Polarization-independent optical path scanning delay device and method

Abstract

The present invention provides a polarization-independent optical path scanning delay device and method, comprising: an optical circulator, the optical circulator having three ports, external incident light is input and output to the first port of the optical circulator; a polarization beam splitter arranged on the output optical path of the second port of the optical circulator; a 1 / 2 wave plate and a moving optical path folding retroreflector arranged in sequence on the reflected optical path of the polarization beam splitter; the moving optical path folding retroreflector arranged on a linear motion mechanism, the linear motion mechanism drives the moving optical path folding retroreflector to move forward and backward along the direction of the output optical path; a 1 / 4 wave plate and a plane reflector arranged in sequence on the transmission optical path of the polarization beam splitter; a fixed optical path folding retroreflector arranged on the reflected optical path of the moving optical path folding retroreflector. The present invention is used to increase the optical path delay of the output light while moving the same linear motion mechanism distance, and is independent of the polarization direction of the input light.

Description

Technical Field

[0001] The invention relates to the field of optical technology, and in particular to a polarization-independent optical path scanning delay device and method. Background Art

[0002] The optical path scanning delay device generates an adjustable optical path for the light of the input and output modules, thereby generating a corresponding optical transmission delay. This type of device plays an important role in a variety of coherent detection optical systems, such as terahertz time-domain spectroscopy systems, infrared Fourier transform spectrometers, time-domain optical coherence tomography systems, autocorrelator ultrashort pulse measurement, pump detection systems, etc. Among them, the scanning delay range and scanning speed (or equivalent to scanning frequency) are several important technical indicators of the optical path scanning delay device.

[0003] There are many types and implementation methods of optical path scanning delay devices on the market, but there is inevitably a mutual restriction between the scanning delay range and the scanning speed. For example, for long optical path scanning, a one-dimensional stepper motor displacement stage is generally used to load a reflector. Although the scanning optical path delay range can reach more than 1ns, it is limited by the movement speed of the stepper motor and the reciprocating frequency of the optical path scanning is limited; and when using a fast-vibrating voice coil motor module, although the reciprocating frequency can reach tens of Hz, the optical path scanning delay range is limited, generally in the order of 100ps.

[0004] Therefore, it is hoped that the problem of how to balance the scanning delay range and the scanning speed to achieve fast and large optical path scanning delay can be solved. Summary of the invention

[0005] In view of the above-mentioned shortcomings of the prior art, the purpose of the present invention is to provide a polarization-independent optical path scanning delay device and method to solve the problem in the prior art of how to balance the scanning delay range and the scanning speed to achieve fast and large optical path scanning delay.

[0006] To achieve the above-mentioned purpose and other related purposes, the present invention provides a polarization-independent optical path scanning delay device, comprising: an optical circulator, the optical circulator having three ports, external incident light is input and output to the first port of the optical circulator; a polarization beam splitter arranged on the output light path of the second port of the optical circulator; a 1 / 2 wave plate and a moving light path folding retroreflector arranged in sequence on the reflected light path of the polarization beam splitter; the moving light path folding retroreflector is arranged on a linear motion mechanism, and the linear motion mechanism drives the moving light path folding retroreflector to move forward and backward along the direction of the output light path; a 1 / 4 wave plate and a moving light path folding retroreflector arranged in sequence on the transmitted light path of the polarization beam splitter. A plate and a plane reflecting mirror; a fixed light path folding retroreflector arranged on the reflecting light path of the moving light path folding retroreflector, so that the fixed light path folding retroreflector can reflect light back to the moving light path folding retroreflector or the reflecting surface of the polarization beam splitter, so that the polarization beam splitter can reflect the light reflected from the fixed light path folding retroreflector to the 1 / 4 wave plate or transmit it to the 1 / 2 wave plate; so that the light reflected back to the reflecting surface of the polarization beam splitter via the plane reflecting mirror is reflected via the reflecting surface to the fixed light path folding retroreflector or is transmitted from the reflecting surface to the second port of the optical circulator, and is output via the third port of the optical circulator.

[0007] In one embodiment of the present invention, an optical coupling component is further included to allow external incident light to be input or output to the first port of the optical circulator through the optical coupling component. The optical coupling component is an optical fiber, a fiber collimator, or a fiber coupler.

[0008] In one embodiment of the present invention, the center heights of the optical paths of the optical coupling component, the optical circulator, the polarization beam splitter, the 1 / 2 wave plate, the moving optical path folding retroreflector, the 1 / 4 wave plate, the plane reflector and the fixed optical path folding retroreflector are located in the same horizontal plane.

[0009] In one embodiment of the present invention, the linear motion mechanism includes: a voice coil motor and a stepper motor.

[0010] In one embodiment of the present invention, the polarization beam splitter is a polarization cube beam splitter.

[0011] In one embodiment of the present invention, the moving light path folding retroreflector is any one of the following: a hollow retroreflector, a retroreflective prism, and a double-piece reflector.

[0012] In one embodiment of the present invention, the fixed light path folding retroreflector is any one of the following: a hollow retroreflector, a retroreflective prism, or a double-piece reflector.

[0013] In one embodiment of the present invention, the optical axis direction of the half wave plate is located in the direction of the bisector of the angle between the s-polarization direction and the p-polarization direction of the polarized light output by the polarization beam splitter.

[0014] In one embodiment of the present invention, the optical axis direction of the quarter wave plate is located in the direction of the bisector of the angle between the s-polarization direction and the p-polarization direction of the polarized light output by the polarization beam splitter.

[0015] To achieve the above-mentioned purpose, the present invention also provides an optical path scanning extension method, comprising the following steps: setting an optical circulator, the optical circulator having three ports, and the external incident light is input and output to the first port of the optical circulator; setting a polarization beam splitter on the output light path of the second port of the optical circulator; sequentially setting a 1 / 2 wave plate and a moving light path folding retroreflector on the reflected light path of the polarization beam splitter; setting the moving light path folding retroreflector on a linear motion mechanism, so that the linear motion mechanism drives the moving light path folding retroreflector to move forward and backward along the direction of the output light path; sequentially setting a 1 / 4 wave plate and a moving light path folding retroreflector on the transmitted light path of the polarization beam splitter. A plane reflecting mirror; a fixed light path folding retroreflector is arranged on the reflecting light path of the moving light path folding retroreflector, so that the fixed light path folding retroreflector can reflect light back to the moving light path folding retroreflector or the reflecting surface of the polarization beam splitter, so that the polarization beam splitter can reflect the light reflected from the fixed light path folding retroreflector to the 1 / 4 wave plate or transmit it to the 1 / 2 wave plate; so that the light reflected back to the reflecting surface of the polarization beam splitter via the plane reflecting mirror is reflected via the reflecting surface to the fixed light path folding retroreflector or is transmitted from the reflecting surface to the second port of the optical circulator, and is output via the third port of the optical circulator.

[0016] As described above, the polarization-independent optical path scanning delay device and method of the present invention have the following beneficial effects: the optical path of the output light is doubled while moving the same linear motion mechanism distance. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic structural diagram of a conventional linear motion device of the present invention in one embodiment;

[0018] Figure 2 It is a schematic structural diagram of a polarization-independent optical path scanning delay device in one embodiment of the present invention;

[0019] Figure 3 It is a schematic structural diagram of a polarization beam splitter of the present invention in one embodiment;

[0020] Figure 4 It is a schematic structural diagram of a quarter wave plate and a plane reflector in one embodiment of a polarization-independent optical path scanning delay device of the present invention;

[0021] Figure 5 It is a schematic diagram showing the optical path structure of p-polarization in a polarization-independent optical path scanning delay device of the present invention in one embodiment;

[0022] Figure 6 It is a schematic diagram showing the optical path structure of s-polarization in one embodiment of a polarization-independent optical path scanning delay device of the present invention;

[0023] Figure 7 It is a schematic flow chart of a polarization-independent optical path scanning delay method in one embodiment of the present invention.

[0024] Component number description

[0025] 11 Optical coupling components

[0026] 12 Optical Path Folding Retroreflector

[0027] 13 Linear motion mechanism

[0028] 14 Output optical coupling components

[0029] 201 Optical coupling components

[0030] 202 Optical Circulator

[0031] 203 Polarization Beam Splitter

[0032] 204 1 / 2 wave plate

[0033] 205 Motion optical path folding retroreflector

[0034] 206 Linear Motion Mechanism

[0035] 207 1 / 4 wave plate

[0036] 208 plane mirror

[0037] 209 Fixed optical path folding retroreflector

[0038] 210 Output optical coupling component DETAILED DESCRIPTION

[0039] The following describes the embodiments of the present invention by specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the following embodiments and features in the embodiments can be combined with each other without conflict.

[0040] It should be noted that the illustrations provided in the following embodiments are only used to illustrate the basic concept of the present invention in a schematic manner. Therefore, the drawings only show components related to the present invention rather than being drawn according to the number, shape and size of components in actual implementation. In actual implementation, the type, quantity and proportion of each component may be changed arbitrarily, and the component layout may also be more complicated.

[0041] The invention discloses a polarization-independent optical path scanning delay device and method, which are used to increase the optical path delay of input light of any polarization state under the condition of moving the same linear motion mechanism distance.

[0042] like Figure 1 As shown, the present invention is an improvement based on the conventional linear motion optical path scanning delay device, and the conventional linear motion optical path scanning delay device includes: an input optical coupling component 11, an optical path folding retroreflective mirror 12, a linear motion mechanism 13 and an output optical coupling component 14. The optical path folding retroreflective mirror 12 is arranged on the linear motion mechanism 13, and the linear motion mechanism 13 drives the optical path folding retroreflective mirror 12 to perform linear motion in the direction indicated by the double arrow in the figure. When the optical path folding retroreflective mirror 12 performs linear motion, the propagation distance of the output light changes, thereby forming an optical path scanning delay. Assuming that the displacement of the linear motion mechanism is Δx (which can be positive or negative, the positive sign indicates that the optical path folding retroreflective mirror is far away from the input optical coupling component 11 and the output optical coupling component 14, and the negative sign indicates that it is close to the input optical coupling component 11 and the output optical coupling component 14), there is an optical path scanning delay Δt=2nΔx / C (C is the speed of light, n is the refractive index of the optical path propagation medium, and the medium is generally air, then n=1).

[0043] like Figure 2 As shown, in one embodiment, a polarization-independent optical path scanning delay device of the present invention comprises:

[0044] The optical circulator 202 has three ports, and the external incident light is input or output to the first port of the optical circulator 202 .

[0045] Specifically, it also includes an optical coupling component 201, so that the external incident light is output through the optical coupling component to the first port of the optical circulator 202.

[0046] Specifically, the optical coupling component 201 is an optical fiber, an optical fiber collimator, or an optical fiber coupler. The optical coupling component 201 is used to input light into the first port of the optical circulator 202 .

[0047] Specifically, the optical circulator 202 is a three-port device with three ports. When light is incident from the first port, it can be emitted from the second port; when light is incident from the second port, it can be emitted from the third port; when light is incident from the third port, no light will be emitted from the first port, so it is often used to separate input light from reverse output light.

[0048] A polarization beam splitter 203 is arranged on the output light path of the second port of the optical circulator 202 .

[0049] Specifically, Figure 3 As shown, the role of the polarization beam splitter 203 is to achieve full reflection or full transmission of incident light of different polarization states, so as to achieve the role of polarization-dependent beam splitting. Any light beam can be decomposed into two linearly polarized light beams, whose polarization states are linearly polarized and whose polarization directions are perpendicular to each other (and the polarization directions of the two light beams are perpendicular to the propagation direction of the light beam). It may be assumed that the polarization direction of one of the beams is perpendicular to the incident plane (the incident plane is a plane determined by the normal of the incident light and the reflection surface, denoted as s-polarized light), and the polarization direction of the other beam is parallel to the incident plane (denoted as p-polarized light). When the polarized light is incident at an angle of 45 degrees to the normal of the reflection surface of the polarization beam splitter 203, the s-polarized light of the polarized light is reflected by the reflection surface, and the p-polarized light of the polarized light is transmitted by the reflection surface.

[0050] Specifically, the polarization beam splitter 203 is a polarization cube beam splitter. Specifically, the output light of the second port of the optical circulator 202 is incident on the polarization cube beam splitter and is incident at an angle of 45 degrees to the normal of the reflection surface of the polarization beam splitter 203 .

[0051] A 1 / 2 wave plate 204 and a moving light path folding retroreflective mirror 205 are sequentially arranged on the reflection light path of the polarization beam splitter 203; the moving light path folding retroreflective mirror 205 is arranged on a linear motion mechanism 206, and the linear motion mechanism 206 drives the moving light path folding retroreflective mirror 205 to move forward and backward along the direction of the output light path.

[0052] Specifically, the reflected optical path of the polarization beam splitter 203 refers to the incident light entering the polarization beam splitter 203 from the output of the second port of the optical circulator 202, and at this time, the input light forms an angle of 45 degrees with the normal of the reflection surface of the polarization beam splitter 203. The input light is decomposed into two polarized light beams, one of which has a polarization direction perpendicular to the incident surface (the incident surface is a plane determined by the incident light and the normal of the reflection surface, denoted as s-polarized light), then the s-polarized light of the polarized light is reflected by the reflection surface, and the optical path where the s-polarized light is reflected is the reflected optical path; and the polarization direction of the other beam is parallel to the incident surface (denoted as p-polarized light), and the p-polarized light directly penetrates the reflection surface, then the optical path where the p-polarized light is located is the transmitted optical path.

[0053] Specifically, the incident light is any polarized light, and the optical axis direction of the 1 / 2 wave plate 204 is located in the direction of the bisector of the angle between the s polarization direction and the p polarization direction of the polarized light. That is, when the polarization direction of the linear polarized light is 45° with the optical axis of the 1 / 2 wave plate 204, the 1 / 2 wave plate 204 can change the polarization direction of the linear polarized light by 90°. That is, the polarized light in the s polarization direction incident on the 1 / 2 wave plate 204 can be converted into the polarized light in the p polarization direction after exiting the 1 / 2 wave plate 204 (similarly, the p polarized light can be converted into the s polarized light).

[0054] Specifically, the linear motion mechanism 206 includes: a voice coil motor and a stepper motor. The linear motion mechanism 206 moves the moving light path folding retroreflector 205 forward and backward along the direction of the output light path. That is, the reflected light after the light is incident on the moving light path folding retroreflector 205 is parallel to the incident light. The incident light and the normal of a reflecting surface of the moving light path folding retroreflector 205 form an angle of 45 degrees. The moving light path folding retroreflector 205 is any one of the following: a hollow retroreflector, a retroreflective prism, and a double-piece reflector. The purpose is to keep the retroreflected light parallel to the incident light and at the same height.

[0055] A quarter wave plate 207 and a plane mirror 208 are sequentially arranged on the transmission light path of the polarization beam splitter 203 .

[0056] Specifically, the quarter wave plate 207 and the plane reflector 208 function to change the angle between the incident linear polarized light and the reflected linear polarized light by 90°. Figure 4 As shown, the incident light is p-polarized light, and the reflected light is s-polarized light. The incident light is polarized light, and the optical axis direction of the 1 / 4 wave plate 207 is located in the direction of the bisector of the angle between the s-polarization direction and the p-polarization direction of the polarized light. The plane reflector 208 is fixed and kept perpendicular to the incident light, ensuring that the incident light can be vertically reflected back to the light path by the plane reflector 208.

[0057] The fixed optical path folding retroreflector 209 is arranged on the reflection optical path of the moving optical path folding retroreflector 205, so that the fixed optical path folding retroreflector 209 can reflect light back to the moving optical path folding retroreflector 205 or the reflection surface of the polarization beam splitter 203, so that the polarization beam splitter 203 can reflect the light reflected from the fixed optical path folding retroreflector 209 to the 1 / 4 wave plate 207 or transmit to the 1 / 2 wave plate 204; so that the light reflected back to the reflection surface of the polarization beam splitter 203 via the plane reflector 208 is reflected to the fixed optical path folding retroreflector 209 via the reflection surface or is transmitted from the reflection surface to the second port of the optical circulator 202, and is output via the third port of the optical circulator 202. Finally, it is output via the output optical coupling component 210.

[0058] Specifically, the fixed light path folding retroreflector 209 is any one of the following: a hollow retroreflector, a retroreflective prism, or a double-piece reflector.

[0059] Specifically, the center heights of the optical paths of the optical coupling component 201, the optical circulator 202, the polarization beam splitter 203, the 1 / 2 wave plate 204, the moving optical path folding retroreflector 205, the 1 / 4 wave plate 207, the plane reflector 208 and the fixed optical path folding retroreflector 209 are located in the same horizontal plane.

[0060] Through this method, without adding a new motion mechanism, the optical path scanning can be doubled by adding some polarization optical elements (passing through the moving optical path folding retroreflective mirror 205 twice). At the same time, the optical path is applicable to input light of any polarization state, and there is no fundamental light loss in the optical path (such as semi-transparent and semi-reflective beam splitters, etc.), which has greater application flexibility.

[0061] Specifically, Figure 5As shown, the optical path on the reflected optical path of the polarization beam splitter 203 is described in detail. The incident light of any polarization direction and polarization state is output from the optical coupling component 201 to the first port of the optical circulator 202, and output from the second port of the optical circulator 202. The light incident to the polarization beam splitter 203 can be decomposed into s-polarized light and p-polarized light, wherein the s-polarized light is reflected by the reflection surface of the polarization beam splitter 203 and is incident to the 1 / 2 wave plate 204. The light emitted from the 1 / 2 wave plate 204 becomes p-polarized light, and after passing through the moving optical path folding retroreflector 205 and the fixed optical path folding retroreflector 209 for the first time, it is incident to the polarization beam splitter 203 again. At this time, the p-polarized incident light will fully pass through the polarization beam splitter 203 and then be incident on the 1 / 2 wave plate 204 again, and the polarization direction will be changed by the 1 / 2 wave plate 204 again to become the s-polarized output light; the s-polarized output light will pass through the moving optical path folding retroreflector 205 and the fixed optical path folding retroreflector 209 for the second time, and then be incident on the polarization beam splitter 203 again. The s-polarized output light is reflected by the polarization beam splitter 203 to the 1 / 4 wave plate 207 and the plane reflector 208, and the polarization direction is changed by 90° to become the p-polarized output light, which is incident on the polarization beam splitter 203, and then fully passes through the polarization beam splitter 203, is reflected to the second port of the optical circulator 202, and is output from the third port of the optical circulator. Finally, it is output through the output optical coupling component 210.

[0062] Specifically, Figure 6 As shown, the optical path on the transmission light path of the polarization beam splitter 203 is described in detail. The incident light of any polarization direction and polarization state is output from the optical coupling component 201 to the first port of the optical circulator 202, and output from the second port of the optical circulator 202. The light incident to the polarization beam splitter 203 can be decomposed into s-polarized light and p-polarized light, wherein the p-polarized light incident to the reflection surface of the polarization beam splitter 203 from the second port of the optical circulator will be fully transmitted through the polarization beam splitter 203 and then emitted to the component composed of a 1 / 4 wave plate 207 and a plane reflector 208; the reflected light will change its polarization direction by 90° to s-polarization, be incident to the polarization beam splitter 203, and be reflected to the fixed optical path folding retroreflector 209, and then after passing through the moving optical path folding retroreflector 205 for the first time, be incident to the 1 / 2 wave plate 204; from 1 The light emitted from the 1 / 2 wave plate 204 is converted into p-polarized polarized light and is incident on the polarization beam splitter 203 again. After fully transmitting through the polarization beam splitter 203, it passes through the fixed optical path folding retroreflector 209 and is incident on the moving optical path folding retroreflector 205 for the second time. The light beam emitted from the moving optical path folding retroreflector 205 passes through the 1 / 2 wave plate 204 and is converted into s-polarized polarized light and is incident on the polarization beam splitter 203. The light beam will be reflected by the polarization beam splitter 203 back to the second port of the optical circulator 202 and output from the third port of the optical circulator 202.

[0063] From the above Figure 5 and Figure 6 It can be seen from the analysis that no matter what polarization state the incident light is in, the incident light will pass through the moving optical path folding retroreflector 205 twice, so the formed optical path scanning delay range is proportional to 4 times the travel of the linear motion mechanism 206 (Δt=4nΔx / C). On the other hand, the optical path lengths of the incident p-polarized and s-polarized light are equal, and the optical paths moving in various dispersive elements (1 / 2 wave plate 204, 1 / 4 wave plate 207, polarization beam splitter 203) are also equal, so the combined light finally formed at the third port of the optical circulator 202 does not introduce additional dispersion.

[0064] Specifically, external incident light is input from the input optical coupling component 201 to the first port of the optical circulator 202. The optical circulator 202 can be optical fiber pigtail light-guided input or free space light-guided input. The input light can also be optical fiber light-guided or free space light-guided. If the external input light and the optical circulator 202 have different light-guiding methods, a fiber collimator / coupler can be used for collimation / coupling (collimation is performed when light is output from the device, and coupling is performed when light is input to the device).

[0065] like Figure 7 As shown, in one embodiment, the optical path scanning extension method of the present invention comprises the following steps:

[0066] Step S71, setting an optical circulator, wherein the optical circulator has three ports, and external incident light is input or output to a first port of the optical circulator;

[0067] Step S72, providing a polarization beam splitter on the output light path of the second port of the optical circulator;

[0068] Step S73, sequentially arranging a 1 / 2 wave plate and a moving light path folding retroreflective mirror on the reflected light path of the polarization beam splitter; arranging the moving light path folding retroreflective mirror on a linear motion mechanism, so that the linear motion mechanism drives the moving light path folding retroreflective mirror to move forward and backward along the direction of the output light path;

[0069] Step S74, sequentially arranging a quarter wave plate and a plane reflector on the transmission light path of the polarization beam splitter;

[0070] Step S75, setting a fixed light path folding retroreflector on the reflecting light path of the moving light path folding retroreflector, so that the fixed light path folding retroreflector can reflect light back to the moving light path folding retroreflector or the reflecting surface of the polarization beam splitter, so that the polarization beam splitter can reflect the light reflected from the fixed light path folding retroreflector to the 1 / 4 wave plate or transmit it to the 1 / 2 wave plate; so that the light reflected back to the reflecting surface of the polarization beam splitter via the plane reflector can be reflected via the reflecting surface to the fixed light path folding retroreflector or transmitted from the reflecting surface to the second port of the optical circulator, and output via the third port of the optical circulator.

[0071] It should be noted that the structures and principles of the above steps correspond one-to-one to the structures in the above polarization-independent optical path scanning delay device, so they will not be described in detail here.

[0072] In summary, the present invention provides a polarization-independent optical path scanning delay device and method. No matter what polarization state the incident light is in, the incident light will pass through the moving optical path folding retroreflector twice, so the optical path scanning delay range formed is proportional to 4 times the stroke of the linear motion mechanism (Δt=4nΔx / C). On the other hand, the optical path lengths of the incident p-polarized and s-polarized light are equal, and the optical paths moving in various dispersion elements (1 / 2 wave plate, 1 / 4 wave plate, polarization beam splitter) are also equal, so the combined light finally formed at the third port of the optical circulator does not introduce additional dispersion. Therefore, the present invention effectively overcomes various shortcomings in the prior art and has a high industrial utilization value.

[0073] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by a person of ordinary skill in the art without departing from the spirit and technical concept disclosed by the present invention shall still be covered by the claims of the present invention.

Claims

1. A polarization-independent optical path scanning delay device, characterized in that: include: An optical circulator, wherein the optical circulator has three ports, and external incident light is input or output to a first port of the optical circulator; A polarization beam splitter disposed on an output optical path of a second port of the optical circulator; wherein the polarization beam splitter is a polarization cube beam splitter; A 1 / 2 wave plate and a moving light path folding retroreflective mirror are sequentially arranged on the reflection light path of the polarization beam splitter; the moving light path folding retroreflective mirror is arranged on a linear motion mechanism, and the linear motion mechanism drives the moving light path folding retroreflective mirror to move forward and backward along the direction of the output light path; wherein the linear motion mechanism includes: a voice coil motor and a stepping motor; A quarter wave plate and a plane reflector are sequentially arranged on the transmission light path of the polarization beam splitter; A fixed optical path folding retroreflector is arranged on the reflecting optical path of the moving optical path folding retroreflector, so that the fixed optical path folding retroreflector can reflect light back to the moving optical path folding retroreflector or the reflecting surface of the polarization beam splitter, so that the polarization beam splitter can reflect the light reflected from the fixed optical path folding retroreflector to the 1 / 4 wave plate or transmit it to the 1 / 2 wave plate; so that the light reflected back to the reflecting surface of the polarization beam splitter via the plane reflecting mirror is reflected via the reflecting surface to the fixed optical path folding retroreflector or is transmitted from the reflecting surface to the second port of the optical circulator, and is output via the third port of the optical circulator.

2. A polarization-independent optical path scanning delay device according to claim 1, characterized in that: It also includes an optical coupling component, so that external incident light is input and output to the first port of the optical circulator through the optical coupling component. The optical coupling component is an optical fiber, a fiber collimator, and a fiber coupler.

3. A polarization-independent optical path scanning delay device according to claim 2, characterized in that The center heights of the optical paths of the optical coupling component, the optical circulator, the polarization beam splitter, the 1 / 2 wave plate, the moving optical path folding retroreflector, the 1 / 4 wave plate, the plane reflector and the fixed optical path folding retroreflector are located in the same horizontal plane.

4. The polarization-independent optical path scanning delay device according to claim 1, characterized in that: The moving light path folding retroreflector is any one of the following: a hollow retroreflector, a retroreflective prism, or a double-piece reflector.

5. The polarization-independent optical path scanning delay device according to claim 1, characterized in that: The fixed light path folding retroreflector is any one of the following: a hollow retroreflector, a retroreflective prism, or a double-piece reflector.

6. The polarization-independent optical path scanning delay device according to claim 1, characterized in that: The optical axis direction of the 1 / 2 wave plate is located in the direction of the bisector of the angle between the s-polarization direction and the p-polarization direction of the polarized light output by the polarization beam splitter.

7. The polarization-independent optical path scanning delay device according to claim 1, characterized in that: The optical axis direction of the 1 / 4 wave plate is located in the direction of the bisector of the angle between the s-polarization direction and the p-polarization direction of the polarized light output by the polarization beam splitter.

8. A polarization-independent optical path scanning delay method, characterized in that: The method comprises the following steps: An optical coupling component and an optical circulator are sequentially arranged, wherein the optical circulator has three ports, and external incident light is input or output to a first port of the optical circulator; Disposing a polarization beam splitter on the output light path of the second port of the optical circulator; A 1 / 2 wave plate and a moving light path folding retroreflective mirror are sequentially arranged on the reflected light path of the polarization beam splitter; the moving light path folding retroreflective mirror is arranged on a linear motion mechanism, so that the linear motion mechanism drives the moving light path folding retroreflective mirror to move forward and backward along the direction of the output light path; wherein the linear motion mechanism includes: a voice coil motor and a stepping motor; A quarter wave plate and a plane reflector are sequentially arranged on the transmission light path of the polarization beam splitter; A fixed light path folding retroreflector is arranged on the reflecting light path of the moving light path folding retroreflector, so that the fixed light path folding retroreflector can reflect light back to the moving light path folding retroreflector or the reflecting surface of the polarization beam splitter, so that the polarization beam splitter can reflect the light reflected from the fixed light path folding retroreflector to the 1 / 4 wave plate or transmit it to the 1 / 2 wave plate; so that the light reflected back to the reflecting surface of the polarization beam splitter via the plane reflecting mirror is reflected via the reflecting surface to the fixed light path folding retroreflector or is transmitted from the reflecting surface to the second port of the optical circulator, and is output via the third port of the optical circulator.

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