a hollow tube light guide having a hollow interior that receives the other light guide;

[0012] The interior of the hollow tube light guide is reflective so that when the movable light guide is in the extended position: (i) light entering the end of the hollow tube light guide can pass through the interior of the hollow tube light guide and be reflected internally into the end of the other light guide, the end of the other light guide facing the end of the hollow tube light guide; and / or (ii) light emitted from the end of the other light guide can pass through the interior of the hollow tube light guide and be reflected internally toward the end of the hollow tube light guide.

[0013] In some examples, the hollow light guide is the fixed light guide. In other examples, the hollow light guide is the movable light guide. In some examples, one of the light guides is a hollow tube (which may be fixed or movable in different examples) and the other light guide is a solid light guide (which may be movable or fixed in different examples). In other examples, both the first light guide and the second light guide are hollow tubes, one of which is fixed and the other is movable. In any case, when the movable light guide moves back and forth, a telescoping motion occurs between the light guides to accommodate the movement of the movable light guide.

[0014] In an apparatus for measuring the optical properties of a medium within an animal, a movable light guide can be moved in and out when the apparatus is fitted to and moved over the animal's body so that a first end of the movable light guide is in good contact with an adjacent portion of the animal's body. This ensures efficient transmission of light from the movable light guide to the animal's body and / or from the animal's body to the movable light guide. The telescopic arrangement of the two light guides and the reflective interior of the hollow tube light guide can accommodate movement while maintaining good light transmission between the light guides. The use of a coaxial telescopic light guide means that the overall cross-sectional area or "footprint" of the light-transmitting portion is small.

[0015] In one example, the fit between the hollow interior of the hollow tube light guide that receives the other light guide and the other light guide is a clearance fit.

[0016] This helps to reduce light losses while still allowing the light guides to move relative to each other. The clearance fit may in particular be a slide fit.

[0017] In one example, the hollow tube light guide is the fixed light guide and is fixed to and supported by the support member, or is integral with the support member to prevent movement relative to the support member.

[0018] In one example, the hollow tube light guide is the movable light guide.

[0019] In one example, one light guide is the hollow tube light guide and the other light guide is a solid optical fiber or a solid optical fiber bundle.

[0020] In one example, the first light guide and the second light guide are both hollow tube light guides, each having a reflective interior, wherein one of the hollow tube light guides is the movable light guide capable of moving into and out of the hollow interior of the other fixed light guide.

[0021] In one example, the light guide module comprises a biasing arrangement for biasing the movable light guide in a direction away from the fixed light guide.

[0022] During use, the biasing arrangement biases the movable light guide in the direction of the subject animal's body, which helps to maintain good contact between the end of the movable light guide and the surface of the subject.

[0023] In one example, the biasing arrangement comprises a spring arranged to bias the movable light guide in a direction away from the fixed light guide.

[0024] In one example, the biasing arrangement comprises a first magnet fixed relative to the movable light guide and a second magnet fixed relative to the fixed light guide, the magnets being arranged to repel each other to bias the movable light guide in a direction away from the fixed light guide.

[0025] In one example, the biasing arrangement is provided by a scroll spring having a plurality of coils, at least one of the first light guide and the second light guide being provided by at least one coil of the scroll spring. In one example, the first light guide and the second light guide are provided by respective coils of the scroll spring.

[0026] In one example, the light guide module comprises:

[0027] a plurality of sets of first and second light guides supported in the support member;

[0028] Wherein for each set of the first light guide and the second light guide:

[0029] one of the first light guide and the second light guide is a fixed light guide, the fixed light guide being fixedly arranged relative to the support member, and wherein the other of the first light guide and the second light guide is a movable light guide, the movable light guide being arranged to be movable back and forth between an extended position and a retracted position relative to the support member;

[0030] The second light guide is coaxially arranged with the first light guide so that light can pass between the first light guide and the second light guide;

[0031] At least one of the fixed light guide and the movable light guide is a hollow tube light guide having a hollow interior that receives the other light guide; and

[0032] The interior of the hollow tube light guide is reflective so that when the movable light guide is in the extended position: (i) light entering the end of the hollow tube light guide can pass through the interior of the hollow tube light guide and be reflected internally into the end of the other light guide, the end of the other light guide facing the end of the hollow tube light guide; and / or (ii) light emitted from the end of the other light guide can pass through the interior of the hollow tube light guide and be reflected internally toward the end of the hollow tube light guide.

[0033] In one example, each movable light guide is capable of moving back and forth relative to the support member independently of the other movable light guides.

[0034] According to a second aspect of the disclosure, there is provided a device adapted to be attached to an animal body for measuring optical properties of a medium in the animal body, the device comprising:

[0035] at least one light source for emitting light towards a body of an animal with which the measuring device is engaged in use;

[0036] at least one light detector for detecting light returning from the animal body;

[0037] a first light guide supported in a support member and a second light guide supported in the support member, the first light guide and the second light guide being associated with the light source for transmitting light from the light source to the animal body or associated with the light detector for transmitting light from the animal body to the light detector;

[0038] wherein one of the first light guide and the second light guide is a fixed light guide, the fixed light guide being fixedly arranged relative to the light source or the light detector, respectively, and wherein the other of the first light guide and the second light guide is a movable light guide, the movable light guide being arranged to be movable back and forth between an extended position and a retracted position relative to the light source or the light detector, respectively;

[0039] wherein the second light guide is coaxially arranged with the first light guide so that light can pass between the first light guide and the second light guide;

[0040] wherein at least one of the fixed light guide and the movable light guide is a hollow tube light guide having a hollow interior that receives the other light guide;

[0041] The interior of the hollow tube light guide is reflective so that when the movable light guide is in the extended position: (i) light entering the end of the hollow tube light guide can pass through the interior of the hollow tube light guide and be reflected internally into the end of the other light guide, the end of the other light guide facing the end of the hollow tube light guide; and / or (ii) light emitted from the end of the other light guide can pass through the interior of the hollow tube light guide and be reflected internally toward the end of the hollow tube light guide.

[0042] In one example, the fit between the hollow interior of the hollow tube light guide that receives the other light guide and the other light guide is a clearance fit.

[0043] In one example, the apparatus comprises a biasing arrangement for biasing the movable light guide in a direction away from the fixed light guide.

[0044] In one example, the biasing arrangement is provided by a spiral spring having a plurality of coils, and at least one of the first light guide and the second light guide is provided by at least one coil of the spiral spring.

[0045] In one example, the hollow tube light guide is the fixed light guide and is fixed to and supported by the support member, or is integral with the support member to be fixed against movement relative to the support member.

[0046] In one example, the hollow tube light guide is the movable light guide.

[0047] In one example, one light guide is the hollow tube light guide and the other light guide is a solid optical fiber or a solid optical fiber bundle.

[0048] In one example, the first light guide and the second light guide are both hollow tube light guides, each having a reflective interior, wherein one of the hollow tube light guides is the movable light guide capable of moving into and out of the hollow interior of the other fixed light guide.

[0049] In one example, the apparatus comprises a plurality of sets of fixed light guides and movable light guides, wherein each set of fixed light guides and movable light guides is associated with a respective one of the light source and the light detector.

[0050] In one example, each movable light guide is capable of moving back and forth relative to the support member independently of the other movable light guides. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] To help understand the present disclosure and show how to implement the embodiments of the present disclosure, the accompanying drawings are used as examples for description, wherein:

[0052] FIG1 shows a schematic side view of an assembly of a known device described in WO 2018 / 033751 A1, a dock for the device, and a light guide arrangement for the device;

[0053] FIG2 shows a schematic side view of a known carrier described in WO 2018 / 033751 A1, the carrier having a plurality of docks in which devices are removably positioned;

[0054] 3A, 3B and 3C respectively show schematic perspective views of a known device, dock and light guide arrangement of the assembly of FIG. 1;

[0055] Figure 4A and 4B Schematic perspective views showing the device and the dock, respectively, Figure 4C shows a perspective view of a first example of a light guide module according to one aspect of the present disclosure;

[0056] Figure 5 shows a schematic side view of an assembly of the apparatus of FIG. 4 , a dock, and a first example light guide module in a first configuration;

[0057] Figure 6 shows a schematic side view of an assembly of the apparatus of FIG. 4 , a dock, and a first example light guide module in a second configuration;

[0058] Fig. 7A , 7B 7C and 7C respectively show the first configuration Figure 4C schematic perspective, side and cross-sectional views of a first example light guide module;

[0059] Fig. 8A , 8Band 8C respectively show the second configuration Figure 4C schematic perspective, side and cross-sectional views of a first example light guide module;

[0060] Fig. 9 A schematic perspective view showing an example of a circuit board, Figure 4A One or more light sources and light detectors of the device are mounted on the circuit board;

[0061] Fig. 10A and 10B showing cross-sectional views of another example of a light guide module according to the present disclosure in a first configuration and a second configuration, respectively;

[0062] Fig.11A and 11B showing cross-sectional views of another example of a light guide module according to the present disclosure in a first configuration and a second configuration, respectively;

[0063] Fig. 12A and 12B showing cross-sectional views of another example of a light guide module according to the present disclosure in a first configuration and a second configuration, respectively;

[0064] Fig.13A and 13B showing cross-sectional views of another example of a light guide module according to the present disclosure in a first configuration and a second configuration, respectively;

[0065] Figures 14 to 17 shows cross-sectional views of other examples of light guide modules according to the present disclosure;

[0066] Fig.18 A cross-sectional view showing another example of a light guide module according to the present disclosure; and

[0067] Fig.19 A cross-sectional view of another example of a light guide module according to the present disclosure is shown. DETAILED DESCRIPTION

[0068] As mentioned above, being able to measure optical properties of biological media is very useful in many applications. For example, measuring changes in chromophore concentrations within an animal, especially a human, can be very useful, for example, chromophores may be found in the blood flowing through the brain, heart, or skeletal muscle, etc. Other example properties include absorption coefficient and decorrelation rate.

[0069] As a particular example, devices are known for performing functional neuroimaging, the purpose of which is to measure regional brain activity. Functional near infrared spectroscopy (fNIRS) is a known non-invasive technique for providing information on vascular and metabolic responses to brain activity. Chromophores can be or include, for example, oxyhemoglobin, deoxyhemoglobin, and oxidized cytochrome c oxidase. Oxyhemoglobin and deoxyhemoglobin can be found in the blood. Oxidized cytochrome c oxidase can be found in tissues. By measuring changes in the concentration of these chromophores, insight can be gained into, for example, active regions of the brain.

[0070] In such a device, one or more light sources emit light (infrared light in the case of fNIRS) toward the subject, and one or more light detectors detect light reflected or transmitted back from the subject. Light guides may be provided, typically one for each light source and each light detector, to maximize the coupling of light from the light sources to the subject and from the subject to the light detectors, thereby improving the signal-to-noise ratio. The light guides may be in the form of or provided by optical fibers.

[0071] The specific arrangement of such a device is disclosed in WO2018 / 033751A1, the entire contents of which are hereby incorporated by reference. Figures 1 to 3 are taken from WO2018 / 033751A1 and will be briefly discussed as a useful background.

[0072] FIG. 1 shows a schematic side view of an assembly of a device 10, a dock 12 for the device 10, and a light-guiding arrangement 14 for the device 10 as described in WO 2018 / 033751 A1. FIG. 2 shows a schematic side view of a carrier 16 as described in WO 2018 / 033751 A1, the carrier having a plurality of docks 12 in which the device 10 is removably positioned. FIG. 3A, 3B and 3C show schematic perspective views of a known device 10, a dock 12 and a light-guiding arrangement 14 of the assembly of FIG. 1, respectively. In this case, the carrier 16 takes the form of a hat or other headgear that fits on the head of the subject. In this case, the dock 12 is permanently fixed to the carrier 16, and the device 10 can be fitted in and removed from the dock 12, so that the number and configuration of the devices 10 on the carrier 16 (and therefore the head of the subject) can be easily changed as needed. In practice, there may be a large number of docks 12 on the carrier 16, and the devices 10 can be filled on all or only some of the docks as needed or desired for the particular subject research being conducted.

[0073] One or more light sources and one or more light detectors are mounted in the device 10. The dock 12 removably receives the device 10 and acts as a mechanical support and retention device for the device 10. The dock 12 and the device 10 may be a friction fit or a snap fit, with ridges and recesses, etc., to secure the device 10 in the dock 12. In this example, the dock 12 also provides power and data input and output connections for the device 10.

[0074] The dock 12 has a plurality of through holes 18 , for example, one through hole 18 for each light source and each light detector, so that light can pass through the dock 12 between the experimental subject and the light source and light detector, respectively.

[0075] With particular reference to FIG. 3C , the light guide arrangement 14 has a plurality of light guides 20. Each light source and each light detector generally corresponds to one light guide 20. Thus, the number and location of the light guides 20 generally correspond to the through holes 18 of the dock 12. The light guides 20 help guide light from the light source to the tissue being tested in the subject, and then from the subject back to the light detector. This helps improve the signal-to-noise ratio by reducing the amount of light loss between the tissue and the device 10.

[0076] The use of such a light guide 20 is particularly advantageous when the subject's head, and in particular the brain, is subjected to experimental investigations, particularly in the case of fNIRS using infrared light. This is because hair has a strong absorption capacity for light, and in particular for near-infrared light, which is often a major factor in preventing a good signal-to-noise ratio measurement result from being obtained. The light guide 20 can be combed through the user's hair, i.e. passed between the hair strands, which means that the light to and from the light source and light detector is less likely to be absorbed by the hair when passing through the light guide 20. This can improve the quality of the detection signal.

[0077] Ideally, the distal end (i.e., the end remote from the light source or light detector, respectively) of each light guide 20 is in contact with the subject's scalp or other body part being studied to minimize light loss and thereby maximize the signal-to-noise ratio. One problem with static light guides is that they do not adapt well to the shape of the subject's scalp or other body part being studied. Angularities, protrusions, or depressions in the scalp or other body part often mean that while some light guides make good contact, other light guides are far away from the scalp or other body part. This is particularly a problem when there are many light guides per unit area, which is what is needed for high-density studies and high-resolution imaging, such as is typically required in the case of fNIRS.

[0078] A known solution is to allow one or more or all of the light guides to move back and forth, especially independently of the other light guides. Examples of this are disclosed in WO2011 / 083563A1, US2015 / 0038811A1 and US2021 / 0259632A1. Each of these documents discloses a device for optical research and imaging, including a device for brain fNIRS, in which a light guide is used to transmit light to or from a subject, and the light guide is movable. The movement of the light guide can enable the light guide to better fit the shape of the body part, thereby facilitating good contact between the light guide and the subject's body. In each of the above documents, the movable light guide is spring-loaded so as to be biased into contact with the subject's body, thereby helping to ensure good contact with the subject's body.

[0079] However, for movable light guides, especially in the case of arrangements such as those disclosed in US2021 / 0259632A1 where the light guides can be moved relative to the light source or light detector, respectively, there is still a problem of how to ensure that light is effectively transmitted from the light source to the light guide, and from the light guide to the light detector, throughout the entire range of movement of the light guide. Specifically, when the light guide is away from the light source or light detector, respectively, the light between the light guide and the light source or light detector may be lost accordingly. The device disclosed in US2021 / 0259632A1 attempts to solve this problem on the light source side by using a prism and a lens plate located between the end of the light guide and the light source to guide and focus the light onto the end of the light guide. The device disclosed in US2021 / 0259632A1 attempts to solve this problem on the light detector side by using a first and second lens located between the end of the light guide and the light detector to collimate and focus the light onto the light detector.

[0080] In the examples described herein, a light guide module is provided for use with a device for measuring the optical properties of a medium within an animal body, the device being fitted to the animal body. Examples and applications of such devices are further described above. In one example, the light guide module has a support member, a first light guide supported in the support member, and a second light guide. One light guide is a fixed light guide, and the other light guide is a movable light guide, which can move back and forth between an extended position and a retracted position relative to the support member. The light guides are coaxially arranged. At least one of the fixed light guide and the movable light guide is a hollow tube light guide, the hollow tube light guide having a hollow interior that receives another light guide. The interior of the hollow tube light guide is reflective. Therefore, when the movable light guide is in the extended position: (i) light entering the end of the hollow tube light guide can pass through the interior of the hollow tube light guide and be reflected internally to the end of another light guide, the end of the other light guide facing the end of the hollow tube light guide; and / or (ii) light emitted from the end of the other light guide can pass through the interior of the hollow tube light guide and be reflected internally toward the end of the hollow tube light guide.

[0081] This ensures efficient transmission of light from the light source to the animal and / or from the animal to the light detector.A hollow tube light guide (fixed in some examples and movable in other examples) with a reflective interior can accommodate movement of the movable light guide while maintaining good light transmission.

[0082] This arrangement maximizes the coupling of light from the light source to the subject, and from the subject to the light detector, even if the movable light guide is relatively far away from the light source or light detector. This reduces the light loss from the light source to the subject and / or from the subject to the light detector. In addition, the hollow tube light guide prevents ambient light from entering the system, which may otherwise reduce the signal-to-noise ratio. In addition, the use of a hollow tube light guide to accommodate the movement of the movable light guide means that the use of collimating and focusing lenses and the like in some known devices to guide light wires in and out of the movable light guide can be avoided. This in turn means that the overall cross-sectional area or "footprint" of the light-transmitting portion is small. This can increase the density of light sources and light detectors (i.e., the number per unit area), which in turn can achieve higher quality and resolution. Alternatively or additionally, this also means that the spacing between adjacent light guides can be relatively large, so that when the device is fitted to the subject's head and the device and light guide are moved on his head, it is easier to comb the light guide through the subject's hair. Furthermore, reduced light losses mean that the diameter of the light guide itself can be smaller, which also makes it easier to comb the light guide through the subject's hair when fitting and positioning the device on the subject's head. Finally, avoiding the use of collimating and focusing lenses and the like also means that the number of interfaces between the light source and the subject and light detector that the light must pass through can be minimized (indeed, in some examples, this can remain unchanged from the arrangement disclosed in WO2018 / 033751A1). This reduces reflection losses that may occur when light passes through interfaces between materials with different refractive indices, again improving the signal-to-noise ratio.

[0083] Reference will now be made to FIGS. 4 to Fig.17 Some specific examples of the present disclosure are described. It should be noted that in different examples, there are many identical or corresponding parts, and for the sake of brevity, their descriptions will not be repeated. Similarly, for the sake of clarity, not all figure numerals are repeated in each figure.

[0084] First, refer to Figure 4. Figure 4A and Figure 4B Schematic perspective views showing the device 100 and the dock 120, respectively, Figure 4C A perspective view of a first example of a light guide module 140 according to one aspect of the present disclosure is shown. For example, the device 100 and the dock 120 generally can be of the type discussed more fully in WO2018 / 033751A1.

[0085] In this example, the device 100 can be removably positioned in a dock 120. The dock 120 removably receives the device 100 and acts as a mechanical support and retention device for the device 100. The dock 120 and the device 100 can be a friction fit or a snap fit, with ridges and recesses, etc., to secure the device 100 in the dock 120. In one example, the dock 120 also provides power and data connections for the device 100. In one example, a plurality of such docks 120 with associated light guide modules 140 can be permanently fixed to a carrier, such as the hat or other headwear mentioned above (see also FIG. 2), which is discussed more fully in WO2018 / 033751A1. In this way, the number and configuration of devices 100 on the carrier (and therefore the head of the subject) can be conveniently changed by clipping the device 100 on or removing it from the dock 120 as needed.

[0086] Alternatively, the device 100 and light guide module 140 may be "permanently" affixed to or as part of a carrier, such as a hat or other headwear, and not easily removed and repositioned, nor provided with a dock to which the device 100 can be removably attached.

[0087] One or more light sources and one or more light detectors are installed in the device 100. Fig. 9 , which shows a schematic perspective view of an example of a circuit board 160, on which one or more light source units 162 and light detector units 164 of the device 100 are positioned. In this example, the circuit board 160 is provided in the device 100 and is a component of the device 100. In the specific example shown, the circuit board 160 has three light source units 162 and four light detector units 164. The three light source units 162 are symmetrically arranged on the circuit board 160, in this example positioned toward the alternating corners of the hexagon. The four light detector units 164 are also symmetrically arranged on the circuit board 160, in this example, three are positioned toward the remaining alternating corners of the hexagon, and the fourth is located at the center of the hexagon.

[0088] Each light source unit 162 has or includes at least one light source 163 for emitting light. In one example, the light source unit 162 has a plurality of light sources 163. In the specific example shown, each light source unit 162 has three light sources 163. Each light source 163 can emit light with a wavelength in a range of, for example, 600 nm to 1000 nm. The light source 163 can emit light with different wavelengths. That is, in one example, each light source unit 162 has a first light source 163 capable of emitting light at a first wavelength, a second light source 163 capable of emitting light at a second wavelength, and a third light source 163 capable of emitting light at a third wavelength, each wavelength being different. In one example, the three wavelengths can be 735 nanometers, 810 nanometers, and 850 nanometers. The light source 163 can be, for example, a light emitting diode (LED). In one example, each light source 163 is powered sequentially when in use, so that at least in a particular light source unit 162, only one light source 163 is emitting light at a time.

[0089] Each photodetector unit 164 has at least one photodetector 165, which may be a photodiode, for detecting light. In the example shown, each photodetector unit 164 has a single photodetector 165. The photodetector 165 is arranged to detect light having a certain wavelength emitted by the light source 163. In one example, each photodetector 165 can continuously detect light when in use.

[0090] The circuit board 160 may be a printed circuit board (PCB). In the example shown, the light source unit 162 and the light detector unit 164, in particular the light source 163 and the light detector 165 contained therein, are mounted directly on the circuit board 160. One benefit of mounting the light source unit 162 and the light detector unit 164, in particular the light source 163 and the light detector 165 contained therein, directly on the circuit board 160 is that (relatively) long connecting lines from the PCB to the light source 163 and the light detector 165 can be avoided, thereby reducing noise and interference. The light detector unit 164 is arranged on the PCB 160, close to the corresponding amplifier and other circuits (not shown), which also helps to reduce the noise generated in the device 100.

[0091] Returning to the dock 120 for a moment, in this example, the dock 120 has seven through holes 122, one for each light source unit 162 and light detector unit 164 of the device 100, for light to pass through. When the dock 120 and the light guide module 140 are assembled together, a portion of the light guide module 140 extends through the through hole 122 of the dock 120 to transmit light, which will be discussed further below.

[0092] Now, the first example of a light guide module 140 is discussed in detail, which functions as or provides a support member to support one or more light guides 142, which are close to and preferably in contact with the animal body, such as the scalp of the head of the experimental subject, during use. As previously mentioned, the light guide module 140 can be provided as a separate component, or it can be part of a larger carrier, such as a hat or other headwear, which is fitted to the animal body during use.

[0093] The light guide 142 is arranged to be movable back and forth in a reciprocating manner, i.e., in and out, relative to the light source 163 and the light detector 165 of the device 100. That is, in this example where a separate light guide module 140 is provided to support the light guide 142, the light guide 142 can be movable back and forth relative to the body of the light guide module 140. Figure 5 and Figure 6 It is shown in Figure 5 The light guide 142 is shown in an extended configuration, i.e., at the farthest distance from the light source 163 and the light detector 165 of the device 100; Figure 6 The light guide 142 is shown in a retracted configuration, i.e., closest to the light source 163 and light detector 165 of the device 100. The in and out movement of the light guide 142 can bring the distal end 144 of the light guide 142 (i.e., the end distal to the light source 163 or light detector 165, respectively) into contact with the scalp or other body part of the subject being studied, as this can accommodate valleys and ridges and the like in the scalp or other body part. Maintaining contact between the distal end 144 of the light guide 142 and the body part can minimize light loss, thereby maximizing the signal-to-noise ratio.

[0094] One problem with allowing the light guide 142 to move back and forth relative to the light source 163 and light detector 165 of the device 100 is that the proximal end 146 of the light guide 142, i.e., the end of the light guide 142 closest to the light source 163 and light detector 165, may become spaced apart from the light source 163 and light detector 165. This means that light may be lost between the light guide 142 and the light source 163 or light detector 165, respectively. This also means that ambient light may enter the transmission path, thereby affecting the illumination of the experimental subject and the quality of the detected return light signal.

[0095] To solve this problem, Figure 7C and Figure 8CAs best shown in the cross-sectional view of FIG. 1 , at least one and preferably each movable light guide 142 is associated with a corresponding second light guide 150. The second light guide 150 is fixed relative to the movable light guide 142 (and therefore also fixed relative to the light guide module 140 in this example). The first movable light guides 142 in this example, which are close to and preferably in contact with the animal body when in use, can be referred to as "distal end" light guides 142 because they are far away from the corresponding light source 163 and light detector 165 of the device 100. The second fixed light guides 150 in this example, which are close to the corresponding light source 163 or light detector 165, can be referred to as "proximal end" light guides 150.

[0096] exist Figure 7C and Figure 8C In the example shown, each fixed light guide 150 is a hollow tube that is coaxially arranged with the corresponding movable light guide 142. The hollow tube fixed light guide 150 has a first distal end 152 and a second proximal end 154, the first distal end being respectively farthest from the light source 163 or the light detector 165 (and therefore being closest to the experimental subject when in use), and the second proximal end being respectively closest to the light source 163 or the light detector 165. When the movable light guide 142 moves back and forth (for example, when the movable light guide 142 moves on the body of the experimental subject), the movable light guide 142 moves back and forth in the hollow tube light guide 150 in a reciprocating or telescopic manner. The inner surface of the hollow tube light guide 150 is reflective. The inner surface of the hollow tube light guide 150 is preferably highly reflective, at least with respect to the light emitted by the light source 163. Therefore, in the case where the movable light guide 142 is used for the light source 163, when the movable light guide 142 moves away from the light source 163 (in Figure 7C , moving downward along the hollow tube light guide 150), any light emitted by the light source 163 to the movable light guide 142 that would otherwise be lost is reflected by the inner surface of the hollow tube light guide 150 toward the movable light guide 142. Similarly, in the case where the movable light guide 142 is used for the light detector 165, when the movable light guide 142 moves away from the light detector 165 (in Figure 7C As the movable light guide 142 moves downward along the hollow tube light guide 150, any light that would otherwise be lost exiting the movable light guide 142 is reflected toward the light detector 165 by the inner surface of the hollow tube light guide 150. Thus, even if the movable light guide 142 is moved away from the light source 163 and the light detector 165 as appropriate, the amount of light that enters and exits the movable light guide 142, the light source 163, and the light detector 165, respectively, can be maximized. This helps achieve a good signal-to-noise ratio.

[0097] The fit between the hollow tube light guide and the other light guides moving inside the hollow tube light guide may be, for example, a clearance fit, in particular a sliding fit.

[0098] In short, providing the second light guide in the form of a hollow tube having a reflective interior and in which the first light guide moves back and forth helps to reduce light losses while still allowing the first light guide to move so as to contact the body of the subject animal in use. This thus maximizes the coupling of light from the light source to the subject, and from the subject to the light detector, even if the movable light guide has been moved away from the light source or light detector accordingly.

[0099] Additionally, the hollow tube light guide may be opaque, at least to ambient light (including visible light and infrared), which may prevent ambient light from entering the system, which may otherwise reduce the signal-to-noise ratio.

[0100] Furthermore, this telescopic arrangement of the light guide means that the use of collimating and focusing lenses and the like, which are used in some known devices to guide the light wires in and out of the movable light guide, can be avoided. This in turn means that the overall cross-sectional area or "footprint" of the light-transmitting portion is small. This can increase the density (i.e., the number per unit area) of light sources and light detectors, which in turn can achieve higher quality and resolution numbers. Alternatively or additionally, this also means that the spacing between adjacent light guides can be relatively large, so that it is easier to comb the light guide through the hair of the subject when the device is fitted to the head of the experimental subject and the device and light guide are moved on their head. In addition, reducing light losses means that the diameter of the light guide itself can be smaller, which also makes it easier to comb the light guide through the hair of the experimental subject when the device is fitted and positioned on the head of the experimental subject. Finally, avoiding the use of collimating and focusing lenses and the like also means that the number of interfaces between the light source and the experimental subject and the light detector that the light must pass through can be minimized (in fact, in some examples, it can remain unchanged from the arrangement disclosed in WO2018 / 033751A1). This reduces reflection losses that can occur when light passes through interfaces between materials with different refractive indices, again improving the signal-to-noise ratio.

[0101] It can be noted that at one extreme of its movement, the movable light guide 142 may completely move out of the hollow tube light guide 150. However, it is preferred that the proximal end 146 of the movable light guide 142 (the end closest to the light source 163 or the light detector 165, respectively) always remain within the hollow tube light guide 150 (e.g., Figure 7C This is true even when the movable light guide 142 is moved to the farthest place from the light source 163 or the light detector as appropriate. This is because it can ensure that the light from the light source 163 enters the movable light guide 142 to the maximum extent by virtue of the light being reflected by the inner surface of the hollow tube light guide 150, and ensure that the light leaving the movable light guide 142 reaches the light detector 165 to the maximum extent.

[0102] In this example, each light source unit 162 and light detector unit 164 of the device 100 has a set or pair of movable light guides 142 and fixed light guides 150. In other examples, not all light source units 162 and light detector units 164 of the device 100 have an associated set or pair of movable light guides 142 and fixed light guides 150.

[0103] The reflective inner surface of the hollow tube light guide 150 can be provided in a variety of ways. For example, the entirety of the hollow tube light guide 150 can be formed of a reflective material, such as a metal, including, for example, stainless steel, etc. Alternatively or additionally, the inner surface of the hollow tube light guide 150 can be coated with a reflective material. A metallic mirror coating or a dielectric high reflective coating can be used. Suitable metallic materials include, for example, aluminum, gold, silver, titanium, etc.

[0104] In one example, the active light guide 142 is biased toward the subject when in use, that is, away from the light source 163 and the light detector 165, that is, biased to an extended configuration. This helps ensure that the active light guide 142 is in good contact with the subject, or at least brings the distal end 144 of the active light guide 142 closer to the subject.

[0105] A variety of different arrangements may be used to bias the movable light guide 142 toward the extended configuration. Figure 7C and Figure 8C In the example shown, for each pair of movable light guide 142 and fixed light guide 150, a biasing arrangement is provided by one or more springs. Figure 7C and Figure 8C In the example shown, a compression spring 170 is provided, in this example a compression coil spring 170, which serves to bias the movable light guide 142 into an extended configuration, ie towards the subject in use.

[0106] In more detail, the light guide module 140 has a generally planar base portion 180 and a through hole 182 through which the first and second light guides 142, 150 pass. An elongated tubular collar 184 is located in each through hole 182 to extend through the through hole. The upper portion of the elongated tubular collar 184 has an external flange 186 around its periphery toward one end. The flange 186 is located in a corresponding recess 188, which is provided in an upward facing portion of the base portion 180, surrounding the through hole 182 of the base portion 180. The flange 186 can be snap-fit ​​or press-fit in the recess 188, and / or can be fixed using an adhesive or some other means. The fixed light guide 150 is positioned in the upper portion of the elongated tubular collar 184. The fixed light guide 150 can be snap-fit ​​or press-fit in the upper portion of the elongated tubular collar 184, and / or can be fixed using an adhesive or some other means. Below the outer flange 186 of the elongated tubular collar 184, the elongated tubular collar 184 has an inner flange 190. The elongated tubular collar 184 may be formed of, for example, black ABS (acrylonitrile butadiene styrene) or some other suitable opaque material.

[0107] The second tubular collar 192 is positioned within the elongated tubular collar 184. The second tubular collar 192 may be formed, for example, of stainless steel or some other hard material. The distal end of the movable light guide 142 is fixed within the second tubular collar 192. As the movable light guide 142 moves back and forth relative to the fixed light guide 150, the second tubular collar 192 moves back and forth within the elongated tubular collar 184. In this example, the upper end of the second tubular collar 192 has an external flange 194 around its periphery. The lower portion of the module 140 has an inwardly facing flange 196 that faces toward the lower portion of the through hole 182. When the movable light guide 142 and the second tubular collar 192 move to the longest extended position ( Figure 7C When the second tubular collar 192 is in the downward position, the outer flange 194 of the second tubular collar 192 abuts against the inner facing flange 196 at the lower portion of the through hole 182 to retain the second tubular collar 192 in the through hole 182.

[0108] The outer flange 194 of the second tubular collar 192 faces (is opposite) the inner flange 190 of the elongated tubular collar 184. The spring 170 is positioned in the cylindrical space between the movable light guide 142 and the lower portion of the elongated tubular collar 184 and is captured between the outer flange 194 of the second tubular collar 192 and the inner flange 190 of the elongated tubular collar 184. The spring 170 is in its resting state (i.e., when the movable light guide 142 is in the Figure 7C Thus, the movable light guide 142 is generally biased in a direction away from the fixed light guide 150, that is, away from the light source 163 or the light detector 165 as the case may be, and more importantly, towards the body of the animal being investigated.

[0109] In addition to using a spring for a biasing arrangement to bias the movable light guide 142 toward the animal's body, other alternatives may be used. Fig. 10A and 10B sectional views of another example of a light guide module according to the present disclosure in a first (extended) configuration and a second (retracted) configuration, respectively. Components identical to those of the first example have the same reference numerals and are not described again. For clarity, not all reference numerals are used in the same manner. Fig. 10A and 10B Repeated in.

[0110] exist Fig. 10A and Fig. 10B In the example of FIG. 1 , there is no tubular collar positioned within the elongated tubular collar 184 and within which the distal end of the movable light guide 142 is fixed. Instead, in this example, the movable light guide 142 itself has an external flange 194 around its periphery. This arrangement can be used in any of the examples described herein. This arrangement helps to reduce the number of parts and can simplify assembly. Similar to the previous example, when the movable light guide 142 is moved to the longest extended position ( Fig. 10A , the outer flange 194 of the movable light guide 142 abuts against the inner flange 196 at the lower portion of the through hole 182 to hold the movable light guide 142 in the through hole 182.

[0111] Figure 7C and Figure 8C The former example in has a spring positioned in a cylindrical space between the movable light guide 142 and the lower portion of the elongated tubular collar 184, while Fig. 10A and Fig. 10B The biasing arrangement in the example of is provided by two (or more) permanent magnets arranged to repel each other. Fig. 10A and Fig. 10B, at least one permanent magnet 200 is disposed at the upper portion (proximal portion) of the cylindrical space between the movable light guide 142 and the lower portion of the elongated tubular collar 184, and at least one permanent magnet 202 is disposed at the lower portion (distal portion) of the cylindrical space between the movable light guide 142 and the lower portion of the elongated tubular collar 184. The upper magnet 200 may be fixed to the inner flange 190 of the elongated tubular collar 184 and / or the upper portion of the adjacent wall of the module 140. Similarly, the lower magnet 202 may be fixed to the outer flange 194 of the movable light guide 142 and / or the lower portion of the movable light guide 142. The magnets 200, 202 are arranged so that the same poles (i.e., NN or SS) face each other, so that the magnets 200, 202 repel each other. Thus, the repulsive action of the opposing magnets 200, 202 biases the movable light guide 142 away from the fixed light guide 150, ie into an extended configuration, and towards the body of an animal in use.

[0112] exist Figure 7C and Figure 8C as well as Fig. 10A and Fig. 10B In the example shown, the active light guide 142 is solid. For example, the solid light guide 142 can be formed of, for example, a single material. Suitable materials include, for example, injection molded plastics, including, for example, polypropylene, polyamide (nylon), polymethyl methacrylate (PMMA), etc. Alternatively, the solid light guide 142 can be formed of multiple layers, such as a core layer and an outer layer having different refractive indices. The solid light guide 142 can have an outer coating formed of an opaque material to prevent light outside the light guide 142 from entering the light guide 142. The outer coating can also prevent light from being transmitted from the inside of the light guide 142 to the outside of the light guide 142. For example, each solid light guide 142 can be formed of, for example, a single optical fiber (one or more layers) or a bundle of optical fibers (each optical fiber having one or more layers). In addition, when there is a second tubular collar, the presence of the second tubular collar 192 may be only for mechanical purposes, so as to provide mechanical support and protection for the active light guide 142 housed therein. Alternatively or additionally, the presence of the second tubular collar 192 may serve optical purposes and may actually be part of an integral light guide provided in part by the active light guide 142. For example, the second tubular collar 192 may have an internal reflective surface (e.g., with a silver, gold, or similar coating) to provide a light guiding function. In this case, the second tubular collar 192 may be considered a functional outer portion of the integral light guide, while the active light guide 142 may be considered an inner portion of the integral light guide provided by the combination of the second tubular collar 192 and the central portion 142 contained therein.

[0113] Fig.11A and Fig. 11B The cross-sectional view schematically shows another example of a light guide module according to the present disclosure, which is Figure 7C and Figure 8C The cross-sectional view of is basically corresponding to that of Figure 7C and Figure 8C The same components have the same reference numerals and are not described in detail herein. For clarity, not all reference numerals are used in the examples. Fig.11A and 11B Repeated in.

[0114] and Figure 7C and 8C as well as Fig. 10A and 10B Compared to the example in Fig.11A and 11B In the example, one or more or all of the movable light guides 142 are not solid, but are hollow tube light guides 142. These movable hollow light guides 142 are arranged to slide back and forth within the fixed hollow light guide 150. As for the previous example with solid movable light guides, in this example, when the movable hollow light guide 142 moves back and forth (for example, when the movable hollow light guide 142 moves on the body of the experimental subject), the movable hollow light guide 142 moves back and forth in a reciprocating or telescopic manner within the fixed hollow tube light guide 150. In the case where the movable hollow light guide 142 is used for the light source 163, when the movable hollow light guide 142 moves away from the light source 163 (in Fig.11A , moving downward along the hollow fixed tube light guide 150), any light emitted by the light source 163 to the movable hollow light guide 142 that would otherwise be lost is reflected by the inner surface of the hollow fixed tube light guide 150 toward the movable hollow light guide 142. Similarly, in the case where the movable hollow light guide 142 is used for the light detector 165, when the movable hollow light guide 142 moves away from the light detector 165 (in Fig.11A As the movable hollow light guide 142 moves downward along the hollow fixed tube light guide 150, any light that would otherwise be lost exiting the movable hollow light guide 142 is reflected by the inner surface of the hollow fixed tube light guide 150 toward the light detector 165. Thus, even if the movable hollow light guide 142 is moved away from the light source 163 and the light detector 165 as appropriate, the amount of light that enters and exits the movable hollow light guide 142, the light source 163, and the light detector 165, respectively, can be maximized. This helps achieve a good signal-to-noise ratio.

[0115] In addition to the fixed light guide 150 being hollow, the movable light guide 142 is also hollow, and the benefit of this is that the interface between the solid material and the air is avoided (such as what happens to the light passing between the solid movable light guide 142 and the hollow fixed light guide 150 in the above example). This can reduce the loss caused by back reflection when the light passes between the solid medium and the air, thereby improving the signal-to-noise ratio again.

[0116] It can be noted that Fig.11A and Fig. 11B An example is shown with Figure 7C and Figure 8C As in the example of the embodiment of the present invention, a spring is used as a biasing arrangement to bias the movable light guide 142 to the extended configuration. In another example with hollow movable and fixed light guides 142, 150, pairs of mutually repelling magnets can be used, such as for Fig. 10A and 10B The examples are described.

[0117] Fig. 12A and Fig. 12B The cross-sectional view schematically shows another example of an optical module according to the present disclosure, which is Figure 7C and Figure 8C The same or corresponding parts as those in the previous examples have the same reference numerals and are not described in detail here. For the sake of clarity, not all reference numerals are used in the Fig. 12A and 12B Repeated in.

[0118] Fig. 12A and 12B Examples with Figure 7C and 8C The main difference compared to the example of is that in this example, the movable light guide 242 at the distal end (lower end) close to the experimental subject when in use is in the form of a hollow tube with a reflective interior, which passes through the fixed light guide 250 at the proximal end (upper end) when the movable light guide 242 moves back and forth. Figure 7C and Figure 8C The arrangement shown is essentially the opposite, Figure 7C and Figure 8C , the proximal end (upper end) of the fixed light guide 150 is a larger hollow tube that receives the movable light guide 142 when the movable light guide 142 moves back and forth.

[0119] exist Fig. 12A and 12B In the example of FIG. 1 , a short tubular collar 284 is positioned in an upper portion of each through hole 182 of the base portion 180. The fixed light guide 250 is fixed to the short tubular collar 284. A cylindrical space 286 is defined between adjacent walls of the short tubular collar 284 and the fixed light guide 250. When the movable light guide 242 moves up to the retracted configuration, the cylindrical space 286 receives the movable light guide 242, and the movable light guide 242 moves on or around the fixed light guide 250.

[0120] exist Fig. 12A and 12B In the example, Figure 7C and 8CSimilar to the example of , the biasing arrangement is shown to be provided by a compression spring. In a variation thereof, Fig. 10A and Fig. 10B Similar to the example of , the biasing arrangement structure can be provided by one or more pairs of mutually repelling magnets.

[0121] In addition, Fig. 12A and Fig. 12B In the example of FIG. 1 , the fixed light guide 250 is shown as a solid light guide. Figure 7C and Figure 8C The example of (although in this example, the relative positions of the solid light guide and the hollow light guide are reversed). In a variant thereof, in addition to the movable light guide 242 being a hollow tube, the fixed light guide 250 may also be a hollow light guide. This is similar to the above reference Fig.11A and 11B The arrangement of the two hollow light guides described is similar, but in this variation, a larger hollow tube light guide 242 that receives a narrower light guide 250 is positioned at the distal (lower) end.

[0122] exist Figure 7C and 8C , Fig.11A and 11B as well as Fig. 12A and 12B In an example, the biasing arrangement for each pair of fixed light guides and movable light guides (whether one is a hollow light guide and one is a solid light guide, and whether the solid light guide is located at the distal end or the proximal end, or both the fixed light guide and the movable light guide are hollow light guides) is provided by a compression spring. As another example, the biasing arrangement for each pair of fixed light guides and movable light guides can be a tension spring. Fig.13A and 13B Such an example is schematically shown in . Note that in this illustrated example, for each pair of fixed light guides and movable light guides, there is a hollow fixed light guide at the proximal end and a solid movable light guide at the distal end. However, all variations discussed above are also applicable, for example, the movable light guide can be hollow, the fixed light guide can be solid, or both light guides can be hollow.

[0123] refer to Fig.13A and 13BIn this example, the movable light guide 342 located at the distal end (lower end) and close to the experimental subject when in use has an external retainer 344, which can be in the form of one or more protruding lugs or annular ridges or the like. The retainer 344 can be formed integrally with the movable light guide 342, or it can be arranged on an external sleeve or collar 346 to which the movable light guide 342 is fixed. In this example, the retainer 344 is along a portion of the length of the movable light guide 342. The first end of the tension spring 400 is connected to the retainer 344 of the movable light guide 342 so as to be retained by the retainer 344. The second end of the tension spring 400 is retained by a second retainer 348, which is fixed relative to the planar base portion 180 of the light guide module 140. In this example, the second retainer 348 is fixed to or integral with an elongated tubular collar 384 located in each through hole 182 to extend through the through hole, in which the movable light guide 342 moves, and in which the fixed light guide 350 is installed. It should be understood that different arrangements can be used to retain the first and second ends of the extension spring 400.

[0124] exist Fig.13A In the resting state shown (i.e., when the movable light guide 342 is in its extended configuration), the tension spring 400 is partially extended and in a stretched state. Thus, the movable light guide 342 is generally biased in a direction away from the fixed light guide 350, i.e., away from the light source or light detector as the case may be, and more importantly, toward the body of the animal being investigated.

[0125] Figures 14 to 17 Other examples of biasing arrangements and movable and fixed light guides are schematically shown in the figures. In each of these examples, the biasing arrangement for biasing the movable light guide to an extended configuration is provided by a scroll spring. In some examples, the movable light guide is provided by a scroll spring and the fixed light guide is provided by a solid or hollow light guide that is typically cylindrical. In one of the examples, the movable light guide and the fixed light guide are provided by corresponding coils of a scroll spring. An advantage of these arrangements is that a separate biasing arrangement provided by a separate compression or tension spring or a pair of magnets, etc. is not required.

[0126] First reference Fig.14 For each pair of light guides, the light guide module 140 has a fixed light guide 450 at the proximal end (upper end) and a movable light guide 442 at the distal end (lower end). The fixed light guide 450 is a solid light guide. It is worth noting that in this example, the movable light guide 442 is provided by a spiral spring 500.

[0127] As is well known, a scroll spring is a compression spring having a plurality of coils. During compression, the coils slide against each other, thereby enabling the spring to be compressed to a short length, with the elasticity of the material of the scroll spring biasing the spring to an extended configuration. Scroll springs are typically in the form of a cone, also known as a conical spring. However, in some cases, the scroll coils may have a parabolic profile. In this example, the scroll spring 500 is typically a right cone (i.e., a cone with an axis passing through the center of the base at right angles to its plane), and the cross-sectional shape is typically circular.

[0128] The proximal end of the spiral spring 500 is fixed to the body of the light guide module 140. The proximal end of the spiral spring 500 is adjacent to the facing end of the fixed light guide 450. The other end (distal end) of the spiral spring 500 extends out of the light guide module 140 and can move back and forth. Therefore, when the light guide module 140 moves on the experimental subject, the spiral spring 500 can compress and extend to adapt to the recesses and ridges and the like on the scalp or other body parts of the experimental subject.

[0129] The scroll spring 500 has a reflective interior, such as being coated with or formed of a reflective material.Thus, in this example, the scroll spring 500 provides a movable light guide at the distal end of the light guide module 140 and provides a biasing arrangement.

[0130] refer to Fig.15 In this example, again for each pair of light guides, the light guide module 140 has a fixed light guide 450 at the proximal end (upper end) and a movable light guide 442 at the distal end (lower end). In this example, the movable light guide 442 is again provided by a spiral spring 500, which has a reflective interior and also provides a biasing arrangement. This example is similar to Fig.14 The example of FIG. 4 is different in that the fixed light guide 450 is a hollow light guide.

[0131] exist Fig.14 and Fig.15 In each example, the spiral spring 500 is oriented so that the narrow end of the spiral spring 500 is toward the proximal end (closest to the light source and light detector, respectively) and the wide end of the spiral spring 500 is toward the distal end (closest to the experimental subject when in use).

[0132] exist Fig.16In another example schematically shown, one or more of the spiral springs 500 are oriented so that the narrow end of the spiral spring 500 is toward the proximal end, and one or more of the spiral springs 500 are oriented so that the wide end of the spiral spring 500 is toward the proximal end. There may be particular advantages to orienting some spiral springs 500 in one way and other spiral springs 500 in another way. For example, it may be ideal if light propagates along the interior of the spiral spring 500 in a direction from the narrow end to the wide end. In this way, since the narrower coils are located within the wider coils at the adjacent edges, light is less likely to be reflected at the junction between adjacent coils in the spiral spring 500. Therefore, in one example, the spiral springs 500 are oriented so that the spiral spring 500 that provides the light guide for the light source is oriented so that the narrow end is located at the proximal end (upper end), and the spiral spring 500 that provides the light guide for the light detector is oriented so that the wide end is located at the proximal end (upper end).

[0133] exist Figures 14 to 16 In each example, the movable light guide 442 is provided by a scroll spring 500 and the fixed light guide 450 is provided by a solid or hollow light guide 450 .

[0134] On the other hand, Fig.17 In the example of , both the movable light guide and the fixed light guide are provided by corresponding coils of the spiral spring 500. Specifically, the spiral spring 500 also has a reflective interior. In addition, the proximal end of the spiral spring 500 is fixed to the body of the light guide module 140, so that the most proximal coil 502 of the spiral spring 500 is fixed and provides a fixed light guide 502. On the other hand, one or more other coils 504 of the spiral spring 500 are movable relative to the body of the light guide module 140, so that these other coils 504 provide one or more movable light guides. The advantage of this arrangement structure is that only a single component (a single spiral spring 500) is required to provide fixed and movable light guides and a biasing arrangement structure.

[0135] In any of the examples of light guide modules 140 described above, it may be advantageous to provide one or more additional measures to prevent or at least reduce the amount of external or ambient light that enters the light transmission path from the light source to the subject and / or from the subject to the light detector. Fig.18 An example is schematically shown in FIG. Fig.18 The examples of are generally corresponding to the examples of, for example, FIG. 7 and FIG. 8 , and the same or corresponding parts are marked with the same reference numerals, but for the sake of clarity, not all reference numerals are shown repeatedly. In these examples, each movable light guide 142 is solid, each fixed light guide 150 is a hollow tube, and the hollow tube is coaxially arranged with the corresponding movable light guide 142, and the corresponding spring 170 biases the movable light guide 142 in a direction away from the fixed light guide 150. Fig.18 In the example of FIG. 1 , the spring 170 is positioned in a cylindrical space between the movable light guide 142 and the lower portion of the elongated tubular collar 184 and between the movable light guide 142 and the downwardly protruding portion of the base portion 180 of the light guide module 140. Fig.18 In the example of FIG. 1 , the movable light guide 142 itself has an outer flange 194, and the spring 170 is captured between the outer flange 194 of the movable light guide 142 and the inner flange 190 of the elongated tubular collar 184. However, the same principles can also be used in one or more other examples described herein, where the light guides and biasing arrangements have different arrangements.

[0136] exist Fig.18 In the example shown, the opaque material 600 is positioned in the cylindrical space. In the example shown, the opaque material 600 is in the form of a single ring that surrounds the outside of the movable light guide 142. The opaque material 600 can also adopt other arrangements, such as using several portions of the opaque material 600 to surround the outside of the movable light guide 142. The opaque material 600 can be formed of, for example, black ABS (acrylonitrile butadiene styrene) or some other suitable opaque material. In the example shown, the opaque material 600 completely extends laterally through the cylindrical space at the lower end of the cylindrical space to fill the space at the lower end. The opaque material 600 can act as a light shielding ring to prevent or at least reduce the amount of external or ambient light that enters the light guide 142, 150, that is, enters the light transmission path from the light source to the experimental object and / or from the experimental object to the light detector. This further helps to improve the signal-to-noise ratio.

[0137] Although in Fig.18 In the example of FIG. 1 , the opaque material 600 is positioned at the lower end of the cylindrical space outside the movable light guide 142 , but a similar opaque material 600 may alternatively or additionally be positioned above the cylindrical space and / or toward the top of the cylindrical space.

[0138] In each of the above examples, the distal ends of the light guides that are closest to the experimental subject when in use (i.e., the ends of these light guides that are respectively farthest from the light source or light detector and therefore closest to the experimental subject when in use) extend a relatively long distance from the generally planar base portion 180 of the light guide module 140. This is useful in many applications. However, in certain applications, such as when the device and thus the light guide module 140 are used to study the brain of an infant or young child and are therefore used on a relatively small head, it will be more effective if the light guide module 140 has a lower profile, that is, the overall vertical height of the light guide module 140 is lower, and in particular, the distal ends of the light guides that are closest to the experimental subject when in use do not extend too far from the generally planar base portion 180 of the light guide module 140.

[0139] Fig.19 One example of a low profile light guide module 140 is schematically shown in FIG. Fig.19 The examples correspond roughly to, for example, FIGS. 7 and 8 and Fig.18 In the examples of the present invention, the same or corresponding parts use the same reference numerals, but for the sake of clarity, not all reference numerals are shown repeatedly. In these examples, each movable light guide 142 is solid, each fixed light guide 150 is a hollow tube, the hollow tube is coaxially arranged with the corresponding movable light guide 142, and the corresponding spring 170 biases the movable light guide 142 in a direction away from the fixed light guide 150. However, the same low-profile principle can also be used in one or more other examples described herein, in which the light guides and biasing arrangements have different arrangements.

[0140] It is worth noting that in each of the above examples, if an offset arrangement is provided, the offset arrangement is positioned on the side of the light guide module 140 that is closest to the experimental subject when in use. For example, referring to Figures 7c and 8c and Fig.18 , a biasing arrangement (eg, spring 170 ) is positioned “below” a major plane of a substantially planar base portion 180 of the light guide module 140 .

[0141] In contrast, Fig.19 In the low profile light guide module 140 of FIG. 1 , the biasing arrangement (here a spring 170) for each movable light guide 142 is positioned "above" the main plane of the generally planar base portion 180 of the light guide module 140, i.e., on the side of the light guide module 140 that is farthest from the experimental subject when in use. The biasing arrangement (here a spring 170) is positioned in the lower portion of the elongated tubular collar 184. This allows the overall vertical height of the light guide module 140 to be greatly reduced compared to the above-described examples.

[0142] In this example, this is accomplished by first positioning the inner flange 190 of the elongated tubular collar 184 of the base portion 180 above the outer flange 186 of the elongated tubular collar 184 (i.e., on the side of the outer flange 186 of the elongated tubular collar 184 that is furthest from the subject when in use). In addition, the lower (active) light guide 142 is relatively short, and the outer flange 194 on the lower (active) light guide 142 is located at a relatively high position. Specifically, in this example, Fig.19 In the rest position shown, the outer flange 194 on the lower (movable) light guide 142 is generally coplanar with the generally planar base portion 180 of the light guide module 140 .

[0143] As in the examples described above, the spring 170 is positioned in the cylindrical space between the movable light guide 142 and the lower portion of the elongated tubular collar 184 and is captured between the outer flange 194 of the movable light guide 142 and the inner flange 190 of the elongated tubular collar 184. However, here, the spring 170 is positioned "above" the major plane of the generally planar base portion 180, making the movable light guide 142 relatively short and the overall vertical height of the light guide module 140 relatively small.

[0144] It is noted again that the same low profile principle (the offset arrangement being "above" the major plane of the generally planar base portion 180 of the light guide module 140) may also be used in one or more other examples described herein where the light guides and offset arrangements have different arrangements.

[0145] For the sake of completeness, it should be noted that Fig.19 The example also shows an opaque material 600, which acts as a light shielding ring to prevent or at least reduce external or ambient light from entering the light guides 142, 150, as described above with reference to Fig.18 described.

[0146] In summary, the examples described herein provide a kit of two (or more) light guides for each light source and one or more of the light detectors of a measuring device. At least one of the light guides is a hollow light guide having a reflective interior in which the other light guide can move relative to each other. The use of the hollow light guide with a reflective interior allows relative movement between the light guides while maintaining good light transmission. This allows the distal light guide to be moved into contact with or at least closer to the body of the experimental subject animal when in use, while minimizing light loss and the entry of ambient light.

[0147] The examples described herein are to be understood as illustrative examples of embodiments of the invention. Further embodiments and examples are also contemplated. Any feature described in connection with any one example or embodiment may be used alone or in combination with other features. In addition, any feature described in connection with any one example or embodiment may also be used in combination with one or more features of any other example or embodiment, or in combination with any combination of any other example or embodiment. In addition, equivalent forms and modified forms not described herein may also be used within the scope of the invention as defined by the claims.

Claims

1. A light guide module for use with an apparatus fitted to an animal body for measuring optical properties of a medium within the animal body, the light guide module comprising: Supporting members; a first light guide supported in the support member; as well as a second light guide supported in the support member; wherein one of the first light guide and the second light guide is a fixed light guide, the fixed light guide being fixedly arranged relative to the support member, and wherein the other of the first light guide and the second light guide is a movable light guide, the movable light guide being arranged to be movable back and forth between an extended position and a retracted position relative to the support member; wherein the second light guide is coaxially arranged with the first light guide so that light can pass between the first light guide and the second light guide; wherein at least one of the fixed light guide and the movable light guide is a hollow tube light guide having a hollow interior that receives the other light guide; The interior of the hollow tube light guide is reflective so that when the movable light guide is in the extended position: (a) light entering the end of the hollow tube light guide can pass through the interior of the hollow tube light guide and be reflected internally into the end of the other light guide, the end of the other light guide facing the end of the hollow tube light guide; and / or (ii) light emitted from the end of the other light guide can pass through the interior of the hollow tube light guide and be reflected internally toward the end of the hollow tube light guide. 2 . The light guide module according to claim 1 , wherein the fit between the hollow interior of the hollow tube light guide receiving the other light guide and the other light guide is a clearance fit.

3. The light guide module according to claim 1 or 2, wherein the hollow tube light guide is the fixed light guide and is fixed to and supported by the support member, or is integral with the support member to prevent movement relative to the support member.

4. The light guide module according to any one of claims 1 to 3, wherein the hollow tube light guide is the movable light guide.

5. The light guide module according to any one of claims 1 to 4, wherein one light guide is the hollow tube light guide, and the other light guide is a solid optical fiber or a solid optical fiber bundle.

6. The light guide module according to any one of claims 1 to 5, wherein the first light guide and the second light guide are both hollow tube light guides, each light guide having a reflective interior, wherein one of the hollow tube light guides is the movable light guide capable of moving in and out of the hollow interior of another fixed light guide.

7. The light guide module according to any one of claims 1 to 6, comprising a biasing arrangement for biasing the movable light guide in a direction away from the fixed light guide.

8. The light guide module according to any one of claims 1 to 7, wherein the biasing arrangement comprises a spring arranged to bias the movable light guide in a direction away from the fixed light guide.

9. The optical waveguide module according to any one of claims 1 to 7, wherein the biasing arrangement structure comprises a first magnet fixed relative to the movable optical waveguide and a second magnet fixed relative to the fixed optical waveguide, the magnets being arranged to repel each other to bias the movable optical waveguide in a direction away from the fixed optical waveguide.

10. The light guide module according to any one of claims 1 to 7, wherein the biasing arrangement is provided by a spiral spring having a plurality of coils, at least one of the first light guide and the second light guide being provided by at least one coil of the spiral spring.

11. The light guide module of claim 10, wherein the first light guide and the second light guide are provided by respective coils of the spiral spring.

12. The light guide module according to any one of claims 1 to 11, comprising: a plurality of sets of first and second light guides supported in the support member; Wherein for each set of the first light guide and the second light guide: one of the first light guide and the second light guide is a fixed light guide, the fixed light guide being fixedly arranged relative to the support member, and wherein the other of the first light guide and the second light guide is a movable light guide, the movable light guide being arranged to be movable back and forth between an extended position and a retracted position relative to the support member; The second light guide is coaxially arranged with the first light guide so that light can pass between the first light guide and the second light guide; At least one of the fixed light guide and the movable light guide is a hollow tube light guide having a hollow interior that receives the other light guide; and The interior of the hollow tube light guide is reflective so that when the movable light guide is in the extended position: (a) light entering the end of the hollow tube light guide can pass through the interior of the hollow tube light guide and be reflected internally into the end of the other light guide, the end of the other light guide facing the end of the hollow tube light guide; and / or (ii) light emitted from the end of the other light guide can pass through the interior of the hollow tube light guide and be reflected internally toward the end of the hollow tube light guide.

13. The light guide module of claim 12, wherein each movable light guide is movable back and forth relative to the support member independently of the other movable light guides.

14. A device adapted to be attached to an animal body for measuring an optical property of a medium within the animal body, the device comprising: at least one light source for emitting light towards a body of an animal with which the measuring device is engaged in use; at least one light detector for detecting light returning from the animal body; a first light guide supported in a support member and a second light guide supported in the support member, the first light guide and the second light guide being associated with the light source for transmitting light from the light source to the animal body or associated with the light detector for transmitting light from the animal body to the light detector; wherein one of the first light guide and the second light guide is a fixed light guide, the fixed light guide being fixedly arranged relative to the light source or the light detector, respectively, and wherein the other of the first light guide and the second light guide is a movable light guide, the movable light guide being arranged to be movable back and forth between an extended position and a retracted position relative to the light source or the light detector, respectively; wherein the second light guide is coaxially arranged with the first light guide so that light can pass between the first light guide and the second light guide; wherein at least one of the fixed light guide and the movable light guide is a hollow tube light guide having a hollow interior that receives the other light guide; The interior of the hollow tube light guide is reflective so that when the movable light guide is in the extended position: (i) light entering the end of the hollow tube light guide can pass through the interior of the hollow tube light guide and be reflected internally into the end of the other light guide, the end of the other light guide facing the end of the hollow tube light guide; and / or (ii) light emitted from the end of the other light guide can pass through the interior of the hollow tube light guide and be reflected internally toward the end of the hollow tube light guide.

15. The apparatus according to claim 14, wherein the hollow tube light guide is the fixed light guide and is fixed to and supported by the support member, or is integral with the support member to be fixed against movement relative to the support member.

16. Apparatus according to claim 14 or 15, wherein the hollow tube light guide is the movable light guide.

17. Apparatus according to any one of claims 14 to 16, wherein one light guide is the hollow tube light guide and the other light guide is a solid optical fibre or a bundle of solid optical fibres.

18. The apparatus of any one of claims 14 to 17, wherein the first light guide and the second light guide are both hollow tube light guides, each light guide having a reflective interior, wherein one of the hollow tube light guides is the movable light guide capable of moving in and out of the hollow interior of the other fixed light guide.

19. Apparatus according to any one of claims 14 to 18, comprising a biasing arrangement for biasing the movable light guide in a direction away from the fixed light guide.

20. The apparatus of claim 19, wherein the biasing arrangement is provided by a scroll spring having a plurality of coils, at least one of the first light guide and the second light guide being provided by at least one coil of the scroll spring.

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