Interference arm module and optical coherence tomography system

Abstract

The embodiment of the invention discloses an interference arm module and an optical coherence tomography system. The interference arm module comprises an optical fiber device assembly and a reference arm assembly; the optical fiber device assembly comprises a plurality of optical fiber devices which are connected to form an interference structure; the interference arm module comprises a first port, a second port, a third port and a fourth port, the first port receives light beams of the light source, and the second port outputs part of the light beams to a to-be-tested sample and receives light beams returned by the to-be-tested sample; part of the light beam enters the reference arm assembly, the reference arm assembly comprises a retroreflection device, and the light beam entering the reference arm assembly is reflected by the retroreflection device, then enters the interference structure again for interference and is output through the third port and the fourth port; the reference arm assembly changes the arm length of the reference arm by adjusting the distance between the retroreflection device and one end of the optical fiber device assembly. The interference arm module provided by the embodiment of the invention has the advantages of compact size, few optical elements, simple spatial light path structure, low debugging difficulty, low cost and the like.

Description

Technical Field

[0001] The present invention relates to the technical field of medical imaging, and in particular to an interference arm module and an optical coherence tomography system. Background Art

[0002] Optical Coherence Tomography (OCT) is a non-invasive high-resolution tomography technology based on low-coherence optical interferometry, which has been widely used in the fields of in vivo biological tissue imaging, sub-surface non-destructive testing, etc. In the OCT system, the Michelson interferometer is the basic component of the OCT optical path structure, among which the reference arm is an indispensable component for realizing coherent interference. Optical elements such as reflectors and prisms are often used in conjunction with mechanical structures to realize flexible adjustment of the length of the reference arm to match the interference with the sample arm.

[0003] The all-fiber interferometer arm module has the advantages of small size, high stability and high consistency, and is widely used in commercial swept-domain OCT imaging systems; the all-fiber interferometer module often uses a fiber delay line as a reference arm. The traditional fiber delay line is composed of two fiber collimators and a refractive element (optical elements such as reflectors and prisms that can deflect light 180 degrees): two fiber collimators are at the same end, and the light beam is input from one end of the optical fiber into the fiber collimator so that the light beam is transmitted in the air to the refractive element. The refractive element deflects the light 180 degrees and couples the light beam into the other fiber collimator and enters the pigtail; when the refractive element moves along the optical axis, the optical path changes, and the light beam is received by another fiber collimator into the fiber pigtail, and a reflective film is coated on the end of the pigtail so that the light can be reflected back along the original path to construct a reference arm.

[0004] However, the traditional optical fiber delay line needs to ensure that the two optical fiber collimators are absolutely parallel to the refractive element so that the optical path and the actual displacement of the refractive element correspond linearly. Therefore, due to the limitations of processing accuracy and the coupling efficiency of the optical fiber collimator, the reference arm of this optical fiber delay line structure often has problems such as unstable return light power and mismatch between physical length and actual optical path during movement, which affects the quality of interferometric imaging. In addition, the traditional delay line needs to add a reflective film-coated reflector to the delay line pigtail. This method of achieving reflector has a large structure size and high cost, and is prone to multi-layer reflection between films, resulting in the generation of artifacts. Summary of the invention

[0005] The embodiment of the present invention provides an interferometer arm module and an optical coherence tomography system. The arm length of the reference arm of the interferometer arm module is adjustable and has the advantages of compact size, few optical elements, simple spatial optical path structure, low debugging difficulty and low cost.

[0006] According to one aspect of the present invention, there is provided an interferometer arm module, comprising an optical fiber device assembly and a reference arm assembly;

[0007] The optical fiber device assembly includes a plurality of optical fiber devices, and the plurality of optical fiber devices are connected to form an interference structure;

[0008] The interference arm module comprises a first port, a second port, a third port and a fourth port, wherein the first port is used to receive a light beam output by a light source, a part of the light beam output by the light source is output to the sample to be tested from the second port after passing through a part of the optical fiber device, and a light beam returned by the sample to be tested is incident into the interference structure from the second port;

[0009] The optical fiber device assembly is connected to the reference arm assembly, and part of the light beam output by the light source is incident on the reference arm assembly after passing through part of the optical fiber device. The reference arm assembly includes a retroreflective device, and the light beam incident on the reference arm assembly is reflected by the retroreflective device and is incident on the interference structure again to interfere with the light beam returned by the sample to be tested, and is output through the third port and the fourth port;

[0010] The reference arm assembly changes the arm length of the reference arm by adjusting the position of the retroreflective device.

[0011] Optionally, the reference arm assembly further includes a fiber collimator, a slide rail and a drive circuit, and the extension direction of the slide rail is parallel to the optical axis direction of the fiber collimator;

[0012] The fiber collimator is fixed to the first end of the slide rail, the retroreflective device is arranged on the slide rail, and the driving circuit is used to change the distance between the retroreflective device and the fiber collimator to change the arm length of the reference arm.

[0013] Optionally, the optical fiber collimator includes a spherical lens collimator, an aspherical lens collimator, a parabolic reflection collimator or an achromatic collimator.

[0014] Optionally, the reference arm assembly further includes a first shell, and the optical fiber collimator, the slide rail, the retroreflective device and the driving circuit are all packaged in the first shell.

[0015] Optionally, the retroreflective device comprises a pyramid.

[0016] Optionally, the plurality of optical fiber devices include a first optical fiber coupler, a second optical fiber coupler, a first optical fiber circulator, and a second optical fiber circulator, wherein the first optical fiber coupler is a 1×2 optical fiber coupler, and the second optical fiber coupler is a 2×2 optical fiber coupler;

[0017] The input end of the first fiber coupler is connected to a light source, the first output end of the first fiber coupler is connected to the first end of the first fiber circulator, the second output end of the first fiber coupler is connected to the first end of the second fiber circulator, the second end of the first fiber circulator is connected to the reference arm assembly, the third end of the first fiber circulator is connected to the first input end of the second fiber coupler, the third end of the second fiber circulator is connected to the second input end of the second fiber coupler, and the two output ends of the second fiber coupler output interference light signals.

[0018] Optionally, the optical path length between the first output end of the first optical fiber coupler and the first end of the first optical fiber circulator is L1, the optical path length between the second output end of the first optical fiber coupler and the first end of the second optical fiber circulator is L2, the optical path length between the second end of the first optical fiber circulator and the reference arm assembly is L3, the optical path length inside the reference arm assembly is L4, the optical path length between the second end of the second optical fiber circulator and the second port is L5, the optical path length between the third end of the second optical fiber circulator and the second input end of the second optical fiber coupler is L6, the optical path length between the first optical fiber circulator and the first input end of the second optical fiber coupler is L7, the optical path length between the first output end of the second optical fiber coupler and the corresponding signal output end is L8, the optical path length between the second output end of the second optical fiber coupler and the corresponding signal output end is L9, and the optical path length between the second port and the sample to be measured is L10;

[0019] Among them, L1=L2, L3=L5, L6=L7, L8=L9, and the optical path difference between L4 and L10 is less than or equal to the coherence length of the light in the interference arm module.

[0020] Optionally, it further includes a second shell, one side of which includes a first optical fiber connection port, a second optical fiber connection port, a third optical fiber connection port, and a fourth optical fiber connection port corresponding to the first port, the second port, the third port, and the fourth port, respectively;

[0021] The optical fiber device assembly and the reference arm assembly are both encapsulated in the second shell, the input end of the first optical fiber coupler is connected to the first optical fiber connection port, the second end of the second optical fiber circulator is connected to the second optical fiber connection port, and the two output ends of the second optical fiber coupler are respectively connected to the third optical fiber connection port and the fourth optical fiber connection port.

[0022] According to another aspect of the present invention, an optical coherence tomography system is provided for realizing three-dimensional imaging of a sample to be measured, wherein the optical coherence tomography system comprises a swept-frequency light source, a balanced detector and the above-mentioned interferometer arm module;

[0023] The output light beam of the frequency-sweeping light source is received by the first port of the interferometer arm module, and the interference signals output by the third port and the fourth port of the interferometer arm module are received by the balanced detector.

[0024] Optionally, the optical fiber device assembly includes a first optical fiber coupler, a second optical fiber coupler, a first optical fiber circulator, and a second optical fiber circulator;

[0025] The output beam of the frequency-sweeping light source is transmitted to the input end of the first optical fiber coupler, and is split into a first split beam and a second split beam by the first optical fiber coupler;

[0026] The first split light beam is transmitted to the first optical fiber circulator via the first output end of the first optical fiber coupler, and the light beam reaches the reference arm assembly via the second end of the first optical fiber circulator. The reference arm assembly adjusts the arm length of the reference arm, and the light beam reaches the retroreflective device via the optical path channel of the reference arm assembly. The retroreflective device retroreflects the light beam along the original path to the first optical fiber circulator, and reaches the first input end of the second optical fiber coupler via the third end of the first optical fiber circulator.

[0027] The second split light beam is transmitted to the second optical fiber circulator via the second output end of the first optical fiber coupler, and the light beam is output to the sample to be tested via the second end of the second optical fiber circulator, and the backscattered light of the sample to be tested is reflected back into the second optical fiber circulator, and reaches the second input end of the second optical fiber coupler via the third end of the second optical fiber circulator;

[0028] The second optical fiber coupler combines the two light beams input from the first input end and the second input end and then divides them into two interference light beams according to a preset ratio. The two interference light beams are respectively transmitted to the balanced detector through the two output ends of the second optical fiber coupler, so that the interference spectrum signal is received, thereby realizing three-dimensional imaging of the sample to be tested.

[0029] The interference arm module provided by the embodiment of the present invention includes an optical fiber device assembly and a reference arm assembly; the optical fiber device assembly includes a plurality of optical fiber devices, and the plurality of optical fiber devices are connected to form an interference structure; the interference arm module includes a first port, a second port, a third port and a fourth port, and receives a light beam output by a light source through the first port, and a part of the light beam output by the light source is output to a sample to be tested through the second port after passing through a part of the optical fiber devices, and a light beam returned by the sample to be tested is incident into the interference structure through the second port; the optical fiber device assembly is connected to the reference arm assembly, and a part of the light beam output by the light source is incident into the reference arm assembly after passing through a part of the optical fiber devices, and the reference arm assembly includes a retroreflective device, and the light beam incident into the retroreflective device is reflected by the retroreflective device and is incident into the interference structure again to interfere with the light beam returned by the sample to be tested, and is output through the third port and the fourth port; the reference arm assembly changes the arm length of the reference arm by adjusting the position of the retroreflective device. The interference structure is formed by connecting all-fiber devices, which has compact size, few optical components, simple spatial optical path structure, and no debugging difficulty; interference can be achieved by only connecting external light sources, detectors and probes; the single-channel optical fiber input and output at the same end of the optical device assembly ensures the collimation of the optical path, and when the physical length of the reference arm changes, the optical path changes in 1:1 correspondence, which is convenient for interference debugging; when the optical path difference changes, the optical power is stable and the fiber coupling efficiency is good, with low attenuation; and it avoids the use of devices with reflective film coated on the end of the pigtail, so that the interference module is small in size and low in cost.

[0030] It should be understood that the contents described in this section are not intended to identify the key or important features of the embodiments of the present invention, nor are they intended to limit the scope of the present invention. Other features of the present invention will become easily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0032] Figure 1 A schematic structural diagram of an interference arm module provided by an embodiment of the present invention;

[0033] Figure 2 A schematic structural diagram of a reference arm assembly provided by an embodiment of the present invention;

[0034] Figure 3 A schematic diagram of an optical path of a reference arm assembly provided by an embodiment of the present invention;

[0035] Figure 4 A schematic diagram of a packaging structure of a reference arm assembly provided by an embodiment of the present invention;

[0036] Figure 5 A schematic structural diagram of another interference arm module provided by an embodiment of the present invention;

[0037] Figure 6 A schematic diagram of the internal packaging structure of an interference arm module provided by an embodiment of the present invention;

[0038] Figure 7 for Figure 6 The overall structural diagram of the corresponding interference arm module;

[0039] Figure 8 A schematic structural diagram of an optical coherence tomography system provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0040] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0041] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0042] Figure 1 FIG. 1 is a schematic diagram of a structure of an interferometer arm module provided in an embodiment of the present invention. The interferometer arm module can be used in an optical coherence tomography system. Figure 1 The interference arm module includes an optical fiber device assembly 10 and a reference arm assembly 20; the optical fiber device assembly 10 includes a plurality of optical fiber devices, and the plurality of optical fiber devices are connected to form an interference structure; the interference arm module includes a first port 101, a second port 102, a third port 103 and a fourth port 104, and the first port 101 is used to receive a light source ( Figure 1The light beam output by the light source passes through some optical fiber devices and is output from the second port 102 to the sample to be tested (not shown). Figure 1 (not shown), the light beam returned by the sample to be tested is incident on the interference structure through the second port 102; the optical fiber device assembly 10 is connected to the reference arm assembly 20, and part of the light beam output by the light source is incident on the reference arm assembly 20 after passing through part of the optical fiber device, the reference arm assembly 20 includes a retroreflective device 21, and the light beam incident on the reference arm assembly 20 is reflected by the retroreflective device 21, and then interferes with the light beam returned by the sample to be tested in the interference structure, and is output through the third port 103 and the fourth port 104; wherein, the reference arm assembly 20 changes the arm length of the reference arm by adjusting the position of the retroreflective device 21.

[0043] For example, continue to refer to Figure 1 Optionally, the plurality of optical fiber devices include a first optical fiber coupler 11, a second optical fiber coupler 12, a first optical fiber circulator 13, and a second optical fiber circulator 14, wherein the first optical fiber coupler 11 is a 1×2 optical fiber coupler, and the second optical fiber coupler 12 is a 2×2 optical fiber coupler; an input end (i.e., a first port 101) of the first optical fiber coupler 11 is connected to a light source ( Figure 1 The first fiber optic coupler 11 is connected to the first end of the first fiber optic circulator 13, the second output end of the first fiber optic coupler 11 is connected to the first end of the second fiber optic circulator 14, the second end of the first fiber optic circulator 13 is connected to the reference arm assembly 20, the third end of the first fiber optic circulator 11 is connected to the first input end of the second fiber optic coupler 12, the third end of the second fiber optic circulator 14 is connected to the second input end of the second fiber optic coupler 12, and the two output ends of the second fiber optic coupler 12 output interference light signals.

[0044] During specific implementation, each optical device needs to meet the interference length requirement when connected. In order to meet the length requirement in the actual structure, a fiber jumper may be required, which can be designed according to actual conditions during specific implementation. The first fiber coupler 11 is a 1×2 fiber coupler, that is, a one-to-two fiber coupler, which is used to split the output beam of the light source into two output ends according to a certain ratio (such as 90 / 10, 99 / 1, 50 / 50, etc., which can be designed according to actual needs) and transmit it to the first fiber circulator 13 and the second fiber circulator 14, wherein part of the beam passes through the second fiber circulator 14 and is output from the second port 102 to the sample to be tested, and the beam (signal light) returned by the sample to be tested passes through the second fiber circulator 14 and is transmitted to the second fiber coupler. 12; another part of the light beam is output to the reference arm assembly 20 after passing through the first fiber circulator 13. The reference arm assembly 20 can adjust the arm length of the reference arm by translating the retroreflective device 21 according to the actual interference condition. The light beam (reference light) returned by the reference arm assembly 20 is transmitted to the second fiber coupler 12 after passing through the first fiber circulator 13. The signal light and the reference light are combined and interfered in the second fiber coupler 12. The interference light signal is output from the two output ends (the third port 103 and the second port 104) of the second fiber coupler 12. The second fiber coupler 12 can be a fiber coupler with a 50 / 50 splitting ratio.

[0045] The technical solution of the embodiment of the present invention forms an interference structure by connecting all-fiber devices, which has compact size, few optical elements, simple spatial optical path structure, and no debugging difficulty; interference can be achieved by only connecting an external light source, a detector and a probe; the single-channel optical fiber input and output at the same end of the optical device component ensures the collimation of the optical path, and when the physical length of the reference arm changes, the optical path changes in 1:1 correspondence, which is convenient for debugging interference; when the optical path difference changes, the optical power is stable and the optical fiber coupling efficiency is good, with low attenuation; and it avoids using devices with reflective film coated on the end of the pigtail, so that the interference module is small in size and low in cost.

[0046] Figure 2 A schematic diagram of the structure of a reference arm assembly provided by an embodiment of the present invention, referring to Figure 2 Optionally, the reference arm assembly 20 also includes a fiber collimator 22, a slide rail 23 and a drive circuit 24, wherein the extension direction of the slide rail 23 is parallel to the optical axis direction of the fiber collimator 22; the fiber collimator 22 is fixed to the first end of the slide rail 23, the retroreflective device 21 is arranged on the slide rail 23, and the drive circuit 24 is used to change the distance between the retroreflective device 21 and the fiber collimator 22 to change the arm length of the reference arm.

[0047] In a specific implementation, the reference arm assembly 20 may further include a fiber collimator fixing mechanical structure, and the driving circuit 24 may include a driving circuit board and a driving motor, and the driving motor drives the retroreflective device 21 to reciprocate on the slide rail 23. Exemplarily, Figure 3A schematic diagram of an optical path of a reference arm assembly provided in an embodiment of the present invention, referring to Figure 3 , the fiber collimator 22 is composed of a fiber ferrule 221 and a collimating lens 222 for collimation. In other embodiments, the fiber collimator 22 may include a spherical lens collimator, an aspherical lens collimator, a parabolic reflection collimator or an achromatic collimator, which may be selected according to actual conditions during implementation. The pigtail 30 is used for outputting and receiving the reference beam. The pigtail 30 outputs the reference beam to the fiber collimator 22, which can convert the reference light transmitted by the fiber into air transmission; the slide rail ( Figure 3 (not shown) is a mechanical device that enables the retroreflective device 21 to move back and forth along the optical axis direction of the optical fiber collimator 22; the retroreflective device 21 is an optical element that can return the light path to its original path. In this embodiment, optionally, the retroreflective device 21 includes a pyramid, Figure 3 The corner cone is taken as an example, which is not a limitation of the embodiments of the present invention. The corner cone is also called a corner cone prism or a total internal reflection (TIR) ​​retroreflector, a corner prism or a three-sided prism; the retroreflective device 21 can reflect the image or light beam 180° relative to the original direction. This type of prism achieves retroreflection through total internal reflection or mirror reflection. If the incident light incident point is at the center of the prism, the light returns along the original path. The driving circuit includes a driving motor, a driving circuit board, and a driving circuit module interface for connecting an external power supply and serial communication, which can drive the retroreflective device 21 to move along the optical axis on the slide rail 23 to achieve adjustable arm length of the reference arm.

[0048] Figure 4 A schematic diagram of a packaging structure of a reference arm assembly provided by an embodiment of the present invention, referring to Figure 4 Optionally, the reference arm assembly further includes a first shell 100 , and the optical fiber collimator, the slide rail, the retroreflective device and the driving circuit are all packaged in the first shell 100 .

[0049] Among them, the fiber collimator is glued to the inner side of the first shell 100, and one end is connected to the external input fiber; the driving circuit and the fixed mechanical structure are fixed to the bottom plate of the first shell 100 by bottom screws. The driving circuit and the fixed mechanical structure are fixed at both ends of the slide rail respectively; the pyramid is glued to the center of the customized mounting seat, and the slide rail is driven by the motor to achieve reciprocating motion. The drive module interface is installed on the outside of the first shell 100, and is connected to the drive circuit inside to achieve the transmission of electrical signals. The other side of the first shell 100 can also include a pigtail with a connector, where the connector can be an APC interface.

[0050] Figure 5 A schematic diagram of another interference arm module provided in an embodiment of the present invention, referring to Figure 5Optionally, the optical path length between the first output end of the first optical fiber coupler 11 and the first end of the first optical fiber circulator 13 is L1, the optical path length between the second output end of the first optical fiber coupler 11 and the first end of the second optical fiber circulator 14 is L2, the optical path length between the second end of the first optical fiber circulator 13 and the reference arm assembly 20 is L3, the optical path length inside the reference arm assembly 20 is L4, the optical path length between the second end of the second optical fiber circulator 14 and the second port 102 is L5, and the optical path length between the third end of the second optical fiber circulator 14 and the second input end of the second optical fiber coupler 12 is L6. The optical path length is L6, the optical path length between the first fiber circulator 13 and the first input end of the second fiber coupler 12 is L7, the optical path length between the first output end of the second fiber coupler 12 and the corresponding signal output end is L8, the optical path length between the second output end of the second fiber coupler 12 and the corresponding signal output end is L9, and the optical path length between the second port 102 and the sample 40 to be tested is L10; wherein, L1=L2, L3=L5, L6=L7, L8=L9, and the optical path difference between L4 and L10 is less than or equal to the coherence length of the light in the interference arm module.

[0051] By satisfying the above conditions, it can be ensured that the signal light and the reference light meet the interference conditions. Specifically, in a certain embodiment, the optical path of L4 includes the inherent optical path length L11 of the reference arm assembly 20 and the actual optical path length L12 of the variable arm length part, that is, L4=L11+L12, and the length range of the optical path change of the variable arm length part can be the optical path length of 0 to 21 cm in the air; ensuring L10=L11+10cm can make the actual optical path length from the output end of the interference arm module to the sample close to the actual optical path of L4.

[0052] Figure 6 A schematic diagram of the internal packaging structure of an interference arm module provided by an embodiment of the present invention, Figure 7 for Figure 6 The overall structure diagram of the corresponding interference arm module is shown in Figure 2. Figure 6 and Figure 7 Optionally, the interference arm module provided in this embodiment further includes a second housing 200, and one side of the second housing 200 includes a first optical fiber connection port 210, a second optical fiber connection port 220, a third optical fiber connection port 230, and a fourth optical fiber connection port 240 corresponding to the first port, the second port, the third port, and the fourth port, respectively; Figure 6 The optical fiber device assembly 10 and the reference arm assembly 20 are both packaged in the second housing 200. The first optical fiber coupler ( Figure 6The input end of the second optical fiber circulator (specific structure not shown) is connected to the first optical fiber connection port 210, the second end of the second optical fiber circulator is connected to the second optical fiber connection port 220, and the two output ends of the second optical fiber coupler are connected to the third optical fiber connection port 230 and the fourth optical fiber connection port 240 respectively.

[0053] The interference arm module also includes a driving circuit module 250 and a driving module interface 260, and the optical fiber connection port can be FC / SC / LC / SMA, which can be designed according to actual needs during specific implementation.

[0054] Figure 8 A schematic diagram of the structure of an optical coherence tomography system provided in an embodiment of the present invention is used to realize three-dimensional imaging of a sample 40 to be measured, referring to Figure 8 The optical coherence tomography system includes a swept-frequency light source 1, a balanced detector 2, and an interferometer arm module 3 provided in the above embodiment; the output light beam of the swept-frequency light source 1 is received by the first port of the interferometer arm module 3, and the interference signals output by the third port and the fourth port of the interferometer arm module 3 are received by the balanced detector 2.

[0055] Optional, continue to refer to Figure 8 The working principle of the optical coherence tomography system provided in this embodiment is as follows: the optical fiber device assembly includes a first optical fiber coupler 11, a second optical fiber coupler 12, a first optical fiber circulator 13, and a second optical fiber circulator 14; the connection relationship thereof refers to the above embodiment and will not be described in detail here. The output light beam of the swept frequency light source 1 is transmitted to the input end of the first optical fiber coupler 11, and is divided into a first split light beam and a second split light beam by the first optical fiber coupler 11; the first split light beam is transmitted to the first optical fiber circulator 13 via the first output end of the first optical fiber coupler 11, and the light beam reaches the reference arm assembly 20 via the second end of the first optical fiber circulator 13. The reference arm assembly 20 adjusts the arm length of the reference arm, and the light beam reaches the reflective device 21 via the optical path channel of the reference arm assembly 20. The reflective device 21 reflects the light beam back along the original path to the first optical fiber circulator 13, and reaches the first input end of the second optical fiber coupler 12 via the third end of the first optical fiber circulator 13; the second split light beam is transmitted to the first optical fiber circulator 13 via the first output end of the first optical fiber coupler 11, and the light beam reaches the reference arm assembly 20 via the second end of the first optical fiber circulator 13. The light beam is transmitted from the second output end of the first optical fiber coupler 11 to the second optical fiber circulator 14, and is output to the sample 40 to be tested through the second end of the second optical fiber circulator 14. The backscattered light of the sample 40 to be tested is reflected back into the second optical fiber circulator 14, and reaches the second input end of the second optical fiber coupler 12 through the third end of the second optical fiber circulator 14; the second optical fiber coupler 12 combines and interferes the two light beams input from the first input end and the second input end, and then divides them into two interference light beams according to a preset ratio. The two interference light beams are respectively transmitted to the balanced detector 2 through the two output ends of the second optical fiber coupler 12, so that the interference spectrum signal is received, thereby realizing three-dimensional imaging of the sample 40 to be tested.

[0056] The above specific implementations do not constitute a limitation on the protection scope of the present invention. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modification, equivalent substitution and improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. An interference arm module, characterized in that: including a fiber optic device assembly and a reference arm assembly; The optical fiber device assembly includes a plurality of optical fiber devices, and the plurality of optical fiber devices are connected to form an interference structure; The interference arm module comprises a first port, a second port, a third port and a fourth port, wherein the first port is used to receive a light beam output by a light source, a part of the light beam output by the light source is output to the sample to be tested from the second port after passing through a part of the optical fiber device, and a light beam returned by the sample to be tested is incident into the interference structure from the second port; The optical fiber device assembly is connected to the reference arm assembly, a portion of the light beam output by the light source is incident on the reference arm assembly after passing through a portion of the optical fiber device, the reference arm assembly includes a retroreflective device, the light beam incident on the reference arm assembly is reflected by the retroreflective device, and is incident on the interference structure again to interfere with the light beam returned by the sample to be tested, and is output through the third port and the fourth port; The reference arm assembly changes the arm length of the reference arm by adjusting the position of the retroreflective device.

2. The interference arm module according to claim 1, characterized in that: The reference arm assembly further comprises a fiber collimator, a slide rail and a driving circuit, wherein the extending direction of the slide rail is parallel to the optical axis direction of the fiber collimator; The fiber collimator is fixed to the first end of the slide rail, the retroreflective device is arranged on the slide rail, and the driving circuit is used to change the distance between the retroreflective device and the fiber collimator to change the arm length of the reference arm.

3. The interference arm module according to claim 2, characterized in that: The optical fiber collimator includes a spherical lens collimator, an aspherical lens collimator, a parabolic reflection collimator or an achromatic collimator.

4. The interference arm module according to claim 2, characterized in that: The reference arm assembly further includes a first shell, in which the optical fiber collimator, the slide rail, the retroreflective device and the driving circuit are all packaged.

5. The interference arm module according to claim 1, characterized in that: The retroreflective element includes a pyramid.

6. The interference arm module according to claim 1, characterized in that: The plurality of optical fiber devices include a first optical fiber coupler, a second optical fiber coupler, a first optical fiber circulator, and a second optical fiber circulator, wherein the first optical fiber coupler is a 1×2 optical fiber coupler, and the second optical fiber coupler is a 2×2 optical fiber coupler; The input end of the first fiber coupler is connected to a light source, the first output end of the first fiber coupler is connected to the first end of the first fiber circulator, the second output end of the first fiber coupler is connected to the first end of the second fiber circulator, the second end of the first fiber circulator is connected to the reference arm assembly, the third end of the first fiber circulator is connected to the first input end of the second fiber coupler, the third end of the second fiber circulator is connected to the second input end of the second fiber coupler, and the two output ends of the second fiber coupler output interference light signals.

7. The interference arm module according to claim 6, characterized in that: The optical path length between the first output end of the first optical fiber coupler and the first end of the first optical fiber circulator is L1, the optical path length between the second output end of the first optical fiber coupler and the first end of the second optical fiber circulator is L2, the optical path length between the second end of the first optical fiber circulator and the reference arm assembly is L3, the optical path length inside the reference arm assembly is L4, the optical path length between the second end of the second optical fiber circulator and the second port is L5, the optical path length between the third end of the second optical fiber circulator and the second input end of the second optical fiber coupler is L6, the optical path length between the first optical fiber circulator and the first input end of the second optical fiber coupler is L7, the optical path length between the first output end of the second optical fiber coupler and the corresponding signal output end is L8, the optical path length between the second output end of the second optical fiber coupler and the corresponding signal output end is L9, and the optical path length between the second port and the sample to be measured is L10; Among them, L1=L2, L3=L5, L6=L7, L8=L9, and the optical path difference between L4 and L10 is less than or equal to the coherence length of the light in the interference arm module.

8. The interference arm module according to claim 6, characterized in that: Also includes a second housing, wherein one side of the second housing includes a first optical fiber connection port, a second optical fiber connection port, a third optical fiber connection port, and a fourth optical fiber connection port corresponding to the first port, the second port, the third port, and the fourth port, respectively; The optical fiber device assembly and the reference arm assembly are both encapsulated in the second shell, the input end of the first optical fiber coupler is connected to the first optical fiber connection port, the second end of the second optical fiber circulator is connected to the second optical fiber connection port, and the two output ends of the second optical fiber coupler are respectively connected to the third optical fiber connection port and the fourth optical fiber connection port.

9. An optical coherence tomography system, characterized in that: Used to realize three-dimensional imaging of a sample to be measured, the optical coherence tomography system comprises a swept-frequency light source, a balanced detector and an interferometer arm module according to any one of claims 1 to 8; The output light beam of the frequency-sweeping light source is received by the first port of the interferometer arm module, and the interference signals output by the third port and the fourth port of the interferometer arm module are received by the balanced detector.

10. The optical coherence tomography system according to claim 9, characterized in that: The optical fiber device assembly includes a first optical fiber coupler, a second optical fiber coupler, a first optical fiber circulator and a second optical fiber circulator; The output beam of the frequency-sweeping light source is transmitted to the input end of the first optical fiber coupler, and is split into a first split beam and a second split beam by the first optical fiber coupler; The first split light beam is transmitted to the first optical fiber circulator via the first output end of the first optical fiber coupler, and the light beam reaches the reference arm assembly via the second end of the first optical fiber circulator. The reference arm assembly adjusts the arm length of the reference arm, and the light beam reaches the retroreflective device via the optical path channel of the reference arm assembly. The retroreflective device retroreflects the light beam along the original path to the first optical fiber circulator, and reaches the first input end of the second optical fiber coupler via the third end of the first optical fiber circulator. The second split light beam is transmitted to the second optical fiber circulator via the second output end of the first optical fiber coupler, and the light beam is output to the sample to be tested via the second end of the second optical fiber circulator, and the backscattered light of the sample to be tested is reflected back into the second optical fiber circulator, and reaches the second input end of the second optical fiber coupler via the third end of the second optical fiber circulator; The second optical fiber coupler combines the two light beams input from the first input end and the second input end and then divides them into two interference light beams according to a preset ratio. The two interference light beams are respectively transmitted to the balanced detector through the two output ends of the second optical fiber coupler, so that the interference spectrum signal is received, thereby realizing three-dimensional imaging of the sample to be tested.

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