Optical measurement attachment apparatus

Abstract

This invention describes an apparatus and a method of use which, in some embodiments, includes an integrated optical window and a mechanism that attaches the apparatus to a surface and also couples to an optical imaging device. The apparatus enables the acquisition of optical images by ensuring a high-quality optical surface and controlling the geometry between the optical imaging device and the surface that is being imaged. The apparatus enables the optical imaging device to be detached and re-attached to the apparatus to enable the acquisition of multiple optical measurements of the same location on the surface at different time points. It may also include a mechanism to stimulate the surface between optical acquisitions.

Description

OPTICAL MEASUREMENT ATTACHMENT APPARATUSCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] The present application claims priority from Australian Provisional Patent Application No.2024903785 titled “OPTICAL MEASUREMENT ATTACHMENT APPARATUS” and fded on 18 November 2024, the content of which is hereby incorporated by reference in its entirety.TECHNICAL FIELD

[0002] The present disclosure relates to optical measurements of a target surface. In a particular form the present disclosure relates to apparatus for obtaining multiple optical measurements of a target surface.BACKGROUND

[0003] Optical measurement techniques use optical apparatus to illuminate a target surface with light, and then measure the response in order to assess the structure, composition or function of a material. The optical apparatus may comprise an emitter apparatus, such as a laser, which emits a light beam towards the target surface, and a receiver apparatus that detects the signal returned from the target surface. One or more optical assemblies may be used to focus the beam towards the target surface, and / or direct the returned signal to the receiver. Signal processing and / or computational apparatus may be used to analyse the responses to perform the desired assessment. Optical measurement techniques may be used to measure one or more optical parameters, and be configured to detect a change in intensity, frequency, phase, polarisation, wavelength, etc. A subset of optical measurement techniques are optical imaging techniques that comprise obtaining multiple optical measurements which are used to reconstruct an image or a volume of the structure, composition or function of a material under the target surface. In this specification, we will typically refer to optical measurement techniques, but it is to be understood that optical imaging techniques are included within this term.

[0004] One example of an optical imaging technique is optical coherence tomography (OCT), in which the target surface is illuminated with light, typically in the near infrared spectrum, and optical backscatter is measured to provide an image of the subsurface structure of the target. Another example is photoacoustic imaging, in which the focused illumination light is used to generate an ultrasound wave in tissue, which is detected using an ultrasound receiver. Other examples of optical measurement techniques include fluorescence, confocal microscopy, multiphoton microscopy, diffuse optical tomography, total internal reflection fluorescence microscopy, phase contrast microscopy, stimulated emission depletion microscopy, near-field scanning optical microscopy, differential interference contrast microscopy, second harmonic imaging microscopy, reflectance spectroscopy, Raman spectroscopy and optical coherenceelastography. These techniques include methods to acquire measurements of the target surface, and also of the material below the target surface. We will refer to the material being measured as the sample and the surface where light is directed into the sample as the target surface .

[0005] However, when applying optical measurement techniques, it can be difficult to acquire high-quality measurements of the sample. In particular, the optical beam can be distorted or attenuated by interactions that occur with the light beam before the light beam reaches the sample, or at the surface of the sample. Additionally, it can be difficult to accurately position the sample relative to the focal plane of the optical assembly, which will adversely affect the quality of the optical measurements.

[0006] Further, in many instances it is desirable or required to acquire multiple measurements at the same location on the sample. For example, when imaging skin using OCT or photoacoustic imaging, it may be useful to acquire measurements of the same section of skin both before and after the skin has undergone heating. Heating of the skin induces increased blood flow and vasodilation. Heating a local region of the skin to 44 degrees Celsius for a period of time such as 30 minutes has been shown to maximally dilate the blood vessels. In some diseases, such as diabetes, the difference between the blood flow at a baseline state (i.e. before heating) and after local heating has been shown to relate to disease state. Differences have also been observed between the baseline, resting blood flow and after local heating in patients with heart failure. The change between the blood flow at a baseline, resting state and after local heating has also been shown to relate to the thermoregulatory response of the human or animal being assessed. Another useful stimulation of the skin is flow-mediated dilation. In flow-mediated dilation, blood flow is restricted to a section of the body for a period of time, possibly by placing a restrictive cuff around a part of the body. For example, an inflatable cuff may be placed around an arm or leg to restrict peripheral blood flow. When the restriction is released, blood flow returns and the blood vessels will dilate. The amount of vessel dilation; the time delay between releasing the restriction and achieving maximal dilation, and the time taken until the blood vessels return to their baseline state are all indicative of the state of the blood vessels and provides information on disease and pathology. By acquiring multiple optical measurements during flow-mediated dilation, we are able to characterise and / or quantify the state of the blood vessels and calculate information about disease and pathology.

[0007] However, a confounding factor in acquiring these measurements is that it can be difficult to acquire measurements from the same location on the skin, due to the time interval between the first and second set of measurements and the need to detach and re -attach the scanner to the subject’s skin between measurements. If the subsequent measurements are acquired at a different location, then any observed changes may be due to the apparatus observing different blood vessels located at different locations under the skin. It is thus desirable to acquire measurements from the same location.

[0008] There is thus a need to provide optical systems, apparatus and methods for accurately positioning the optical system to acquire a set of optical measurements from a sample, including repeatedly acquiring measurements from the same location of the sample, or to at least provide a useful alternative to existing optical systems, apparatus and methods.SUMMARY

[0009] An optical measurement attachment system and associated method of use will be described which comprises a first optical measurement attachment which can be secured to a target surface, such as the skin of a human, and which can be repeatedly coupled and decoupled from a second coupling arrangement. The second coupling arrangement is fitted to an optical measurement apparatus used for taking optical measurements of, or under, the target surface. The optical measurement attachment apparatus supports an optical barrier such as an optical window close to the target surface, and various arrangements are described that allow a fluid layer to be created between the optical barrier and the target surface to improve the quality of the captured optical measurements. The ability to decouple the first optical measurement attachment from the typically bulky optical measurement apparatus via the second coupling arrangement facilitates the collection of high quality measurements, and the ability to repeatedly de-couple and recouple facilitates the capture of repeated time spaced measurements of the same target surface.

[0010] According to a first aspect, there is provided an optical measurement attachment apparatus comprising:a body;an optically transparent fluid barrier that forms at least of a portion of a proximal surface of the body; anda first coupling apparatus configured for removable attachment to a second coupling apparatus configured to attach to, or is part of, an optical measurement apparatus,wherein, when used, the body is configured to be secured to a target surface using a securing arrangement that is independent of the second coupling apparatus, and the optically transparent fluid barrier is configured to allow light from the optical measurement apparatus to pass through the optically transparent fluid barrier and into the target surface, and a fluid is placed on a surface or released into a gap between the optically transparent fluid barrier and the target surface such that the fluid contacts both the optically transparent fluid barrier and the target surface to form a fluid layer and the body is configured to allow excess fluid to flow off or away from the optically transparent fluid barrier.

[0011] In one form the body further comprises one or more fluid channels adjacent to the optically transparent fluid barrier to allow the excess fluid to flow off or away from the optically transparent fluid barrier.

[0012] In some forms, the fluid channels may be formed in the proximal surface and the optically transparent fluid is placed on the proximal surface of the optically transparent fluid barrier or the target surface prior to securing the body to the target surface and as the body is secured to the target surface, excess fluid is driven off or away from the optically transparent fluid barrier. The fluid channels may extend distally away from the proximal surface or may be grooves extending from the optically transparent fluid barrier to an edge of the body.

[0013] In one form the body further comprises a first cavity extending distally of the proximal surface and wherein the optically transparent fluid barrier forms at least a portion of a distal wall of the cavity, and the one or more fluid channels are formed in one or more walls of the first cavity. The fluid channels may be formed in a second portion of the distal wall of the cavity, and / or the fluid channels may be formed in one or more side walls of the first cavity. The depth of the first cavity may be selected based on one or both of a viscosity of the fluid and a depth of field of the optical measurement apparatus.

[0014] In some forms, the optical measurement attachment apparatus further comprises:a fluid movement apparatus configured to drive the fluid into or through the first cavity such that when the optically transparent fluid barrier is located in a measurement position the fluid fills the gap between the optically transparent fluid barrier and a target surface on which the body is located.

[0015] In one form, the fluid movement apparatus comprises an optically transparent fluid barrier support configured to support the optically transparent fluid barrier and to guide movement of, or move, the optically transparent fluid barrier into the measurement position, wherein in use, prior to moving the optically transparent fluid barrier into the measurement position the first cavity is at least partially filled with the fluid and when the optically transparent fluid barrier is moved into the measurement position the movement is configured to drive fluid out of the first cavity. In a further form, the optically transparent fluid barrier support may comprise a support body with a proximal end portion and an interior distal cavity extending distally of the optically transparent fluid barrier, and the proximal end portion is configured to be received in a distal portion of the first cavity and driven towards the proximal surface to drive the fluid present in the first cavity out of the first cavity. In a further form, the fluid movement apparatus may comprise a conduit extending from an interior aperture located in a side wall of the first cavity to or through an outer wall of the body or to a fluid reservoir to allow fluid to be introduced into the first cavity, and when the optically transparent fluid barrier is moved into the measurement position the proximal end portion is configured to drive fluid out of the conduit. In a further form, the first cavity may be a shaft with a first axis and a constant interior cross sectional profile, and the proximal end portion has an exterior wall portion with a cross sectional profile matching the constant interior cross sectional profile to allow the proximal end portion to be received in the shaft and the exterior wall portion is configured with a first length in the first axial direction (i.e. aligned with the first axis) exceeding a second length in the first axial direction of the interior aperture such that when the optically transparentfluid barrier is moved into the measurement position the exterior wall portion covers the interior aperture to close the conduit. In a further form, the fluid movement apparatus may further comprise a locking mechanism for locking the optically transparent fluid barrier in the measurement position wherein the locking mechanism comprises a deformable or resilient projection located on the exterior wall of the support body and a matching receiving portion located on an interior surface of the body, such that when the proximal end portion is received in the first cavity, the deformable or resilient projection is deformed or compressed until it reaches the receiving portion.

[0016] In one form, optical measurement attachment apparatus may further comprise a locking mechanism for locking the optically transparent fluid barrier in the measurement position.

[0017] In one form, wherein the fluid movement apparatus may comprise a conduit extending from an interior aperture located in a side wall of the first cavity to or through an outer wall of the body or to a fluid reservoir to allow the fluid to be introduced into the first cavity, or to be driven out of the first cavity when the first cavity is filled or partially filled.

[0018] In one form the optically transparent fluid barrier may be fixed in the measurement position, and the first cavity comprises a first aperture in a side wall, and the fluid movement apparatus is a pump configured to drive the fluid from a fluid reservoir into the first cavity through the first aperture, or a pump configured to draw fluid in the first cavity through the first aperture.

[0019] In one form, when the apparatus further comprises the fluid movement apparatus, the optically transparent fluid barrier forms at least part of a distal surface of the first cavity located above the proximal aperture and forms part of an optical path extending from the proximal aperture through the body of the optical measurement attachment apparatus to a distal aperture in the body. In a further form, the measurement position is located to define an optical path of a predetermined length.

[0020] In one form, when the apparatus further comprises the fluid movement apparatus, the optical measurement attachment apparatus may further comprise a locking mechanism for locking the optically transparent fluid barrier in the measurement position.

[0021] In one form, when the fluid movement apparatus is in the measurement position, the optically transparent fluid barrier may be located within 200 microns of the target surface.

[0022] In one form, when the apparatus further comprises the fluid movement apparatus, the optically transparent fluid barrier is an optical window that may be mounted on an angle with respect to a plane defined by the proximal aperture in the proximal surface, wherein the angle is less than 10 degrees.

[0023] In one form, the optically transparent fluid barrier is an optical window. In one form, one surface is flat and an opposing surface is slanted with a slant angle of less than 10 degrees.

[0024] In some forms, the optical measurement attachment apparatus further comprises a cover for the proximal surface, and the cover further includes a releasable fluid reservoir containing the fluid, and the fluid reservoir is further configured to release the fluid onto one or both of the proximal surface of the optically transparent fluid barrier and the target surface prior to or as the cover is removed.

[0025] In some forms, the first coupling arrangement comprises a plurality of castellations and one or more magnets located in a distal portion of the body.

[0026] In one form, the optical measurement attachment apparatus may further comprise the securing arrangement configured to attach and secure the body to the target surface. In a further form, the securing arrangement may be an adhesive portion located on the proximal surface and configured to attach and secure the body to the target surface.

[0027] In one form, the first coupling apparatus may further comprise a rotational alignment arrangement that is configured to allow the optical measurement attachment apparatus to be repeatedly attached to the second coupling apparatus in the same rotational orientation. In some forms each of the first and second coupling apparatus further comprise an alignment indicator, wherein one alignment indicator is fixed and the other alignment indicator is a moveable alignment indicator that may be placed at a range of rotational orientations. In some forms matching castellations may be formed in first and second coupling apparatus to assist in ensuring rotational alignment. In a further form, the moveable alignment indicator is formed of a magnetic material and is magnetically attached to the respective coupling apparatus.

[0028] In one form, the optical measurement attachment apparatus may further comprise a stimulation apparatus configured to allow stimulation of the target surface when the apparatus is attached to the target surface. In a further form, the stimulation apparatus may be a heating apparatus surrounding, adjacent, or integrated with the proximal surface.

[0029] In one form, the optical measurement attachment apparatus may further comprise a pressure control system configured to control a pressure on the target surface. The pressure control system may include a feedback arrangement including one or more force sensors and an indicator to indicate if the pressure is within an acceptable range, or it may be configured to apply a target pressure.

[0030] In one form, one or more of the body, the first coupling apparatus, the second coupling apparatus, or the pressure control system is configured to control a location of a focal plane of the system. The location may be a depth in the target surface.

[0031] Any of the above forms may be combined with the optical measurement attachment apparatus of the first aspect. Further any of the above forms may be combined with any other form. That is any of the above features or forms maybe combined in any combination with any of the other features or forms. According to a second aspect, there is provided an optical measurement attachment system comprising the optical measurement attachment apparatus of the first aspect (and any of the above additional features, forms or variations), and a second coupling apparatus configured to attach to an optical measurement apparatus.

[0032] In one form, the first coupling arrangement comprises an annular magnet located in a distal portion of the body and the second coupling arrangement comprises a magnetically sensitive material. In one form, the first coupling arrangement comprises a magnetically sensitive material located in a distal portion of the body and the second coupling arrangement comprises an annular magnet. In some forms the first and second coupling arrangements comprises matching castellations.

[0033] In one form, the system further comprises a stimulating apparatus comprising one or more stimulating elements surrounding, adjacent, or integrated with the proximal surface, an integrated power supply and stimulation controller, and a cable connecting the integrated power supply and stimulation controller to the one or more stimulating elements. In a further form, the cable is a removable cable comprising a connector in one or both ends of the cable and in use the cable is removably connected to one or both of the optical measurement attachment apparatus and the integrated power supply and stimulator controller. In further forms, the stimulation apparatus may be a heater, and the one or more stimulating elements are one or more heating elements.

[0034] In one form, the system further comprises a fluid comprising glycerol, water, ultrasound gel, water based optically transparent lubricant, or an optically transparent oil. The system may further comprises a syringe or a pipette containing the fluid, and / or a fluid carrier configured to attach to a proximal end of the body, and comprising a second cavity, wherein in use, the second cavity is adjacent to the optically transparent fluid barrier and fluid is introduced into the second cavity either prior to or after the fluid carrier is attached to the body, and then the fluid carrier is removed and the body is secured to the target surface.

[0035] According to a third aspect, there is provided a method of collecting one or more optical measurements from or in a target surface using the optical measurement attachment apparatus of the first aspect, comprising:forming a fluid layer between the optically transparent fluid barrier of the optical measurement attachment apparatus and the target surface and allowing excess fluid to flow off or away from the optically transparent fluid barrier wherein the fluid layer is formed either by placing a fluid on one or more of the target surface, the proximal surface of the optical measurement attachment apparatus, and the optically transparent fluid barrier, and securely placing the optical measurement attachment apparatus on the target surface such that the fluid contacts both the optically transparent fluid barrier and the target surface to form the fluid layer, or by securely placing the optical measurement attachment apparatus on the target surface and releasing an optical fluid into a gap between the optically transparent fluid barrier and the target surface such that the fluid contacts both the optically transparent fluid barrier and the target surface to form the fluid layer;coupling the first coupling apparatus of the optical measurement attachment apparatus to the second coupling apparatus attached to a first optical measurement apparatus; andcapturing a first set of one or more optical measurements using the first optical measurement apparatus.

[0036] In a further form, the fluid escapes the edge portion into one or more fluid channels in the body located adjacent to the optically transparent fluid barrier.

[0037] In a further form the fluid is placed or released prior to securing the optical measurement apparatus to the target surface. In an alternative form the fluid is placed or released after or whilst securing the optical measurement apparatus to the target surface .

[0038] In a further form, placing the optical measurement attachment apparatus on a target surface comprises securing the optical measurement attachment apparatus to a target surface using a securing arrangement; and the method further comprises:uncoupling the first optical measurement apparatus;coupling the first coupling apparatus to the second coupling apparatus attached to the first optical measurement apparatus, or to a third coupling apparatus attached to a second optical measurement apparatus; andcapturing a second set of one or more optical measurements using the first optical measurement apparatus or the second optical measurement apparatus.

[0039] In a further form the first coupling apparatus of the optical measurement attachment apparatus is attached to the second coupling apparatus of a first optical measurement apparatus in a first rotational orientation, and securely placing the optical measurement attachment apparatus on a target surface comprises securing the optical measurement attachment apparatus to a target surface using a securing arrangement; and the method further comprises:uncoupling the first optical measurement apparatus;coupling the first coupling apparatus to the second coupling apparatus attached to the first optical measurement apparatus in the first rotational orientation, or to a third coupling apparatus attached to a second optical measurement apparatus in the first rotational orientation; andcapturing a second set of one or more optical measurements using the first optical measurement apparatus or the second optical measurement apparatus.

[0040] In a further form, the method further comprises stimulating the target surface for a first time period between capturing the first set of one or more optical measurements and the second set of one or more optical measurements.

[0041] In a further form, the stimulation comprises one or more of heating the target surface using a heating apparatus, stimulating the target surface with a stimulating apparatus, or stimulating the target surface with a chemical or a pharmaceutical substance, or stimulating a person, an animal or a biological tissue associated with the target surface with a pharmaceutical substance .

[0042] In one form, the fluid comprises glycerol, water, an ultrasound gel, a water based optically transparent lubricant, or an optically transparent oil.BRIEF DESCRIPTION OF DRAWINGS

[0043] Embodiments of the present disclosure will be discussed with reference to the accompanying drawings wherein:

[0044] Figure 1 A is a side view of an optical measurement attachment system above a target surface, and comprising an optical measurement attachment apparatus and an optical measurement apparatus (or second) coupling apparatus according to an embodiment;

[0045] Figure IB is a bottom rear perspective view of the embodiment of the optical measurement attachment apparatus shown in Figure 1A showing the proximal surface, optically transparent fluid barrier in the form of an optical window, and fluid channels located adjacent to the optical window;

[0046] Figure 1C is a sectional view through the embodiment of the optical measurement attachment apparatus shown in Figure 1A;

[0047] Figures ID through 1H show a method of use of the embodiment of optical measurement attachment apparatus shown in Figure 1A, in which Figure ID shows the optical measurement attachment apparatus above a securing arrangement in the form of an annular pad with adhesive on both proximal and distal surfaces prior to securing to the target surface along with a syringe containing a fluid, FigureIE shows the pad secured to the target surface, Figure IF shows the central aperture of the annular securing pad fdled with the optical fluid from the syringe, Figure 1G shows the optical measurement attachment apparatus securely placed on the annular securing pad and Figure 1H shows a sectional view of Figure 1G through section AA of Figure 1G showing the fluid forming a layer between the optically transparent fluid barrier and the target surface and excess fluid flow away from the optically transparent fluid barrier and into fluid channels adjacent to the optically transparent fluid barrier;

[0048] Figures II and 1 J are respectively exploded side and exploded perspective views of the embodiment of the optical measurement attachment system shown in Figure 1A;

[0049] Figures IK, IL, IM and IN are respectively assembled top, first side, second side, and bottom views of the embodiment of the optical measurement attachment system shown in Figure 1A;

[0050] Figure 10 is a flowchart of a method of attaching an optical measurement apparatus to a target surface according to an embodiment;

[0051] Figure 2 is a side view of the optical measurement attachment apparatus shown in Figure 1 A and an embodiment of a cover comprising a pad with an adhesive proximal surface filled with a fluid in a central aperture and a peelable protective layer;

[0052] Figure 3A, 3B and 3C are respective side and perspective views of the optical measurement attachment system shown in Figure 1A attached to a stimulation apparatus according to embodiment;

[0053] Figures 3D, 3F and 3G are respective side, top and perspective views of the optical measurement attachment apparatus shown in Figure 1A and cable connector for connection to the stimulation apparatus according to embodiment;

[0054] Figure 3E is an end view of the cable connector for connection to the stimulation apparatus according to embodiment;

[0055] Figures 3H and 31 are respective side and top views of the assembled optical measurement attachment system shown in Figure 3B attached to the optical measurement apparatus and the stimulation apparatus according to embodiment;

[0056] Figure 4A is a side sectional view of another embodiment of an optical measurement attachment apparatus;

[0057] Figure 4B is a bottom view of the embodiment of an optical measurement attachment apparatus shown in Figure 4A;

[0058] Figure 4C is a botom view of another embodiment of an optical measurement atachment apparatus;

[0059] Figure 5 is side view of several embodiments of the optically transparent fluid barrier;

[0060] Figure 6A is a side view of an optical measurement attachment system comprising an optical measurement atachment apparatus and an optical measurement apparatus coupling apparatus according to an embodiment;

[0061] Figures 6B, 6C, 6D and 6E are respective first side, second side, oblique and top views of the optical measurement atachment apparatus shown in Figure 6A according to an embodiment;

[0062] Figure 6F is a section view through section A-A of Figure 6C illustrating the optical window prior to movement into a measurement position to allow a filling of first cavity with an optically transparent fluid according to an embodiment;

[0063] Figure 6G is a section view through section A-A of Figure 6C illustrating the optical window in a measurement position according to an embodiment;

[0064] Figures 6H, 61, and 6K are respective first side, top and oblique and top views of the optical measurement apparatus coupling apparatus shown in Figure 6A according to an embodiment;

[0065] Figure 6J is a section view through section A-A of Figure 6H according to an embodiment;

[0066] Figures 7A to 7F are top, first oblique, first side, second oblique, second side, and sectional views of a rotational alignment arrangement according to an embodiment;

[0067] Figure 7G is a side view of an optical measurement attachment apparatus showing hidden components according to another embodiment;

[0068] Figures 7H and 71 are a schematic illustration of the fluid movement apparatus according to an embodiment;

[0069] Figure 7J is a schematic illustration of the fluid movement apparatus according to another embodiment;

[0070] Figures 8A to 8H are illustrations of the steps of the method of attaching an optical measurement apparatus to a target surface according to an embodiment;

[0071] Figure 9A shows an embodiment of the optical measurement attachment apparatus attached to skin (target surface) of the foot of a human prior to attaching the optical measurement apparatus;

[0072] Figure 9B shows the assembled optical measurement attachment system including the optical measurement attachment apparatus connected to the second coupling apparatus 70 which is attached to an OCT scanner (the optical measurement apparatus) which is being used to take a measurement on the foot of a human;

[0073] Figure 10A is first black and white image of blood vessels of a human captured by an optical coherence tomography apparatus coupled to an embodiment of an optical measurement attachment system; and

[0074] Figure 10B is second black and white image of blood vessels after heating of the skin captured by an optical coherence tomography apparatus coupled to an embodiment of an optical measurement attachment system.

[0075] In the following description, like reference characters designate like or corresponding parts throughout the figures.DESCRIPTION OF EMBODIMENTS

[0076] Embodiments of an optical measurement attachment apparatus 10, an optical measurement attachment system 1, and a method 100 for using an optical measurement attachment system will be described. The optical measurement attachment system 1 comprises an optical measurement attachment apparatus 10 and an optical measurement apparatus coupling apparatus 70, or more concisely, a second coupling apparatus 70, configured to attach to an optical measurement apparatus 90 used to obtain one or more optical measurements. A securing arrangement 15, which is independent of the second coupling apparatus 70, may be used to secure the optical measurement attachment apparatus to the target surface 2. In the description that follows proximal and distal are defined with respect to the target surface 2.Embodiments of the system 1 are configured to reliably collect or obtain a single set of measurements from an optical measurement apparatus 90 placed on a target surface 2 (where a set may be one or more measurements). Additionally, the system is configured to allow collection of two or more sets of optical measurements when the optical measurement apparatus 90 is removed between the sets of measurements whilst the optical measurement attachment apparatus 10 is left secured in place on the target surface 2 via the securing arrangement 15. To improve the quality of the measurements a fluid layer is created between the optically transparent fluid barrier (e.g. optical window) 22 in the optical measurement attachment apparatus 10 and the target surface 2. The fluid in the fluid layer fills in any minor undulations in the target surface and the presence of the fluid layer reduces any optical mismatches between a light beampassing through the optical window into the target surface, such as a human’s skin, which can generate unwanted reflections or aberrations. That is the fluid acts as an impedance matching substance to enhance transmission of the optical beam into the target surface, as well as reception of reflected or re -emitted optical signals from within the target surface. The fluid also assists in preventing the trapping or formation of air bubbles which may cause unwanted reflections and reduce the quality of transmission of the optical beam into the target surface and any subsequent reflected or re -emitted optical signals.

[0077] The system and apparatus may be used to obtain optical measurements of a range of target samples and applications using an optical measurement apparatus 90. Some optical measurement apparatus, such as optical coherence tomography (OCT) apparatus have a fixed focal length and a depth of field of a few hundred microns up to around a millimetre, and it is desirable to locate the focal plane a few hundred microns below the target surface, so that as much of the sample region as possible is in focus. This includes medical diagnostic applications where the apparatus may be applied to a patient’s skin or any human’s skin, for example an OCT apparatus may be configured to collect an image of the subsurface structure such as the blood microvessels (e.g., blood vessels in the range of 30pm- 200pm in diameter) down to around 1 mm or so under the skin. However, it is to be understood that the system, apparatus and methods described herein may be used for optical measurements or optical images of any objects where it is desirable to reliably capture a measurement of a target sample, or where it is desirable to obtain multiple measurements at the same locations at two or more time points. That is, the system may be used on humans, animals, plants, biological samples, food, as well as soils, structural members, building materials, physical structures, 3D printed objects, and other non-biological samples. For example, a measurement of a human could be performed to assess their skin blood flow to predict how well they can thermoregulate or to assess their capacity to heal wounds in their skin. A measurement could be taken of a physical structure to characterise a property of the substructure, or a change in the substructure, that may be evidence of fatigue, cracking, or wear. The target surface 2 may thus be flexible, deformable, and / or resilient surfaces, as well as rigid surfaces. The apparatus is configured to make it easy for an operator to collect measurements by allowing an optical measurement attachment apparatus to be decoupled from the optical measurement apparatus which is typically large and cumbersome to place. The user can easily place the attachment apparatus onto the target surface and ensure that the optical window is in a desired position to enable capturing optical measurements before attaching a typically larger and cumbersome optical measurement apparatus. Further the modular nature allows the measurement apparatus to be uncoupled and removed from the optical measurement attachment apparatus which remains attached to the target surface. This facilitates reliable capture at the same location for widely spaced capture time points, or to allow two different optical measurement apparatus to capture measurements over the same target surface.

[0078] Several embodiments will now be described to illustrate various features and variations. As there are various features, and to keep the disclosure compact, it is to be understood that features shown in one embodiment (or variation) may be used in another embodiment, unless explicitly disclaimed or where they are clearly an alternative or incompatible feature. It is expected that the skilled person will select various features as required depending upon the specific requirements of the application.

[0079] Various embodiments are described that are designed to allow fluid 66 to be placed or released to form a fluid layer between the optically transparent fluid barrier (e.g. optical window) 22 in the optical measurement attachment apparatus 10 and the target surface 2, and which allow excess fluid to flow off or away from the optically transparent fluid barrier. These include both static systems in which placing and or securing the optical measurement attachment apparatus 10 creates the fluid layer, or active systems in which fluid is actively driven into or through a cavity in which the optically transparent fluid barrier 22 is a distal surface, or gap between the optically transparent fluid barrier 22 and target surface 2 to form the fluid layer. Figures 1A through 4C illustrate static embodiments in which the secure placement of the optical measurement attachment apparatus 10 is used to create the fluid layer, and Figures 6A through 8H illustrate embodiments in which the system is designed with a fluid movement apparatus to drive the fluid to form the fluid layer. In some embodiments the body 12 of the optical measurement attachment apparatus 10 includes one or more fluid channels 30 to allow excess fluid to flow off or away from the optically transparent fluid barrier.

[0080] Referring now to Figure 1A there is shown a side view of an embodiment of an optical measurement attachment system 1 above a target surface 2, and comprises an optical measurement attachment apparatus 10 (i.e., the first coupling apparatus) and an optical measurement apparatus coupling apparatus 70 which we will more concisely refer to as the second coupling apparatus. This arrangement allows repeated coupling and decoupling of the optical measurement apparatus coupling apparatus 70 from the optical measurement attachment apparatus 10. Figure IB is a bottom rear perspective view of the embodiment of the optical measurement attachment apparatus shown in Figure 1A and Figure 1C is a sectional view through the embodiment of the optical measurement attachment apparatus shown in Figure 1A. Figures ID through 1H show a method of use of the embodiment of optical measurement attachment apparatus shown in Figure 1A, Figures II and 1J are respectively exploded side and exploded perspective views of the embodiment of the optical measurement attachment system shown in Figure 1A and Figures IK, IL, IM and IN are respectively assembled top, first side, second side, and bottom views of the embodiment of the optical measurement attachment system shown in Figure 1A. Figure 10 is a flowchart of a method of collecting one or more optical measurements from or in the target surface using an embodiment of the optical measurement attachment system (i.e. method of use of the optical measurement apparatus).

[0081] The optical measurement attachment apparatus 10 comprises a body 12 that supports an optically transparent fluid barrier 22 and a first coupling arrangement 38 for coupling (or connection) to a second coupling arrangement 81 of the second coupling apparatus 70. The body has a proximal surface 12 which is placed on the target surface 2. The proximal surface 14 may be configured to secure the body 12 to the target surface, for example via an adhesive on the proximal surface 14 or via a separate securing arrangement 15, such as an annular pad with adhesive on both proximal and distal layers (see Figures ID through 1H). As shown in Figures IB and 1C, in this embodiment the optically transparent fluid barrier 22 is an optical window and the body 12 is a two part body comprised of a lower optical window support body 24 and an upper body 28. The lower optical window support body 24 supports the optically transparent fluid barrier 22 and has a screw thread to allow the lower optical window support body 24 to be screwed into a proximally extending portion (i.e., shaft portion) of the upper body 28. The upper body also includes the first coupling arrangement 38 on a distal portion.

[0082] In this embodiment the optical window support body 24 is formed as a central shaft which supports the optically transparent fluid barrier 22 with a lower disk shaped support 27 extending laterally (or radially) from the central shaft to act as a support platform for the body 12 on the target surface 2, either directly on the target surface 2 or via a securing arrangement 15. A series of fluid channels 30 are located adjacent the optically transparent fluid barrier 22 and extend through the lower disk shaped support 27. In this embodiment the optically transparent fluid barrier 22 is located at the proximal end of central shaft and distal exterior portion of the shaft is fitted with a screw thread 60 which is screwed into a matching thread on the proximally extending portion (i.e. shaft portion) of the upper body 28. The optically transparent fluid barrier 22 acts as a barrier to stop fluid located below the body from entering the central shaft, and also forms an interior cavity 42 in the central shaft through with the optical beam from the measurement apparatus 90 can pass.

[0083] The optically transparent fluid barrier 22 may form at least a portion of a distal wall of the cavity 16, and the fluid channels 30 may be formed in one or more walls of the cavity 16. As shown in Figure IB the fluid channels 30 may are formed in a second portion of the distal wall of the cavity 16. In other embodiments one or more fluid channels may be formed in one or more side walls of the cavity 16. In some embodiments a depth of the first cavity 16 is selected based on one or both of a viscosity of the fluid 66 and a depth of field of the optical measurement apparatus 90. The viscosity of the fluid affects how rapidly the fluid flows, and thus can form the fluid layer. For example, with a low viscosity fluid, the depth may be small, as there is greater likelihood of flow of fluid away from the optically transparent fluid barrier 22 before it is secured, and this may increase the risk of trapping of air bubbles in the gap between the optically transparent fluid barrier 22 and the target surface 2. A higher viscosity fluid may allow a larger depth for the cavity.

[0084] In this embodiment the lower disk shaped support 27 also integrates (or supports) an annular stimulation element 46, which in this embodiment is a heating element. The heating element is comprised of a printed circuit board (PCB) ring in which multiple individual heating elements are mounted. A port 93 is provided in the lower disk shaped support 27 for connection of a cable to a stimulation (e.g. heater) controller and integrated power supply (e.g. a battery) 96. In other embodiments the heating element could be replaced with another stimulating element (e.g. mechanical vibrations, or electromagnetic), or may be omitted completely. In other embodiments, the cable is permanently connected to the optical measurement attachment apparatus 10 but may be connected or disconnected from the stimulation controller and integrated power supply 96.

[0085] In some applications, the flow of blood in the skin is impacted by how much pressure the optical measurement attachment system, and in particular the proximal surface 14, applies to the target surface 2 during a measurement. This may be affected by factors such as the weight and orientation of the optical measurement attachment system (and in particular the optical measurement apparatus 90 which tends to be the heaviest and bulkiest part of the system), the thickness or substructure of the skin 2, and whether a user or a support structure is holding or supporting the optical measurement apparatus 90 during measurements. In some cases, if too much pressure is applied to the skin, the excess pressure can drive out blood or restrict blood flow within the imaging region adversely impacting or even preventing measurement of blood flow. For example, the skin over the foot is thin compared to that over an arm, and thus is more sensitive to the applied pressure.

[0086] Thus, in some embodiments the optical measurement system may be configured with a pressure control system to control the amount of pressure on the target surface, (i.e., the amount of pressure can be varied) or the optical measurement system configured to exert a predetermined amount of pressure on the target surface. In the following discussion the terms pressure and force will be used interchangeably given they are related concepts (i.e. pressure is force per unit area). Also the predetermined amount of pressure may be a target value, or an acceptable range of values, and may be determined through a calibration process. The pressure control system may include a feedback arrangement including one or more force sensors and an indicator to indicate if the pressure is within an acceptable range, e.g., so a user can make an adjustment if the desired amount of pressure is not being applied, or the system may be configured to either apply the desired amount of pressure or to actively sense the amount of pressure and adjust the system to apply the desired amount of pressure. That is the feedback system could be automated, or semimanual where one or more indicators are used to indicate to a user if the pressure is acceptable or not (e.g., matches a target value or is withing an acceptable range). The pressure control system may be located in the first attachment apparatus 10, the second coupling apparatus 70 or some combination.

[0087] In some embodiments the pressure control system comprises one or more force sensors 25 to measure the force (or a pressure) exerted by the body on the target surface. The force sensors may beintegrated into the lower shaped support 27, or some other part of the body, or in the second coupling apparatus 70. The force sensors 25 may be a strain gauge, a piezoresistive material or a piezoelectric material, a material that changes its capacitance when a load is applied, or a sensor that uses induction to measure force, or an optical sensor such as a Bragg grating or interferometry based sensor. A control system or a reporting circuit or system may also be incorporated and be configured to measure if the force matches the predetermined target value or is within an acceptable range. An output indicator may be used to indicate if the force is within the range or not. For example, a green LED could be switched on if the pressure is within range, or optionally a red LED could be switched on if the pressure is outside of the range. The indicator could also be an audio emitter that emits a sound (e.g., a beep or series of beeps) if the sensor is within the range or outside of the range. In some embodiments a user could observe the image generated by the optical measurement apparatus and an indicator displayed on the screen to indicate if the force is within an acceptable range, for example based on analysing the image.

[0088] The pressure control system may be configured to control the pressure using a mechanical arrangement. For example the mechanical arrangement could be a spring based arrangement that comprises two flat annular rings with one or more springs located between the two rings, and an adjustment arrangement provided to allow one of the rings to be driven towards the other ring to compress the springs between the two plates. The adjustment arrangement may be a screw thread based arrangement so that the second plate can to be raised or lowered by rotating (screwing) the adjustment arrangement. In other embodiment the adjustment arrangement may be a lever and a cam arrangement or a motorised system could be used to drive the second plate towards the first plate.

[0089] In one embodiment the spring based arrangement could be located in the optical measurement attachment apparatus 10 where the first ring is the annular ring 46 and the second ring and coiled springs are located within the body. The springs could be selected to have a spring rate sufficient to generate the target force. The height of the second ring could be adjustable using a lever on the exterior of the optically transparent fluid barrier support 24 to drive a cam, or a screw thread arrangement between the body 12 and the optically transparent fluid barrier support 24. In another embodiment this arrangement could be located in the second coupling arrangement 70 and associated with a screw thread used to screw the second coupling arrangement 70 onto the optical measurement apparatus 90 so that the amount of pressure applied by the second coupling apparatus to the first attachment apparatus is controlled by adjusting the connection of the second coupling arrangement 70 to the optical measurement apparatus 90.

[0090] In some embodiments the optical measurement apparatus may be supported on a support arrangement, such as set of adj ustable / pi votable linked support arms, which may be used to control the pressure applied to the target surface (e.g., by taking some of the weight / force of the optical measurement apparatus 10). This could be used in conjunction with a force sensor which indicates when the pressure (or force) applied to the target surface is within the desired range.

[0091] Some optical measurement apparatus, such as OCT apparatus have a fixed focal length and a depth of field of several hundred of microns (e.g. 300-700 microns), and it is desirable to locate the focal plane a few hundred microns below the target surface, so that as much of the sample region as possible is in focus. Thus in some embodiments one or more of the body, the first coupling apparatus, the second coupling apparatus, or the pressure control system is configured to control a location of a focal plane of the system. The location may be a depth in the target surface. The location of the focal plane may be controlled or varied controlling the length of the optical path and / or a height or location of the optical transparent fluid barrier 22 (e.g. lens) in order to control the depth / location of the focal plane. In some embodiments the pressure control system is configured such that when the predetermined (target) pressure is applied, the focal plane is also located at the desired location or depth. For example, in the above example using a pair of rings and springs, the height of the second ring may be adjusted such that the height which compresses the springs to apply the target pressure is also an acceptable height for capturing measurements (e.g. places the focal plane just under the skin).

[0092] In other embodiments the stimulating element 46 could be a pressure stimulation apparatus to control the pressure applied by to the target surface 2, for example by annular ring 46, and thus enable measurements at two different pressures (e.g. a low pressure and a high pressure). For example, the above described spring arrangement could be integrated into the optical measurement apparatus 10 and lever and cam or screw thread used to adjust a height of the second ring with respect to the first ring 46. For example the second ring could be located at two heights with respect to the first ring 46 creating two pressure states (e.g. a low pressure and a high pressure). A first set of measurements could be taken with the second ring at a first height, and a second set of measurements taken with the second ring at the second height (springs more compressed). Measurements at the two different pressures can then be compared.

[0093] In this embodiment the proximal surface of the body is formed by the proximal surface of the lower disk shaped support 27, proximal surface of the heating element and the proximal surface of the optically transparent fluid barrier 22. In this embodiment the annular surface comprising the fluid channels 30 and optical window are slightly recessed with respect to the heating surface to create a small cavity 16. That is the proximal surface 14 is not a completely flat surface and comprises of multiple parts at different respective heights. In other embodiments the fluid channels 30 and the optical window may be aligned with the heating surface to create a flat proximal surface 14.

[0094] The use of a two part body with the parts connected via a screw thread arrangement allows adjustment of the total distal length (or height) of the body 12. Some optical measurement apparatus, such as OCT apparatus have a fixed focal length and a depth of field of several hundred of microns (e.g. 300-700 microns), and it is desirable to locate the focal plane a few hundred microns below the target surface, so that as much of the sample region as possible is in focus. This allows adjustment of the length of theoptical path 80 to compensate or adjust for the different focal lengths of different optical measurement apparatus 90, including whilst the body remains secured to the target surface.

[0095] Figures ID though 1H illustrate how a fluid layer may be formed between the optically transparent fluid barrier 22 of the optical measurement attachment apparatus 10 and the target surface 2. As shown in Figure ID a securing arrangement 15 in the form of a double sided adhesive annular pad 15 is stuck to the target surface as shown in Figure IE, and the central aperture 16 in the annular pad 15 filled will fluid 66 from syringe 69. Then the proximal surface 14 of the body 12 is placed on the distal surface of the annular pad 15 as shown in Figure 1G. The body is then pressed into the pad 15 to secure the body to the adhesive pad 15 and thus target surface 2, and the fluid 66 in the central aperture forms a fluid layer between the target surface 2 and the optically transparent barrier 22 with excess fluid flowing into the fluid channels 30 as shown in Figure 1H.

[0096] As will be further discussed below, the fluid layer may be formed in various ways. Figure 10 is a flow chart of a method 100 of collecting one or more optical measurements from or in the target surface using an embodiment of the optical measurement attachment system described herein. The method comprises a step 110 of forming a fluid layer between the optically transparent fluid barrier of the optical measurement attachment apparatus and the target surface and allowing excess fluid to flow off or away from the optically transparent fluid barrier. As discussed above and illustrated in Figures ID through 1H, the fluid layer may be formed by placing a fluid on one or more of the target surface, the proximal surface of the optical measurement attachment, and the optically transparent fluid barrier, and securely placing the optical measurement attachment apparatus on a target surface such that the fluid contacts both the optically transparent fluid barrier and the target surface to form the fluid layer (and then allowing excess fluid to flow off or away from the optically transparent fluid barrier). Alternatively, for example as illustrated in Figures 6A to 6G, the fluid layer may be formed by securely placing the optical measurement attachment apparatus on a target surface, and releasing an optical fluid into a gap between the optically transparent fluid barrier and the target surface such that the fluid contacts both the optically transparent fluid barrier and the target surface to form the fluid layer (and allowing excess fluid to flow off or away from the optically transparent fluid barrier). Thus, in creating the fluid layer, the temporal order of placement of the respective parts and release of fluid may be varied. In some embodiments once the fluid is released it may be allowed to passively form the fluid layer, for example due to viscosity related effects (or forces) and gravity. In some embodiments releasing of fluid may include driving the fluid to form the fluid layer.

[0097] Embodiments of the optical measurement attachment apparatus 10 are configured to allow repeated coupling and decoupling of the optical measurement apparatus coupling apparatus 70 from the optical measurement attachment apparatus 10. With reference to Figures II through IM, the first coupling arrangement 38 comprises a plurality of castellations formed of alternating projections 56 and notches 54which match with corresponding notches 84 and projections 82 in a second set of castellations that form the second coupling arrangement 81. As shown in Figures II and 1J, the coupling arrangement further comprises a magnetic coupling arrangement comprising a first ring 68 formed of a magnetic material which is located in a top portion of the body 12 adjacent the castellations 81, and a second ring 74 is formed of a magnetic material with a complimentary polarity to the first ring, or is a magnetically sensitive material, and is located near the second set of castellations 81 and either forms the proximal surface of the optical measurement apparatus coupling apparatus 70 or is located sufficiently near the proximal surface to allow magnetic attraction between the first ring 68 and second ring 74. It will also be understood that the first ring 68 may be formed of a magnetically sensitive material if the second ring 74 is formed of a magnetic material.

[0098] The optical measurement apparatus coupling apparatus 70 comprises a coupling body 72 which is configured to be attached to an optical measurement apparatus 90 and the second coupling arrangement 81 configured to couple with the first coupling arrangement 38 of the optical measurement attachment apparatus 10. In this embodiment the second coupling arrangement 81 is set of castellations comprising projections 82 and notches 84 to match corresponding notches 54 and projections 56 in the first coupling arrangement 38, along with a steel ring 74.

[0099] In this embodiment optical measurement apparatus coupling apparatus 70 is a two part body comprising the coupling body 72 which is attached to attachment arrangement 76 which comprises the second coupling arrangement 81. In this embodiment the attachment arrangement 76 comprises a shaft with an external screw thread to match a screw thread 77 located on an internal central aperture of the coupling body 72. The attachment arrangement 76 further comprises a proximal (or lower) annular portion on which steel ring 74 is mounted along with castellations. The aperture 79 in the proximal annular portion through which the optical beam can pass. The coupling body 72 further comprises a fixed alignment marker 88. The use of a two part body and screw thread arrangement allows further adjustment of the length of the optical measurement apparatus coupling apparatus 70, and thus the optical path 80 to adjust for different focal lengths or depth of fields of different optical measurement apparatus 90.

[0100] With reference to Figure II, step 130 of the method for collecting one or more optical measurements from or in the target surface comprises coupling the first coupling apparatus 38 of the optical measurement attachment apparatus 10 to the second coupling apparatus 70 attached to a first optical measurement apparatus 90; and step 140 comprises capturing a first set of one or more optical measurements using the first optical measurement apparatus 90. Additionally, the method may further comprise uncoupling 150 the first optical measurement apparatus 10 from the second coupling apparatus 70, and then, for example after some time delay, recoupling 170 the first coupling apparatus 10 to the second coupling apparatus 70 attached to the first optical measurement apparatus 90, or to a third coupling apparatus 70' attached to a second optical measurement apparatus 90', and then capturing 180 asecond set of one or more optical measurements using the first optical measurement apparatus 90 or the second optical measurement apparatus 90'.

[0101] In some embodiments, it may be desirable to capture repeated measurements in the same orientation or location. Thus, in some embodiments, the first coupling apparatus 38 of the optical measurement attachment apparatus 10 is attached to the second coupling apparatus 70 in a first rotational orientation, and then when recoupling the second coupling apparatus 70 or a third coupling apparatus 70', these are recoupled in the same rotational orientation. A visual guide may be used to assist the operator to reconnect the second coupling apparatus to the first coupling apparatus in the first rotational orientation, or they may be configured to only allow reconnection in the first rotational orientation. Various arrangements may be used to assist in using the same rotational orientation or alignment for multiple measurements. In the embodiment shown in Figures 1A to IN, a fixed alignment marker 88 is provided on the second coupling apparatus 70, and an alignment marker 58 is attached to the optical measurement attachment apparatus 10 which remains in place during all measurements. In these embodiments the alignment marker 58 is a steel clip which is fitted around the shaft, and which is held in place by magnetic attraction to magnet 68 in the first coupling arrangement 80 (attached to the base of the upper body 28). A laterally extending arm ending in a pointed tip is formed in the clip. Once the second coupling apparatus 70 is first attached to the optical measurement attachment apparatus 10, the clip can be attached such that the tip aligns with fixed alignment marker 88 of the second coupling apparatus 70. Alternatively, the clip could be first attached to the optical measurement attachment apparatus 10, then the second coupling apparatus 70 is coupled to the optical measurement attachment apparatus 10, and fixed in place such that the fixed alignment marker 88 is over the tip of the clip 58. Other arrangements could also be used.

[0102] The method 100 may further comprise cleaning the target surface, proximal surface, and / or optical window prior to placing the optical measurement apparatus on the target surface. This may be performed using alcohol, an alcohol wipe, or other solvent or cleaning product. The step of securing the optical measurement apparatus 10 to a target surface 2 using a securing arrangement 15 may be performed using a range of chemical and / or physical compounds and materials including the use of adhesives, adhesive patches or tapes, screws, fasteners, suction / pressure apparatus etc. In some embodiments, the securing arrangement may include a material that is adhesive on one side, and the adhesive side is placed over the optical measurement attachment apparatus 10 and the target surface 2 such that it adheres to part of the optical measurement attachment apparatus 10 and the target surface 2. In some embodiments, the adhesive material may be an adhesive bandage or tape such as fixomull™ or hypafix™ and which is either of a fixed size or can be cut to the required size to fix the optical measurement attachment apparatus 10 to the target surface 2.

[0103] In some embodiments a cover 17 may be provided to protect the optical window and / or proximal surface 14. For example, if the proximal surface is coated with an adhesive, the cover 17 may beused to prevent contamination of the adhesive and preserve the adhesive properties prior to placing the optical measurement attachment apparatus 10 on the target surface 2. In some embodiments the cover 17 is peelable layer.

[0104] In the embodiment shown in Figures ID to 1H, the fluid 66 is placed on the target surface 2 within aperture 16 of the securing arrangement 15. In other embodiments the fluid 66 could be placed (or injected) directly onto the proximal surface of the optically transparent fluid barrier just prior to placing the body on the target surface 2, or adhesive pad 15. In other embodiments the cover 17 may be used to supply the fluid 66. Figure 2 is a side view of the optical measurement attachment apparatus shown in Figure 1A and shows an embodiment of a cover 17 comprising a pad with an adhesive proximal surface filled with a fluid 66 in a central aperture and a peelable protective layer 17. Just prior to use the peelable layer is removed 17, and the optical measurement attachment apparatus 10 is securely placed on the target surface 2, during which the fluid 66 forms the fluid layer between the optically transparent fluid barrier 22 and the target surface 2. A second peelable cover may also be placed over the fluid channels 30 and removed prior to placement to allow excess fluid to escape during placement and securing of the optical measurement attachment apparatus 10 to the target surface 2. In other embodiments the cover could comprise a sealed fluid reservoir with removable distal and proximal wall sections, such as retractable walls (i.e. can move in a lateral direction). During placement of the optical measurement attachment apparatus 10, the walls may be slid laterally to release fluid in the gap between optical measurement attachment apparatus 10 to the target surface 2, and then the optical measurement attachment apparatus 10 is secured to the target surface 2. The choice of where the optical fluid is placed may be based on the viscosity of the fluid, and securing mechanism. With highly viscous fluids there is more resistance to flow compared to low viscosity liquids, and these give additional time to place and secure (or securely place) the optical measurement apparatus 10 on the target surface 2 before the fluid is able to flow away such that there may be insufficient fluid to form the fluid layer.

[0105] The method 100 may further comprise the step 160 of stimulating the target surface for a first time period between capturing the first set of one or more optical measurements and the second set of one or more optical measurements. Figure 3A and 3B are respective side and perspective views of the optical measurement attachment system shown in Figure 1A attached to a stimulation apparatus 96, which in this embodiment is an integrated power supply and stimulator controller. Figures 3C, 3H and 31 are respective perspective, side and top views of the assembled optical measurement attachment system shown in Figure 3B attached to the optical measurement apparatus and the stimulation apparatus 96 according to embodiment. Figures 3D, 3F and 3G are respective side, top and perspective views of the optical measurement attachment apparatus shown in Figure 1A and cable connector for connection to the stimulation apparatus according to embodiment. Figure 3E is an end view of the cable connector for connection to the stimulation apparatus according to embodiment. The cable 92 may be a removablecable and may comprise a connector in one or both ends of the cable for removable connection to one or both of the optical measurement apparatus and the stimulation apparatus 96. Each removable connection may be formed as a port comprising matching connector components such as a plug and a socket (i.e. different types of connectors). Thus, a first port 47 may be provided between the body 12 and a first end of the cable 92, and / or a second port 93 may be provided between a second end 94 of the cable 92 and the integrated power supply and integrated power supply and stimulator controller 96. The choice of which component forming the port has the plug and which component has the socket is largely arbitrary (and thus interchangeable) and can be determined based on the factors such as ease of manufacture, ease of use, robustness / reliability considerations etc. In some embodiments the optical measurement attachment 10 is a disposable (i.e. single use) part and the cable 92 is permanently connected to the body of the optical measurement apparatus (i.e. is also disposable) and has a connector in the second end for removable connection to the integrated power supply and stimulator controller 96 (i.e. not first port 47 and just the second port 93). In other embodiments the cable 92 is a separate part (which may or may not be disposable) and is separately connected to the optical measurement apparatus (via first port 47) and the stimulation apparatus 96 (via second port 93) as required. In embodiments where the body or lower support surface 27 incorporate a force sensor 25, the control circuit may be located in the stimulation apparatus 96. An indicator 95, such as an LED, may also be provided in the housing of the stimulation apparatus 96. Power and signals to the force sensor 25 may be provided by cable 92.

[0106] In this embodiment, the stimulator is a heating element which as illustrated in Figures II and 1 J is an annular printed circuit board (PCB) fitted with multiple heating elements. The first port 47 comprises a first socket 47a formed in the heating ring 46 for connection to a plug type connector (not shown) in first end of cable 92. A cable guide 49 is located in the lower disk shaped support 27 for guiding connection (insertion) of the first end of cable 92 into the first socket 47a. As shown in Figure 3C, a port cover 51 is provided to cover the first socket 47a when the first port 47 is not used (i.e. no cable 92 plugged in). The second end of the cable 92 has a controller connector 94 including a plug type connector 93a as shown in Figure 3E for connection to a matching socket (not shown) in the stimulation controller and integrated power supply (e.g. battery unit) 96, to form second port 93. This is used to control delivery of stimulation (e.g. heat) to the target surface 2 between or during measurements.

[0107] Other embodiments of the optical measurement attachment apparatus 10 may be used. Figure 4A is a side sectional view of another embodiment of an optical measurement attachment apparatus. In this embodiment, the optical window support body 24 is formed as a central shaft which the supports the optically transparent fluid barrier 22. In this embodiment, rather than using a disk shaped support as the lower support 27, a set of legs 45 extend out from the shaft and are fitted with support feet 45a. Figure 4B shows a bottom view showing 4 equispaced legs 45 and feet 45a. Figure 4C shows another embodiment in which three feet are used where one foot is fitted with an alignment marker 58.The feet may comprise the heating elements and / or adhesive layer. In other embodiments for example where the target surface is not a human or animal, the feet may include other securing arrangements such as pins, nails, or other fasteners which may be inserted into the target surface away from the optically transparent fluid barrier 22. In this embodiment the optically transparent fluid barrier 22 is not recessed and is placed directly on the target surface 2, and there are no fluid channels. Instead, the fluid 66 is placed on the proximal side of the optically transparent fluid barrier 22 or on the target surface 2, and excess fluid is allowed to flow in the open area surrounding the shaft and the optically transparent fluid barrier 22.

[0108] In the embodiment shown in Figure 1A to IM, the optically transparent fluid barrier 22 is an optical window with a flat proximal surface and distal surface. In some embodiments, one or both of the proximal and distal surfaces need not be flat and may be inclined / slanted or curved (i.e. a lens). Inclined or slanted lens may be used to prevent or reduce the capture of reflections. Figure 5 shows an optically transparent fluid barrier 22a formed as an optically flat window (i.e. both surfaces flat and parallel), an optically transparent fluid barrier 22b with an inclined distal surface, an optically transparent fluid barrier 22c with an inclined proximal surface, and an optically transparent fluid barrier 22b with a curved distal surface (i.e. a lens). An inclined or slanted distal surface may be used to reduce capture of reflections from the transmitted beam off either the distal or proximal surface (e.g. prior to the beam entering the fluid) or of the return signal. This may be used to assist in improving the signal to noise by deflecting non-informative high intensity reflections. An incline on the proximal surface may also be used to direct fluid flow, for example to direct excess fluid to fluid channel 30. The incline angle may be less than 10°. The optically transparent fluid barrier 22 may be formed of glass, plastic, or other optically transparent material sufficient to stop fluid passing through the barrier 22.

[0109] In some embodiments the optical measurement attachment system 1 may further comprises a fluid movement apparatus 20 configured to drive fluid to fill any gaps between the optically transparent fluid barrier 22 and the target surface 2 (i.e., an active system). In these embodiments a first cavity 16 extends distal of a proximal aperture 18 in a proximal surface 14 of the body 12. In some embodiments the optical measurement attachment apparatus 10 is configured to allow an optically transparent fluid barrier to be placed closely above the target surface, such as within 200 microns, including partially in contact with the target surface . The fluid movement apparatus 20 is configured to drive fluid to fill any gaps between the optically transparent fluid barrier 22 and the target surface 2. The presence of this fluid reduces any optical mismatches between a light beam passing through the optically transparent fluid barrier into the target surface, such as a human’s skin, which can generate unwanted reflections or aberrations. Additionally, the fluid movement may drive out air or air bubbles present between the optically transparent fluid barrier and the target surface which if present, may adversely affect the quality of measurements by introducing distortions, optical discontinuities or unwantedreflections. The optically transparent fluid barrier may be permanently fixed in a measurement location and located with the first cavity such that it forms at least a distal surface of the first cavity. In this embodiment the gap between the target surface and the proximal side of the optically transparent fluid barrier is the first cavity and the fluid movement apparatus is configured to drive fluid into, through or out of the first cavity to fill the gap. In some embodiments, in the measurement position the optically transparent fluid barrier may form at least part of a distal surface of the first cavity, or it may located in the proximal aperture, such that it is within 200 microns of the target surface and / or partially in contact with the target surface. In these embodiments the fluid movement apparatus may be configured to move or drive the optically transparent fluid barrier 22 into the measurement location, and / or to drive fluid into or through the first cavity to fill any gaps between the optically transparent fluid barrier 22 and the target surface 2 when the optically transparent fluid barrier is in the measurement position, or when moving to the measurement position. In some embodiments, the proximal and distal surfaces of the optically transparent fluid barrier may be parallel with each other. In some embodiments, the optically transparent fluid barrier may have a wedge shape such that the proximal and distal surfaces of the optically transparent fluid barrier are not parallel to each other. These embodiments may be used where it is desirable to reduce back reflections from one of the surfaces of the optically transparent fluid barrier. In some embodiments the proximal surface of the optically transparent fluid barrier may be parallel to the target surface, whilst the distal surface of the optically transparent fluid barrier may be at an angle to the light beam emitted by the optical measurement apparatus 90 which can reduce unwanted back reflections from the distal surface of the optically transparent fluid barrier back to the optical measurement apparatus 90. In other embodiments the distal surface of the optically transparent fluid barrier may be parallel to the target surface, whilst the proximal surface of the optically transparent fluid barrier may be at an angle to the light beam emitted by the optical measurement apparatus 90 which can reduce unwanted back reflections from the proximal surface of the optically transparent fluid barrier back to the optical measurement apparatus 90.

[0110] The fluid movement apparatus 20 is configured to drive fluid movement and may be manually driven, for example by allowing relative movement between parts, or driven by an automated arrangement such as a pumping system, a motor system to drive relative movement of parts. In some embodiments the optically transparent fluid barrier is configured to move, such that movement of the optically transparent fluid barrier into the measurement position either drives fluid flow or initiates another component to drive fluid flow. A control system including a microprocessor and one or more motors and sensors could be configured to control movement of the optically transparent fluid barrier and / or generate and control movement of parts to drive fluid flow. However, in other embodiments the optically transparent fluid barrier could be fixed, and a manual pumping system or an automated pumping or other system used to create fluid movement. Again, a control system could be used to control movement of parts to drive fluid flow. Regardless of the mechanism the fluid movement acts to drive outair bubbles and ensure any gaps between the optically transparent fluid barrier and the target surface are filled with fluid. In some embodiments the fluid movement apparatus 20 may be configured to control the flow rate of fluid into, through or out of the first cavity. This may be achieved by controlling the rate of movement of a drive component that is used to direct fluid into the cavity, or to drive fluid through or out of the cavity. For example, a motor may be used to control a pump or the velocity of the optically transparent fluid barrier that is used to push fluid out of the first cavity. Similarly, the size of apertures in the first cavity may be selected to facilitate laminar flow of fluid into or out of the cavity and reduce the likelihood of the creation of air bubbles in the fluid due to turbulence or pressure effects.

[0111] Referring now to Figure 6A, there is shown a side view of an optical measurement attachment system 1 for placement on or securing to a target surface 2 according to an embodiment. The optical measurement attachment system comprises an optical measurement attachment apparatus 10 and a second coupling apparatus 70 configured to attach to an optical measurement apparatus. The target surface acts as a reference for proximal and distal components in the following discussion. This embodiment is further illustrated in Figures 6B, 6C, 6D and 6E which are respective first side, second side, oblique and top views of the optical measurement attachment apparatus shown in Figure 6A. The optical measurement attachment apparatus 10 comprises a body 12 having a proximal surface 14 and a first cavity 16 extending distally of a proximal aperture 18 in the proximal surface 14. A first coupling apparatus 38 is configured for removable attachment to the second coupling apparatus 70 configured to attach to an optical measurement apparatus 90. In this embodiment the fluid movement apparatus is configured to drive a fluid into or through the first cavity such that when an optically transparent fluid barrier is located in a measurement position, the fluid fills a gap between the optically transparent fluid barrier and a target surface on which the body is located.

[0112] In the measurement position 26, the optically transparent fluid barrier 22 forms at least part of a distal surface of the first cavity 16 located above the proximal aperture 18 and forms part of an optical path 80 extending from the proximal aperture 18 through the body 12 of the optical measurement attachment apparatus 10 to a distal aperture 40 in the body. In this embodiment the optically transparent fluid barrier 22 separates the first cavity 16, extending from the proximal aperture 18 to the proximal side of the optically transparent fluid barrier 22, from the second cavity 42 which extends from the distal side of the optically transparent fluid barrier 22 to the distal aperture 40.

[0113] Various embodiments of fluid movement apparatus 20 may be used to drive fluid into or out of the cavity 16. In some embodiments movement of the optically transparent fluid barrier into the measurement position 26 may also drive out fluid from the cavity 16. In the embodiment shown in Figures 6A to 6K the fluid movement apparatus 20 comprises an optically transparent fluid barrier support 24 configured to support the optically transparent fluid barrier 22 and configured to guide movement of, or move, the optically transparent fluid barrier into the measurement position 26, inconjunction with a conduit 30 that extends from an interior aperture 32 located in a side wall 34 of the first cavity 16 to or through an outer wall 36 of the body 12 or to a fluid reservoir. In some embodiments the fluid movement apparatus 20 may control the rate at which fluid flows into or out of the first cavity 16 to minimise aeration or the introduction of air bubbles into the fluid. The rate may be controlled by mechanical means, such as by controlling the stiffness or friction between parts as well as the size of the interior aperture(s) or conduits. For example, a syringe may be used to inject the fluid into the cavity in which the plunger materials are chosen to provide high friction and thus slow the movement of the plunger. Fluid could be provided in a squeezable reservoir with stiff walls to resist the squeezing action and slow the rate of flow of fluid out of the reservoir. The interior aperture 32 may be made large to reduce pressure across the aperture and allow a large volume of fluid to flow through the aperture. The shape of the conduit 30 may be made so to reduce aeration of fluid as it enters the cavity 16 or to reduce turbulence in the flow of the fluid as it enters the first cavity 16. In some embodiments, the interior aperture 32 may be made larger than some other sections of the conduit 30, for example cone-shaped near the interior aperture 32 so cross-sectional area increases with proximity to the interior aperture 32. In some embodiments the rate may be controlled using an electronic control system such as microcontroller and / or pumps. The rate may be controlled to maintain flow in a laminar flow range. The optically transparent fluid barrier attachment apparatus is a two-component system in which the body 12 is a first component, and the optically transparent fluid barrier support 24 is a second component received in the body 12.

[0114] The optically transparent fluid barrier support 24 comprises a support body 48 (also referred to as an optically transparent fluid barrier support body) with a proximal end portion 50 and an interior distal cavity 42 extending distally of the optically transparent fluid barrier 22. The optically transparent fluid barrier is held fixed with respect to the support body 48, and in this embodiment the optically transparent fluid barrier 22 is mounted on an angle with respect to a plane defined by the proximal aperture 18 in the proximal surface 14 (e.g., is oblique or inclined in a cross-sectional view). In some embodiments this angle is less than 10 degrees. The use of an inclined optically transparent fluid barrier may assist in capturing optical measurements by preventing unwanted reflections at interface surfaces being directed back towards the optical measurement apparatus (or device) 90. The thickness of the optically transparent fluid barrier may also be selected to allow identification and exclusion of reflections from the distal surface of the optically transparent fluid barrier. The proximal end portion 50 is configured to be received in a distal portion of the first cavity 16 and is driven towards the proximal surface 14 to move the optically transparent fluid barrier into the measurement position 26 and to drive fluid present in the first cavity 16 out of the first cavity.

[0115] In this embodiment the first cavity 16 is a shaft with a side wall 34 with a constant interior cross sectional profile, and the proximal end portion 50 has an exterior wall portion 52 with crosssectional profile matching the constant interior cross sectional profile to allow the proximal end portion to be received in the shaft. In this embodiment the constant cross-sectional profile is a circular profile such that the shaft is a cylindrical shaft. However, in other embodiments other cross-sectional profiles could be used such as square, hexagonal or polygon. Irregular cross-sectional profiles such as a circular shaft with a key and matching projection could also be used to ensure a constant rotational orientation.

[0116] As most clearly shown in Figures 6D, 6F and 6G, the distal end of the optically transparent fluid barrier support 24 is configured with a screw thread arrangement 60 which engages with a plurality of resilient arms 39 extending from the body 12. The resilient arms 39 are functionally equivalent to the thread in the proximal portion of the upper body 28 shown in Figure 1C. This allows the optically transparent fluid barrier support body 48 to be screwed into the body 12 until the optically transparent fluid barrier is located in the measurement position. That is the thread of the optically transparent fluid barrier support body 48 is configured such that each rotation acts to lower the optically transparent fluid barrier towards the measurement position. A stop may be provided in the side wall 34 of the body to stop rotation past the measurement location. This is further illustrated in Figures 6F and 6G that are section views through section A-A of Figure 6C and illustrate the optically transparent fluid barrier prior to movement into a measurement position and in the measurement position. Prior to movement, fluid may be introduced into the first cavity 16, for example via conduit 30. The optically transparent fluid barrier 22 forms part of the distal surface of the cavity and thus movement of the optically transparent fluid barrier 22 towards the target surface then drives any excess fluid as well as any air or air bubbles present in the cavity 16 after the initial filling out of the cavity, for example via the conduit 30. In this embodiment the body contains a cavity or shaft within which the optically transparent fluid barrier is located (supported by the optically transparent fluid barrier support 24) to create an optical path through the body. The optically transparent fluid barrier acts as a separator or wall to create the first (proximal) cavity, which is to be filled with a fluid, and a second (distal) cavity 42 which is filled with air and leads to the optical measurement apparatus. The optically transparent fluid barrier 22 thus forms part of the distal surface of the first cavity. The first cavity 16 is then reduced to a small fluid filled gap formed between the target surface and the optically transparent fluid barrier (with the optically transparent fluid barrier forming part of the distal surface of the cavity). The use of an inclined optically transparent fluid barrier may also assist in driving air or air bubbles out of the cavity, for example by directing them to the interior aperture 32 of the conduit 30. In this embodiment the optically transparent fluid barrier may be moved such that it is effectively part of the proximal surface such that the first cavity is reduced to a very small gap over the target surface, which may be as small as 100-200 microns.

[0117] In this embodiment the optically transparent fluid barrier 22 is an optical window in which the proximal side is inclined, and one side portion of the window extends slightly below the proximal surface 14 of the body 12 so that it may be in contact with, or very close to, the target surface 2whilst the opposing side portion is held a fixed distance above the target surface. The fixed distance is defined by the incline angle of the optical window. This then allows the mid portion of the optical window to be located within a short distance such as 100-200 microns from the target surface. Further as the focal length of the optical measurement apparatus 90 is known, the length of the various components of the optical measurement attachment apparatus can be designed (or defined) so that when the optical window is in the measurement position the mid portion of the optical window is in a known position relative to the focal plane of the optical measurement apparatus 90. In some embodiments the focal plane is located a few hundred microns below the target surface, so that as much of the sample region as possible is in focus. Thus, the optically transparent fluid barrier does not need to be positioned at the focus of the optical measurement apparatus, but may be at a desired or predetermined distance from the focal plane. The system can be designed so that when the optically transparent fluid barrier is in the measurement position, the length of the optical path 80 through the system places the optically transparent fluid barrier in the desired position relative to the focal plane or at a desired distance from the optical measurement apparatus 90. Additionally, the system may be configured so that the length of the optical path 80 is variable or adjustable, to cater to a range of different optical measurement apparatus 90, or to allow fine control of the location of the optically transparent fluid barrier to obtain high precision (i.e. in-focus) measurements. For example, in this embodiment the use of the screw thread arrangement allows the height of the optically transparent fluid barrier to be adjusted over a vertical (distal) range. In some embodiments a motor could be used to drive rotation of the optically transparent fluid barrier support with respect to the body (i.e. screw in or out) to assist with focussing the optical measurement apparatus 90 prior to obtaining optical measurements. Additionally, or alternatively the attachment arrangement 76 of the second coupling apparatus 70 may comprise a screw thread to allow additional control of the optical path 80 (see Figures 6H to 6K).

[0118] In this embodiment the optically transparent fluid barrier is fixed within the optically transparent fluid barrier support 24 and the optically transparent fluid barrier support moves with respect to the body to guide and move the optically transparent fluid barrier. However, in other embodiments the body 12 may form the optically transparent fluid barrier support 24 in which the optically transparent fluid barrier 22 is directly moved with within the body. In other embodiments the optically transparent fluid barrier may not be fixed and be moveable within the optically transparent fluid barrier support 24. For example, movement of the optically transparent fluid barrier support with respect to the body may be used to provide gross scale movement, for example to drive out fluid as the optically transparent fluid barrier is moved into the measurement position, whilst movement of the optically transparent fluid barrier with the optically transparent fluid barrier support allows fine scale movements, for example to improve the focus of measurements.

[0119] Once in the measurement position, the optically transparent fluid barrier may be held in place due to frictional forces, such as those between the screw thread 60 and resilient arms 39. In some embodiments a locking mechanism 29 may also be provided for locking the optically transparent fluid barrier 22 in the measurement position 26. For example, a pin or screw could be driven laterally against the optically transparent fluid barrier support body 48 to prevent further rotation or movement.

[0120] In this embodiment the exterior wall portion 52 of the proximal end portion 50 of the optically transparent fluid barrier support 24 acts as a closure mechanism to close the interior aperture 32 as the optically transparent fluid barrier 22 is moved into the measurement position. In this embodiment the first cavity 16 is a shaft with a first axis and the optically transparent fluid barrier support 24 is configured to move vertically along the same first axis (e.g., proximally and distally), and the exterior wall portion is configured with a length in the first axial direction (first axial length, e.g. aligned with the first axis) exceeding a second length in the axial direction of the interior aperture 32 of the conduit 30, or is configured such that when the optically transparent fluid barrier is moved (screwed) into the measurement position the exterior wall portion covers the interior aperture 32 to close the conduit 30. If the interior aperture 32 is circular, the second length may be the diameter of the interior aperture 32. In other embodiments a closure mechanism may comprise a valve or a motor driven door that is configured to close the interior aperture 32 and / or seal the conduit 30 once sufficient fluid has been driven out of the cavity. This seal may then act to retain fluid pressure or otherwise contribute to retaining fluid in the gap between the optically transparent fluid barrier and the surface.

[0121] When the optical measurement attachment apparatus 10 is placed on the target surface, the proximal surface may trap a portion of the surface within the proximal aperture. Frictional forces between the proximal surface 14 and the target surface 2 may then be sufficient to keep the optical measurement attachment apparatus in place over the trapped portion of the target surface 2 whilst one or more optical measurements are obtained. This trapping ensures that even if the surface is moved, the same trapped portion of the target surface remains below the optically transparent fluid barrier 22. In some embodiments a securing arrangement 15 is configured to attach and secure the body 12 of the optical measurement attachment apparatus 10 to the target surface 2. This securing arrangement can be used to ensure the optical measurement attachment system remains in the same location on the target surface when attaching the second coupling apparatus 70 to the optical measurement attachment apparatus 10, or in preparation for collecting a measurement or when collecting multiple measurements, and in particular two or more sets of measurements with some time delay between the two sets. The securing arrangement is independent of the second coupling apparatus 70. This allows the optical measurement attachment apparatus 10 to be secured to the target surface 2 using the securing arrangement 15 prior to coupling the first coupling apparatus 38 to the second coupling apparatus 70 configured to attach to an optical measurement apparatus 90. This also allows the optical measurement attachmentapparatus 10 to remain secured in place on the target surface 2 when the second coupling apparatus 70 is detached (de-coupled) and the optical measurement apparatus 90 is removed. For example, the optical measurement attachment apparatus 10 may be secured to a first human and then the optical measurement apparatus 90 is coupled to the optical measurement attachment apparatus 10 on the first human (via the second coupling apparatus 70) and one or more measurements taken. Then the optical measurement apparatus 90 is removed (by decoupling the second coupling apparatus 70), and then moved to a second human where it is attached (again using the same second coupling apparatus 70) to another instance of an optical measurement attachment apparatus 10 secured to the target surface on the second human. After taking measurements on the second human (and potentially other humans), the optical measurement apparatus 90 may be brought back to the first human and reattached (again using the same second coupling apparatus 70) to the first optical measurement attachment apparatus 10 which has remained secured to the first human. Securing the optical measurement attachment apparatus 10 to the target surface may be performed at a different time, or as a separate action (or procedure) to securing the optical measurement attachment apparatus 10 (via the first coupling apparatus 38) to the second coupling apparatus 70 and optical measurement apparatus 90, and allows the optical measurement attachment apparatus 10 to remain in place independent of whether or not the optical measurement apparatus 90 is attached. The time delay may allow for stimulation of the target surface to obtain before and after comparison measurements, or to allow two or more different optical measurements measure the same location on the target surface.

[0122] The securing arrangement 15 may be provided as an integrated part of the optical measurement attachment apparatus, or one or more components may be attached to at least a portion of the proximal surface of the body prior to, or at the time of use, or the securing arrangement 15 may be used to attach and secure the body 12 to the target surface 2 at the time of use. As outlined above, the securing arrangement is independent of the second coupling apparatus 70, such that securing the optical measurement attachment apparatus 10 to the target surface 2 is performed as a separate action from attaching to the second coupling apparatus 70 and allows the optical measurement attachment apparatus 10 to remain secured to the target surface independent of whether or not the second coupling apparatus 70 is attached (e.g. so that the optical measurement apparatus 90 can be removed and later reattached whilst the optical measurement attachment apparatus 10 remains in place on the target surface 2). In the embodiment shown in figure 6A, the securing arrangement 15 is an adhesive layer with a central aperture. In this embodiment the central aperture has a circular diameter which has a diameter equal to or larger than the diameter of the proximal aperture 18 in the proximal surface 14. That is the central aperture is configured so as not obscure the optically transparent fluid barrier and allow the target surface 2 to be viewed through the optically transparent fluid barrier. In some embodiments the securing arrangement may be an annular double side adhesive layer or tape. This can be applied at the time of use by first adhering one side to the proximal surface, and then the second side to the target surface (or vice versa). Inanother embodiment a material pad or layer such as wound dressing or ECG pad covered with an adhesive layer and removable covering is fixed to the base of the body and arranged such that the adhesive layer (when the cover is removed) forms the proximal surface 14.

[0123] In some embodiments the securing arrangement 15 is an adhesive material or compound applied to at least a portion of the proximal surface 14, and / or the target surface 2, and used to adhere the proximal surface to the target surface. The adhesive may then be later removed using a chemical and / or physical action. For example, later removal may be facilitated by use of a chemical such as a solvent which may be introduced by the fluid conduit 30 or placed around the proximal surface 14 where it may act to weaken or dissolve the adhesive to allow removal of the optical measurement apparatus from the surface (possibly in conjunction with mechanical force). In other embodiments physical actions may be used to weaken to the adhesive, such as by heating the area using a heating element 46, or by irradiating the adhesive with a light source such as a UV laser which acts to physically weaken the adhesive to allow removal of the optical measurement apparatus from the surface.

[0124] In some embodiments (including those without a fluid movement apparatus 20) mechanical securing arrangements could be used including a range of fasteners such as screw, pins, bolts which can be driven into the target surface. In other embodiments a pressure or vacuum based securing arrangement may be used, such as a cylindrical structure with an interior cavity with apertures in the proximal surface which is attached to the proximal surface or the proximal end of the optical measurement attachment apparatus. In this later case the proximal surface of the cylindrical structure with the apertures may be adjacent to the proximal surface 14 of the body, and form part of the proximal surface of the system 1. The pressure in the interior cavity may be reduced to create suction onto the surface (via the apertures) and thus secure the optical measurement attachment apparatus to the surface target. A valve may be provided to the interior cavity which can be opened to allow a return to atmosphere pressure in the interior cavity resulting in a loss of suction to allow removal of the optical measurement attachment apparatus to the target surface 2. The valve and a pump may also be used to remove air from the interior cavity, or the walls of the cylindrical structure may be resilient, and mechanical force may be used to compress the cylindrical structure and force air out of the cavity when the valve is open. The valve may then be closed to secure the optical measurement attachment apparatus to the target surface 2 and released to allow removal.

[0125] In this embodiment movement of the optically transparent fluid barrier into the measurement position acts to drive our excess fluid from the first cavity 16. The excess fluid may flow back out the conduit 30, or it may be forced out of the proximal aperture of the proximal cavity through the securing arrangement. The material of the securing arrangement may be selected to be porous or be otherwise configured with channels to allow the fluid to be driven out through securing arrangement.

[0126] As shown in Figures 6A, and 6H to 6K, the second coupling apparatus 70 for coupling to the optical measurement apparatus 90 (referred to as the optical measurement apparatus coupling apparatus) comprises a coupling body 72 with a second coupling arrangement 74 located on the proximal portion of the coupling body 72 and configured to match the first coupling apparatus 38 of the optical measurement attachment apparatus 10. The optical measurement apparatus coupling apparatus 70 further comprises an attachment arrangement 76, such as screw thread or clamp arrangement, for attaching the optical measurement apparatus coupling apparatus to the optical measurement apparatus 90. A third cavity 78 passes through the coupling body 72 and forms part of the optical path 80 (i.e. comprises a proximal and distal aperture). In this embodiment the distal or top surface of the body 12 is formed as an annular ring structure 53 with castellations comprising alternating notches 54 and distally directed projections 56 and a first magnetic structure 68 formed as a ring of a magnetic material or a magnetically permeable material such as steel. The second coupling arrangement 74 of the coupling apparatus 70 is similarly formed with a ring like structure with an alternating series of proximally directed projections 82 and notches 84 which match the respective notches 54 and projections 56 in the body 12 and a complimentary second magnetic structure 86 formed as a ring of a magnet or a magnetically permeable material to attach to first ring structure 68. That is, if the ring structure 68 is a magnet the second ring structure 86 may be a complimentary magnet or steel, and vice versa. In some embodiments the ring structure 68 is a steel ring and the second ring structure 86 is a magnet. This facilitates keeping the cost of the optimal measurement attachment apparatus 10 low, facilitating use as a disposable part, while the second coupling arrangement may be a reusable part, and thus include more expensive components such as magnets. Other structures besides rings may be used, for example a distributed set of magnets may be used. The locations may also be selected to control the angular alignment of the optical measurement attachment apparatus 10 with respect to the second coupling apparatus 70. For example, the magnets and complimentary magnets / magnetically sensitive material may be each be distributed in the same unique or non-symmetrical pattern so that the two parts can only be attached in one angular orientation. This enables the optical measurement attachment apparatus 10 to be repeatedly coupled and decoupled from the optical measurement apparatus coupling apparatus 70 in the same angular orientation or alignment.

[0127] Figures 6A to 6K illustrate one embodiment. However, it is to be understood that in other embodiments, other arrangements, configurations and variations may be used (e.g. some components may be common to multiple variations and whilst others may be changed to suit the specific requirements of the application). To further illustrate the scope several variants will be discussed, but it is to be understood these are examples only, and other variations maybe used.

[0128] In other embodiments another rotational alignment arrangement may be used to control the rotational orientation or alignment of the optical measurement attachment apparatus 10 with respect to the second coupling apparatus 70 to allow the optical measurement attachment apparatus 10 to berepeatedly coupled and decoupled from the optical measurement apparatus coupling apparatus 70 in the same angular orientation or alignment. In the embodiment shown in Figures 6A to 6K an alignment marker 58 is formed in the side of the body 12 to give a rotational angular reference along with an alignment marker 88 in the body 72 of the second coupling arrangement 74 (e.g. to create a reference orientation).

[0129] Castellations or other arrangements may initially allow the second coupling arrangement to be connected to the first coupling arrangement in a predefined set of orientations, or in any orientation, and then a locking mechanism may be used to lock the coupled parts in the current orientation (e.g. a reference or first angular orientation) so that any recoupling can then only occur in the original orientation. As the optical measurement apparatus 90 are often heavy or bulky, this allows an operator to find a favourable initially orientation in which to connect the second coupling arrangement to the first coupling arrangement, and to then have this initial (reference) angular orientation locked or saved so that the optical measurement apparatus 90 can be removed and later reattached in the same reference angular orientation.

[0130] Figure 7A to 7F are top, first oblique, first side, second oblique, second side, and sectional views of a rotational alignment arrangement 200 according to an embodiment. In this embodiment the first coupling apparatus 38 comprises a ring structure 202 on which projections 204 (e.g. castellations) are formed in the top (distal) surface which are received in matching apertures 84 in the second coupling apparatus 70. The projections 204 may be formed of a magnetic sensitive material (e.g. steel) or be magnetic and allow attachment of the first coupling apparatus to the second coupling apparatus in a single angular orientation. In other embodiments they may be formed of a non-magnetic material and simply be received in matching apertures in the second coupling apparatus. The outer wall of the ring structure 202 comprises a projecting ring 206. The cross-sectional profile 208 of the ring like structure 202 comprises a receiving cavity 210. The distal end 212 of the body 12 or the optically transparent fluid barrier support 24 is formed with a complimentary cross-sectional profile 214 including key projection 216. Initially a gap 218 is provided between the ring like structure 202 and the distal end 212 to allow free rotational movement of the ring like structure 202 with respect to the distal end 212. The outer surface of the distal end 212 of the body 12 or the optically transparent fluid barrier support 24 is formed with a screw thread 220. A locking ring 222 is configured to fit over the ring structure 202 and the distal end 212, and comprises an interior key projection 224 configured to be received in the screw thread 220. Additionally, an interior cavity 226 is formed in the wall of the locking ring 222 defined by an upper shoulder 228 and a lower shoulder 230. The size and location of the interior cavity 226 is configured to receive the projecting ring 206 of the ring like structure 202.

[0131] Thus, when attaching the second coupling apparatus 70 to the first coupling apparatus 38, the ring like structure 202 can be rotated until the projections 204 align with the matching cavities 84 inthe second coupling apparatus 70. Then the locking ring 222 may be rotated to drive the upper shoulder 228 in a distal direction (i.e. to screw down the locking ring 222). Continued rotation drives the upper shoulder onto the projecting ring, and drives or forces the ring like structure 202 towards the distal end 212 in order to close the gap 218, and lock the parts together, and prevent further rotation of the ring like structure 202 with respect to the distal end 212. The parts may be held together through frictional forces (e.g. by choosing appropriate materials or surface treatments), or an additional securing arrangement 232 may be used, such as pin or screw which can be driven from or through the outer wall of the locking ring 222 and into the outer wall of the distal end 212. This then creates a reference rotational orientation between the first coupling apparatus 38 and the second coupling apparatus 70. It will also be understood that this is an example and that other locking arrangements and other variations on this arrangement could be used. In this embodiment the matching cavities 84 for the projections 204 are in fixed locations in the second coupling apparatus. In other embodiments, these could be configured to rotate, and a similar locking arrangement provided on the second coupling apparatus 70. In these embodiments, this would allow both the projections 204 and matching cavities to be rotated until aligned, and then both locked in place.

[0132] An alignment marker 58 may be provided in the locking ring 222 to match an alignment marker 88 in the second coupling apparatus 70 to facilitate recoupling in the locked reference rotational orientation. As the reference orientation is linked to the location of the projections 204 in the ring like structure 202, and as the upper outer side wall of the ring like structure is exposed when locking ring 222 is screwed on, one or more alignment markers 58 may be provided in the upper outer side wall of the ring like structure which align with a respective marker 88 in the second coupling arrangement.

[0133] Alignment markers 58 and 88 on the respective first 38 and second 70 coupling apparatus may be physical markings, ink marking placed using an ink marker, or a lighting arrangement could be used. In one embodiment a first LED could be placed around the first coupling apparatus 38 or on the body 12, and a second LED could be placed around the second coupling apparatus. The second LED could be located on a rotatable and lockable sleeve. In use, once the second coupling apparatus is coupled to the first coupling apparatus, the sleeve could be rotated to align the first and second LEDs and then locked in place. In other embodiments the sleeve could be fixed and a ring of LEDS could be provided around the sleeve. A button could be provided with each LED to allow activation of the respective LED. In use, once the second coupling apparatus is coupled to the first coupling apparatus, the operator could select the button of the closest LED on the second coupling apparatus. In an alternative the locations of the first LED and second LED or LEDS may be switched (e.g. multiple LEDS on the first coupling apparatus 38. Other optical arrangements, including the use of light pipes could also be provided to assist in recording and identifying the reference rotational alignment.

[0134] In one embodiment the screw thread 60 shown in Figures 6A to 6G may instead be a set of adjacent rings. In this embodiment the ends of the resilient arms 39 of the body 12 are configured clip into each of the rings to allow the optically transparent fluid barrier support 24 to be slid into and out of the body. This allows the optically transparent fluid barrier to be located at a predefined set of heights or locations within the shaft. Each ring acts as a locking mechanism to hold the optically transparent fluid barrier at the specific location / height.

[0135] In some embodiments a locking mechanism 29 is used for locking the optically transparent fluid barrier in the measurement position. In some embodiments the locking mechanism comprises a deformable or resilient projection located on the exterior wall of the support body and a matching receiving portion located on an interior surface of the body, such that when the proximal end portion is received in the first cavity, the deformable or resilient projection is deformed or compressed until it reaches the receiving portion. A complimentary arrangement could be used, e.g. deformable or resilient projection on the proximal end portion and matching receiving portion on the body. In one embodiment the deformable projection is an O-ring located around the optically transparent fluid barrier support body 48. In other embodiment a clipping arrangement may be used. For example, the locking mechanism may be provided by the resilient arms of the body which are received in a matching receiving portion in the body.

[0136] Figure 7G is a side view of an optical measurement attachment apparatus 10 according to another embodiment showing an embodiment of a locking mechanism 29. Similar to the embodiment shown in Figures 6A to 6G, the optically transparent fluid barrier support 24 is received in a shaft in the body 12, and movement of the optically transparent fluid barrier 22 in the proximal direction is used to drive fluid out of the cavity 16 via conduit 30 as the optically transparent fluid barrier is moved into the measurement position. In this embodiment the distal end of the shaft is shaped with an inclined section followed by a receiving cavity 64 to match inclined section and a deformable projection 62 in the optically transparent fluid barrier support body 48. In this embodiment the deformable projection 62 is in the form of an O-ring located around the optically transparent fluid barrier support body 48 and is configured to be received in receiving cavity 64 formed in the interior wall of the body 12. This arrangement forms a locking mechanism 29 to lock the optically transparent fluid barrier support 24 (and optically transparent fluid barrier) in the measurement position.

[0137] In another embodiment illustrated in Figures 7Hand 71, the body 12 is a first cylinder and the optically transparent fluid barrier support body 48 is a second cylinder configured such that the interior diameter of the first cylinder (body) matches the exterior diameter of the second cylinder (optically transparent fluid barrier support). At least one interior aperture 32 and a conduit 30 are provided in the side wall of the body 12. As can be seen in Figure 7H the target surface 2 is undulating, and may be a resilient surface such as skin. A fluid may be introduced into the cavity via the conduit 30.Figure 7H shows the cavity 16 initially filled with fluid and air 3 located between the optically transparent fluid barrier 22 and top of the fluid surface. Some air bubbles are present in the fluid. Movement of the optically transparent fluid barrier in the proximal direction then drives fluid and air out of the cavity via the aperture 32 and conduit 30. Figure 71 then shows the gap between the optically transparent fluid barrier 22 and the target surface 2 filled with fluid.

[0138] In other embodiments the cavity 16 may be prefilled with fluid and sealed in place, for example using a cover. If the fluid is sufficiently viscous, the cover may be removed just prior to placement of the optical measurement apparatus, and viscosity will largely retain the fluid in the cavity (e.g. the fluid may be a gel like substance). In other embodiments the cover may be configured such that it can be slid out and removed after placement on the target surface.

[0139] In some embodiments a motor may be configured to drive the movement of the optically transparent fluid barrier support 24, and allow electronic control of the height of the optically transparent fluid barrier 22. A motor could also be used to drive a door to close the interior aperture 32 of the conduit 30.

[0140] In some embodiments multiple conduits 30 and interior apertures 32 may be provided to allow fluid to flow into and out of the cavity via multiple locations. In some embodiments two or more apertures and conduits may be used to create a flow path, e.g. so fluid flows in through one aperture and out through another to create a direction of flow within the cavity. In some embodiments the optically transparent fluid barrier may be fixed in the measurement position with the optically transparent fluid barrier 22 forming at least a part of distal surface of the cavity 16. A fluid movement apparatus 20 is configured to drive fluid into or through the first cavity. Figure 7J is a schematic illustration of fluid movement apparatus according to another embodiment in which two sets of apertures are provided in the side walls of the cavity 16. A fluid reservoir and a pump are used to drive fluid into the first aperture, through the cavity 16 and then out of the second aperture. In other embodiments a pump could be used to first pump fluid into the cavity and drive out any air. The pump out could also be used to partially pump out some fluid and to create fluid movement to assist in drawing out any air or air bubbles. Multiple rounds of pumping fluid in and out could be performed to create fluid movement if desired.

[0141] The fluid may be a fluid such as glycerol, water, ultrasound gel, water based optically transparent lubricant, an optically transparent oil, or another optically transparent fluid. The fluid may be selected based on the application and optical measurement apparatus, for example to select an optical fluid with an index of refraction similar to the optically transparent fluid barrier 22 or the target surface 2 to provide good impedance matching properties and reduce reflections. In the case of biological applications including use on skin, the fluid may also be selected to be non-irritating or non-toxic. In some embodiments the fluid may soak into the target surface and provide an improved or more gradualchange in the index of refraction (i.e., improved impedance matching). For example, in some embodiments glycerol may be used as it absorbed into the top layers of skin which can facilitate capturing optical measurements of sub-structures such as blood micro vessels in the upper layers of the human’s skin in optical coherence tomography (OCT) applications.

[0142] In some embodiments a stimulation apparatus 46 is configured to allow stimulation of the target surface when the optical measurement attachment apparatus 10 is attached to the target surface. In one embodiment the stimulation apparatus is a heating apparatus surrounding, adjacent, or integrated with the proximal surface, for example as illustrated in Figures 1A to IM, Figures 3A to 31 or Figure 6A. The modular nature of the system in which the second coupling arrangement may be removed and then later reattached allow the capture of sets of optical measurements before and after stimulation. More generally stimulation between measurements may include the stimulating the target surface with a stimulating apparatus, or stimulating the target surface with a chemical or a pharmaceutical substance, or stimulating a person, an animal, or a biological tissue associated with the target surface with a pharmaceutical substance. The stimulation apparatus may be an electromagnetic stimulation apparatus including lasers, light sources, RF emitters, a radiation apparatus configured to emit an energetic particle (e.g., X-ray, alpha-emitters) to provide radiation-based stimulation, as well as acoustic stimulation apparatus such as an ultrasound apparatus or transducer, or a pressure stimulation apparatus to control the pressure applied by the proximal surface 14 of the body on the target surface 2, and thus enable measurements at two different pressures (e.g. a low pressure and a high pressure). For example a configuration of springs could be used which can be switched between two configurations (e.g. low pressure and a high pressure).

[0143] The optical measurement apparatus may be manufactured or configured to be sterilisable or provided as a sterile apparatus (e.g. sterilised and packaged), or otherwise easily cleanable between uses (e.g. easily wiped down with an alcohol wipe). The optical measurement apparatus may be designed as a single use product, or it may be reused. The choice of materials may be selected based on the requirements single use or repeated use including the ability to sterilise the apparatus. The various parts may be 3D printed, injection moulded, cast, machined, or otherwise formed and assembled based on the intended application.

[0144] Figure 10 is a flow chart of a method 100 of collecting one or more optical measurements from or in the target surface using an embodiment of the optical measurement attachment system described herein. The method comprises a step 110 of forming a fluid layer between the optically transparent fluid barrier of the optical measurement attachment apparatus and the target surface and allowing excess fluid to flow off or away from the optically transparent fluid barrier. The fluid barrier may either be formed by placing a fluid on one or more of the target surface, the proximal surface of the optical measurement attachment, and optically transparent fluid barrier, and securely placing the optical measurement attachment apparatus on a target surface such that the fluid contacts both the opticallytransparent fluid barrier and the target surface to form the fluid layer (and allowing excess fluid to flow off or away from the optically transparent fluid barrier). Alternatively the fluid layer may be formed by securely placing the optical measurement attachment apparatus on a target surface, and releasing an optical fluid into a gap between the optically transparent fluid barrier and the target surface such that the fluid contacts both the optically transparent fluid barrier and the target surface to form the fluid layer (and allowing excess fluid to flow off or away from the optically transparent fluid barrier). That is, in creating the fluid layer, the temporal order of placement of the respective parts and release of fluid may be varied. Step 110 may be separated into sub steps of placing or releasing the fluid, and securely placing the optical measurement attachment apparatus 10 to the target surface as shown in Figures ID through 1H. Securely placing may comprise placing, and then securing the optical measurement apparatus 10 to the target surface, or it may be performed as a single action. Placing or releasing of the fluid, may be performed prior to securing the optical measurement apparatus to the target surface, or the fluid may be placed or released after securing the optical measurement apparatus to the target surface. In some embodiments step 110 may further comprises a sub-step 120 of driving the fluid into or through the first cavity 16 such that when the optically transparent fluid barrier 22 is located in the measurement position the fluid fills a gap between the optically transparent fluid barrier and the target surface to form the fluid layer, for example using the embodiment shown in Figures 6A to 6G. Step 130 comprises coupling the first coupling apparatus of the optical measurement attachment apparatus to the second coupling apparatus attached to a first optical measurement apparatus, and optionally, in a first rotational orientation; and step 140 comprises capturing a first set of one or more optical measurements using the first optical measurement apparatus. The rate of movement of the fluid into, through, or out of the gap or cavity 16 may be controlled to minimise the likelihood of the formation of bubbles in the fluid. This may be controlled by the operator, e.g., by slowly moving the parts, or the fluid movement apparatus may be configured to prevent rapid movement or flow, for example by using stiff parts, friction between parts, flow restrictors, or by controlling the size of the interior aperture(s) 32 or by controlling the shape of the conduit 30. In some embodiments a control system many be used to control flow rate by controlling one or more motors, valves, pumps or other components. The control system may be a component such as motor or pump configured to operate at a predefined rate (e.g. simple predetermined / fixed control system), or the control system may comprise a microcontroller (or microprocessor) and one or more motors and pumps which are controlled by the microcontroller. The control system may also include one or more sensors which may be used by the microcontroller to control the motors or pumps. Software codes or instructions may be used to control the microcontroller.

[0145] The method is further illustrated in Figures 8Ato 8H which illustrated of the steps of the method of attaching an optical measurement apparatus to a surface according to an embodiment. In this embodiment the body 12 is a first cylinder with a conduit 30 in the side wall, and the optically transparent fluid barrier support body 24 is a second cylinder configured such that the interior diameter of the firstcylinder (body) matches the exterior diameter of the second cylinder (optically transparent fluid barrier support). Figure 8 A shows the empty body 12 prior to placement, and Figure 8B shows the body 12 placed on the target surface 12 (step 110). Figure 8C to 8E illustrate step 120 shown a fluid being driven into the cavity 16 via conduit 30 for example using a syringe or pump 67 which provides fluid from fluid reservoir. Figure 8D shows the optically transparent fluid barrier support body 24 being lowed into the shaft of the body filled with fluid and air, and Figure 8E shows the body in the measurement position with the air, and most of the fluid driven out of cavity 16 leaving fluid in a small gap (reduced size cavity 16) between the optically transparent fluid barrier and the target surface 2. The optically transparent fluid barrier forms the distal surface of the cavity 16. Figure 8F illustrates steps 130 and 140 of attaching the second coupling apparatus 70 to the first coupling apparatus 38 of the body 12, followed by collection of one or more optical measurements (indicated by vertical arrows).

[0146] Figure 8G then illustrates steps 150 and 160 in which the second coupling apparatus 70 is uncoupled from the first coupling apparatus 38, and then the target surface is stimulated for a first time period using a stimulation apparatus 46 such as a heating element. Figure 8H then illustrates steps 170 and 180 of reconnecting the first coupling apparatus 38 to the second coupling apparatus 70 attached to the first optical measurement apparatus 90 in the first rotational orientation (or, alternatively a third coupling apparatus attached to a second optical measurement apparatus in the first rotational orientation), and then capturing a second set of one or more optical measurements using the first optical measurement apparatus or the second optical measurement apparatus indicated by the vertical arrows.

[0147] Figures 9A and 9B illustrate the use of an embodiment of an optical measurement attachment system 1 attached to the foot of a human prior to taking a measurement with an optical coherence tomography (OCT) measurement apparatus (the optical measurement apparatus 90). In this embodiment skin of the foot is the target surface 2. Figure 9B shows the assembled optical measurement attachment system 1 including the optical measurement attachment apparatus 10 connected to the second coupling apparatus 70 which is attached to the OCT measurement apparatus 90 which is being used to take a measurement on the skin 2 of the foot of the human. In this embodiment the stimulation controller and integrated power supply 96 are attached to the optical measurement attachment apparatus 10 via cable 92.

[0148] Figures 10A and lOBare two scans that were acquired using the optical measurement attachment system 1 attached to an optical coherence tomography scanner (an embodiment of an optical measurement apparatus 90). Figure 10A is first black and white image 600 of blood vessels 602 of a human captured by an optical coherence tomography apparatus coupled to an embodiment of an optical measurement attachment system and Figure 10B is second black and white image 610 of blood vessels 612 after heating of the skin captured by an optical coherence tomography apparatus coupled to an embodiment of an optical measurement attachment system.

[0149] Figure 10A show a baseline scan, showing blood flow at rest. Figure 10B show the same location after the skin has been locally heated using the heating element 46. These scans show blood vessels over a field of view of 3.2mm x 3.2mm, to a depth of approximately 1mm below the skin surface. These small blood vessels are referred to as the ‘microvasculature’ and have a diameter in the range 30 microns - 200 microns. Figure 10B shows blood vessels with increased diameter, relative to Figure 10A, in response to heating. The blood vessels 602 in Figure 10A are also visible 612 in Figure 10B, showing that the two scans are closely aligned even though the optical scanner 90 was detached from the optical measurement attachment apparatus 10 between scans.

[0150] Embodiments as described herein may be used for medical diagnostic applications where the apparatus may be applied to a human’s skin. However, it will be understood that the system, apparatus and methods described herein may be used for optical measurements or optical images of any objects where there is a requirement to capture multiple measurements at the same locations at two or more time points. That is the system is not limited to use on human patients, but may be used on any humans, animals, plants, biological samples, food, soils, structural members, building materials, physical structures, 3D printed objects, etc. The modular nature allows the measurement apparatus to be uncoupled and removed from the optical measurement attachment apparatus which remains attached to the target surface. This facilitates reliable capture at the same location for widely spaced capture time points (e.g. the time interval between measurements is sufficient that there may be a change or response to stimulation detectable in the optical measurements acquired of the body).

[0151] Embodiment of the apparatus, system and methods have numerous advantages over existing systems. The system is a modular system that decouples the placement of the optically transparent fluid barrier from the measurement process. This allows placement of the optical measurement attachment apparatus 10 including the optically transparent fluid barrier 22 before coupling of the optical measurement attachment apparatus to the second coupling apparatus which is fitted to typically large and unwieldy optical measurement apparatus. Embodiments of the system 1 are configured to reliably collect or obtain a single set of measurements from an optical measurement apparatus 90 placed on a target surface 2 (where a set may be one or more measurements). The optical measurement apparatus can be easily removed from the optical measurement attachment apparatus and later recoupled, or another optical measurement apparatus attached to capture optical measurements over the same target surface 2. This provides a system which is configured to allow collection two or more set of optical measurements spaced apart in time. The optical measurement attachment apparatus 90 is removed between the sets of measurements whilst the optical measurement attachment apparatus 10 is left secured in place on the target surface 2. Embodiments of the optical measurement attachment apparatus 10 may allow an optically transparent fluid barrier to be placed closely above the target surface, such as within 200 microns or less. Various embodiments have been described which can be used to create a fluid layerbetween the optically transparent fluid barrier 22 and the target surface 2. This may be created during secure placement of the optical measurement attachment 10 on the target surface, or the optical measurement attachment system 1 may be configured with a fluid movement apparatus to drive fluid to fill any gaps between the optically transparent fluid barrier and the target surface. The secure placement of the optical measurement attachment, or fluid movement apparatus, may drive out air or air bubbles, or prevent them being trapped between the optically transparent fluid barrier and the target surface which if present, may adversely affect the quality of measurements by introducing distortions, impedance discontinuities or unwanted reflections.

[0152] The reference to any prior art in this specification is not, and should not be taken as, an acknowledgement or any form of suggestion that such prior art forms part of the common general knowledge.

[0153] It will be understood that the terms “comprise” and “include” and any of their derivatives (e.g. comprises, comprising, includes, including) as used in this specification, and the claims that follow, is to be taken to be inclusive of features to which the term refers, and is not meant to exclude the presence of any additional features unless otherwise stated or implied.

[0154] In some cases, a single embodiment may, for succinctness and / or to assist in understanding the scope of the disclosure, combine multiple features. It is to be understood that in such a case, these multiple features may be provided separately (in separate embodiments), or in any other suitable combination. Alternatively, where separate features are described in separate embodiments, these separate features may be combined into a single embodiment unless otherwise stated or implied. This also applies to the claims which can be recombined in any combination. That is a claim may be amended to include a feature defined in any other claim. Further a phrase referring to “at least one of’ a list of items refers to any combination of those items, including single members. As an example, “at least one of: a, b, or c” is intended to cover: a, b, c, a-b, a-c, b-c, and a-b-c.

[0155] It will be appreciated by those skilled in the art that the disclosure is not restricted in its use to the particular application or applications described. Neither is the present disclosure restricted in its preferred embodiment with regard to the particular elements and / or features described or depicted herein. It will be appreciated that the disclosure is not limited to the embodiment or embodiments disclosed, but is capable of numerous rearrangements, modifications and substitutions without departing from the scope as set forth and defined by the following claims.

Claims

CLAIMS1. An optical measurement attachment apparatus comprising:a body;an optically transparent fluid barrier that forms at least of a portion of a proximal surface of the body; anda first coupling apparatus configured for removable attachment to a second coupling apparatus configured to attach to, or is part of, an optical measurement apparatus,wherein, when used, the body is configured to be secured to a target surface using a securing arrangement that is independent of the second coupling apparatus, and the optically transparent fluid barrier is configured to allow light from the optical measurement apparatus to pass through the optically transparent fluid barrier and into the target surface, and a fluid is placed on a surface or released into a gap between the optically transparent fluid barrier and the target surface such that the fluid contacts both the optically transparent fluid barrier and the target surface to form a fluid layer and the body is configured to allow excess fluid to flow off or away from the optically transparent fluid barrier.

2. The optical measurement attachment apparatus as claimed in claim 1, wherein the body further comprises one or more fluid channels adjacent to the optically transparent fluid barrier.

3. The optical measurement attachment apparatus as claimed in claim 2, wherein the one or more fluid channels are formed in the proximal surface, and in use the optically transparent fluid is placed on the proximal surface of the optically transparent fluid barrier or the target surface prior to securing the body to the target surface and as the body is secured to the target surface, excess fluid is driven off or away from the optically transparent fluid barrier.

4. The optical measurement attachment apparatus as claimed in claim 2, wherein the body further comprises a first cavity extending distally of the proximal surface and wherein the optically transparent fluid barrier forms at least a portion of a distal wall of the cavity, and the one or more fluid channels are formed in one or more walls of the first cavity.

5. The optical measurement attachment apparatus as claimed in claim 4, wherein the one or more fluid channels are formed in a second portion of the distal wall of the cavity.

6. The optical measurement attachment apparatus as claimed in claim 4 or 5, wherein a depth of the first cavity is selected based on one or both of a viscosity of the fluid and a depth of field of the optical measurement apparatus.

7. The optical measurement attachment apparatus as claimed in claim 4, wherein the apparatus further comprises a fluid movement apparatus configured to drive the fluid into or through the first cavity such that when the optically transparent fluid barrier is located in a measurement position the fluid fills the gap between the optically transparent fluid barrier and the target surface on which the body is located.

8. The optical measurement attachment apparatus as claimed in any one of claims 1 to 7 wherein the optically transparent fluid barrier is an optical window.

9. The optical measurement attachment apparatus as claimed in claim 8, wherein one surface is flat and an opposing surface is slanted with a slant angle of less than 10 degrees.

10. The optical measurement attachment apparatus as claimed in any one of claims 1 to 9, further comprising a cover for the proximal surface, and the cover further includes a releasable fluid reservoir containing the fluid, and the fluid reservoir is further configured to release the fluid onto one or both of the proximal surface of the optically transparent fluid barrier and the target surface prior to or as the cover is removed.

11. The optical measurement attachment apparatus as claimed in any one of claims 1 to 10, further comprising the securing arrangement configured to attach and secure the body to the target surface.

12. The optical measurement attachment apparatus as claimed in any one of claims 1 to 11 wherein the first coupling apparatus further comprising a rotational alignment arrangement that is configured to allow the optical measurement attachment apparatus to be repeatedly attached to the second coupling apparatus in the same rotational orientation.

13. The optical measurement attachment apparatus as claimed in claim 12 wherein each of the first and second coupling apparatus further comprise an alignment indicator, wherein one alignment indicator is fixed and the other alignment indicator is a moveable alignment indicator that may be placed at a range of rotational orientations.

14. The optical measurement attachment apparatus as claimed in any one of claims 1 to 13, further comprising a stimulation apparatus configured to allow stimulation of the target surface when the apparatus is attached to the target surface .

15. An optical measurement attachment system comprising the optical measurement attachment apparatus as claimed in any one of claims 1 to 14, and a second coupling apparatus configured to attach to an optical measurement apparatus.

16. The system as claimed in claim 15, further comprising a stimulating apparatus comprising one or more stimulating elements surrounding, adjacent, or integrated with the proximal surface, an integrated power supply and stimulation controller, and a cable connecting the integrated power supply and stimulation controller to the one or more stimulating elements.

17. The optical measurement attachment apparatus as claimed in any one of claims 1 to 16 further comprising a pressure control system configured to control a pressure on the target surface.

18. The optical measurement attachment apparatus as claimed in any one of claims 1 to 17, wherein one or more of the body, the first coupling apparatus, the second coupling apparatus or the pressure control system is configured to control a location of a focal plane of the system.

19. A method of collecting one or more optical measurements from or in a target surface using the optical measurement attachment apparatus as claimed in any one of claims 1 to 18, comprising:forming a fluid layer between the optically transparent fluid barrier of the optical measurement attachment apparatus and the target surface and allowing excess fluid to flow off or away from the optically transparent fluid barrier wherein the fluid layer is formed either by placing a fluid on one or more of the target surface, the proximal surface of the optical measurement attachment apparatus, and the optically transparent fluid barrier, and securely placing the optical measurement attachment apparatus on the target surface such that the fluid contacts both the optically transparent fluid barrier and the target surface to form the fluid layer, or by securely placing the optical measurement attachment apparatus on a target surface, and releasing an optical fluid into a gap between the optically transparent fluid barrier and the target surface such that the fluid contacts both the optically transparent fluid barrier and the target surface to form the fluid layer;coupling the first coupling apparatus of the optical measurement attachment apparatus to the second coupling apparatus attached to a first optical measurement apparatus; andcapturing a first set of one or more optical measurements using the first optical measurement apparatus.

20. The method as claimed in claim 19, wherein securely placing the optical measurement attachment apparatus on a target surface comprises securing the optical measurement attachment apparatus to a target surface using a securing arrangement; and the method further comprises:uncoupling the first optical measurement apparatus;coupling the first coupling apparatus to the second coupling apparatus attached to the first optical measurement apparatus, or to a third coupling apparatus attached to a second optical measurement apparatus; andcapturing a second set of one or more optical measurements using the first optical measurement apparatus or the second optical measurement apparatus.

Images