CN111436907A - A cerebral vascular imaging device based on swept-frequency adaptive optics OCT - Google Patents

Abstract

The invention relates to the technical field of optical imaging, in particular to a cerebrovascular imaging device based on sweep frequency adaptive optics OCT, which comprises: the device comprises a sweep frequency light source, an optical fiber coupler, a reference arm, a sample arm, a detector and a control processor; one end of the optical fiber coupler is respectively connected with the sweep frequency light source and the detector; the other end of the optical fiber coupler is respectively connected with the reference arm and the sample arm; the other end of the sample arm is over against a sample to be detected; the control processor is respectively connected with the detector and the sample arm; the cerebrovascular imaging device provided by the invention can greatly improve the system resolution and does not need contrast agents.

Description

A cerebral vascular imaging device based on swept-frequency adaptive optics OCT

technical field

The invention belongs to the technical field of optical imaging, and in particular relates to a cerebral blood vessel imaging device based on frequency-sweeping adaptive optics OCT.

Background technique

Cerebrovascular disease is a relatively serious disease with relatively high mortality and disability rates. It is very important to develop advanced examination techniques for cerebrovascular disease.

Optical tomography coherence tomography (OCT) has been widely used in biomedical imaging since its birth. It is characterized by fast imaging speed, high resolution, and non-invasiveness to the human body. OCT has also been applied to angiography as a new angiography technique: optical tomographic coherence tomography angiography (OCTA), and adaptive optics (AO) combined with OCT can make the resolution of the device very high With the development of hardware, the technical performance of swept-frequency light source (SS) has been improved, and the application of swept-frequency OCT has also been widely used. Compared with traditional laser light sources, swept-frequency light sources have good equipment sensitivity and can be more The depth information of the device can be detected well, and the swept-frequency adaptive optics OCT device (AO-SS-OCT), which combines adaptive optics and swept-frequency OCT, can greatly improve the resolution of the device on the one hand. On the other hand, the device can better detect the information on the depth and better image the blood vessels.

At present, the examination techniques for cerebral blood vessels include magnetic resonance angiography (MRA), CT angiography (CTA) and digital subtraction angiography (DSA), but their resolutions are relatively low, among which the resolution of MRA is millimeter level. The resolution of DSA is sub-millimeter level; and MRA, CTA and DSA all need to inject contrast agents. Although contrast agents are also widely used in vascular imaging technology, there is still a lot of controversy about the safety of contrast agents. There is a risk of harm to human organs and even death.

Therefore, it is of great significance to provide a cerebrovascular examination method with higher resolution and without contrast agent.

SUMMARY OF THE INVENTION

In order to solve the above problems, the present invention provides a cerebral vascular imaging device based on swept-frequency adaptive optics OCT, so as to solve one or more technical problems existing in the prior art, and at least provide a beneficial option or create conditions.

In order to achieve the above object, an embodiment of the present invention provides a cerebrovascular imaging device based on swept-frequency adaptive optics OCT, including: a swept-frequency light source, an optical fiber coupler, a reference arm, a sample arm, a detector, and a control processor;

One end of the optical fiber coupler is respectively connected to the swept frequency light source and the detector; the other end of the optical fiber coupler is respectively connected to the reference arm and the sample arm; the other end of the sample arm is facing the sample to be tested; the control processor is respectively connected with the detector and the sample arm;

the frequency swept light source for providing initial light;

The optical fiber coupler is used to divide the initial light emitted by the frequency sweep light source into two paths, and the two paths of initial light enter the reference arm and the sample arm respectively;

The reference arm is used for collimating the incoming light beam and then reflecting it to obtain a reference light, and the reference light returns to the fiber coupler along the original path;

The sample arm includes a second collimating mirror, several 4F systems, a first scanning galvanometer, a second scanning galvanometer, a deformable mirror, a second plane mirror, a focusing lens, a beam splitter, and a wavefront sensor;

The light beam entering the sample arm is collimated by the second collimating mirror and then passes through the beam splitter, enters a 4F system and reaches the first scanning galvanometer, and then passes through a 4F system and reaches the second scanning galvanometer. Enter the deformable mirror through a 4F system, then reach the second plane mirror through a 4F system, and finally focus to the sample to be tested through the focusing lens;

The sample light reflected from the surface of the sample to be tested returns through the original path and is divided into two beams when it reaches the beam splitter. One beam is reflected by the beam splitter and enters the wavefront sensor, and the other beam is returned to the fiber coupler through the beam splitter. , the sample light entering the fiber coupler interferes with the reference light to generate an interference signal.

the detector, for collecting the interference signal and transmitting the interference signal to the control processor;

The control processor is used for processing and calculating the received interference signal to generate a cerebral blood vessel image.

Further, the detector is a balanced detector.

Further, the optical fiber coupler includes a first coupler, a second coupler and a third coupler;

The first coupler, the second coupler, and the third coupler are all 2×2 fiber optic couplers;

One input end of the first coupler is connected to the frequency sweep light source, the other input end is connected to the balanced detector, an output end of the first coupler is empty, and the other output end is connected to the first coupler. One input end of the two couplers is connected;

An input end of the third coupler is connected to the balanced detector, and the other input end is empty; an output end of the third coupler is connected to the other input end of the second coupler, and the other The output terminal is empty;

One output end of the second coupler is connected to the reference arm, and the other output end is connected to the sample arm.

Further, the reference arm includes a first collimating mirror and a first plane mirror, and the light beam entering the reference arm is collimated by the first collimating mirror and then reaches the first plane mirror, and is reflected by the first plane mirror to obtain a reference light, the reference light. The light travels back into the fiber coupler.

Further, the 4F system consists of two toric mirrors.

Further, the deformable mirror is an electrostatically driven MEMS deformable mirror.

Further, the wavefront sensor includes a 132×132 microlens array and an area array camera.

Further, the control processor includes a first control processor and a second control processor, the first control processor is electrically connected to the wavefront sensor and the deformable mirror, respectively, and the second control processor is respectively It is electrically connected with the first scanning galvanometer, the second scanning galvanometer and the detector.

Further, the center wavelength of the frequency sweep light source is 1040-1310nm, the scanning rate is 50-100KHZ, and the coherence length is 10-15mm.

The beneficial effects of the present invention are as follows: the present invention discloses a cerebral vascular imaging device based on swept-frequency adaptive optics OCT, comprising a swept-frequency light source, an optical fiber coupler, a reference arm, a sample arm, a detector, and a control processor. The Cerebral Vascular Imaging Device can greatly improve the system resolution by introducing adaptive optical elements such as a wavefront sensor and a deformable mirror into the sample optical path, by capturing the wavefront phase difference, and then adjusting the deformable mirror by controlling the processor. The frequency sweep light source is adopted to improve the test sensitivity and to better detect the depth information of the system; and the cerebral vascular imaging device of the present invention does not need a contrast agent, thereby avoiding harm to the human body.

Description of drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the accompanying drawings required in the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some of the present invention. In the embodiments, for those of ordinary skill in the art, other drawings can also be obtained according to these drawings without creative labor.

1 is a schematic structural diagram of a cerebral vascular imaging device based on swept frequency adaptive optics OCT according to an embodiment of the present invention;

2 is a schematic structural diagram of a wavefront sensor in an embodiment of the present invention;

FIG. 3 is a schematic structural diagram of an area scan camera in an embodiment of the present invention.

Detailed ways

The concept, specific structure and technical effects of the present disclosure will be clearly and completely described below in conjunction with the embodiments and the accompanying drawings, so as to fully understand the purposes, solutions and effects disclosed in the present disclosure. It should be noted that the embodiments in the present application and the features of the embodiments may be combined with each other in the case of no conflict.

Referring to FIG. 1 , a cerebrovascular imaging device based on swept-frequency adaptive optics OCT provided by an embodiment of the present invention includes a swept-frequency light source 1, an optical fiber coupler, a reference arm, a sample arm, a detector 25, and a control processor ;

One end of the optical fiber coupler is connected to the frequency sweep light source 1 and the detector 25 respectively; the other end of the optical fiber coupler is respectively connected to the reference arm and the sample arm; the other end of the sample arm is facing the sample to be tested; the control process The detectors are respectively connected with the detector 25 and the sample arm;

The frequency sweep light source 1 is used to provide initial light;

The optical fiber coupler is used to divide the initial light emitted by the frequency sweep light source 1 into two paths, and the two paths of initial light enter the reference arm and the sample arm respectively;

The reference arm is used for collimating the incoming light beam and then reflecting it to obtain a reference light, and the reference light returns to the fiber coupler along the original path;

The sample arm includes a second collimating mirror 7, a beam splitter 8, a wavefront sensor 9, a first toroidal mirror 10, a second toric mirror 11, a first scanning galvanometer 12, a third toric mirror 13, Four toroidal mirror 14 , second scanning galvanometer mirror 15 , fifth toroidal mirror 16 , sixth toroidal mirror 17 , deformable mirror 18 , seventh toroidal mirror 19 , eighth torus mirror 20 , second plane mirror 21 , focusing lens 22; wherein, the first toroidal mirror 10 and the second toroidal mirror 11, the third toroidal mirror 13 and the fourth toroidal mirror 14, the fifth toroidal mirror 16 and the sixth torus mirror 17, the The seventh ring mirror 19 and the eighth ring mirror 20 respectively form four 4F systems.

The light beam entering the sample arm is collimated by the second collimating mirror 7 and then passes through the beam splitter 8, enters a 4F system and reaches the first scanning galvanometer 12, and then passes through a 4F system and reaches the second scanning galvanometer. The mirror 15 enters the deformable mirror 18 through a 4F system, then reaches the second plane mirror 21 through a 4F system, and finally is focused to the sample to be tested through the focusing lens 22 .

The sample light reflected by the surface of the sample to be tested returns through the original path, and is divided into two beams when reaching the beam splitter 8, one beam is reflected by the beam splitter 8 and enters the wavefront sensor 9, and the other beam passes through the beam splitter 8 and returns to the desired beam. The optical fiber coupler, the sample light entering the optical fiber coupler interferes with the reference light to generate an interference signal.

The detector 25 is used to collect the interference signal and transmit the interference signal to the control processor;

The control processor is used for processing and calculating the received interference signal to generate a cerebral blood vessel image.

As a further improvement of the above technical solution, the detector 25 is a balanced detector, and the fiber coupler includes a first coupler 2, a second coupler 3 and a third coupler 4; the first coupler 2, the second coupler 4 The coupler 3 and the third coupler 4 are both 2×2 fiber couplers; one input end of the first coupler 2 is connected to the frequency sweep light source 1 , and the other input end is connected to the detector 25 . One output end is empty, the other output end is connected with an input end of the second coupler 3; an input end of the third coupler 4 is connected with the detector 25, and the other input end is empty; an output end of the third coupler 4 The end is connected with the other input end of the second coupler 3, and the other output end is empty; one output end of the second coupler 3 is connected with the reference arm, and the other output end is connected with the sample arm;

As a further improvement of the above technical solution, the reference arm includes a first collimating mirror 5 and a first plane mirror 6. The light beam entering the reference arm is collimated by the first collimating mirror 5 and then reaches the first plane mirror 6, and passes through the first plane mirror. 6. After the reflection, the reference light is obtained, and the reference light returns to the fiber coupler along the original path;

As a further improvement of the above technical solution, the control processor includes a first control processor 23 and a second control processor 24, and the first control processor 23 is electrically connected to the wavefront sensor 9 and the deformable mirror 18, respectively, The second control processor 24 is electrically connected to the first scanning galvanometer 12 , the second scanning galvanometer 15 and the detector 25 respectively.

When the cerebrovascular imaging device provided in this embodiment works, the initial light emitted by the swept-frequency light source 1 enters a 2×2 first coupler 2 and is divided into two beams of light, one beam is empty, and the other beam enters the second coupler In 3, the light entering the second coupler 3 is divided into two beams, one beam enters the reference arm, is collimated by the first collimator The original way returns to the fiber coupler; the other beam enters the sample arm, is collimated by the second collimating mirror 7 and then passes through the beam splitter 8, and then enters the first toric mirror 10 and the second toric mirror 11. The formed 4F system reaches the first scanning galvanometer 12, and then enters the second scanning galvanometer 15 through the 4F system composed of the third toroidal mirror 13 and the fourth toroidal mirror 14, and then passes through the fifth toric mirror 16 and the fourth toric mirror 14. The 4F system composed of the sixth toroidal mirror 17 enters the deformable mirror 18, and finally passes through the 4F system composed of the seventh toroidal mirror 19 and the eighth toroidal mirror 20 to become a beam of parallel light, and passes through the second plane mirror 21. Reflect, focus on the surface of the cerebrovascular tissue to be detected through the focusing lens 22;

After the light is reflected on the cerebrovascular tissue, the sample light is obtained. The sample light returns along the original path. When it reaches the beam splitter 8, a part of it is reflected by the beam splitter 8 and enters the wavefront sensor 9. The wavefront phase difference is captured, and then transmitted to the first beam splitter. The control processor 23, the first control processor 23 adjusts the deformable mirror 18 after calculation to achieve the purpose of correcting the wavefront aberration; another part of the light passes through the beam splitter 8, enters the second coupler 3, and enters the The sample light of the second coupler 3 interferes with the reference light to generate an interference signal. The interference signal is divided into two equal rays, and then enters the detector 25 through the first coupler 2 and the third coupler 4 respectively. The interference signal received by the detector 25 is transmitted to the second control processor 24 through analog-to-digital conversion, and the second control processor 24 performs data processing according to the information transmitted by the detector 25 to obtain a cerebrovascular map.

The deformable mirror 18 is one of the important components in the adaptive optics system. It compensates for the phase distortion of the wavefront by changing its own surface shape, and acts as a wavefront correction device to correct the wavefront error. Therefore, the deformable mirror 18 is related to the entire adaptive optics. The correction capability and correction accuracy of the optical system. In the prior art, there are those that change the surface shape through piezoelectric control, and some that change the surface shape through electrostatic drive. In a preferred embodiment of the present invention, the deformable mirror 18 is The MEMS deformable mirror produced by Boston Micromachines Corporation (BMC) uses electrostatic drive, which does not produce hysteresis like piezoelectric deformable mirrors when deforming, and can quickly change the wavefront phase, which greatly improves the working performance of the system.

2 and 3 , the wavefront sensor 9 provided by the embodiment of the present invention is also one of the important components in the adaptive optics system, which is usually a Hartmann-Shack wavefront sensor, which is usually composed of a set of microlens arrays 901 It is composed of an area array camera 902. The specific working principle is as follows: The microlens array with the same aperture size and focal length divides the main aperture into several sub-apertures for imaging respectively. and the light intensity distribution to calculate the spot centroid of each image point. By comparing with the standard ideal point position, the average slope of the wavefront in the sub-aperture range divided by the microlens array can be obtained from the geometric relationship. The wavefront phase distribution across the aperture. Therefore, the more apertures of the microlens array, the more sensitive the sensor, but due to the constraints of processing cost, it needs to be considered comprehensively. In a preferred embodiment of the present invention, the wavefront sensor 9 is composed of a 132×132 microlens array 901 and an area scan camera 902 , and the microlens array can be replaced according to requirements to increase the flexibility and adaptability of the system.

The frequency sweep light source 1 is the main factor affecting the resolution of the device. The ideal frequency sweep light source 1 needs to satisfy linear frequency sweep, narrow instantaneous line width, wide sweep frequency range and high output power. Therefore, preferably, the present invention implements The center wavelength of the frequency sweep light source 1 of the example is 1040-1310nm, the scanning rate is 50-100KHZ, and the coherence length is 10-15mm; The coherence length is 12mm, for example, the OCT1060 product produced by AXSUN can be selected; in another embodiment, the center wavelength of the frequency sweep light source 1 is 1200nm, the scanning rate is 70KHZ, and the coherence length is 15mm.

In the embodiment of the present invention, by introducing adaptive optical elements such as the wavefront sensor 9 and the deformable mirror 18 into the sample optical path, by capturing the wavefront phase difference, and then adjusting the deformable mirror 18 by controlling the processor, the system resolution can be greatly improved . Further, the swept frequency light source 1 is adopted, and the test sensitivity is improved through parameter optimization selection, and the depth information of the system can be better detected. The resolution is high and can reach the micron level. On the other hand, the system can better detect information at a higher depth and better image blood vessels. Moreover, the cerebral vascular imaging device based on the frequency-sweeping adaptive optics OCT of the present invention does not need a contrast agent, and is completely non-invasive for detection, thereby avoiding damage and potential risks to the human body.

Meanwhile, the cerebral blood vessel imaging device based on frequency-sweeping adaptive optics OCT of the present invention has reasonable optical path design and compact structure.

Based on the disclosure and teaching of the above specification, those skilled in the art to which the present invention pertains can also make changes and modifications to the above embodiments. Therefore, the present invention is not limited to the specific embodiments disclosed and described above, and some modifications and changes to the present invention should also fall within the protection scope of the claims of the present invention. In addition, although some specific terms are used in this specification, these terms are only for convenience of description and do not constitute any limitation to the present invention.

Claims (9)

1. a cerebrovascular imaging device based on frequency sweep adaptive optics OCT, is characterized in that, comprises: frequency sweep light source, optical fiber coupler, reference arm, sample arm, detector, control processor; One end of the optical fiber coupler is respectively connected to the swept frequency light source and the detector; the other end of the optical fiber coupler is respectively connected to the reference arm and the sample arm; the other end of the sample arm is facing the sample to be tested; the control processor is respectively connected with the detector and the sample arm; the frequency swept light source for providing initial light; The optical fiber coupler is used to divide the initial light emitted by the frequency sweep light source into two paths, and the two paths of initial light enter the reference arm and the sample arm respectively; The reference arm is used for collimating the incoming light beam and then reflecting it to obtain a reference light, and the reference light returns to the fiber coupler along the original path; The sample arm includes a second collimating mirror, several 4F systems, a first scanning galvanometer, a second scanning galvanometer, a deformable mirror, a second plane mirror, a focusing lens, a beam splitter, and a wavefront sensor; The light beam entering the sample arm is collimated by the second collimating mirror and then passes through the beam splitter, enters a 4F system and reaches the first scanning galvanometer, and then passes through a 4F system and reaches the second scanning galvanometer. Enter the deformable mirror through a 4F system, then reach the second plane mirror through a 4F system, and finally focus to the sample to be tested through the focusing lens; The sample light reflected from the surface of the sample to be tested returns through the original path and is divided into two beams when it reaches the beam splitter. One beam is reflected by the beam splitter and enters the wavefront sensor, and the other beam is returned to the fiber coupler through the beam splitter. , the sample light entering the fiber coupler interferes with the reference light to generate an interference signal; the detector, for collecting the interference signal and transmitting the interference signal to the control processor; The control processor is used for processing and calculating the received interference signal to generate a cerebral blood vessel image. 2 . The cerebral vascular imaging device based on swept frequency adaptive optics OCT according to claim 1 , wherein the detector is a balanced detector. 3 . 3. The cerebrovascular imaging device based on swept frequency adaptive optics OCT according to claim 2, wherein the optical fiber coupler comprises a first coupler, a second coupler and a third coupler; The first coupler, the second coupler, and the third coupler are all 2×2 fiber optic couplers; One input end of the first coupler is connected to the frequency sweep light source, the other input end is connected to the balanced detector, an output end of the first coupler is empty, and the other output end is connected to the first coupler. One input end of the two couplers is connected; An input end of the third coupler is connected to the balanced detector, and the other input end is empty; an output end of the third coupler is connected to the other input end of the second coupler, and the other The output terminal is empty; One output end of the second coupler is connected to the reference arm, and the other output end is connected to the sample arm. 4 . The cerebral vascular imaging device based on swept frequency adaptive optics OCT according to claim 1 , wherein the reference arm comprises a first collimator mirror and a first plane mirror, and the light beam entering the reference arm is passed through the first collimator. 5 . The collimating mirror reaches the first plane mirror after being collimated, and is reflected by the first plane mirror 6 to obtain reference light, and the reference light returns to the fiber coupler along the original path. 5 . The cerebral vascular imaging device based on swept-frequency adaptive optics OCT according to claim 1 , wherein the 4F system consists of two toric mirrors. 6 . 6 . The cerebral vascular imaging device based on swept frequency adaptive optics OCT according to claim 1 , wherein the deformable mirror is an electrostatically driven MEMS deformable mirror. 7 . 7 . The cerebral vascular imaging device based on swept-frequency adaptive optics OCT according to claim 1 , wherein the wavefront sensor comprises a 132×132 microlens array and an area array camera. 8 . 8. The cerebrovascular imaging device based on swept-frequency adaptive optics OCT according to claim 1, wherein the control processor comprises a first control processor and a second control processor, and the first control processor The second control processor is respectively electrically connected to the wavefront sensor and the deformable mirror, and the second control processor is electrically connected to the first scanning mirror, the second scanning mirror and the detector, respectively. 9 . The cerebral vascular imaging device based on swept-frequency adaptive optics OCT according to claim 1 , wherein the center wavelength of the swept-frequency light source is 1040-1310 nm, the scanning rate is 50-100 KHZ, and the coherence length is 10 . -15mm.

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