Endoscopic optical coherence tomography system

Abstract

The invention discloses an endoscopic optical coherence tomography system which comprises a light source, an optical coupler, an optical fiber probe, a reference arm, a reference reflector, a photoelectric detector and a data acquisition card, light emitted by the light source is distributed to the optical fiber probe and the reference arm through the optical coupler, light beams emitted by the optical fiber probe are subjected to circular scanning, meanwhile, the optical fiber probe retracts, and the data acquisition card is connected with the optical fiber probe. The light, scattered by the pipe wall, of the optical fiber probe interferes with the light, reflected by the reference arm through the reference reflector, of the reference arm, and the interference light returns to the optical coupler, is detected by the photoelectric detector and is transmitted to the data acquisition card; the inner probe arm control device controls the inner probe arm to move in the tube cavity, and the light source adopts an instantaneous narrow-bandwidth laser. According to the invention, the instantaneous narrow-bandwidth laser is adopted and has low attenuation, so that the coherence length of oct can be obviously increased, more available imaging distances can be obtained, and the imaging quality can be improved.

Description

Technical Field

[0001] The invention relates to an endoscopic optical coherence tomography system, belonging to the technical field of OCT imaging. Background Art

[0002] Endoscopic optical coherence tomography (OCT) technology has been gradually widely used in clinical practice. Its main applications are lung imaging, esophageal imaging, cardiovascular lining imaging, etc. Endoscopic OCT provides tissue structure information and can identify esophageal lesions, lung lesions, cardiovascular plaques, and guide stent placement. Figure 1 The figure shows intracardiac OCT. It can be seen that intracardiac OCT can clearly display the condition of the inner wall of the cardiovascular system, and its resolution is ten times better than that of traditional intracardiac ultrasound (100 micron level vs. 10 micron level).

[0003] Traditional endoscopic OCT is limited by the light source scanning speed, and can produce images at about 200 frames per second. Higher imaging speed can enhance the imaging quality in the withdrawal direction (three-dimensional imaging: horizontal, longitudinal depth, and probe withdrawal direction), allowing doctors to see the lumen wall more clearly. Therefore, how to improve the imaging speed of OCT is the research focus in this field. Summary of the invention

[0004] The invention discloses an endoscopic optical coherence tomography system, which can significantly increase the coherence length of OCT by using an instantaneous narrow bandwidth swept laser, thereby obtaining more available imaging distance.

[0005] The technical solution adopted by the present invention is: an endoscopic optical coherence tomography system, including: a light source, an optical coupler, a fiber optic probe, a reference arm, a reference reflector, a photodetector and a data acquisition card. The light emitted by the light source is distributed to the fiber optic probe and the reference arm through the optical coupler. The light beam emitted by the fiber optic probe performs a circular scan, and the fiber optic probe is withdrawn at the same time to achieve a three-dimensional spiral scan. The light scattered back by the fiber optic probe by the tube wall interferes with the light reflected back by the reference arm through the reference reflector. The interference light returns to the optical coupler, is detected by the photodetector, and is transmitted to the data acquisition card for imaging. The system also includes an inner probe arm control device, which controls the movement of the inner probe arm in the tube cavity. The system is characterized in that the light source adopts an instantaneous narrow bandwidth laser.

[0006] By using instantaneous narrow bandwidth lasers, the coherence length of OCT can be significantly increased to obtain more usable imaging distance. Instantaneous narrow bandwidth lasers are now commercially available, such as Thorlabs' VCSEL swept lasers. The swept lasers used in traditional OCT can only provide a usable imaging distance of several millimeters. If narrow instantaneous lasers are used, the usable imaging distance can be increased to centimeters.

[0007] Preferably, the instantaneous narrow bandwidth laser is a VCSEL swept frequency laser.

[0008] Preferably, the fiber optic probe is a multi-beam probe, which refers to more than two beams. Using a multi-beam probe such as a dual-beam probe, thanks to the long coherence distance brought by the instantaneous narrow bandwidth laser, each laser scan can obtain two or more longitudinal structural information (i.e., longitudinal information of two or more different lateral positions) on average, at the same imaging time and the same withdrawal speed, double or more times the number of images can be obtained. The scanning trajectory is more intensive, so more images are obtained and better final imaging quality is achieved. The probe withdrawal speed can also be increased, thereby reducing the time used for imaging while ensuring the imaging quality, which is of obvious clinical significance. For example, during cardiovascular imaging, it is necessary to flush the blood vessels with a developer, which increases the burden on the patient's kidneys. The shorter the imaging time, the lighter the burden on the patient.

[0009] Preferably, the multi-beam probe refers to adding an optical element to a fiber optic probe to split the light, and there is a certain optical path difference between the light beams.

[0010] Preferably, the optical path difference is greater than a preset longitudinal imaging distance. For example, when performing cardiovascular endoscopic imaging, the generally preset longitudinal imaging distance is 2-3 mm, and the optical path difference needs to be set to be greater than 2-3 mm.

[0011] Preferably, the optical element is a beam splitter, a spherical mirror, a micro prism, a micro reflector, a self-focusing lens or a multi-focal diffraction mirror.

[0012] The beneficial effects of the present invention are as follows:

[0013] The patent of the present invention achieves a two-fold or even three-fold increase in imaging speed by using an extremely narrow instantaneous bandwidth laser to obtain a large coherence distance and using a multi-beam endoscopic probe. In this way, more OCT images can be obtained within the same imaging time, thereby improving the imaging speed and the imaging quality of the entire cavity, especially the imaging quality in the withdrawal direction. The present invention can also reduce the time used for imaging while ensuring the imaging quality, benefiting from faster imaging quality, such as intra-cardiovascular OCT, and increase the imaging speed, thereby reducing the amount of developer used. Compared with traditional high-speed sweeping lasers, extremely narrow instantaneous bandwidth lasers are relatively cheap and have been widely promoted in the market, which can effectively reduce the cost of OCT devices. Therefore, the present invention has broad commercial prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is an intravascular OCT image.

[0015] Figure 2It is a schematic diagram of the OCT imaging system structure and imaging principle.

[0016] Figure 3 Schematic diagram of the principle of obtaining a long coherence distance by using a narrow instantaneous bandwidth laser.

[0017] Figure 4 It is a comparison of the scanning trajectories of a single-beam probe and a multi-beam probe (taking a double-beam probe as an example).

[0018] Figure 5 It is a schematic diagram of the structure for realizing laser beam splitting.

[0019] The specific implementation of the present invention is further described below in conjunction with the accompanying drawings. DETAILED DESCRIPTION

[0020] The present invention is further described below in conjunction with embodiments, but the description of the embodiments does not impose any limitation on the protection scope of the present invention.

[0021] Unless otherwise defined, all technical terms and scientific terms used herein have the same meaning as those generally understood by those skilled in the art of the present invention, and the terms used in the specification of the present invention herein are only for the purpose of describing specific embodiments, and are not intended to limit the present invention. In addition, although demonstrations of parameters containing specific values ​​may be provided herein, it should be understood that the parameters do not need to be exactly equal to the corresponding values, but can be approximated to the corresponding values ​​within an acceptable error tolerance or design constraint. The directional terms mentioned in the embodiments, such as "up", "down", "front", "back", "left", "right", etc., are only directions with reference to the accompanying drawings. Therefore, the directional terms used are used to illustrate rather than to limit the scope of protection of the present invention.

[0022] Unless otherwise specified, the materials and instruments used in the following examples can be obtained from conventional commercial channels.

[0023] Example 1

[0024] like Figure 2 As shown, an endoscopic optical coherence tomography system includes: a light source, an optical coupler, a fiber optic probe, a reference arm, a reference reflector, a photodetector and a data acquisition card. The light source adopts an instantaneous narrow bandwidth laser, such as a Thorlabs VCSEL swept laser. The light emitted by the light source is distributed to the fiber optic probe and the reference arm through the optical coupler. The light beam emitted by the fiber optic probe performs a circular scan, and the fiber optic probe is withdrawn at the same time to achieve a three-dimensional spiral scan. The light scattered back by the fiber optic probe by the tube wall interferes with the light reflected back by the reference arm through the reference reflector. The interference light returns to the optical coupler, is detected by the photodetector, and is transmitted to the data acquisition card. The system also includes an inner probe arm control device, which controls the movement of the inner probe arm in the tube cavity.

[0025] like Figure 3 As shown, the use of instantaneous narrow bandwidth lasers has low attenuation compared to traditional lasers such as External Cavity Lasers (ECL) or Fourier Domain Mode-Locked (FDML) lasers, which can significantly increase the coherence length of OCT and obtain more available imaging distance.

[0026] like Figure 4 As shown, by using a multi-beam probe such as a dual-beam probe, thanks to the long coherence distance brought by the instantaneous narrow bandwidth laser, each laser scan can obtain an average of longitudinal structural information at two different lateral positions, and double the number of images can be obtained at the same imaging time and the same retraction speed.

[0027] The device for realizing laser beam splitting is a prior art, which can be used as follows: Figure 5 The device shown realizes laser beam splitting by installing a beam splitter, a spherical mirror, a micro prism, a micro reflector, a self-focusing lens or a multi-focal diffraction mirror on the probe.

[0028] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. An endoscopic optical coherence tomography system, comprising: A light source, an optical coupler, a fiber optic probe, a reference arm, a reference reflector, a photodetector and a data acquisition card. The light emitted by the light source is distributed to the fiber optic probe and the reference arm via the optical coupler. The light beam emitted by the fiber optic probe performs a circular scan, and the fiber optic probe retracts at the same time to achieve a three-dimensional spiral scan. The light scattered back by the tube wall from the fiber optic probe interferes with the light reflected back by the reference arm via the reference reflector. The interference light returns to the optical coupler, is detected by the photodetector, and is transmitted to the data acquisition card for imaging. The system also includes an inner probe arm control device, which controls the movement of the inner probe arm in the tube cavity. The system is characterized in that the light source adopts an instantaneous narrow bandwidth laser.

2. The endoscopic optical coherence tomography system according to claim 1, characterized in that: The instantaneous narrow bandwidth laser is a VCSEL swept frequency laser.

3. The endoscopic optical coherence tomography system according to claim 1, characterized in that: The optical fiber probe is a multi-beam probe.

4. The endoscopic optical coherence tomography system according to claim 3, characterized in that: The multi-beam probe refers to adding optical elements to a fiber optic probe to split the light, and there is a certain optical path difference between the light beams.

5. The endoscopic optical coherence tomography system according to claim 4, characterized in that: The optical path difference is above a preset longitudinal imaging distance.

6. The endoscopic optical coherence tomography system according to claim 4, characterized in that: The optical element refers to a beam splitter, a spherical mirror, a micro prism, a micro reflector, a self-focusing lens or a multi-focal diffraction mirror.

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