ESD protected optical imaging probes

Abstract

An optical imaging probe is disclosed comprising a cable comprising an electrical conductor and one or more optical fibers, a probe head configured to receive a first extremity of the cable and comprising a surface made of an electrically conductive material, wherein the optical imaging probe further comprises a ground terminal arranged at a second extremity of the cable, and an electrostatic discharge, "ESD", arrangement configured for discharging charges accumulated on the electrically conductive surface of the probe head to the ground terminal via the electrical conductor of the cable.

Description

[0001] ESD PROTECTED OPTICAL IMAGING PROBES

[0002] The present invention relates to ESD protected optical imaging probes, especially for medical purposes.

[0003] Electrostatic discharge (ESD) is a sudden and momentary flow of electric current between two differently charged objects when brought close together. ESD can cause harmful effects like sparks and lead to failure of electronic components such as integrated circuits, when subjected to high voltages. Sensitive components need thus to be protected and grounding is especially important for effective ESD control. ESD norms have been developed for all fields of application. In the medical field, norms for ESD immunity in view of patient safety are particularly stringent.

[0004] Electrostatic Discharge is in that context particularly critical for surface inspection imaging probes. Such imaging probes allow to detect and uncover physiological and pathological functions. Their principle of operation consists in exciting a surface with light and measuring the spectral information of the light output from the excited surface. Such imaging probes are typically handheld by an operator and typically come in contact with surfaces of objects and / or persons under inspection. When in contact, the surfaces of such imaging probes can accumulate electrostatic charges which can discharge to the electronic devices connected to such imaging probes.

[0005] An object of the invention, next to other objects, is to provide ESD protected optical imaging probes, especially suitable for medical applications.

[0006] This object, next to other objects, is met by a device according to claim 1. Specifically, this is met by an optical imaging probe comprising a cable comprising an electrical conductor and one or more optical fibers, a probe head configured to receive a first extremity of the cable and comprising a surface made of an electrically conductive material. The optical imaging probe further comprises a ground terminal for connection with a second extremity of the cable, and an electrostatic discharge (ESD) arrangement configured for discharging charges accumulated on the electrically conductive surface of the probe head to the ground terminal via the electrical conductor of the cable.

[0007] In this way, electrostatic charges accumulated on a surface of the probe head during use can be discharged in a safe manner to the ground via an electrical path formed by the ESD arrangement and the electrical conductor of the cable. This enables to limit ESD protective measures associated with the electronic devices connected downstream of the optical imaging probe as ESD charges are not propagated from the optical imaging probe to the rest of the system. By providing an ESD protected optical imaging probe, the size of the typically mobile medical devices incorporating such optical imaging probes can be kept to a minimum. As well, the provided discharge path allows meeting the stringent ESD medical norms. According to a preferred embodiment, the ESD arrangement comprises a probe side ESD unit located at the first extremity of the cable, preferably inside said probe head, said probe side ESD unit being configured for discharging charges accumulated on the surface of the probe to the cable. Preferably the probe side ESD unit is electrically connected on one side to the surface of the probe and on the other side to the electrical conductor of the cable.

[0008] According to a preferred embodiment, the ESD arrangement comprises a ground side ESD unit located at the second extremity of the cable, said ground side ESD unit being configured for discharging the charges from the cable to the ground terminal.

[0009] In this way, the optical imaging probe remains easy to use as the ESD arrangement is arranged at one or both ends of the cable, and the cable portion remains unaffected. Preferably, the ESD arrangement may be integrated within the probe head and at the other extremity of the cable, not affecting thus the ergonomics of a probe head arranged at the end of a flexible cable.

[0010] According to a preferred embodiment, the electrical conductor extends through the cable. In this way the ESD arrangement forms with the electrical (metallic) conductor of the cable a continuous discharge path for ESD charges to the ground terminal. The electrical conductor may preferably extend through the cable at least from the probe side ESD unit to the ground side ESD unit. According to a preferred embodiment, the electrical conductor is arranged around the one or more optical fibers, wherein preferably the electrical conductor is a metallic braid or spiral part of a protective sheath arranged around said one or more optical fibers. Typically, protective sheathes for light conductors in medical and industrial applications comprise a protective metallic flat wire spiral or braid combined with an outer silicone coating (and optionally a fiber braiding). Such sheathes are flexible while having high tensile strength and being resistant to torsion and transversal pressure. Such protective sheathes are primarily meant for mechanical protection of the optical fibers housed therein. In this way, a standard protective sheath for optical fibers can be easily integrated into the ESD protection path. The standard protective sheathes for optical fibers meant for mechanical purposes can in this way be repurposed to also serve for ESD protection. Alternatively, the optical cable may comprise a separate ground wire specifically arranged for transferring the ESD charges to the ground terminal.

[0011] According to a preferred embodiment, the ESD arrangement comprises a first electrically conductive member arranged in between the probe head and the electrical conductor of the cable to electrically connect said probe head and said electrical conductor. In this way, an electrical discharge path can be arranged between the probe head (in particular an outer surface thereof) and the electrical conductor of the cable.

[0012] According to a preferred embodiment, the first conductive member is further a gripping member for mechanically gripping the cable, in particular for mechanically gripping an outer surface of the cable. In this way, both mechanical and electrical connection can be realised by the same element, in order to simplify the optical imaging probe.

[0013] According to a preferred embodiment, the probe side ESD unit comprises a fastening member for fastening the first conductive member to the probe head and to the cable. In this way, mounting of the ESD arrangement to the probe head and the cable can be controlled via one purely mechanical fastening member. The fastening member may be made of plastic for instance and need not be electrically conductive.

[0014] According to a preferred embodiment, the fastening member, the first conductive member and the probe head are tubular elements arranged coaxially along a mounting axis to receive the cable extending longitudinally through them. In this way, space can be saved to keep the size of the probe head to a minimum and as well provide an integrated solution in which only the probe head comes in mechanical contact with the outside world.

[0015] According to a preferred embodiment, the probe head comprises a cavity for housing the fastening member and the first conductive member. In this way, an elegant design is obtained in that the fastening member and the first conductive member can be dissimulated inside the probe head improving hygiene as only the outer surface of the probe head will be in contact with the outside environment.

[0016] According to a preferred embodiment, the fastening member is configured to press the first conductive member inside the cavity parallel to the mounting axis along a first direction when fastened to the probe head. In this way, the conductive member can be easily mechanically mounted inside the probe head.

[0017] According to a preferred embodiment, when pressed inside the cavity, a plurality of first portions of the first conductive member come in contact with the probe head and a plurality of second portions of the first conductive member come in contact with the electrical conductor of the cable, wherein the plurality of first and second portions are electrically connected with each other. In this way, the ESD arrangement on the probe head side, i.e. the probe side ESD arrangement, the cable and the probe head can be assembled in one go.

[0018] According to a preferred embodiment, the fastening member has an outer threaded portion for engaging with an inner threaded portion of the probe head provided inside the cavity.

[0019] Alternatively, other purely mechanically fastening means may be envisaged like a bayonet or clamping means. Glue is typically not desirable for hygiene and durability reasons but may be envisaged depending on circumstances.

[0020] According to a preferred embodiment, the cavity has a conically shaped portion, and the first conductive member has a complementary conically shaped outer portion. The complementary conically shaped outer portion of the conductive member is shaped for engaging with the conically shaped portion of the cavity when the fastening member presses the first conductive member along the first direction. In this way, the electrical connection by physical contact between the first conductive element with both the probe head and the electrical (metallic) conductor of the cable, and at the same time the mechanical gripping of the first conductive member to the cable are obtained.

[0021] According to a preferred embodiment, the probe head is made of metal, preferably having a surface treatment suitable for medical applications. In this way, hygiene regulations for medical devices can be respected.

[0022] According to a preferred embodiment, the probe head comprises a tip and a handle. In this way, the probe head can be assembled and dismounted to be mounted to an cable in a convenient manner. According to a preferred embodiment, the tip has an outer surface with an opening through which the end of the cable is exposed. In this way, a probing surface can be obtained. Typically, the outer surface surrounding the opening is substantially flat. Alternatively, the outer surface may be convex. Alternatively to an opening, an optical interface (for instance a light window, a lens) may be used to couple the light in and out of the one or more optical fibers at the outer surface.

[0023] According to a preferred embodiment, the handle has an inner tubular shape for receiving the cable extending along the axis of the tubular portion and preferably an outer tubular shape for being handheld. In this way, an ergonomic shape for manipulating the imaging probe head can be obtained wherein the probe head lies in the continuity of the cable.

[0024] According to a preferred embodiment, the handle houses the cavity in which the first conductive member and the fastening member are arranged. In this way, mounting of the first conductive member by fastening the fastening member can be performed when the tip is removed from the handle giving access to the cavity inside the handle. This allows a simple mounting of the probe head.

[0025] According to a preferred embodiment, the probe head further comprises a second electrically conductive element arranged between the tip and the handle and configured to form an electrical path to discharge electrostatic charges accumulated on the tip to the handle. In this way, electrical connection between the tip and the handle can be ensured despite the probe head being in two pieces.

[0026] According to a preferred embodiment, the second conductive element is mechanically connecting the tip and the handle. In this way, by forcing mechanical contact, electrical contact can be ensured by contact. Preferably, the second conductive element is a wave spring. Such a wave spring made of metal achieves both a mechanical elastic constraint as well as a spatially regular electrical distribution of ESD charges over its whole structure. Alternatively, a regular coil spring or other metallic element with elastic properties may be used as second conductive element.

[0027] According to a preferred embodiment, the ESD arrangement comprises on the ground terminal side a resistive element in between the electrical (metallic) conductor of the cable and the ground terminal. The resistive element may be part of the ground side ESD unit. In this way, the discharge of the ESD charges to the ground terminal can be controlled. The resistive element may be a resistor having a resistance between 1 Megaohm and 5 Megaohms.

[0028] According to a preferred embodiment, the ground side ESD unit comprises a housing and a third electrically conductive element arranged in between the electrical (metallic) conductor of the cable and said housing. According to a preferred embodiment, the ground side ESD unit further comprises a fourth electrically conductive element for connecting the ground side housing to the resistive element. The connection from the electrical (metallic) conductor to the ground terminal can be housed in a housing for an elegant and hygienic design.

[0029] According to a preferred embodiment, the optical imaging probe further comprises one optical input terminal connected to one or more of the one or more optical fibers, for connection to the light source, and one optical output terminal connected to the remaining of the one or more optical fibers for connection to an external analysing device. In this way, the optical imaging probe may be connected to further electronic devices for providing the light for exposing a surface under inspection and for analysing the light from the exposed inspected surface. Preferably the cable comprises a single optical read fiber connected to the optical output terminal and a plurality of optical feed fibers connected to the optical input terminal, wherein within the cable the plurality of feed fibers are preferably disposed around the read fiber.

[0030] This and other aspects of the present invention will now be described in more detail, with reference to the appended drawings showing currently preferred embodiments of the invention, wherein:

[0031] - Figure 1 illustrates a longitudinal side view of an optical imaging probe according to an embodiment of the invention;

[0032] - Figure 2 illustrates a cross section of the cable shown in Figure 1 ;

[0033] - Figure 3 illustrates a cross section of an input optical cable as shown in Figure 1 ;

[0034] - Figure 4 shows a schematic cross section of an output optical cable as shown in Figure 1 ;

[0035] - Figure 5 shows a front view of a probe head according to an embodiment;

[0036] - Figure 6 shows an exploded longitudinal side view of the probe head according to Figure 1 ;

[0037] - Figure 7 shows a cross section of a probe head according to an embodiment;

[0038] - Figure 8 illustrates an enlarged view of Figure 7 ;

[0039] - Figure 9 illustrates a perspective view of a gripper according to an embodiment;

[0040] - Figure 10 illustrates a perspective back view of the imaging probe of Figure 1;

[0041] - Figures 11 illustrates a longitudinal cross section of a ground side ESD unit according to an embodiment; Figure 12 shows an enlarged view of Figure 11 ;

[0042] Figure 13 illustrates another longitudinal cross section of a ground side ESD unit according to an embodiment (in another plane than Figure 11).

[0043] Figure 1 illustrates a longitudinal side view of an optical imaging probe according to an embodiment of the invention. The optical imaging probe 1000 comprises an cable 200 comprising optical fibers (non-visible because arranged inside), a probe head 100 configured to receive a first extremity of the cable 200 and to expose at a surface 110a of the probe head 100 an end of the optical fibers of the cable 200. The optical image probe 1000 may be regarded as comprising a connecting portion 300 for connection to external components, in particular to a light source, to an external analysing device (not represented) and to a ground reference. The connecting portion 300 may comprise a ground side ESD unit housing 310, an optical output cable 320, a, optical output terminal 330, a ground terminal 350, an optical input cable 360 and an optical output terminal 370. The optical imaging probe 1000 comprises in particular a ground terminal 350 for connection to an external ground reference and connected to a second extremity of the cable 200, and an Electrostatic Discharge (ESD) arrangement (partially non-visible because partially arranged inside the probe head 100) configured for discharging charges accumulated on the surface of the probe head 110 to the ground terminal 350 via the cable 200. The probe head 100 may have an external surface made of metal with for example a surface treatment suitable for medical applications. The probe head 100 may comprises a tip 110 with the surface 110a and an handle 150 The tip 110 and the handle 150 may both be made of metal. Charges accumulated on the tip 110 and / or on the handle 150 may discharged using the ESD arrangement to the ground terminal 350 according to embodiments of the invention as will be further explained with reference to Figures 6-13.

[0044] The ESD arrangement comprises a probe head side ESD unit (non-visible in Figure 1 because arranged entirely inside the probe head 100) located at a first extremity of the cable 200 connected to the probe head 100, inside said probe head 100 and a ground side ESD unit (partially visible, housing 310) located at the other extremity of the cable 200 for connection with the ground terminal 350. The probe head side ESD unit is configured for discharging charges accumulated on the surface 110a of the probe head 100 to the cable 200, said ground side ESD unit being configured for discharging the charges from the cable 200 to the ground terminal 350.

[0045] The optical imaging probe 100 may further comprise one optical input terminal 370 connected to one or more fibers of the cable 200 and one optical output terminal 330 connected to the remaining of the optical fibers of the cable 200. The optical input terminal 370 may be for connection to an external light source (not represented). The optical output terminal 330 may be for connection to an external analysing device. An input cable 360 may connect a housing 310 which is part of the ground side ESD unit, to the optical input terminal 330. A ground cable 340 may connect the ground side ESD unit housing 310 to the ground terminal 350. An output cable 320 may connect the ground side ESD unit housing 310 to the optical output terminal 370.

[0046] Figure 2 illustrates a cross section of the cable 200 shown in Figure 1 , Figure 3 illustrates a cross section of an optical cable 320 shown in Figure 1 while Figure 4 shows a schematic cross section of an optical cable 360 shown in Figure 1. From inside to outside, the cable 200 of Figure 2 may comprise a read optical fiber 210, six feed optical fibers 220, a coating sleeve 230, a void 240, an electrical (metallic) conductor 250, an optional glass fiber braid, and an outer coating 270. The read optical fiber 210 may be arranged for transmitting light sensed at the probe head 100 to the external analysing device, i.e. to the optical output terminal 330. The feed optical fibers 220 may be identical fibers, each arranged for transmitting light provided from the external light source to the probe head 100, i.e. from the optical input terminal 370. The coating sleeve 230 may be a silicone sleeve arranged around all the fibers 210, 220 to form with them an inner cable. The electrical (metallic) conductor 250 may be a metallic layer. In particular the metallic layer may be a metallic braid or spiral part forming with the outer coating 270, a protective sheath arranged around the inner cable. In between the inner cable and the sheath, a void 240 may be left to allow for flexibility of the whole cable 200. Although not visible in figure 1 , inside the ground side ESD unit housing 310, the cable 200 may be split into the optical cable 320, the ground cable 340 and the optical cable 360. In this way, as illustrated in Figure 3, the output cable 320 may comprise the read fiber 210, a void 321 and an outer coating 322, while the input cable 360 may comprise the feed fibers 220 and an outer coating 362 as illustrated in Figure 4. The read optical fiber 210 may run without discontinuity from the surface 100a of the probe head 100 to the optical output terminal 330, as part of the cable 200 and as part of the output cable 320. The feed optical fibers 220 may each run without discontinuity from the optical input terminal 370 to the surface 100a of the probe head 100, as part of the input cable 360 and as part of the cable 200.

[0047] Figure 5 shows a front view of a probe head according to an embodiment. The tip 110 of the probe head 100 may comprise an external (sensing) surface 110a with an opening 111 through which ends of the optical fibers 210 and 220 of the cable 200 are exposed to the outside environment. The tip 110 may further comprise a side surface 110b. The read and feed optical fibers 210 and 220 may be oriented inside the probe head 100 to be butt coupled to the surface 110a, i.e. substantially perpendicularly to the surface of the opening 111. The end surfaces of the read and feed optical fibers 210 and 220 may be arranged to be substantially flush with the external surface 110a of the tip 110.

[0048] Figure 6 shows an exploded longitudinal side view of the probe head according to Figure 1. The optical imaging probe 1000 may comprise the tip 110 already shown in Figures 1 and 5, an electrically conductive element 120, a fastening member 130, an electrically conductive member 140 and the handle 150 already shown in Figure 1. The electrically conductive member 120 may be made of an electrically conductive material. The electrically conductive member 140 may be made of an electrically conductive material. The electrically conductive element 120 may be arranged in use between the tip 110 and the handle 150. The electrically conductive element 120 may be configured to form an electrical path to discharge electrostatic charges accumulated on the tip 110 to the handle 150. The electrically conductive element 120 may be a wave spring both mechanically and electrically coupling the tip 110 and the handle 150. For that reason, the electrically conductive member 120 may further be referred to as a coupler. The coupler 120 may be arranged in a cavity formed in use between an inner surface 1 lOd of the tip 110 and an inner surface 150d of the handle 150.

[0049] The electrically conductive member 140 may be arranged in use between an inner (conical) surface 150b of the handle 150 and the electrical (metallic) conductor 250 of the cable 200. In this way, the electrically conductive member 140 may electrically connect the handle 150 of the probe head 100 and the electrical (metallic) conductor 250 to provide a electrostatic discharge path from the handle 150 to the electrical (metallic) conductor 250. The electrically conductive member 140 may further act as gripping member for mechanically gripping the cable 200, in particular for mechanically gripping an outer surface of the cable 200, more in particular the outer coating 270 of the cable 200. For that reason, the electrically conductive member 140 may be further referred to as a gripper.

[0050] The fastening member 130 may be configured to fasten the gripper 140 to the probe head 100 and to the cable 200. The handle 150 may comprise a cavity 151 for housing the fastening member 130 and the gripper 140. The cavity 151 may be formed by the inner conical surface 150b and an inner surface 150c adjacent to the inner conical surface 150b. The fastening member 130 may be configured in use to engage with the probe head 100 in particular with the handle 150 and to press the gripper 140 inside the cavity 151 parallel to the mounting axis A along a first direction such that a plurality of first portions 141 of the gripper 140, which may be referred to as outer contacting portions 141, come in contact with the inner (conical) surface 150b of the handle 150 and a plurality of second portions 143 (non-visible in Figure 6, see Figure 8 and Figure 9) of the gripper 140, which may be referred to as inner contacting portions 143, come in contact with the electrical (metallic) conductor 250 of the cable 200. The outer contacting portions 141 may be arranged on an outer surface of the gripper 140, while the inner contacting portions 143 may be arranged on an inner surface of the gripper 140. A plurality of inner gripping portions 141 may further be present on an inner surface of the gripper 140 for gripping the cable 200. A plurality of grooves 145 may be spaced apart along the circumference of the gripper to form the plurality of first portions 141 and second portions 142. The mechanical arrangement of the gripper 140 will be further detailed in Figure 9. The fastener 130 may comprise a threaded portion 131 for engaging with a threaded portion on the inner surface 150c of the handle 150. As shown in Figure 6, the cable 200 may comprise an end portion 200a without the coating sleeve 230, the electrical (metallic) conductor 250, the braid 260 and the outer coating 270, a first intermediate portion 200b without the electrical (metallic) conductor 250, the braid 260 and the outer coating 270, a second intermediate portion 200c without the braid 260 and the outer coating and a normal section 200d with all layers according to figure 2. Along the end portion 200a, the feed fibers are exposed, along the first intermediate portion 200b, the coating sleeve 230 is exposed. Along the second intermediate portion 200b, the electrical (metallic) conductor 250 may be exposed. Along the normal section 200d, the outer coating 270 is exposed. Figures 7-9 will now explain how the different sections 200a, 200b are in use connected to the different parts of probe head 100.

[0051] Figure 7 illustrates a cross section of a probe head 100 mounted onto a cable 200 according to an embodiment while figure 8 illustrates an enlarged view of Figure 7. The coupler 120, the fastening member 130, the gripper 140 and the handle 150 may be tubular elements arranged coaxially along a mounting axis A to receive the cable 200 extending longitudinally through them. The end portion 200a of the cable 200 may debouche at the surface 110a of the tip 110. The end portion 200b of the cable 200 may debouche in use in between the fastener 130 and the coupler 120. The end portion 200c of the cable 200 may be exposed in the cavity 151 to make contact with the gripper 140. The normal section 200d may extend in use inside the gripper 140 such that the inner gripping portions 142 may grip the outer coating 270 of the cable 200 while the inner connecting portions 143 may contact the electrical (metallic) conductor 250. The fastener 130 may be arranged as a tubular element having an outer peripheral surface 131, an upper flange 133 and a lower flange 132. The upper and lower flanges 133 and 132 may be defined perpendicular to the tubular axis of the fastener 130. The outer surface 131 may have a threaded portion for engaging with an inner surface 150c of the handle 150 forming with the inner conical surface 150b the cavity 151 receiving both the fastener 130 and the gripper 140. The upper flange 133 may comprise a slit for receiving a screwdriver type of tool to screw the fastener 130 inside the handle 150 along a direction B. When fastening the fastener 130, the lower flange 132 of the fastener may come in contact with a flange portion 144 of the gripper 140 pushing in this way the gripper 140 inside the cavity 151 along the direction B. By moving the flange portion 144 along direction B, the outer contacting portions 141 come in contact with the inner conical surface 150b and together with the inner gripping surfaces 142 and the inner contacting portions 143 hinge towards the axis A.

[0052] Further Figure 8 illustrates how the coupler 120 is arranged in used between the tip 110 and the handle 150. The handle 150 may comprise a flange inner surface 150d, oriented substantially perpendicular to the axis A of the handle 150. The coupler 120 may be a wave spring. The wave spring 120 may have multiple turns interconnected to form a mesh. Multi Turn (Peak-to Peak) wave springs may replace coil helical compression springs, requiring only one -half or less of axial space to provide the same force, making them ideal for use in space-constrained environments. Further the interconnections between turns ensure conductions of charges in a spatially spread manner. The wavespring 120 may be compressed in use inside a cavity 112 formed in between an inner surface HOd of the tips, oriented substantially parallel to the outer surface 110a, and the flange inner surface 150d of the handle 150. Further the tip 110 may comprise a collar flange 1 lOe matching a collar 150e of the handle 150. The collar flange 1 lOe of the tip and the collar 150e of the flange may be mechanically fixed together by any suitable means, in particular using glue. The wavespring 120 may ensure the presence of an electric discharge path for charges accumulated on the tip 110a of the tip 110 to the handle 150. As can be seen in Figure 8, the optical fibers 210 and 220 extend from the cavities 112 and 151 through an opening 111 in the tip 110 till the outer surface 110a of the tip 110.

[0053] Figure 9 illustrates further a perspective view of the gripper 140 according to an embodiment. The gripper 140 may comprise a plurality of grooves 145 extending longitudinally along most of the length of the gripper 140, typically along at least 80%, preferably 90%, of the length of the gripper 140. The grooves 145 may be regularly spaced apart along the circumference of the gripper 140 to form the plurality of first portions 141 and second portions 142. The grooves 145 may be dimensioned such that the effort exerted when screwing the fastener 130 inside 150 deforms the portions 141, 142 and 143 away from their initial positions and towards the interior axis A of the gripper, and thus towards the cable 200. In this way, the gripper 140 is forced to at the same time to make contact between surfaces 141 and 150b, between surfaces 143 and 250, between surfaces 142 and 270. Both electrical and mechanical connections of the probe head side ESD unit are thus realised via displacement of the fastener 130.

[0054] Figure 10 illustrates a perspective back view of the imaging probe of Figure 1. This Figures shows in particular how the connecting portion 300 of the imaging probe 1000 for connection to external components. The ground side ESD unit housing 310 may output the input cable 360 going to the optical input terminal 370, the ground cable 340 going to the ground terminal 350 and the output cable 320 going to the optical output terminal 330.

[0055] Figure 11 illustrates a first longitudinal cross section of the ground side ESD unit including the housing 310 according to an embodiment. The ground side ESD unit comprises the ground side ESD unit housing 310, a second fastener 130’ and a second gripper 140’ (the same reference numbers being used for similar elements). In essence the inner constitution of the ground side ESD unit may be regarded as identical to the one of the probe side ESD unit. The housing 310 has an inner cavity similar to cavity 151 of handle 150 such that the same elements 130 and 140 may be used to create a discharge path from the conductor 250 towards the housing 310. As illustrated in the enlarged view of Figure 12, in use, the outer portions 141’ of the second gripper 140’ makes electrical and mechanical contact with the inner conical surface 310b while the inner gripping portions 142’ of the second gripper 140’ make mechanical contact with the outer coating 270 at the ground side extremity of the cable 200, and the inner contacting portions 143’ make electrical and mechanical contact with the electrical (metallic) conductor 250 at the ground side extremity of the cable 200. Further inside housing 310, the optical fiber 210 and the multiple optical fibers 220 may be split to form the input cable 360 and the output cable 320.

[0056] Figure 13 illustrates a second longitudinal cross section of the of the ground side ESD unit including the housing 310 of figure 10 along a different plane passing through the ground cable 340. The ground side ESD unit may comprise a resistive element 317 arranged in between the housing 310 and the ground cable 340. The resistive element 317 may have a resistance between 1 and 5 MOhms, and preferably may be an off the shelf component. The value of the resistance may be selected to ensure a safe ESD discharge to the ground. The ground side ESD unit may further comprises an additional electrically conductive element 315 for connecting the ground side housing 310 to the resistive element 317. The element 315 may be a screw for mechanically and electrically connecting the housing 310 and the resistor 317. In this way a discharge path may be formed between the conductor 250 to the ground terminal 350 via the gripper 140’, the screw 315, the resistor 317 and the output cable 340.

[0057] Whilst the principles of the invention have been set out above in connection with specific embodiments, it is understood that this description is merely made by way of example and not as a limitation of the scope of protection which is determined by the appended claims.

[0058] Further embodiments are described in the following clauses:Clause 1. An optical imaging probe comprising:

[0059] - a cable comprising an electrical conductor and one or more optical fibers,

[0060] - a probe head configured to receive a first extremity of the cable, said probe head comprising a surface made of an electrically conductive material,

[0061] - a ground terminal for connection to a second extremity of the cable, and

[0062] - an electrostatic discharge, “ESD”, arrangement configured for discharging charges accumulated on the electrically conductive surface of the probe head to the ground terminal via the electrical conductor of the cable.

[0063] Clause 2. Optical imaging probe according to clause 1, wherein the ESD arrangement comprises a probe head side ESD unit located at the first extremity of the cable, preferably inside said probe head, said probe side ESD unit being configured for discharging charges accumulated on the electrically conductive surface of the probe head to the cable.

[0064] Clause 3. Optical imaging probe according to any of the previous clauses, wherein the ESD arrangement comprises a ground side ESD unit located at the second extremity of the cable, said ground side ESD unit being configured for discharging the charges from the cable to the ground terminal. Clause 4. Optical imaging probe according to any of the previous clauses, wherein the electrical conductor extends through the cable.

[0065] Clause 5. Optical imaging probe according to any of the previous clauses, wherein the electrical conductor is arranged around the one or more optical fibers, wherein preferably the electrical conductor is a metallic braid or spiral part of a protective sheath arranged around said one or more optical fibers.

[0066] Clause 6. Optical imaging probe according to any of the above clauses, wherein the ESD arrangement comprises a first electrically conductive member arranged in between the probe head and the electrical conductor of the cable to electrically connect said probe head and said electrical conductor.

[0067] Clause 7. Optical imaging probe according to the previous clause, wherein the first conductive member is further a gripping member for mechanically gripping the cable, in particular for mechanically gripping an outer surface of the cable.

[0068] Clause 8. Optical imaging probe according to any of the last two clauses, wherein the ESD arrangement comprises a fastening member for fastening the first conductive member to the probe head and to the cable.

[0069] Clause 9. Optical imaging probe according to the previous clause, wherein the fastening member and the first conductive member are tubular elements arranged coaxially along a mounting axis to receive the cable extending longitudinally through them.

[0070] Clause 10. Optical imaging probe according to any of the last two clauses, wherein the probe head comprises a cavity for housing the fastening member and the first conductive member.

[0071] Clause 11. Optical imaging probe according to the previous clause, wherein the fastening member is configured to press the conductive member inside the cavity parallel to the mounting axis along a first direction when fastened to the probe head.

[0072] Clause 12. Optical imaging probe according to the previous clause, wherein when the first conductive member is pressed inside the cavity, a plurality of first portions of the first conductive member come in contact with the probe head and a plurality of second portions of the first conductive member come in contact with the electrical conductor of the cable, wherein the plurality of first and second portions are electrically connected with each other.

[0073] Clause 13. Optical imaging probe according to any of previous clauses 10-12, wherein the fastening member has an outer threaded portion for engaging with an inner threaded portion of the probe head provided inside the cavity.

[0074] Clause 14. Optical imaging probe according to any of previous clauses 10-13, wherein the cavity has a conically shaped portion, and the first conductive member has a complementary conically shaped outer portion. Clause 15. Optical imaging probe according to any of the above clauses, wherein the probe head is made of metal, preferably has a surface treatment suitable for medical applications.

[0075] Clause 16. Optical imaging probe according to any of the above clauses, wherein the probe head comprises a tip and a handle.

[0076] Clause 17. Optical imaging probe according to the previous clause, wherein the tip has an outer surface with an opening through which the ends of the one or more optical fibers are exposed. Clause 18. Optical imaging probe according to any of the last two clauses, wherein the handle has an inner tubular shape for receiving the cable extending along the axis of the tubular shape.

[0077] Clause 19. Optical imaging probe according to any of clauses 16-18 and any of clauses 10-15, wherein the handle houses the cavity in which the first conductive member and the fastening member are arranged.

[0078] Clause 20. Optical imaging probe according to any of the above clauses 16-19, wherein the probe head further comprises a second electrically conductive element arranged between the tip and the handle and configured to form an electrical path to discharge electrostatic charges accumulated on the tip to the handle.

[0079] Clause 21. Optical imaging probe according to the previous clause, wherein the second conductive element is mechanically connecting the tip and the handle, wherein the second conductive element is preferably a wave spring.

[0080] Clause 22. Optical imaging probe according to any of the above clauses, wherein the ESD arrangement comprises on the ground side a resistive element in between the electrical conductor of the cable and the ground terminal.

[0081] Clause 23. Optical imaging probe according to at least clause 3 and optionally any of the above clauses, wherein the ground side ESD unit comprises a housing and a third electrically conductive element arranged in between the electrical conductor of the cable and said housing.

[0082] Clause 24. Optical imaging probe according to the above last two clauses, wherein the ground side ESD unit further comprises a fourth electrically conductive element for connecting the ground side housing to the resistive element.

[0083] Clause 25. Optical imaging probe according to any of the above clauses, further comprising one optical input terminal connected to one or more of the one or more optical fiber, for connection to the light source, and one optical output terminal connected to the remaining of the one or more optical fibers for connection to an external analysing device.

[0084] Clause 26. Optical imaging probe according to the previous clause, wherein the cable comprises a single optical read fiber connected to the optical output terminal and a plurality of optical feed fibers connected to the optical input terminal, wherein within the cable the plurality of feed fibers are disposed preferably around the read fiber.

Claims

CLAIMS1. An optical imaging probe comprising:- a cable comprising an electrical conductor and one or more optical fibers,- a probe head configured to receive a first extremity of the cable, said probe head comprising a surface made of an electrically conductive material,- a ground terminal for connection to a second extremity of the cable, and- an electrostatic discharge, “ESD”, arrangement configured for discharging charges accumulated on the electrically conductive surface of the probe head to the ground terminal via the electrical conductor of the cable, wherein the electrical conductor is a metallic braid or spiral part of a protective sheath arranged around said one or more optical fibers.

2. Optical imaging probe according to claim 1 , wherein the ESD arrangement comprises a probe head side ESD unit located at the first extremity of the cable, preferably inside said probe head, said probe side ESD unit being configured for discharging charges accumulated on the electrically conductive surface of the probe head to the cable.

3. Optical imaging probe according to any of the previous claims, wherein the ESD arrangement comprises a ground side ESD unit located at the second extremity of the cable, said ground side ESD unit being configured for discharging the charges from the cable to the ground terminal.

4. Optical imaging probe according to any of the previous claims, wherein the electrical conductor extends through the cable.

5. Optical imaging probe according to any of the above claims, wherein the ESD arrangement comprises a first electrically conductive member arranged in between the probe head and the electrical conductor of the cable to electrically connect said probe head and said electrical conductor.

6. Optical imaging probe according to the previous claim, wherein the first conductive member is further a gripping member for mechanically gripping the cable, in particular for mechanically gripping an outer surface of the cable.

7. Optical imaging probe according to any of the last two claims, wherein the ESD arrangement comprises a fastening member for fastening the first conductive member to the probe head and to the cable.

8. Optical imaging probe according to the previous claim, wherein the fastening member and the first conductive member are tubular elements arranged coaxially along a mounting axis to receive the cable extending longitudinally through them.

9. Optical imaging probe according to any of the last two claims, wherein the probe head comprises a cavity for housing the fastening member and the first conductive member.

10. Optical imaging probe according to the previous claim, wherein the fastening member is configured to press the conductive member inside the cavity parallel to the mounting axis along a first direction when fastened to the probe head.

11. Optical imaging probe according to the previous claim, wherein when the first conductive member is pressed inside the cavity, a plurality of first portions of the first conductive member come in contact with the probe head and a plurality of second portions of the first conductive member come in contact with the electrical conductor of the cable, wherein the plurality of first and second portions are electrically connected with each other.

12. Optical imaging probe according to any of previous claims 9-11, wherein the fastening member has an outer threaded portion for engaging with an inner threaded portion of the probe head provided inside the cavity.

13. Optical imaging probe according to any of previous claims 9-12, wherein the cavity has a conically shaped portion, and the first conductive member has a complementary conically shaped outer portion.

14. Optical imaging probe according to any of the above claims, wherein the probe head is made of metal, preferably has a surface treatment suitable for medical applications.

15. Optical imaging probe according to any of the above claims, wherein the probe head comprises a tip and a handle.

16. Optical imaging probe according to the previous claim, wherein the tip has an outer surface with an opening through which the ends of the one or more optical fibers are exposed.

17. Optical imaging probe according to any of the last two claims, wherein the handle has an inner tubular shape for receiving the cable extending along the axis of the tubular shape.

18. Optical imaging probe according to any of claims 15-17 and any of claims 9-14, wherein the handle houses the cavity in which the first conductive member and the fastening member are arranged.

19. Optical imaging probe according to any of the above claims 15-18, wherein the probe head further comprises a second electrically conductive element arranged between the tip and the handle and configured to form an electrical path to discharge electrostatic charges accumulated on the tip to the handle.

20. Optical imaging probe according to the previous claim, wherein the second conductive element is mechanically connecting the tip and the handle, wherein the second conductive element is preferably a wave spring.

21. Optical imaging probe according to any of the above claims, wherein the ESD arrangement comprises on the ground side a resistive element in between the electrical conductor of the cable and the ground terminal.

22. Optical imaging probe according to at least claim 3 and optionally any of the above claims, wherein the ground side ESD unit comprises a housing and a third electrically conductive element arranged in between the electrical conductor of the cable and said housing.

23. Optical imaging probe according to the above last two claims, wherein the ground side ESD unit further comprises a fourth electrically conductive element for connecting the ground side housing to the resistive element.

24. Optical imaging probe according to any of the above claims, further comprising one optical input terminal connected to one or more of the one or more optical fiber, for connection to the light source, and one optical output terminal connected to the remaining of the one or more optical fibers for connection to an external analysing device.

25. Optical imaging probe according to the previous claim, wherein the cable comprises a single optical read fiber connected to the optical output terminal and a plurality of optical feed fibers connected to the optical input terminal, wherein within the cable the plurality of feed fibers are disposed preferably around the read fiber.

Images