Endoscope

Abstract

Endoscope (300; 600), including: a set of one or more optical fibers (306; 605) connecting a proximal end (308; 608) of the endoscope to a distal end (310; 610) of the endoscope, wherein the set of one or more optical fibers is arranged to receive, at the proximal end of the endoscope, first light generated by a first light source (302; 602) and fluorescence excitation light for fluorescence-guided surgery generated by a second light source; a fluorescent material (304; 604) positioned at the distal end of the endoscope to: to receive the first light from the set of one or more optical fibers and to emit light that has a different spectrum than the first light; and the fluorescence excitation light from the set of one or more optical fibers to receive and scatter the fluorescence excitation light; and a filter (611) at the distal end of the endoscope, which is arranged to filter the fluorescence excitation light in order to attenuate components of the fluorescence excitation light with a fluorescence detection wavelength.

Description

BACKGROUND

[0001] An endoscope is an inspection instrument that can be used during minimally invasive surgeries. An endoscope can be inserted into a patient's body through an opening, which can be a natural opening such as the mouth, or through a port, to gain access to the surgical site during surgery. An endoscope typically includes a camera and an interface for connecting to a light source and is typically used to illuminate and image the surgical site for a surgeon during minimally invasive surgery. A video feed from the camera is displayed on a surgeon's display during surgery to allow the surgeon to view the surgical site. Some endoscopes have a rigid body, while some other endoscopes have a flexible body.Typically, the imaging quality is higher with a rigid endoscope compared to a flexible endoscope, whereas a flexible endoscope is typically more maneuverable than a rigid endoscope and may therefore be able to obtain a better view of the surgical site.

[0002] An endoscope is an elongated instrument with a proximal end and a distal end. The proximal end of the endoscope is not intended to be inserted into a patient, whereas the distal end of the endoscope is intended to be inserted into a patient, for example, during surgery. Fig. Figure 1 illustrates an arrangement for coupling light from a light-emitting diode (LED) 102 and a phosphor 104 into an optical fiber 106 for use in a conventional endoscope. The LED 102 and the phosphor 104 may have any suitable shape, but typically high-power LEDs are planar, with the phosphor coated on top, as shown in Fig. 1 shown.

[0003] An LED is a semiconductor device that emits light when current flows through it. The color of light emitted by an LED is determined by the energy required for electrons to cross the semiconductor's band gap. As a result, most LEDs emit light within a narrow range of wavelengths, allowing them to exhibit a strong characteristic color. However, it is often desirable for an endoscope to illuminate a surgical site with light that appears essentially white. Illuminating the surgical site with white light is usually most useful for a surgeon viewing the images of the surgical site provided by the endoscope. White light can be obtained by using a layer of light-emitting phosphor on the LED.

[0004] A phosphor is a substance that exhibits the phenomenon of luminescence. This means that a phosphor emits light when exposed to a specific type of radiant energy. Phosphors are designed to absorb and emit at specific wavelengths, and those that absorb blue light, such as wavelengths in the 440-455 nm range, are very efficient in terms of the ratio between the radiant power they can emit and the radiant power they receive. Therefore, conventional white LEDs tend to produce blue light and use a phosphor to convert the blue light into white light.

[0005] With reference to Fig. 1, LED 102 is a blue LED and is coated with phosphor 104, which is configured to absorb a portion of the blue light emitted by LED 102 and emit green and red light. A portion of the blue light emitted by LED 102 passes through or is scattered by phosphor 104. The resulting combination of blue, green, and red light emitted by the arrangement of LED 102 and phosphor 104 appears as white light.

[0006] The optical fiber 106 is a cylindrical dielectric waveguide that transmits light along its axis by the process of total internal reflection. Fig. Figure 1 shows the end of the optical fiber 106, which is located near the arrangement of the LED 102 and the phosphor 104. The LED is a surface emitter. The radial lines in Fig. 1 around the arrangement of the LED 102 and the phosphor 104 illustrates that the light is radiated over a large area. Only a portion of the light emitted by the LED 102 and the phosphor 104 is received by the optical fiber 106. A lens may be used to focus the light emitted by the LED 102 and the phosphor 104 onto the optical fiber 106, although it is still the case that a substantial portion of the light emitted by the LED 102 and the phosphor 104 is not received by the optical fiber 106. Furthermore, the optical fiber 106 only receives light over a much smaller angular cone than that emitted by the LED. Therefore, the coupling of light from the LED 102 into the optical fiber 106 is inefficient, i.e., a significant portion of the radiant energy emitted by the LED 102 does not travel through the optical fiber 106. This can cause a problem when LEDs are used with an endoscope for performing endoscopy, e.g.B. for minimally invasive surgery. For example, to direct enough light into the optical fiber 106 to produce sufficient illumination of the tissue at the surgical site, high-power LEDs and a set (or "bundle") of one or more large-diameter optical fibers are required. For example, a conventional endoscope for endoscopy may comprise a bundle of optical fibers with a diameter in the range of 3 mm to 5 mm. Such a large bundle of optical fibers is heavy, large, and inflexible. As a rule, it is advantageous for instruments that penetrate a patient's body during minimally invasive surgery to be lightweight, flexible (i.e., maneuverable), and small (especially with a small cross-section, e.g., diameter).

[0007] Fig. Figure 2 illustrates a distal end of a conventional endoscope including an optical fiber 206. Light exits the distal end of the optical fiber 206 within a cone, as indicated by the light emitted from the top of the optical fiber 206 in Fig. 2 exiting arrows. The distal end of the endoscope can also contain a camera (in Fig. 2 not shown) to capture images of the surgical site. In some endoscopes, a camera is located at the proximal end of the endoscope rather than at the distal end of the endoscope. Typically, the output cone of light emerging from the optical fiber 206 does not evenly illuminate the field of view of the endoscope's camera. In particular, the edges of the field of view typically have poor illumination. As an example, the optical fiber 206 may have a light cone with a half angle (in Fig. 2 marked 202) of 37 degrees, while the endoscope camera can have a field of view with a half-angle of 40 degrees.

[0008] The illumination of the surgical site provided by an endoscope could be improved by placing the LED at the distal end of the endoscope. However, LEDs are known to generate too much heat, making this not a practical option. Furthermore, an LED would often be too large to be placed at the distal end of the endoscope. For example, an LED might be larger than the endoscope itself, primarily due to the need for heat dissipation. For an endoscope intended to be used for surgery, i.e., where the distal end of the endoscope is to be inserted into a patient's body, positioning the LED at the distal end of the endoscope is therefore not acceptable. SUMMARY

[0009] This Summary is provided to introduce, in a simplified form, a selection of concepts that are further explained in the detailed description below. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to limit the scope of the claimed subject matter.

[0010] According to a first aspect of the invention, an endoscope (300; 600) is provided, comprising: a set of one or more optical fibers (306; 605) connecting a proximal end (308; 608) of the endoscope to a distal end (310; 610) of the endoscope, the set of one or more optical fibers being arranged to receive, at the proximal end of the endoscope, first light generated by a first light source (302; 602) and fluorescence excitation light for fluorescence-assisted surgery generated by a second light source; a phosphor (304; 604) arranged at the distal end of the endoscope to: to receive the first light from the set of one or more optical fibers and to emit light having a different spectrum than the first light; and to receive the fluorescence excitation light from the set of one or more optical fibers and to scatter the fluorescence excitation light; and a filter (611) at the distal end of the endoscope arranged to filter the fluorescence excitation light to attenuate components of the fluorescence excitation light having a fluorescence detection wavelength.

[0011] In one example, an endoscope may be provided that includes: a set of one or more optical fibers connecting a proximal end of the endoscope to a distal end of the endoscope, the set of one or more optical fibers being arranged to receive light generated by a light source at the proximal end of the endoscope; and a phosphor disposed at the distal end of the endoscope to: receive light from the set of one or more optical fibers and emit light having a different spectrum than the light from the light source.

[0012] The endoscope may further include a light interface configured to receive the light generated by the light source and provide the light to the set of one or more optical fibers at the proximal end of the endoscope.

[0013] The light source can be a laser.

[0014] The diameter of the set of one or more optical fibers can be less than 500 µm.

[0015] The endoscope may be flexible over at least part of its length from the proximal end to the distal end.

[0016] The light emitted by the phosphor may have a wider wavelength range than the light generated by the light source.

[0017] The spectrum of light produced by the light source may have a peak within a wavelength range of 400 nm to 500 nm.

[0018] According to a human visual system, the light produced by the light source can be perceived as blue light, and the light emitted by the phosphor can be perceived as white light.

[0019] The endoscope may further comprise a camera, and wherein the phosphor is arranged to emit light over a range of angles greater than a range of angles encompassed in a field of view of the camera.

[0020] The endoscope may further include one or more mirrored surfaces at the distal end of the endoscope positioned around the phosphor to reflect light emitted rearwardly from the phosphor.

[0021] The one or more mirrored surfaces may form an open cylinder around the phosphor. The one or more mirrored surfaces may comprise: a first mirrored surface which is flat and circular and is positioned behind the phosphor, and one or more other mirrored surfaces forming the side walls of the open cylinder around the phosphor.

[0022] The first mirrored surface may have a hole in which a portion of the set of one or more optical fibers is positioned.

[0023] The set of one or more optical fibers may also comprise only a single optical fiber.

[0024] The set of one or more optical fibers may be further arranged to receive additional light from a further light source at the proximal end of the endoscope. The phosphor may be further arranged to receive the additional light from the set of one or more optical fibers and to scatter the additional light.

[0025] The additional light source can be a laser.

[0026] The additional light can be fluorescence excitation light for fluorescence-assisted surgery.

[0027] The endoscope may further comprise a filter at the distal end of the endoscope arranged to filter the fluorescence excitation light to attenuate components of the fluorescence excitation light having a fluorescence detection wavelength.

[0028] The endoscope may be a surgical endoscope configured to illuminate and image a surgical site during a surgical procedure.

[0029] The proximal end of the endoscope may be configured to be attached to a distal end of a surgical robotic arm.

[0030] According to a second aspect of the invention, there is provided a method of operating an endoscope (600) comprising a set of one or more optical fibers (606) connecting a proximal end (608) of the endoscope to a distal end (610) of the endoscope; the method comprising: Receiving first light generated by a first light source (602) at the set of one or more optical fibers at the proximal end of the endoscope; Receiving fluorescence excitation light generated by a second light source at the set of one or more optical fibers at the proximal end of the endoscope; Receiving, from the set of one or more optical fibers, the first light at a phosphor (604) located at the distal end of the endoscope; Emitting light from the phosphor, wherein the light emitted by the phosphor has a different spectrum than the first light; Receiving, from the set of one or more optical fibers, the fluorescence excitation light at the phosphor; Scattering the fluorescence excitation light from the phosphor; and Filtering the fluorescence excitation light at the distal end of the endoscope to attenuate components of the fluorescence excitation light having a fluorescence detection wavelength.

[0031] In one example, a method of operating an endoscope comprising a set of one or more optical fibers connecting a proximal end of the endoscope to a distal end of the endoscope may be provided, the method comprising: Receiving light generated by a light source at the set of one or more optical fibers at the proximal end of the endoscope; Receiving, from the set of one or more optical fibers, light at a phosphor located at the distal end of the endoscope; and Emitting light from the phosphor, wherein the light emitted by the phosphor has a different spectrum than the light from the light source.

[0032] The above features may be combined as desired, as would be apparent to one skilled in the art, and may be combined with any of the aspects of the examples described herein. SHORT DESCRIPTION OF THE CHARACTERS

[0033] Examples are described in detail below with reference to the accompanying drawings, in which: Fig. Figure 1 illustrates an arrangement for coupling light from an LED and a phosphor into an optical fiber for use in a conventional prior art endoscope; Fig. Figure 2 illustrates a distal end of a prior art endoscope; Fig. 3 illustrates a system including an endoscope according to the examples described herein; Fig. 4 is a flow diagram for a method of operating an endoscope according to the examples described herein; Fig. 5 illustrates a distal end of an endoscope according to the examples described herein; and Fig. 6 illustrates a surgical robotic system including an endoscope according to the examples described herein.

[0034] The accompanying drawings illustrate various examples. Those skilled in the art will understand that the element boundaries illustrated in the drawings (e.g., boxes, groups of boxes, or other shapes) represent only one example of the boundaries. In some examples, an element may be formed as multiple elements, or multiple elements may be formed as a single element. Where appropriate, common reference numerals are used in the figures to indicate similar features. DETAILED DESCRIPTION

[0035] The following description is provided by way of example to enable any person skilled in the art to make and use the invention. The present invention is not limited to the embodiments described herein, and various modifications of the disclosed embodiments will be apparent to those skilled in the art.

[0036] In the examples described herein, a phosphor is located at the distal end of the endoscope. A light source provides light to an optical fiber at the proximal end of the endoscope, and the light travels through the optical fiber to the distal end of the endoscope. At least a portion of the light is absorbed by the phosphor, and the phosphor re-emits light from the distal end of the endoscope. The light emitted by the phosphor has a different spectrum than the light from the light source. In particular, the light emitted by the phosphor has a wider range of wavelengths than the light from the light source. The phosphor emits the light over a wide range of angles (e.g., the phosphor is a 4π emitter). In particular, phosphors absorb light and subsequently emit light in any direction.An arrangement in which the phosphor, but not the light source, is located at the distal end of the endoscope provides good, uniform illumination of the surgical site (e.g., across the entire field of view of an endoscope camera) without the light source generating heat at the distal end of the endoscope and without the light source increasing the size of the distal end of the endoscope.

[0037] Furthermore, in the examples described herein, a laser can be used as the light source instead of an LED. Unlike the light emitted by an LED, the light emitted by a laser has low divergence, which allows a laser beam to be kept narrow over long distances and the laser light to be focused to a tight spot. By using a laser as the light source, the light can be delivered into a small optical fiber much more efficiently than when using an LED as the light source. In other words, the light from a laser can be coupled into an optical fiber with very high efficiency because the light comes from a small, low-divergence source.For example, sufficient radiant energy to adequately illuminate a surgical site can be delivered to the distal end of the endoscope by coupling the light from a laser into an optical fiber having a diameter in the range of 200 µm to 300 µm. As described in the Background section above, when using an LED as the light source, the diameter of a bundle of optical fibers 106 in an endoscope would typically need to be in the range of 3 mm to 5 mm for sufficient radiant energy to reach the distal end of the endoscope to adequately illuminate a surgical site. By using a laser as the light source instead of an LED, the diameter of a set of one or more optical fibers of the endoscope can therefore be reduced by approximately an order of magnitude.A smaller diameter of the set of one or more optical fibers means that the optical fiber(s) is / are small, lightweight, and flexible, all of which are advantageous properties for instruments intended to enter a patient's body during minimally invasive surgery.

[0038] Fig. 3 illustrates a system 301 including an endoscope 300 according to examples described herein and a light source 302. The endoscope 300 includes a light interface 303, a phosphor 304, and a set of one or more optical fibers 306. The light source 302 generates light and provides the light to the light interface 303 of the endoscope 300 using another set of one or more optical fibers 305. It should be noted that it is more efficient to couple light from a single laser into a single optical fiber than to couple light from a single laser into a bundle of fibers due to the gaps that would exist between the fibers in a bundle.Therefore, in the main examples described herein, the set of one or more optical fibers 306 comprises only a single optical fiber, but it is understood that in other examples, the set of one or more optical fibers 306 may comprise a plurality of optical fibers, i.e., it may be a bundle of optical fibers, each carrying light from a different laser, for example. Similarly, in the main examples described herein, the further set of one or more optical fibers 305 comprises only a single optical fiber, but it is understood that in other examples, the further set of one or more optical fibers 305 may comprise a plurality of optical fibers, i.e., it may be a bundle of optical fibers. The endoscope 300 has a proximal end 308 and a distal end 310.The proximal end 308 of the endoscope 300 is not intended to be inserted into a patient, whereas the distal end 310 of the endoscope 300 is intended to be inserted into a patient, e.g., during surgery. The proximal end 308 of the endoscope 300 includes the light interface 303 and a proximal end of the optical fiber 306. The distal end 310 of the endoscope 300 includes the phosphor 304 and a distal end of the optical fiber 306. The optical fiber 306 connects the proximal end 308 of the endoscope 300 to the distal end 310 of the endoscope 300. The light interface 303 is configured to receive the light generated by the light source 302 (via the optical fiber 305) and provide the light to the optical fiber 306 at the proximal end of the endoscope 300.Light received at the proximal end of the optical fiber 306 can travel through the optical fiber 306 to the distal end of the optical fiber 306.

[0039] In conventional systems (e.g., as described in the Background section above), a light source is located outside the endoscope, and light generated by the light source is guided to the endoscope using a thick bundle of optical fibers, e.g., a 5 mm diameter bundle of optical fibers. This thick bundle of optical fibers may consist of thousands of individual optical fibers, each typically 60 micrometers in diameter. A light interface may couple the light between the bundle of optical fibers that guide light to the endoscope and a bundle of endoscope optical fibers that guide light from the proximal end to the distal end of the endoscope. However, in these conventional systems, the coupling of light between the bundles of optical fibers is poor because the individual optical fibers are not perfectly aligned with each other.In contrast, in examples described herein, the set of optical fibers 305 comprises a single thin optical fiber (e.g., with a diameter of 300 µm), and the set of optical fibers 306 comprises a single thin optical fiber (e.g., with a diameter of 300 µm). Using a laser as the light source 302 makes it possible to use individual thin optical fibers as the optical fibers 305 and 306 while ensuring that sufficient light reaches the distal end of the endoscope to illuminate the surgical site during minimally invasive surgery. The light interface 303 couples the light from the optical fiber 305 into the optical fiber 306. Coupling light between individual 300 µm optical fibers at the light interface 303 is more efficient than coupling light between bundles of 60 µm optical fibers.

[0040] In some alternative examples (not shown in the figures), a single set of one or more optical fibers (e.g., a single optical fiber) could carry the light from the light source all the way to the phosphor at the distal end of the endoscope. In these alternative examples, the endoscope could not have a light interface.

[0041] In general, the light source 302 can be an LED or a laser. In the examples described herein, the light source 302 is a laser. As described above, using a laser as the light source enables more efficient coupling between the light source 302 and the optical fiber 306 (via the optical fiber 305 and the light interface 303), which in turn allows the diameter of the optical fiber 306 to be reduced by an order of magnitude compared to using an LED as the light source. The diameter of the optical fiber 306 can be less than 500 µm. To provide some specific examples, the optical fiber 306 can have a diameter of 200, 300, or 365 µm.

[0042] The phosphor 304 could be any suitable phosphor. For example, cerium(III)-doped yttrium aluminum garnet (YAG:Ce3+) can be used, which is capable of absorbing blue light and emitting light in a broad range of wavelengths from greenish to reddish, with most of its output in the yellow wavelength range. The yellow emission, combined with the remaining blue emission, produces white light. In another example, the phosphor can be a mixture of blue-, green-, and red-emitting phosphors that absorb violet or ultraviolet light, resulting in a light source with a superior color rendering index. Many other suitable phosphors are available.

[0043] Fig. 4 is a flowchart for a method of operating the endoscope 300 in the system 301. In step S402, the light source 302 generates light, e.g., blue laser light. That is, the light from the light source can be perceived as blue light according to a human visual system. The spectrum of the light from the light source can, for example, have an intensity peak in a wavelength range of 400 nm to 500 nm. To provide a specific example, the light source 302 can be a laser that generates light with a wavelength of 450 nm. The light generated by the light source 302 is provided via the optical fiber 305 to the light interface 303 at the proximal end 308 of the endoscope 300. The light interface 303 provides the light generated by the light source 302 to the optical fiber 306 at the proximal end 308 of the endoscope 300.

[0044] The optical fiber 306 is arranged to receive light generated by the light source 302 at the proximal end 308 of the endoscope 300. If the light source 302 is a laser, most of the light generated in step S402 can be received by the optical fiber 306. The light generated by the light source can be focused (e.g., using a set of one or more lenses) into the optical fiber 305. Focusing the light from a laser onto the tip of the optical fiber is advantageous for obtaining good coupling of the light into the optical fiber. For example, a light beam generated by a laser can have a diameter of 1000 µm with parallel beams. A lens can focus the beam to a point that then fits into the optical fiber (which can, for example, have a diameter of 300 µm).Focusing results in beams with a range of converging angles, but these angles are smaller than the acceptance angle of the optical fiber, thus achieving good coupling. The light is received at the proximal end of the optical fiber 306. The light travels through the optical fiber 306 to the distal end 310 of the endoscope 300.

[0045] The phosphor is arranged at the distal end 310 of the endoscope 300 to receive light from the optical fiber 306, i.e., to receive light from the distal end of the optical fiber 306. In step S406, the phosphor 304 receives (at least a portion of) the light from the optical fiber 306. The light received at the phosphor 304 is absorbed by the phosphor 304. That is, the light received at the phosphor 304 excites the phosphor 304.

[0046] In step S408, the phosphor emits light. As described above, the light emitted by the phosphor 304 has a different spectrum than the light from the light source 302. In particular, the light emitted by the phosphor 304 in step S408 has a substantially high intensity over a wider wavelength range than the light from the light source 302. The light emitted by the phosphor 304 includes light with green and red wavelengths due to the relaxation of the excited states of the phosphor 304. The phosphor 304 does not absorb all of the light it receives. Therefore, the light emitted by the phosphor 304 also includes a portion of the blue light received by the optical fiber, which is not absorbed by the phosphor 304 but scattered. The light emitted by the phosphor 304 can be perceived by a human visual system as white light (e.g.,a mixture of red, green, and blue light). Furthermore, the phosphor emits light over a wide range of angles (e.g., the phosphor can be a 4π emitter).

[0047] The light emitted by phosphor 304 during a surgical procedure strikes the patient's tissue at the surgical site. Part of the light is absorbed by the tissue, part of the light is scattered in the tissue, and the remaining part of the light is reflected back. A light sensor (e.g., a camera) at the proximal (or distal) end of the endoscope receives light reflected back from the tissue. If the light sensor is implemented at the proximal end of the endoscope, the reflected light can be received at the distal end of the endoscope and guided, e.g., through a channel arrangement that can combine glass and hollow sections, from the distal end to the proximal end of the endoscope to the sensor. Using the reflected light received by the light sensor, an image of the tissue can be created.The light sensor may be configured to distinguish between light of different wavelengths, e.g., by implementing sensors that receive light in a specific wavelength range (e.g., sensors for receiving red light, sensors for receiving green light, and sensors for receiving blue light, and possibly sensors for receiving light outside the visible spectrum), and / or by applying wavelength-dependent filtering to the light it receives.

[0048] To reiterate part of the above description, in the examples described herein, a phosphor mounted at the distal tip of an endoscope is excited using light from a blue laser coupled into a small optical fiber. This produces an intense light at the distal tip of the endoscope without the heat associated with the blue light source being generated at the distal end of the endoscope. Furthermore, it should be noted that the phosphor 304 naturally has a high scattering coefficient, so that not only the re-emitted green and red light from the phosphor is emitted over 4π radians, but also the residual blue laser light is emitted over 4π radians. As described above, the endoscope includes a camera (in Fig. 3 not shown), and the phosphor is arranged to emit light over a range of angles (e.g., over 4π radians) that is greater than a range of angles encompassed by a field of view of the camera. For example, the camera may have a field of view of 80 degrees. Accordingly, during a surgical procedure, when the distal end 310 of the endoscope 300 (including the phosphor 304) is inserted into a patient, the light emitted by the phosphor 304 provides uniform white illumination across the entire field of view of the endoscope's camera.

[0049] Furthermore, the endoscope may be flexible over at least part of its length from the proximal end 308 to the distal end 310. For example, it may be the case that only the distal end 310 of the endoscope 300 is flexible, with the rest of the endoscope being rigid, i.e., having a rigid body. Enabling the endoscope 300 to have a thin optical fiber 306 allows the endoscope to be more maneuverable, e.g., by allowing greater tilt of the tip (i.e., greater tilt of the distal end 310) of the endoscope 300. A thinner optical fiber can be bent more easily and to a greater extent than a thicker optical fiber, and no light is lost from the sides of the optical fiber as long as the angle through which the optical fiber bends does not exceed an allowable bending threshold defined by the properties of the optical fiber.

[0050] Fig. 5 illustrates an example of a distal end 510 of the endoscope. The distal end 510 includes the phosphor 304 and the set of one or more optical fibers 306 (which, as mentioned above, is referred to herein only as an optical fiber, but may be a bundle of multiple optical fibers). The distal end 510 further includes one or more mirrored surfaces 502 positioned around the phosphor 304 to reflect light emitted rearwardly by the phosphor 304. In this way, more of the light emitted by the phosphor 304 can be directed to be within a hemisphere generally facing forwardly from the distal end of the endoscope.Here, the term "rearward" refers to a direction from the phosphor 304 to the distal end of the optical fiber 306 that provides light to the phosphor 304, and the term "forward" refers to a direction opposite the rearward direction. When the endoscope is in a straight position, "rearward" refers to a direction toward the proximal end of the endoscope, and "forward" refers to a direction away from the proximal end of the endoscope, as shown in FIG. Fig. 5. It should be noted that the endoscope is arranged such that a camera of the endoscope receives light within a field of view located entirely within the forward-facing hemisphere illuminated by the light emitted by the phosphor 304.

[0051] The phosphor 304 emits light in all directions, i.e., it is a 4π emitter. By placing the phosphor 304 in an open mirror chamber, the intensity of the light emitted forward can be increased. For example, the chamber could have a cylindrical shape. In particular, the one or more mirrored surfaces 502 may form an open cylinder around the phosphor 304. An open end of the open cylinder may point forward from the phosphor 304. That is, the one or more mirrored surfaces 502 may comprise: (i) a first mirrored surface 5021 forming a base surface of the open cylinder, which is flat and circular, and positioned behind the phosphor 304 (i.e.,positioned at a location that is 'rear' with respect to the position of the phosphor); and (ii) one or more other mirrored surfaces 5022 forming sidewalls of the open cylinder around the phosphor 304. To give two examples, the sidewalls of the open cylinder may be formed as a single continuous surface or as two mirrored surfaces, each in the shape of one half of a cylindrical sidewall. The phosphor 304 may be positioned approximately in the center of the open top surface of the open cylinder. In this way, light emitted in a generally forward direction from the phosphor 304 will not strike any of the mirrored surfaces 502; whereas light emitted in a generally rearward direction from the phosphor 304 will strike (and be reflected) one or more of the mirrored surfaces 502.The light may be reflected one or more times before leaving the mirror chamber in a generally forward direction. It should be noted that by arranging the mirrored surfaces in a cylindrical shape, as shown in . Fig. 5, a more uniform emission of light from the endoscope tends to be provided than by arranging the mirrored surfaces in a "box" or cuboid shape, due to the additional corners in a box or cuboid shape.

[0052] As in Fig. 5, the first mirrored surface 5021 has a hole 504 in which a portion of the optical fiber 306 is positioned. This allows the distal end of the optical fiber to be positioned adjacent to the phosphor 304, so that light traveling through the optical fiber can be directly provided to the phosphor 304. The shape and size of the hole 504 can match the shape and size of the cross-section of the optical fiber 306, so that a portion of the optical fiber 306 can be positioned within the hole 504 without leaving large gaps around the edge of the optical fiber 306. This allows the optical fiber 306 to directly provide light to the phosphor 304 with only a slight reduction in the reflection area of ​​the mirrored surface 5021. The optical fiber 306 can pass through the hole 504 (as in Fig. 5), or the optical fiber may terminate at the hole 504, ie, the distal end of the optical fiber may be located at the hole 504.

[0053] In another example, only a single mirrored surface may be present. For example, only the first mirrored surface 5021 may be present and positioned behind the phosphor 304. In this example, the side walls 5022 would not be present. This may be easier to manufacture than the Fig. 5 and may provide a lighter and smaller distal end for the endoscope, but may be less effective at directing as much of the light emitted by the phosphor 304 in a generally forward direction.

[0054] As described above, the endoscope of the examples described herein may be a surgical endoscope configured to illuminate and image a surgical site during a surgical procedure. The endoscope may be a handheld endoscope, wherein a surgeon or other member of a surgical team may hold the endoscope and manually position it. Alternatively, the endoscope may be attached to a surgical robotic arm and moved by controlling the movement of the surgical robotic arm. In particular, the proximal end of the endoscope may include an interface via which the endoscope may be connected to a surgical robotic arm. Thus, the proximal end of the endoscope may be configured to be attached to a distal end of a surgical robotic arm.

[0055] Fig. 6 illustrates a surgical robotic system 601 including an endoscope 600 and a light source 602. The endoscope 600 includes a proximal end 608 and a distal end 610 (similar to the proximal end 308 and distal end 310 of the endoscope 300 described above). The endoscope 600 includes a set of one or more optical fibers 606 (similar to the optical fiber 306 described above) connecting the endoscope proximal end 608 to the endoscope distal end 610. The proximal end 608 includes a light interface 603, a sensor 612 (e.g., a camera for capturing images of a surgical site), and a robot interface 614. The light interface 603 is arranged to receive light generated by the light source 602 via a set of one or more optical fibers 605 and to provide the light generated by the light source 602 to the set of one or more optical fibers 606.The set of one or more optical fibers 605 may be referred to in this description as a single optical fiber 605, although it should be understood that multiple optical fibers may be present in the set 605; and similarly, the set of one or more optical fibers 606 may be referred to in this description as a single optical fiber 606, although it should be understood that multiple optical fibers may be present in the set 606. The light source 602 is similar to the light source 302 described above and is implemented as a laser (although in other examples, it may be implemented as an LED). The distal end 610 of the endoscope 600 includes a phosphor 604 (similar to the phosphor 304 described above). The distal end 610 may also include a filter 611, which may be useful when the endoscope is used for fluorescence-assisted surgery, as described below.The surgical robot system 601 also includes a surgical robot arm 616. The surgical robot arm 616 can have arm segments (in . Fig. 6 not shown) which are connected by joints (in Fig. 6 (not shown) that can be manipulated to control the movement of the surgical robotic arm. The surgical robotic arm 616 includes an interface 618 at a distal end of the surgical robotic arm. The robot interface 614 of the endoscope 600 is configured to connect to the interface 618 of the surgical robotic arm 616 so that the endoscope 600 can be controlled via the surgical robotic arm 616. The surgical robotic system 601 also includes a control system 620 and a display 626. The control system 620 includes a memory 622 and a processor 624. The control system 620 is coupled to the surgical robotic arm 616 and the display 626.The control system 620 is configured to control the movement of the surgical robot arm 616 (and thus the movement of the endoscope 600 when the endoscope 600 is connected to the surgical robot arm 616) by sending control signals to the surgical robot arm 616 to control the movement of the joints of the surgical robot arm 616. The control system 620 is also configured to send a signal to the light source 602 (e.g., via interfaces 618, 614, and 603) to control when the light source 602 is turned on and off.

[0056] Light from the surgical site may be received at the distal end 610 of the endoscope 600. The light received at the distal end 610 of the endoscope 600 may be light emitted from the distal end 610 of the endoscope (e.g., from the phosphor 604) and reflected from tissue at the surgical site. The light received at the distal end 610 of the endoscope 600 may travel along a channel arrangement (e.g., including glass and hollow sections) from the distal end 610 to the proximal end 608, where it may be provided to the sensor 612 (e.g., via the light interface 603). The sensor 612 is configured to detect the light to obtain image data representing an image of the surgical site. The control system 620 is configured to receive image data (e.g., for frames of a video sequence) captured by the sensor 612. The control system 620 may process the image data (e.g.,to apply image processing such as correcting bad pixels, noise reduction, white balance, etc.) to determine the frames of the video sequence, which can then be sent to the display 626 where they can be displayed, e.g., to a surgeon performing the operation. The memory 622 of the control system 620 can be a non-transitory computer-readable medium and can be used to store image data and / or computer-executable instructions that can be executed by the processor 624, e.g., to perform the processing steps on the image data to determine the frames of the video sequence to be displayed on the display 626.

[0057] In some examples, the Fig. 6 may represent multiple light sources. One or more optical channels may be used. For example, a separate optical channel may be used for each light source. Alternatively, a single optical channel may be used by multiple light sources if these light sources emit light at different wavelengths (so that the light from the different sources can be distinguished by wavelength division multiplexing). The light sources 602 may include, in addition to a light source (e.g., a laser) that generates blue light as described above, another light source to generate additional light that can be received at the proximal end of the optical fiber via the light interface 603.The further light source may be implemented as a laser, allowing the optical fiber 606 to have a small diameter (as described above), and in other examples, the further light source may be an LED. The further light source is configured to generate light with a peak wavelength different from that of the blue light generated by the first light source described above. A camera or other sensor could be included (e.g., in addition to the sensor 612) at the proximal end 608 of the endoscope 600 for detecting light with the wavelength of the light from the further light source. In other examples, the camera(s) (or "sensor(s)") may be placed at the tip (i.e., the distal end 610) of the endoscope 600. For example, the sensor 612 may be placed at the distal end 610 and not at the proximal end 608 of the endoscope 600.

[0058] The additional light generated by the additional light source travels along the optical fiber to the distal end of the endoscope. The phosphor is positioned to receive the additional light from the optical fiber and scatter the additional light. In this way, the phosphor scatters the additional light over a wide range of angles (e.g., over 4π radians) from the distal end of the endoscope. The additional light can be fluorescence excitation light for fluorescence-guided surgery. For example, the additional light source can generate light with a wavelength in the near-infrared range, e.g., with a wavelength in a range of 700 nm to 850 nm. To give a specific example, the additional light source can generate light with a wavelength of 770 nm. Fluorescence-guided surgery (FGS) is a medical imaging technique used to detect fluorescently labeled structures during surgery.During FGS, a fluorescent material may be injected into a patient's bloodstream, and the fluorescent material may accumulate more in some tissues (e.g., cancer cells) than in others. An example of a fluorescent material is indocyanine green (ICG). The fluorescent material can be excited by shining fluorescence excitation light (light with a 'fluorescence excitation wavelength' that specifically excites the fluorescent material) onto the fluorescent material. The fluorescent material then emits light with a 'fluorescence detection wavelength' as ​​the fluorescent material relaxes from the excited state. The fluorescence detection wavelength is different from the fluorescence excitation wavelength. In particular, the fluorescence detection wavelength is usually longer than the fluorescence excitation wavelength, i.e.It is usually further in the infrared spectrum, away from the visible wavelengths. For example, the fluorescence detection wavelength can be in the range of 830 nm to 900 nm. To give a specific example, ICG can be excited at 800 cm (i.e., the fluorescence excitation wavelength can be 800 nm), and the fluorescence can be detected at 830–900 nm (i.e., the fluorescence detection wavelength can be in the range of 830 nm to 900 nm). It should be noted that the penetration depth of the light into the patient's tissue would be very small in the visible wavelengths (e.g., 100 µm), but can reach up to 1–2 cm when using an excitation wavelength in the near-infrared range (e.g., in the range of 700 nm to 850 nm).By placing the phosphor at the distal end of the endoscope, uniform illumination of the fluorescence excitation light through the endoscope is provided across the surgical site for fluorescence-assisted surgery.

[0059] In some examples, both the white light from the phosphor 604 and the fluorescence excitation light are emitted simultaneously. In some other examples, the white light and the fluorescence excitation light may each be emitted individually, in an alternating manner. In these other examples, the rate at which the system switches between emitting white light and emitting fluorescence excitation light may be rapid, e.g., it may switch 60 times per second.

[0060] The endoscope can be fitted with a filter (e.g. filter 611, shown in Fig.6) at the distal end of the endoscope. The filter can be arranged over the front of the phosphor. The filter can be arranged to filter the fluorescence excitation light to attenuate components of the fluorescence excitation light at the fluorescence detection wavelength. In this way, a weak output from the phosphor at the fluorescence detection wavelength can be rejected. This means that the sensor (e.g., sensor 612) can more easily identify the light emitted by the fluorescent material when not as much light at the fluorescence detection wavelength is coming from the phosphor. A fluorescence image (i.e., an image showing the light received by sensor 612 at the fluorescence detection wavelength) and a visible light image (i.e., an image showing the light received at the visible wavelengths) can be overlaid (e.g.,by the control system 620) and displayed to a surgeon on the display 626.

[0061] It is understood that the endoscope described herein could be intended for purposes other than surgery. For example, the endoscope could be used for non-medical applications, such as in industrial settings for processes such as non-destructive testing and borehole investigations. For example, the endoscope could be used to view the interior of a manufactured article, such as an automobile engine, through an inspection port.

[0062] The applicant hereby discloses in isolation each individual feature described herein and each combination of two or more such features, insofar as such features or combinations can be carried out based on the present description as a whole in light of the common knowledge of a person skilled in the art, regardless of whether such features or combinations of features solve the problems disclosed herein, and without limiting the scope of the claims. The applicant points out that aspects of the present invention may consist of each of these individual features or a combination of features. In view of the foregoing description, it will be obvious to a person skilled in the art that various modifications can be made within the scope of the invention.

Claims

[1] Endoscope (300; 600), comprising: a set of one or more optical fibers (306; 605) connecting a proximal end (308; 608) of the endoscope to a distal end (310; 610) of the endoscope, the set of one or more optical fibers being arranged to receive, at the proximal end of the endoscope, first light generated by a first light source (302; 602) and fluorescence excitation light for fluorescence-assisted surgery generated by a second light source; a phosphor (304; 604) arranged at the distal end of the endoscope to: to receive the first light from the set of one or more optical fibers and to emit light having a different spectrum than the first light; and the fluorescence excitation light from the set of one or more optical fibers to receive and scatter the fluorescence excitation light; and a filter (611) at the distal end of the endoscope arranged to filter the fluorescence excitation light to attenuate components of the fluorescence excitation light having a fluorescence detection wavelength. [2] The endoscope of claim 1, further comprising a light interface (303; 603) configured to receive the first light generated by the first light source and provide the light to the set of one or more optical fibers at the proximal end of the endoscope. [3] The endoscope according to claim 1 or 2, wherein the first light source is a laser. [4] Endoscope according to one of the preceding claims, wherein the diameter of the set of one or more optical fibers is less than 500 µm. [5] An endoscope according to any one of the preceding claims, wherein the endoscope is flexible over at least part of its length from the proximal end to the distal end. [6] An endoscope according to any one of the preceding claims, wherein the light emitted by the phosphor has a wider wavelength range than the first light generated by the first light source. [7] An endoscope according to any one of the preceding claims, wherein the spectrum of the first light generated by the first light source has a peak value within a wavelength range of 400 nm to 500 nm. [8] An endoscope according to any preceding claim, wherein the first light generated by the first light source is perceived as blue light according to a human visual system and the light emitted by the phosphor is perceived as white light. [9] An endoscope according to any preceding claim, wherein the endoscope further comprises a camera, and wherein the phosphor is arranged to emit light over a range of angles greater than a range of angles encompassed in a field of view of the camera. [10] An endoscope according to any preceding claim, wherein the endoscope further comprises one or more mirrored surfaces (502) at the distal end (510) of the endoscope positioned around the phosphor to reflect light emitted rearwardly from the phosphor. [11] The endoscope of claim 10, wherein the one or more mirrored surfaces form an open cylinder around the phosphor, the one or more mirrored surfaces comprising: a first mirrored surface (5021) which is flat and circular and is positioned behind the phosphor, and one or more other mirrored surfaces (5022) forming side walls of the open cylinder around the phosphor. [12] The endoscope of claim 11, wherein the first mirrored surface includes a hole (504) in which a portion of the set of one or more optical fibers is positioned. [13] An endoscope according to any one of the preceding claims, wherein the set of one or more optical fibers comprises only a single optical fiber. [14] Endoscope according to one of the preceding claims, wherein the second light source is a laser. [15] The endoscope of any preceding claim, wherein the endoscope is a surgical endoscope (601) configured to illuminate and image a surgical site during a surgical procedure. [16] The endoscope of claim 15, wherein the endoscope is further configured to detect fluorescently labeled structures during a fluorescence-assisted surgery. [17] An endoscope according to any one of the preceding claims, wherein the proximal end of the endoscope is adapted to be attached to a distal end of a surgical robot arm (616). [18] An endoscope according to any preceding claim, wherein the second light source generates the fluorescence excitation light having a peak wavelength different from the peak wavelength of the first light generated by the first light source. [19] An endoscope according to any one of the preceding claims, wherein the second light source generates the fluorescence excitation light having a wavelength in a range of 700 nm to 850 nm.

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