阅读说明：本技术 一种用于光学相干层析成像的集成参考臂 (Integrated reference arm for optical coherence tomography ) 是由 马欢 王社锋 许涛 黄超 于 2020-05-13 设计创作，主要内容包括：本发明涉及一种用于光学相干层析成像的集成参考臂,包括光纤耦合器、偏振调节器和光学延迟器,所述光纤耦合器的一个端口连接的光纤缠绕在偏振调节器至少一圈后连接到光学延迟器,本发明中光纤耦合器的参考臂端连接的延迟光纤与光学延迟器连接来延长光线行程,从而达到好的耦合干涉效果,还在中间通过偏振调节器改变光纤内部应力,进而改变光线的折射状态,从而对光线进行偏振控制。(The invention relates to an integrated reference arm for optical coherence tomography, which comprises an optical fiber coupler, a polarization regulator and an optical retarder, wherein an optical fiber connected with one port of the optical fiber coupler is wound around the polarization regulator for at least one circle and then is connected to the optical retarder, and a delay optical fiber connected with the reference arm end of the optical fiber coupler is connected with the optical retarder to prolong the light stroke, so that a good coupling interference effect is achieved, and the internal stress of the optical fiber is changed through the polarization regulator in the middle, so that the refraction state of the light is changed, and the polarization control is performed on the light.)

1. An integrated reference arm for optical coherence tomography, characterized by: the optical fiber coupler comprises an optical fiber coupler, a polarization regulator and an optical retarder, wherein an optical fiber connected with one port of the optical fiber coupler is wound on the polarization regulator for at least one circle and then is connected to the optical retarder.

2. The integrated reference arm for optical coherence tomography according to claim 1, wherein: the optical fiber is wound on the front and the back of the polarization regulator and is fixed respectively.

3. The integrated reference arm for optical coherence tomography according to claim 2, wherein: the polarization regulator comprises a polarization adjusting motor and a polarization adjusting rocker arm, the polarization adjusting rocker arm is connected to an output shaft of the polarization adjusting motor through a crank, the optical fibers are wound on the polarization adjusting rocker arm for at least one circle, and fixing seats for fixing the optical fibers are arranged on two sides of the polarization adjusting rocker arm.

4. The integrated reference arm for optical coherence tomography according to claim 3, wherein: the optical retarder comprises a collimating mirror and a delay assembly, the optical fiber is a delay optical fiber and is connected to a collimating optical fiber port of the collimating mirror, the delay assembly comprises a sliding reflection pyramid and a fixed reflection pyramid, the sliding reflection pyramid is installed on a sliding block which slides along a linear sliding rail, a light beam outlet of the collimating mirror faces the sliding reflection pyramid, the fixed reflection pyramid is installed between the sliding reflection pyramid and the collimating mirror and is close to the collimating mirror, the distance between the central line of the fixed reflection pyramid and the central line of the sliding reflection pyramid is equal to the distance between the central line of the fixed reflection pyramid and the central line of the collimating mirror, and the central line of the fixed reflection pyramid, the central line of the sliding reflection pyramid and the central line of the collimating mirror are located on the same plane.

5. The integrated reference arm for optical coherence tomography according to claim 4, wherein: the slider is fixedly connected with an adjusting nut of the screw-nut pair, and an adjusting screw of the screw-nut pair is connected with an output shaft of the optical delay motor.

6. The integrated reference arm for optical coherence tomography according to claim 5, wherein: the integrated reference arm further comprises a variable optical attenuator, the variable optical attenuator comprises an attenuation motor and an attenuation sheet, the attenuation sheet is connected with an output shaft of the attenuation motor, the attenuation sheet is of an eccentrically arranged semicircular structure, and the attenuation sheet is located in front of the collimating mirror.

7. The integrated reference arm for optical coherence tomography according to claim 6, wherein: the circle center of the attenuation sheet and the output shaft of the attenuation motor are eccentrically arranged along the straight edge of the attenuation sheet, and the arc edge of the attenuation sheet is positioned right in front of the collimating mirror.

8. The integrated reference arm for optical coherence tomography according to claim 7, wherein: the integrated reference arm comprises a closed shell, the deviation adjusting motor, the fixed seat, the optical delay motor, the linear slide rail, the attenuation motor, the optical fiber coupler and the collimating mirror are fixed at the bottom of the shell, an optical fiber positioning groove is formed in the bottom of the shell, a driving controller for controlling the deviation adjusting motor, the optical delay motor and the attenuation motor is arranged in the shell, and a power supply interface and a USB interface which are connected with the driving controller are arranged on the side wall of the shell.

9. The integrated reference arm for optical coherence tomography according to claim 8, wherein: the optical fiber coupler is a 2x2 optical fiber coupler, four ports of the optical fiber coupler are respectively an input end, a reference arm end, a sample arm end and an optical signal acquisition end, the delay optical fiber is connected to the reference arm end, the input end is connected with the input optical fiber, the sample arm end and the optical signal acquisition end are respectively connected with the sample optical fiber and the signal acquisition optical fiber, the sample optical fiber and the signal acquisition optical fiber extend out from an optical fiber output port on the side wall of the shell, and the input optical fiber is connected to an optical fiber connector on the side wall of the shell.

10. The integrated reference arm for optical coherence tomography according to claim 9, wherein: and one half of the optical fiber connector is positioned inside the shell and connected with the input optical fiber, and the other half of the optical fiber connector is positioned outside the shell and connected with the light source optical fiber.

Technical Field

The invention relates to the technical field of optical scanning imaging, in particular to an integrated reference arm for optical coherence tomography.

Background

Optical Coherence Tomography (OCT) is a real-time non-invasive three-dimensional imaging technique. Since the advent of OCT technology in 1996, it has been widely applied to various medical fields such as ophthalmology, digestive tract, cardiovascular system, skin, etc., and research on related subjects in laboratories and commercialized products are in a vigorous development stage. The OCT technology is based on the principle of low coherent light interference, and the device core is an interferometer. The interferometer generally has two forms of a free space and an optical fiber, and because the optical fiber has the characteristics of small volume, high stability and the like, the OCT generally adopts a 2x2 optical fiber coupler or other variable optical fiber devices as a core component of the interferometer. The interferometer comprises four ports respectively corresponding to a light source, a sample arm, a reference arm and an optical signal acquisition device, and the parts are added together to form a core component of the OCT.

Early OCT belongs to time-domain OCT, i.e. a broadband optical signal is sampled in a time-sequential space. The mainstream OCT products in the market are frequency domain OCT, that is, optical signals are sampled in a frequency space. Frequency domain OCT is divided into two forms: one is to adopt a broadband light source and a spectrometer as acquisition equipment; the other is to adopt a sweep frequency light source and a high-speed photodiode or a balanced detector as acquisition equipment. These two forms of OCT are otherwise similar, except for the light source and the optical signal acquisition device.

The primary function of the sample arm is to send probe light to the sample being tested and to collect return signals from the sample. The design of the sample arm depends mainly on the form of the sample to be tested. For example, a common ex vivo sample, the corresponding sample arm is typically an optical structure resembling a scanning microscope; for a living body lumen, the sample arm needs to contain a scanning probe like an endoscope; for the fundus, the sample arm design is to ensure that the optical signal passes through the pupil as unimpeded as possible to the fundus, while allowing for anterior ocular segment focus adjustment.

The reference arm of OCT is relatively less variable and the primary function is to provide a stable reference signal to interfere with the signal returned by the sample arm to further acquire the image. The reference arm includes two forms: one type is a free-space reference arm, which is mainly composed of an optical delay line, and generally provides optical path adjustment to match the optical path of the sample arm; the other type is a fiber reference arm, such reference beams completely propagate in the fiber, are slightly influenced by the outside, are relatively stable, but cannot freely adjust the optical path, and the optical path adjusting function is generally placed in the sample arm by adopting the OCT of such reference arm. Compared with an optical fiber reference arm, the free-space reference arm has larger volume, but has the advantages that the optical path is convenient to adjust, the adaptability is strong, and even the same reference arm can be matched with different sample arms to form a complete OCT. In any type of reference arm, the signal directly reflected back is often much higher than the signal strength returned back from the sample arm, and in order to match the two signal strengths, an attenuator is generally added to the reference arm to properly attenuate the reference arm signal. In addition, in consideration of the phenomena of birefringence of the optical fiber and the like, an optical fiber polarization adjusting device is generally required to be added in the OCT optical path, so that the two paths of signals are matched as much as possible in the aspect of polarization, and finally, a good signal is obtained. Therefore, in a broad sense, the OCT reference arm should include not only the optical delay line but also the optical attenuator and the polarization adjuster.

Optical delay line products used for OCT in the current market are generally single-function, need purchase or process optical delay line, optical fiber polarization regulator, adjustable attenuator respectively by oneself and assemble the debugging, use manual regulation to be the main moreover, only be applicable to the building of laboratory platform, development speed is slow, the integration degree of difficulty is big.

Disclosure of Invention

In order to solve the above technical problem, the present invention provides an integrated reference arm for optical coherence tomography.

The technical scheme of the invention is as follows: an integrated reference arm for optical coherence tomography comprises a fiber coupler, a polarization regulator and an optical retarder, wherein a port-connected optical fiber of the fiber coupler is wound around the polarization regulator for at least one circle and then is connected to the optical retarder.

Preferably, the optical fiber is wound around the front and the back of the polarization regulator and fixed respectively.

Preferably, the polarization regulator comprises a polarization adjusting motor and a polarization adjusting rocker arm, the polarization adjusting rocker arm is connected to an output shaft of the polarization adjusting motor through a crank, the optical fiber is wound on the polarization adjusting rocker arm for at least one circle, and fixing seats for fixing the optical fiber are arranged on two sides of the polarization adjusting rocker arm.

Preferably, the optical retarder includes a collimating mirror and a delaying assembly, the optical fiber is a delaying optical fiber and is connected to a collimating optical fiber port of the collimating mirror, the delaying assembly includes a sliding reflection pyramid and a fixed reflection pyramid, the sliding reflection pyramid is installed on a slider sliding along a linear slide rail, a light beam outlet of the collimating mirror faces the sliding reflection pyramid, the fixed reflection pyramid is installed between the sliding reflection pyramid and the collimating mirror and is adjacent to the collimating mirror, a distance between a center line of the fixed reflection pyramid and a center line of the sliding reflection pyramid is equal to a distance between a center line of the fixed reflection pyramid and a center line of the collimating mirror, and the center line of the fixed reflection pyramid, the center line of the sliding reflection pyramid and the center line of the collimating mirror are located on the same plane.

Preferably, the slider is fixedly connected with an adjusting nut of a screw-nut pair, and an adjusting screw of the screw-nut pair is connected with an output shaft of the optical delay motor.

Preferably, the integrated reference arm further comprises a variable optical attenuator, the variable optical attenuator comprises an attenuation motor and an attenuation sheet, the attenuation sheet is connected with an output shaft of the attenuation motor, the attenuation sheet is of an eccentrically arranged semicircular structure, and the attenuation sheet is located in front of the collimating mirror.

Preferably, the circle center of the attenuation sheet and the output shaft of the attenuation motor are eccentrically arranged along the straight edge of the attenuation sheet, and the arc edge of the attenuation sheet is positioned right in front of the collimating mirror.

Preferably, the integrated reference arm comprises a closed shell, the deviation adjusting motor, the fixed seat, the optical delay motor, the linear slide rail, the attenuation motor and the collimating mirror are fixed at the bottom of the shell, an optical fiber positioning groove is formed in the bottom of the shell, a driving controller for controlling the deviation adjusting motor, the optical delay motor and the attenuation motor is arranged in the shell, and a power interface and a USB interface which are connected with the driving controller are arranged on the side wall of the shell.

Preferably, the optical fiber coupler is a 2x2 optical fiber coupler, four ports of the optical fiber coupler are respectively an input end, a reference arm end, a sample arm end and an optical signal acquisition end, the delay optical fiber is connected to the reference arm end, the input end is connected to an input optical fiber, the sample arm end and the optical signal acquisition end are respectively connected to a sample optical fiber and a signal acquisition optical fiber, the sample optical fiber and the signal acquisition optical fiber extend from an optical fiber output port on a side wall of the housing, and the input optical fiber is connected to an optical fiber connector on the side wall of the housing.

Preferably, one half of the optical fiber connector is positioned inside the shell and connected with the input optical fiber, and the other half of the optical fiber connector is positioned outside the shell and connected with the light source optical fiber.

The invention has the beneficial effects that:

the delay optical fiber connected with the reference arm end of the optical fiber coupler is connected with the optical retarder to prolong the light stroke, so that a good coupling interference effect is achieved, the internal stress of the optical fiber is changed through the polarization regulator in the middle, the refraction state of the light is further changed, and the polarization control is performed on the light.

The invention also provides a variable optical attenuator which can make the collimated light beam emitted by the collimating mirror pass through the outer circumference of the attenuation sheet and make part of the light beam be shielded by the outer circumference of the attenuation sheet, the attenuation sheet is in an eccentrically arranged semicircular structure, and the shielded area of the light beam of the attenuation sheet can be changed through the rotation of the attenuation sheet, thereby achieving the purpose of continuously adjusting the optical attenuation.

The integrated reference arm electric control polarization regulator, the adjustable optical attenuator and the optical delayer adjust the light path of the delay optical fiber in the integrated reference arm in real time to enable the light path to correspond to the light path of the sample optical fiber, so that light returned by the delay optical fiber and the sample optical fiber is interfered in the optical fiber coupler, and the stability of the output light path of the signal acquisition optical fiber is improved.

The integrated reference arm combines the polarization regulator, the variable optical attenuator and the optical retarder by using simple and ingenious design, and has high integration level and simple maintenance.

The invention forms a closed loop system by connecting the driving controller and each interface with the upper computer and other OCT components, can compensate the drift change of the optical signal in the system in real time, and improves the stability and the usability of the OCT system.

Drawings

FIG. 1 is a schematic top view of the internal structure of the present invention;

FIG. 2 is a schematic perspective view of the housing of the present invention;

FIG. 3 is a schematic view of the structure of an attenuator;

FIG. 4 is a control schematic block diagram of a drive controller;

FIG. 5 is a circuit schematic of the drive controller;

FIG. 6 is a schematic diagram of a stepper motor drive circuit in the drive controller;

FIG. 7 is a schematic circuit diagram of a USB adapter chip in the drive controller;

FIG. 8 is a schematic diagram of a power supply circuit in the drive controller;

FIG. 9 is a functional block diagram of the present invention in use in OCT;

in the figure: 1-a drive controller; 2-a bias-adjusting motor; 3-offset rocker arm; 4, fixing the base; 5-an optical fiber coupler; 6-optical fiber positioning groove; 8-damping motor; 9-collimating the fiber port; 10-a collimating mirror; 11-optical delay motor; 12-a photoelectric switch; 13-linear slide rail; 14-adjusting the nut; 15-sliding reflective pyramid; 16-a slide block; 17-an attenuation sheet; 18-fixed reflective pyramid; 20-power interface; 21-USB interface; 22-a housing; 23-optical fiber joint; 24-fiber output port.

Detailed Description

Detailed description of the invention with reference to fig. 1-9:

the technical scheme of the invention is as follows: