WO2016123660A1

WO2016123660A1 - An optical scanning device

Info

Publication number: WO2016123660A1
Application number: PCT/AU2016/000032
Authority: WO
Inventors: Bryden Christopher QUIRK; Robert Ainsley Mclaughlin; Dirk LORENSER
Original assignee: The University Of Western Australia
Priority date: 2015-02-06
Filing date: 2016-02-05
Publication date: 2016-08-11

Abstract

The present disclosure provides an optical scanning device for acquiring an image or performing a measurement of a material. The optical scanning device comprises an optical element arranged to receive electromagnetic radiation from the material when the optical element is positioned within the material. The electromagnetic radiation is used to form the image of the material. The optical scanning device further comprises a member supporting at least a portion of the optical element. The member is moveable between first and second configurations. The optical scanning device further comprises an actuator arranged to cause movement of the member between the first and second configurations. The optical scanning device is arranged such that movement of the member between the first and second configurations causes a translating movement of the at least a portion of the optical element.

Description

AN OPTICAL SCANNING DEVICE

Field of the Invention

The present invention relates to an optical scanning device, such as an optical scanning device for acquiring an image of biological tissue.

Background of the Invention

Optical imaging systems using imaging technologies such as optical coherence tomography (OCT) are capable of acquiring high-resolution images of biological tissue. However, the imaging light does not penetrate very far into tissue, limiting the imaging depth and restricting these technologies for use in the assessment of superficial tissue. For example, OCT is typically only able to acquire an image of the superficial 2-3mm of tissue, and confocal microscopy is limited to 100-200 m. In these optical imaging systems, scanning of the biological tissue is usually achieved by using scanning galvanometer mirrors to deflect the light beam across the field of view at high speeds. Typically, one mirror scans in the x-axis, and one mirror scans the y-axis.

There is a need for miniaturising these optical imaging systems such that the optical imaging system can be inserted into the human body to allow imaging of deeper regions of the biological tissue. However, standard galvanometer mirrors are too large to be incorporated into a miniaturised optical imaging system.

Summary of the Invention

In accordance with a first aspect of the present invention, there is provided an optical scanning device for acquiring an image or performing a measurement of a material, the optical scanning device comprising:

an optical element arranged to receive electromagnetic radiation from the material when the optical element is

positioned within or between the material, the electromagnetic radiation being used to form the image of the material;

a member supporting at least a portion of the optical element, the member being moveable between first and second configurations; and an actuator arranged to cause movement of the member between the first and second configurations;

wherein the optical scanning device is arranged such that movement of the member between the first and second

configurations causes a translating movement of the at least a portion of the optical element.

The term "material" as used herein is intended to encompass any matter including, for example, biological material such as biological tissue, organic materials such as food, and non- biological material such as a silicone material or the like.

In an embodiment, the optical scanning device has an axis and a component of the actuator is arranged to move in a direction that is transversal to the axis and the translating movement of the at least a portion of the optical element may be in a direction along the axis . The optical scanning device may be arranged such that the translating movement has a direction that is substantially transversal to at least a portion of the member .

Embodiments of the present invention provide significant advantages. In particular, in the medical field the optical scanning device may be provided such that the optical element can be inserted into biological tissue or a body lumen such as a blood vessel. For example, the optical element, or a distal end of the optical element, may be positioned at a distal end of a probe, such as a needle probe, and the optical element may be remote from the member and the actuator. Further, an image of the material can be acquired at a relatively high scanning rate. Also, there is no need for providing a scanning mirror such as a galvanometer mirror.

In one example, the actuator comprises at least one

piezoelectric device that is connected to the member. Thus, the piezoelectric device is arranged such that at least a portion of the piezoelectric device moves in response to a change in a suitable applied voltage and the device is arranged such that that movement causes movement of the member between the first and second configurations.

In one embodiment, the piezoelectric device comprises a

cantilever wherein a first end of the cantilever is connected to the member and a second end of the cantilever that is opp OSite to the first end is anchored to a base. In this embodiment, if a voltage is applied to the cantilever, the cantilever may bend thereby causing the first end of the cantilever to move relative to the second end which is anchored to the base. For example, the cantilever may comprise a piezoelectric material.

Alternatively, the cantilever may be coupled to a piezoelectric component, such that a change in an applied suitable voltage causes movement of the piezoelectric component thereby causing movement of the cantilever.

In a specific embodiment, the optical scanning device comprises a pair of cantilevers. In this embodiment, the member may be supported at respective end portions of the pair of cantilevers.

A periodically varying voltage may be applied to the

piezoelectric device. The voltage may be periodically varied at resonance frequency of the piezoelectric actuator. If the piezoelectric device comprises at least one cantilever, the optical scanning device may be arranged such that the resonance frequency can be altered by changing the length of the at least one cantilever. For example, an extension may be attached to the cantilever.

In an embodiment, the member is composed of a material that is flexible. The member may be in the form of a flexible beam. In this regard, the optical scanning device may comprise a pair of cantilevers such that the flexible beam is supported at

respective end portions of the pair of cantilevers. In one example, the flexible beam is an optical fibre.

In an alternative embodiment, the member is in the form of a flexible sheet.

In a further embodiment, the member is articulated. In other words, the member comprises a joint, such as a hinge. For example, the member may comprise a pair of legs that is

connected via the hinge. In this embodiment, the actuator is arranged to move the member between a substantially straight configuration and an angled configuration.

If the optical scanning device comprises a plurality of

piezoelectric devices, the optical scanning device may be arranged such that movement of the plurality of piezoelectric devices is synchronized. By synchronising these movements and positioning the piezoelectric devices appropriately, forces applied to the flexible member by movement of the piezoelectric devices are balanced. Furthermore, the optical element may be positioned at a centre point of the flexible member. A person skilled in the art will appreciate that other suitable

arrangements are envisaged.

In one example, the optical scanning device is arranged such that the plurality of piezoelectric devices moves towards each other and away from each other. For example, when a positive voltage is applied to the optical scanning device, the

piezoelectric devices may move towards each other. However, a person skilled in the art will appreciate that any suitable movement of the piezoelectric devices is envisaged.

The acguired image may provide information in relation to a mechanical property of the material, such as biological tissue. The mechanical property may relate to an elasticity of the material, such as an elasticity of biological tissue. For example, the mechanical property may relate to the Young's modulus or any other suitable modulus of the material .

Alternatively, the mechanical property may relate to a

viscoelasticity or any other mechanical property. In the medical field, the optical element may have a size such that the optical element can be inserted into biological tissue, or a body lumen. For example, for intravascular applications the optical element may have a size such that the optical element can be inserted into a blood vessel. For endoscopic applications, the optical element may have a size such that the optical element can be inserted into a natural orifice of the body such as the airways, the colon or the oesophagus. For applications that require scanning in or between tissue, the optical element may have a size such that the optical element can be incorporated or accommodated within a needle so that the optical element can be inserted into biological tissue.

Examples of needles include, but are not limited to, biopsy needles, hypodermic needles, needles specifically designed for imaging inside tissue, which may be soft or solid.

A person skilled in the art will appreciate that embodiments of the present invention may be used for acquiring an image or measurements in various in-vivo and ex-vivo environments, including for example, lung, prostate, breast, liver and brain tissue and regions there between.

In an embodiment, the optical scanning device is arranged to employ optical coherence tomography ("OCT") . However, other imaging methods are envisaged, such as fluorescence, confocal microscopy, multi-photon 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 and Raman spectroscopy.

The optical element may comprise an optical light guide such as an optical fibre for transmitting light from a light source and/or an optical scanner which may or may not be part of the optical scanning device. In a specific example, the optical light guide is in the form of a bundle of optical fibres.

In an embodiment, the optical scanning device is arranged such that the optical element is rotatable. In this regard, the optical scanning device may comprise a further actuator, such a a motor. The optical scanning device may be arranged such that the optical element is rotated and translated substantially simultaneously. In this way, a 3D image may be created.

In an embodiment, the actuator comprises a thermoelectric actuator. Thus, if heat is applied to the thermoelectric actuator, the member moves between the first and second

configurations and thereby causes the translating movement the optical element.

In a further embodiment, the actuator may be a magnetic

actuator. Thus, if a magnetic field is applied to the magneti actuator, the member moves between the first and second

configurations and thereby causes the translating movement of the optical element.

More generally, the actuator may be a microelectromechanical systems (MEMS) component. The MEMS actuators may utilise a range of technologies to actuate, including those based on

electrostatic, piezoelectric and thermoelectric effects.

In accordance with a second aspect of the present invention, there is provided a probe for acquiring an image or performing a measurement of a material, the probe comprising:

a distal end for insertion into or between the material; and

the optical scanning device in accordance with the first aspect of the present invention.

The probe typically is elongate. The distal end of the probe may be sharpened or blunt .

The probe may be in the form of at least one of: a needle probe, an intravascular probe, and an endoscopic probe.

In one embodiment, the probe comprises a first member and a second member, wherein the second member comprises a hollow region for at least partially accommodating the first member. For example, the probe may be arranged to provide a sliding fit between the first and second members. The first member may be arranged for translation along an axis of the probe and both the first and second members may be arranged for rotation about the axis .

The optical element may be incorporated in or attached to the first member of the probe. For example, the first member may comprise a hollow portion for accommodating the optical element. In this regard, the optical element may be arranged at a side portion of the first member such that an image of a material region can be acquired that is adjacent to the probe. In addition, the outer member may have an inlet, such as an aperture or a window, to enable the optical element to acquire the image of the material when the first member with the optical element is accommodated within the second member.

The probe may further comprise an optical light guide such as an optical fibre for transmitting electromagnetic radiation to and/or from the optical element.

In accordance with a third aspect of the present invention, there is provided a method of acquiring an image or performing a measurement of a material, the method comprising:

providing the material;

positioning an optical element of the optical scanning device within or between the material;

directing electromagnetic radiation into the material; when the optical element is positioned within the

material, receiving electromagnetic radiation from the material at the optical element;

moving a member that supports at least a portion of the optical element between first and second configurations, thereby causing a translating movement of the at least a portion of the optical element; and

acquiring multiple measurements of the material using the electromagnetic radiation received at the optical element during the translating movement.

The method may comprise aggregating the multiple measurements into an image .

The method may comprise a step of rotating the optical scanning device. Rotating the optical scanning device may be performed substantially simultaneously with the translating movement of the at least a portion of the optical element.

In an embodiment, the method may be conducted such that a series of 2D images of the material are acquired. In addition, the method may comprise a step of creating a 3D image of the material using the series of 2D images.

In accordance with a fourth aspect of the present invention, there is provided a method of acquiring an image or performing a measurement of a material, the method comprising:

providing a material;

providing the optical scanning device in accordance with the first aspect of the present invention;

positioning the optical element of the scanning device within or between the material;

acquiring multiple measurements of the material using the optical scanning device.

Brief Description of the Drawings

The present invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

Figure 1 is a schematic representation of an optical scanning device in accordance with an embodiment of the present Figure 2a shows a schematic representation of an elongated probe in accordance with an embodiment of the present invention;

Figure 2b shows a photograph of the probe of Figure 2a;

Figure 3 shows a schematic illustration of configurations of the probe of Figures 2a and b for acquiring 2D and 3D image data;

Figures 4 and 5 show exemplary image data acquired using the probe shown in Figures 2a and b; and

Figure 6 illustrates a method in accordance with an embodiment of the present invention. Description of an Embodiment of the Invention

Embodiments of the present invention relate to an optical scanning device suitable for acquiring an image of a material, such as biological tissue. The optical scanning device may comprise a probe, such as a needle probe, an endoscopic probe an intravascular probe, such that an optical element of the optical scanning device can be inserted into biological tissue or a body lumen. The optical scanning device comprises an optical element, an actuator and a member that can be moved between first and second configurations .

The optical element is arranged to receive electromagnetic radiation from the material, such as biological tissue, when the optical element is positioned within the material. The received electromagnetic radiation is then used to form the image of the material. For example, if the optical scanning device comprises a probe, the probe may have a distal end for inserting into the material. In an example, the optical element comprises an optical fibre or a bundle of optical fibres that receive electromagnetic radiation from the material and subsequently transmits it to an optical scanner. In addition, the optical element may be arranged to direct electromagnetic radiation into the material. In this regard, the optical element may also be connected to a light source.

The member of the optical scanning device is further arranged to support at least a portion of the above mentioned optical element. For example, if the optical element comprises an optical fibre, the member may support an end portion of the optical fibre.

The member may be implemented by different components. In one example, the member is provided in the form of a flexible beam or a flexible sheet. In other words, the member is at least partially composed of a material that is flexible. In another example, the member comprises a joint, such as a hinge.

The optical scanning device further comprises an actuator for actuating the flexible member. The actuator is arranged to cause movement of the member between the first and second configurations. For example, the member may move from a substantially straight configuration to an angled configuration or a curved configuration.

The optical scanning device is arranged such that movement of the member between first and second configurations causes a translating movement of the optical element. In this way, when the optical element is positioned within a material, the optical element can be translated relative to the material in order to form an image of the material.

Referring now to Figure 1, there is shown a schematic

representation of an optical scanning device 100 in accordance with an embodiment of the present invention. As mentioned above, the optical scanning device 100 comprises an actuator 101, 102. In this example, the actuator is a

piezoelectric actuator 101, 102 that is arranged to bend or expand when a voltage is applied to the optical scanning device 100. A person skilled in the art will appreciated that the actuator 101, 102 may alternatively be a thermoelectric

actuator, a magnetic actuator or any other suitable actuator.

The piezoelectric actuator comprises a pair of piezoelectric cantilevers 101, 102. In order to use the piezoelectric cantilevers 101, 102 as actuators, respective first ends of the cantilevers 101, 102 are anchored at a common base and

respective second ends of the cantilevers that are opposite to the first ends are movable. Thus, if a voltage is applied to the pair of cantilevers 101, 102, the respective second ends of the cantilevers 101, 102 move relative to the anchored ends of the cantilevers 101, 102.

In this particular example, the piezoelectric cantilevers 101, 102 are capable to move towards each other and away from each other as indicated by the arrows in Figure 1.

It will be appreciated that the pair of cantilevers 101, 102 may be anchored at different bases. Furthermore, an optical scanning device comprising one or more than two cantilevers is envisaged. For example, instead of a pair of piezoelectric cantilevers, the optical scanning device 100 may comprise a piezoelectric cantilever 101 and a cantilever 102 that is not piezoelectric. Alternatively, the flexible beam 103, 104 may be connected to one piezoelectric cantilever and a wall portion of a probe .

Further, it will be appreciated that the piezoelectric actuator may comprise at least one cantilever that is coupled to a piezoelectric component such that movement of the piezoelectric component causes movement of the at least one cantilever. For example, the optical scanning device may comprise a pair of cantilevers that is connected by a piezoelectric component. A change of a suitable applied voltage may cause the piezoelectric component to expand, thereby moving the pair of cantilevers away from each other.

Referring back to Figure 1, the free ends of the piezoelectric cantilevers 101, 102 are connected to a member that is provided in the form of a flexible beam 103, 104. The flexible beam 103, 104 is illustrated in two configurations, i.e. before bending as indicated by reference numeral 103 and after bending as

indicated by reference numeral 104. In this embodiment, the optical scanning device 100 is arranged such that when the pair of cantilevers 101, 102 move towards each other, for example by changing an applied voltage, the flexible beam 103, 104 bends from a first configuration to a second configuration. For example, when no voltage is applied to the pair of cantilevers 101, 102, the flexible beam may be configured in a first configuration as indicated by reference numeral 103, and when a voltage is applied to the pair of cantilevers 101, 102, the flexible beam is caused to bend to be configured in the second configuration as indicated by reference numeral 104.

It will be appreciated that a periodically varying voltage may be applied to the optical scanning device 100. In this regard, the arrangement of the optical scanning device 100 may define a resonance frequency at which the range of movement of the cantilevers and therefore the bending of the flexible beam 103, 104 is maximal. Thus, the voltage may be periodically varied at resonance frequency of the optical scanning device 100.

Further, it will be appreciated that more than one flexible beam may be provided. For example, each flexible beam may be connected to a pair of piezoelectric cantilevers . The flexible beam 103, 104 supports a portion of an optical element 105, 106 that is arranged to direct light 107 into the material and receive light from the material. In this example, the optical element 105, 106 comprises an optical fibre 108. The optical fibre 108 transmits detected light to an optical scanner. It will be appreciated that the optical element 105, 106 may comprise a bundle of optical fibres such that

electromagnetic radiation can be received at a plurality of lateral positions. The optical scanner may for example be an OCT system that uses the received light to form the image of the material. In this regard, the received light may be near-infrared light. However, other imaging methods are envisaged, such as fluorescence, confocal microscopy, multi-photon 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 and Raman spectroscopy.

The optical scanning device 100 is arranged such that bending of the flexible beam 103, 104 causes a translating movement of the optical element 105, 106. In this example, the translating movement of the optical element 105, 106 is substantially perpendicular to a central axis of the flexible beam 103, 104. In Figure 1, the optical element is illustrated in two

configurations, i.e. at minimal translation as indicated by numeral 105 and at maximal translation as indicated by numeral 106. By translating the optical element 105, 106, the light beam 107 is moved accordingly which enables the optical scanning device 100 to acquire an image along a larger field of view.

The embodiment shown in Figure 1 provides significant

advantages. In particular, relatively high speed scanning over a large field of view is facilitated. Furthermore, unlike conventional designs as mentioned in the Background of the Invention, there is no requirement for the use of a scanning mirror for deflecting a beam of light that is directed into the material .

It should be noted that in this example the two cantilevers 101, 102 are synchronised. In this way, the forces applied to the flexible beam 103, 104 by the cantilevers 101, 102 are balanced, allowing the optical element 105, 106 to remain steady during the translating movement. In addition, as shown in Figure 1, the optical element 105, 106 is supported at a centre point of the flexible beam 103, 104.

In a further embodiment of the present invention (not shown) , the member is provided in the form of a flexible sheet. In this embodiment, the flexible sheet may be connected to more than two piezoelectric devices, for example one at each corner of the flexible sheet. If more than two cantilevers are provided, it would be advantageous to position the cantilevers in a geometry that balances the forces when the cantilevers are actuated. In another embodiment (not shown), the member comprises a joint, such as a hinge. In this regard, the member may be provided in the form of a pair of rigid legs that are connected via the joint. In this regard, the member may be moved between a substantially straight configuration and a substantially angled configuration.

Referring now to Figures 2a and b, there is shown a schematic representation and a photograph of a needle probe 200 in accordance with an embodiment of the present invention.

In this particular example, the needle probe 200 comprises a rigid base 201 and a pair of cantilevers 202 that are anchored to the rigid base 201. The pair of cantilevers 202 are

piezoelectric and similar to the pair of cantilevers 101, 102 shown in Figure 1. Specifically, the pair of piezoelectric cantilevers 202 are arranged to move towards each other and away from each other. An extension 203 is attached to each of the free ends of the cantilevers 202. By attaching an extension to the cantilevers 202, the resonance frequency of the cantilevers 202 can be altered. In this example, the extension 203 is attached to achieve a greater range of movement of the piezoelectric cantilevers 202.

Similar to the optical scanning device 100, the needle probe 200 as shown in Figures 2a and b comprises a member in the form of a flexible beam 204 that is attached to the free ends of the extensions 203. The flexible beam 204 in this example is provided by a relatively short length of an optical fibre that is attached to the plastic extensions 203 of the cantilevers 202. In this example, the flexible beam 204 supports an internal needle 205 that encases an optical element 206. The internal needle 205 together with the optical element 206 is attached to a centre point of the flexible beam 204. Furthermore, the cantilevers 202 are positioned so that their movement is synchronised. In this way, the forces exerted by the

cantilevers 202 to the flexible beam 204 and to the base 201 are balanced, allowing the optical element 206 to remain steady during scanning. In other words, vibration of the optical element 206 that is perpendicular to the axis of the internal needle 205 can be minimised. Similar to the optical scanning device 100 shown in Figure 1, the optical element 206 is connected to an optical scanner by an optical fibre 207.

A change of voltage applied to the piezoelectric cantilevers 202 causes the piezoelectric cantilevers 202 to move towards each other. As a consequence, the flexible beam 204 bends and the internal needle 205 is translated in a direction that is substantially perpendicular to the central axis of the flexible beam 204.

The needle probe 200 further comprises an outer needle 208 that is attached to a casing of the needle probe 200 and that is rigidly connected to the base 201. The outer needle 208 comprises a distal end for inserting the needle probe 200 into biological tissue. In this example, the distal end is

sharpened. However, the distal end may alternatively be blunt. This may be advantageous for certain medical applications, for example when a needle probe is inserted into the brain of a patient.

The outer needle 208 comprises a hollow region for accommodating the inner needle 205. In particular, the outer needle 208 has a tubular shape and is arranged to provide a sliding fit between the inner needle 205 and the outer needle 208 such that the inner needle 205 can translate inside the outer needle 208.

It will be appreciated that the inner needle 205 may be replaced by an alternative support structure. For example, the optical element 206 may have a collar or bushing around it so that the optical element 206 can translate within the outer needle 208. Further, a low-friction coating may be applied to the optical element, such as polytetrafluoroethylene (also known as Teflon) . Further exemplary coatings for the optical element are described in US6187369 Bl and US6673453 B2.

The outer needle 208 further comprises an inlet in the form of an imaging window 209. In this example, the imaging window 209 is relatively long and thin and has been etched into a side portion of the outer needle 208.

In the embodiment shown here, the imaging window has been etched into the large outer needle and left uncovered. In other embodiments, the imaging window may be covered with a non- permeable, optically-transparent surface. This has the

advantage of stopping tissue and fluids from becoming caught inside the needle, as these can interfere with the movement of the optical probe. In some embodiments, the non-permeable, optically-transparent surface may comprise a polyimide such as, but not limited to, Kapton .

The needle probe 200 can be configured in an imaging

configuration. In this regard, the optical element 206 encased within the inner needle 205 is positioned such that

electromagnetic radiation can be directed and received through the imaging window 209 of the outer needle 208. As the optical element translates back and forth, an image can be acquired along the length of the imaging window 209. By actuating the cantilevers 202 at their resonant frequency, the range of translating movement of the optical element 206 can be maximised. The extensions 203 attached to the cantilevers 202 alter the resonant frequency of the cantilevers 202. This enables the ability to tailor the resonant frequency to the application, making it higher or lower as appropriate. In addition, a lower resonant frequency typically corresponds to a larger range of movement, i.e. the inner needle 205 and the optical element 206 will achieve a longer stroke. Thus, a slower scanning movement of the optical element 206 may result in a longer field of view. Accordingly, a higher scanning speed of the optical element 206 may result in a smaller field of view. In this particular example, the range of the translating movement of the optical element 206 is in the range 1mm - 5mm.

The needle probe 200 provides significant advantages. In particular, a long and thin needle probe 200 can be provided that enable a medical clinician to insert the needle probe 200 into biological tissue.

The needle probe 200 may alternatively be provided in the form of an endoscopic probe or an intravascular probe (not shown) . When the probe is provided as an endoscopic probe, the probe may have a size suitable for inserting the probe into a natural orifice of the human body, such as the colon, airways or the oesophagus. When the probe is provided as an intravascular probe, the probe may have a size suitable for inserting the probe into a blood vessel. Referring back to Figures 2a and b, the needle probe 200 is able to acquire a 2D OCT image in a plane that is parallel to the central axis of the needle probe 200.

In this example, the needle probe 200 further comprises a motor for rotating the optical element 205 during image acquisition. This allows the acquisition of a series of 2D OCT images at different orientations that can be reconstructed to form a 3D volume of image data around the needle probe 200. In this example, the motor is connected to the outer needle 208 such that the outer needle 208 together with the inner needle 205 and the optical element 206 can be rotated within the biological tissue. However, other arrangements are envisaged. For example, the imaging window of the outer needle may extend along at least part of the diameter of the outer needle, such that when the inner needle is rotated within the outer needle, images can be acquired through the imaging window. Exemplary configurations of the needle probe 200 for acquiring the above mentioned 3D volume of image data are illustrated in Figure 3.

In this particular embodiment, the needle probe 200 employs a relatively fast translating movement of the optical element 206 within the outer needle 208 and a relatively slow rotation of the needle probe 200. The translating movement of the optical element 206 and the rotation of the needle probe 200 are conducted substantially simultaneously such that a 3D volume of image data can be acquired from multiple translations, each at a different orientation of the optical element 206 into the biological tissue.

This arrangement has the particular advantage that a relatively slow rotation of the needle probe 200 minimises the risk of damaging the surrounding biological tissue. At the same time, as the optical element 206 together with the inner needle 205 are translated within the outer needle 208, the surrounding tissue is protected from the relatively fast translating movement by virtue of the outer needle 208.

Figure 4 and Figure 5 show example 2D OCT images acquired with the needle probe 200 as shown in Figures 2a and b. In

particular, the images were acquired by inserting the needle probe 200 into fresh ex vivo human breast tissue, i.e. after the breast tissue had been removed from the patient during breast cancer surgery.

Figure 5 shows an image of an area of adipose (fat) tissue taken from a patient undergoing a mastectomy. Figure 6 shows a mixture of breast parenchyma and adipose taken from a patient undergoing a lumpectomy. The horizontal extent of these two images is approximately 2mm, while the vertical extent is approximately 1mm.

With reference to Figure 6, there is illustrated a flow chart of a method 600 of acquiring an image of a material in accordance with an embodiment of the present invention. In a first step 602 the material of which an image is acquired is provided. The material may be any suitable material

including biological tissue, organic material or non-biological material .

In a further step 604, an optical element is positioned within or between the provided material. The optical element may be similar to the optical element 105, 106 of the optical scanning device 100 or the optical element 206 of the needle probe 200.

The optical element is used to direct electromagnetic radiation into the material in step 606. The electromagnetic radiation may be visible or invisible light, such as near-infrared light.

In a next step 608, electromagnetic radiation is received from the material at the optical element. Depending on the imaging technique, the electromagnetic radiation may be scattered by th material or emitted by the material.

In a further step 610, a member that supports the optical element is moved between first and second configurations thereby causing a translating movement of the optical element. For example, if the member is flexible, movement between first and second configurations may relate to bending the member.

In step 612, an image of the material is formed using the electromagnetic radiation received at the optical element during the translating movement. For example, if the method employs an OCT imaging technique, an OCT image is formed.

The method 600 may further comprise a step of rotating the optical element within the material. For example, the optica element or the optical scanning device may be rotated

simultaneously to the translating movement of the optical element. In this way, a volume of image data of the material may be acquired as illustrated in Figure 3.

In the claims which follow and in the preceding description of the invention, except where the context requires otherwise due to express language or necessary implication, the word

"comprise" or variations such as "comprises" or "comprising" is used in an inclusive sense, i.e. to specify the presence of the stated features but not to preclude the presence or addition of further features in various embodiments of the invention.

Claims

The Claims defining the Invention

1. An optical scanning device for acquiring an image or performing a measurement of a material, the optical scanning device comprising:

an optical element arranged to receive electromagnetic radiation from the material when the optical scanning device is positioned within or between the material, the electromagnetic radiation being used to form the image of the material;

a member supporting at least a portion of the optical element, the member being moveable between first and second configurations; and

an actuator arranged to cause movement of the member between the first and second configurations;

2. The optical scanning device of claim 1 having an axis and wherein a component of the actuator is arranged to move in a direction that is transversal to the axis and wherein the translating movement of the at least a portion of the optical element is in a direction along the axis.

3. The optical scanning device of claim 1 or 2 wherein the optical scanning device is arranged such that the translating movement has a direction that is substantially transversal to at least a portion of the member.

4. The optical scanning device of any one of the preceding claims comprising a cantilever, a first end of the cantilever being connected to the member and a second end of the cantilever that is opposite to the first end being anchored to a base.

5. The optical scanning device of claim 4 wherein the cantilever comprises a piezoelectric material .

6. The optical scanning device of claim 4 wherein the cantilever is coupled to a piezoelectric component.

7. The optical scanning device of any one of claims 4 wherein the cantilever is one of a pair of cantilevers.

8. The optical scanning device of any one of the preceding claims wherein the member is composed of a material that is flexible .

9. The optical scanning device of claim 8 wherein the member is in the form of a flexible beam.

10. The optical scanning device of claim 8 wherein the member is in the form of a flexible sheet.

11. The optical scanning device of any one of the preceding claims wherein the member is articulated.

12. The optical scanning device of any one of the preceding claims being arranged such that the acquired image provides information in relation to a mechanical property of the material .

13. The optical scanning device of any one of the preceding claims having a size such that the optical scanning device can be inserted into biological tissue, or a body lumen.

14. The optical scanning device of any one of the preceding claims wherein the optical scanning device is arranged to emplo optical coherence tomography ("OCT") .

15. The optical scanning device of any one of the preceding claims wherein the optical element comprises an optical fibre for transmitting electromagnetic radiation to an optical scanner.

16. The optical scanning device of any one of the preceding claims being arranged such that the optical element is

rotatable .

17. The optical scanning device of any one of the preceding claims being arranged such that the optical element is rotated and translated substantially simultaneously.

18. The optical scanning device of any one of the preceding claims wherein the actuator comprises at least one piezoelectri device that is connected to the member.

19. The optical scanning device of claim 18 when dependent on claim 4 wherein the piezoelectric device comprises the

cantilever .

20. The optical scanning device of any one of the preceding claims wherein the actuator comprises a plurality of

piezoelectric devices, and wherein the optical scanning device is arranged such that movement of the plurality of piezoelectric devices is synchronized.

21. The optical scanning device of any one of the preceding claims wherein the actuator comprises a thermoelectric actuator

22. The optical scanning device of any one of the preceding claims wherein the actuator comprises an electrostatic actuator.

23. The optical scanning device of any one of the preceding claims wherein the actuator comprises a magnetic actuator.

24. A probe for acquiring an image or performing a measurement of a material, the probe comprising:

a distal end for insertion into the material; and

the optical scanning device of any one of the preceding claims .

The probe of claim 24 being in the form of at least one needle probe, an intravascular probe, and an endoscopic

26. The probe of claim 24 or 25 comprising a first member and a second member, wherein the second member comprises a hollow region for at least partially accommodating the first member and wherein the optical scanning device is incorporated in or attached to the first member of the probe.

27. The probe of claim 26 comprising wherein the first member is arranged for translation along an axis of the probe and both the first and second members are arranged for rotation about the axis .

28. A method of acquiring an image or performing a measurement of a material, the method comprising:

providing the material;

providing the optical scanning device of any one of claims 1 to 23; positioning the optical element of the optical scanning device within or between the material ;

29. The method of claim 28 comprising moving the member to cause a translating movement of the optical element.

30. The method of claim 29 comprising rotating the optical element.

31. The method of claim 30 wherein rotating the optical element is performed substantially simultaneously with the translating movement of the optical element.

32. The method of any one of claims 28 to 31 being conducted such that a series of 2D images of the material are acquired.

33. The method of claim 32 comprising creating a 3D image of the material using the series of 2D images.