1. Technical Field
This application relates to imaging systems and, more particularly, to optical probes.
2. Related Art
Optical probes are often used to capture images of subjects that may be hidden from open view. For example, a physician may guide an optical probe into a bodily lumen, such as a blood vessel, to capture images of blockages, occlusions, plaques, or other subjects within the vessel. One imaging technique that uses optical probes is Optical Coherence Tomography (“OCT”). In OCT, a light source sends light waves through an optical waveguide, such as an optical fiber. The light waves are output from the optical fiber and directed against the subject to be imaged. At least some of the light reflects off the subject and is captured by optical fiber. The light reflected off the subject is then analyzed to create an image of the subject.
Some optical imaging probes are designed in a “side-viewing” implementation. These probes are helpful when the area to be imaged is positioned on a side of the probe rather than in-line with the end of the probe. For example, an OCT optical probe may direct light against a side wall of a blood vessel to analyze the plaque on the sides of the vessel wall as the probe is guided through the vessel. Some imaging systems apply torque to a portion of the optical probe to change a direction of the light output from the side of the probe. For example, a physician in an OCT procedure may rotate the proximal end of the probe to change the direction of the light output from the distal end of the probe to create a 360 degree image of a portion of a vessel wall.
In some situations, rotation of the optical probe may cause non-uniform rotational distortion (“NURD”) problems. For example, mechanical drag on various portions of the probe may result when the optical probe is rotating in a space with a small diameter or several curves. The mechanical drag causes some portions of the probe to rotate differently than other portions of the probe. This non-uniform rotation may lead to significant distortions and artifacts in the images captured by the rotating optical probe. Thus, a need exists for an optical probe that more resistant to rotational distortion effects.
Optical probes may be used to capture images of a subject. In one implementation, an optical probe includes an optical reflector, an electric motor, and an optical waveguide. The electric motor includes a rotor that is mechanically coupled with the optical reflector. The optical waveguide is optically coupled with the optical reflector.
In another implementation, the optical probe includes an optical reflector mechanically coupled with an electric motor. The electric motor comprises a motor shaft that defines an opening for an optical waveguide to transmit light through the electric motor to the optical reflector. The electric motor is configured to rotate the optical reflector about an axis of the motor shaft.
In yet another implementation, the optical probe includes an optical reflector, a motor shaft, a permanent magnet, and a coil. The motor shaft defines an opening for an optical waveguide to transmit light through the motor shaft to the optical reflector. The permanent magnet is mechanically coupled with the optical reflector. The coil is positioned relative to the permanent magnet so that a magnetic field generated in response to an input electric current passing through the coil causes rotation of the permanent magnet and the optical reflector about the motor shaft.
Other systems, methods, features and advantages will be, or will become, apparent to one with skill in the art upon examination of the following figures and detailed description. It is intended that all such additional systems, methods, features and advantages be included within this description, be within the scope of the invention, and be protected by the following claims.
An optical probe system may be used to capture images of a subject. For example, a physician may guide an optical probe into a bodily lumen, such as a blood vessel, to capture images of blockages, occlusions, plaques, or other subjects within the vessel. The optical probe may direct light against the subject and capture light reflected back from the subject. The light reflected off the subject is analyzed to create an image of the subject. Optical probes may also be used to perform other functions, such as data communication through optical fibers.
The optical probes described herein include an electric motor that rotates a portion of the probe to change a direction of the light output from the probe. In implementations where the electric motor of the probe rotates only a sub-portion of the light path through the probe while leaving other portions of the light path stationary, some of the problems associated with non-uniform rotational distortion (“NURD”) may be avoided. For example, the electric motor may be configured to rotate only a light emitting/capturing distal end portion of the probe while leaving all or a majority of the optical waveguide through the probe substantially stationary. In this configuration, the substantially static optical waveguide that carries the light along the length of the probe would not experience the rotational irregularities seen in dynamically rotated waveguides, which may improve the performance of the probe.
In the implementation of
The distal tip 110 in one implementation is a catheter housing portion at the distal end of the probe 104. The distal tip 110 rotates with the rotor of the electric motor 108. The optical reflector 112 may be mechanically coupled with the distal tip 110 so that the optical reflector 112 rotates with the distal tip 110. For example, the optical reflector 112 may be connected with a housing component of the distal tip 110. The distal tip 110 in the implementation of
The electric motor 108 is mechanically coupled with the optical reflector 112 so that the motor 108 may rotate the optical reflector 112 in response to an input electric current to the motor 108. The input electric current passes from the control unit 106 through the power supply link 116 to the electric motor 108. The power supply link 116 may include one or more power supply lines between the control unit 106 and the electric motor 108.
In one implementation, the electric motor 108 may include a rotor coupled with the optical reflector 112. The rotor may be coupled with the optical reflector 112 by either a direct or indirect connection. In one implementation, the rotor is connected with a housing component, such as the distal tip 110 of the probe 104, which is connected with the optical reflector 112. In this implementation, rotation of the rotor causes rotation of the housing component, which causes rotation of the optical reflector 112. The electric motor 108 may be a brushed motor, brushless motor, direct current motor, alternating current motor, stepper motor, or another device that converts electrical energy into mechanical energy. In one implementation, the motor may be a modified version of a small diameter micro geared motor, such as the 1.5 mm diameter micro-motor available from the Namiki Precision Jewel Co., Ltd. For example, a general purpose motor may be modified to have a hollow shaft sized to allow passage of the optical waveguide 114.
The electric motor 108 may define an opening for the optical waveguide 114 to transmit light through at least a portion of the electric motor 108 to the optical reflector 112. In one implementation, the electric motor 108 may include a hollow motor shaft with a passageway through the hollow center of the motor shaft that allows passage of the optical waveguide 114. The opening through the electric motor 108 allows the optical waveguide 114 to pass through the motor 108 so that the optical waveguide 114 can be optically coupled with the optical reflector 112. The optical waveguide 114 and the optical reflector 112 are optically coupled in configurations where light output from the optical waveguide 114 is able to reach the optical reflector 112. The optical waveguide 114 and the optical reflector 112 are also optically coupled in configurations where light from the optical reflector 112 is able to reach the optical waveguide 114. The optical coupling may be achieved directly, such as through an air or vacuum medium, or indirectly, such as through a lens or other optical coupling device. In one implementation, the optical waveguide 114 is optically coupled with the optical reflector 112 in a manner that allows rotation of the optical reflector 112 without corresponding rotation of the optical waveguide 114. For example, the optical waveguide 114 may remain stationary while the optical reflector 112 rotates to change the output direction of light from the probe 104.
The optical waveguide 114 comprises a medium that guides electromagnetic waves in the optical spectrum. In one implementation, the optical waveguide comprises a physical structure, such as an optical fiber. The optical fiber may be formed from a glass, polymer, or semiconductor. The optical waveguide 114 may pass all the way through the electric motor 108 (e.g., along the entire length of a hollow motor shaft) or may pass through only a sub-portion of the electric motor 108 (e.g., along only a sub-portion of the entire length of a hollow motor shaft).
In the implementation of
The power source 122 supplies electrical current to the probe 104. For example, the electrical current from the power source 122 may be passed through the power source link 116 to drive the electric motor 108 of the probe 104. The power source 122 may be a direct current (DC) power supply or an alternating current (AC) power supply.
The user interface 124 provides a user of the optical probe system 102 with control over the rotation of the optical reflector 112 of the optical probe 104. For example, the user interface 124 may include a switch, dial, graphical user interface, or other rotation control mechanism. In one implementation, the user interface 124 comprises an “on/off” switch that either drives the motor at one speed or leaves the motor in an off state. In another implementation, the user interface 124 allows for a motor speed selection capability, such as through a variable position dial, analog voltage supplier, or processor-controlled user interface. The user interface 124 may control the rotation speed of the motor 108 by controlling the amount of electric current passed to the motor 108.
The processor 126 may control the delivery of power to the probe 104, control the delivery of light to the probe 104, and/or perform image processing. For example, the processor 126 may analyze data related to the light received back from the probe 104 to create an image. Also, the processor 126 may control how the motor of the probe 104 is driven, such as by creating power pulse sequences to achieve the desired rotation characteristics.
The use of two separate waveguides allows one of the waveguides to be stationary while the other of the waveguides rotates. In the implementation of
The optical waveguide 406 in one implementation may be an optical fiber that guides light through an open core/shaft of a motor so that the light reaches the output tip of the system. In another implementation, the optical waveguide 406 may be an optically clear motor core/shaft that allows light transmission. For example, the optical waveguide 406 may be an optically clear portion of the motor shaft that is optically coupled with another optical waveguide 404. Another waveguide, such as an optical fiber, may then direct light to the optically clear core/shaft. Thus, the optically clear core/shaft (e.g., the waveguide 406) could rotate with the motion of the motor while leaving the other optical waveguide (e.g., the waveguide 404) substantially stationary.
The optical connector 408 serves to align the end of one waveguide with the end of another waveguide so that light may pass between the waveguides. In one implementation, the optical connector 408 includes a notch 410 in a portion of the optical connector 408 sized to receive a proximal end portion of the hollow motor shaft 212. The notch 410 is positioned to hold the optical path of the optical waveguide 406 in alignment with the optical path of the optical waveguide 404 during rotation of the hollow motor shaft 212.
The optical waveguide 504 passes through an opening in the motor shaft 506 so that light may pass through the motor of the probe 502 and reach the optical reflector 514. The motor shaft 506 in the optical probe 502 may be stationary. For example, the motor of the optical probe 502 does not rotate the motor shaft 506. Rather, the rotor of the motor rotates about the motor shaft 506.
The electric motor of the optical probe 502 includes the coils 508 and 509, and the permanent magnets 510 and 511. In the implementation of
The optical probe 502 in
The power supply link 522 may pass through at least a portion of the motor shaft 506. In one implementation, the motor shaft 506 defines an opening on a side of the shaft to allow the one or more lines of the power supply link 522 to exit the hollow center of the motor shaft 522 and connect with the motor of the probe 502. The power supply link 522 may comprise one or more power supply lines that provide electric current to the coils 508 and 509. For example, the power supply link 522 may include a first power line to the coil 508 and a second power line to the coil 509. The control unit that provides power to the power lines of the power supply link 522 may stagger the application of electric current to the power lines to provide a rotational movement of the permanent magnets 510 and 511 about the motor shaft 506. For example, the control unit may pulse each of the coils 508 and 509 out of phase with each other so that the coils 508 and 509 cause the magnets 510 and 511 to rotate. Specifically, the coils 508 and 509 generate magnetic fields when an input electric current is passing through the coils 508 and 509. The coils 508 and 509 are positioned to be near the permanent magnets so that an interaction between the magnetic fields and the permanent magnets 510 and 511 is strong enough to cause rotation of the permanent magnets 510 and 511 about the motor shaft 506.
The permanent magnets 510 and 511 of the probe 502 are coupled with the distal tip catheter housing 512. The distal tip catheter housing 512 is coupled with the optical reflector 514. Thus, the permanent magnets 510 and 511, which serve as rotors of an electric motor of the optical probe 502, are coupled with the optical reflector 514 and can cause rotation of the distal tip catheter housing 512 and the optical reflector 514 about a longitudinal axis of the motor shaft 506.
The rotation guide components 518 and 520 may be disposed between the rotating portion of the optical probe 502 and the stationary motor shaft 506. The rotation guide components 518 and 520 allow rotation around the motor shaft 506 with reduced friction and increased stability. In one implementation, the rotation guide components 518 and 520 may be disposed between the distal tip catheter housing 512 and the motor shaft 506. In another implementation, the rotation guide components 518 and 520 may be disposed between the motor shaft 506 and the rotating magnets 510 and 511. The rotation guide components 518 and 520 may be bearings, bushings, or other devices to guide the rotation of the magnets about the motor shaft 506. The rotation guide components 518 and 520 may provide a slip coupling between the rotating portion of the optical probe 502 and the stationary motor shaft 506. For example, the rotation guide components 518 and 520 may rotate with the magnets 510 and 511, the distal tip catheter housing 512, and the optical reflector 514 while sliding along a surface of the motor shaft 506. In one implementation, the rotation guide components 518 and 520 may be formed in a disk shape with a hole that fits around the motor shaft 506.
In the implementation of
While various embodiments of the invention have been described, it will be apparent to those of ordinary skill in the art that many more embodiments and implementations are possible within the scope of the invention. Accordingly, the invention is not to be restricted except in light of the attached claims and their equivalents.