White light splitting interference spectrometer and white light splitting interference optical system

Abstract

The invention relates to the technical field of optical detection, and particularly provides a white light splitting interference spectrometer and a white light splitting interference optical system.The white light splitting interference spectrometer comprises a light inlet, a collimation assembly, a diffraction assembly, a focusing assembly and a camera; the light inlet is connected with an incident optical fiber, the diffraction assembly comprises a polaroid and a volume phase holographic grating, the collimation assembly comprises coaxially arranged glued collimation lenses, and the focusing assembly comprises at least one coaxially arranged glued focusing lens; the polaroid and the glued collimating lens are coaxially arranged and are both located on a first light path, the glued focusing lens is both located on a second light path, the camera is arranged at the emergent end of the second light path, and light output by the volume phase holographic grating is focused on the image plane of the camera through the glued focusing lens. According to the method, the technical problem that the final imaging quality is poor due to poor precision and low energy efficiency of a spectrograph in the prior art is solved.

Description

Technical Field

[0001] This invention relates to the field of optical detection technology, and in particular to a white light spectrometer and a white light spectrometer interferometric optical system. Background Technology

[0002] White light spectroscopic interferometry (FD-OCT) is characterized by its non-contact nature, high precision, and high speed. It is often used to measure optical and geometric parameters such as refractive index, thickness, distance, and displacement, or to indirectly measure physical quantities such as temperature and pressure using these parameters. In terms of application scenarios, this technology is mainly used to inspect biological tissues, thin films, or parts.

[0003] In the FD-OCT system, a white light source is used for interference, and a spectrometer is used to separate the interference light of different wavelengths. For example... Figure 1 The white-light spectroscopic interferometry spectrometer shown in the related technology uses interferometric light originating from an optical fiber, collimated by an off-axis parabolic mirror, and incident at a certain angle onto a diffraction grating. The diffraction grating separates light of different wavelengths into monochromatic light propagating in different directions, which is then imaged at the image plane by a single cemented doublet lens and a plane mirror. However, in reality, on the one hand, pixels have a certain size, and light of a certain linewidth is distributed on each pixel; on the other hand, during the spectral splitting process, the light spots of each wavelength are not ideal points, but rather light spots of a certain size. These two factors cause the camera pixels to actually receive a superposition of many light spots of a certain wavelength range, or quasi-monochromatic light with a certain linewidth. This situation leads to a shorter detectable distance, i.e., a smaller measurement range, and spectral distortion also occurs in the low-frequency band. Summary of the Invention

[0004] This invention provides a white light spectrometer and a white light spectrometer interferometric optical system, which solves the technical problem that the spectrometers in related technologies suffer from poor accuracy and low energy efficiency, resulting in poor final imaging quality.

[0005] To achieve the above objectives, the present invention is implemented using the following technical solution:

[0006] In a first aspect, embodiments of the present invention provide a white light spectrometer, comprising: an entrance port, a collimation assembly, a diffraction assembly, a focusing assembly, and a camera;

[0007] The light inlet is connected to the incident optical fiber, which is used to provide the interference light signal to be analyzed.

[0008] The diffraction component includes a polarizer and a volume phase holographic grating, the collimation component includes a cemented collimating lens arranged coaxially, and the focusing component includes at least one cemented focusing lens arranged coaxially.

[0009] The polarizer and the cemented collimating lens are coaxially arranged and both are located on the first optical path. The first optical path is a straight optical path from the light inlet to the volume phase holographic grating. The angle between the first optical path and the volume phase holographic grating is 48.5°-49.5°.

[0010] The cemented focusing lenses are all located on the second optical path, which is the optical path between the volume phase holographic grating and the camera. The angle between the incident end of the second optical path and the volume phase holographic grating is 48°-50°. The camera is set at the exit end of the second optical path. The light output by the volume phase holographic grating is focused on the image plane of the camera by the cemented focusing lenses.

[0011] Furthermore, the cemented collimating lens is a cemented doublet achromatic lens, and the focusing assembly includes two cemented focusing lenses, which are cemented doublet focusing lenses.

[0012] Furthermore, the polarizer is disposed between the light entrance and the cemented doublet achromatic lens.

[0013] Furthermore, it also includes a reflector disposed between the two cemented doublet focusing lenses to redirect the second optical path so that the reflected second optical path faces the end closer to the light inlet.

[0014] Furthermore, it also includes an optical cavity, which is disposed within a quadrilateral housing;

[0015] The quadrilateral shell includes three first sides and one second side. The three first sides correspond to the first optical path, the second optical path before reflection, and the second optical path after reflection, respectively. The size of the second side does not exceed that of the first side.

[0016] Both the light inlet and the camera are located on the second side.

[0017] Furthermore, the optical cavity includes a first sub-cavity, a second sub-cavity, and a third sub-cavity;

[0018] The light inlet is located at one end of the first sub-cavity, and the volume phase holographic grating is located at the other end of the first sub-cavity; along the first direction pointing from the light inlet to the volume phase holographic grating, the polarizer and the cemented doublet achromatic lens are arranged coaxially in sequence;

[0019] The volume phase holographic grating is also disposed at one end of the second sub-cavity, the reflector is disposed at the other end of the second sub-cavity, and one of the double cemented focusing lenses is disposed in the second sub-cavity. The angle between the reflector and the volume phase holographic grating is 0°±2°.

[0020] The reflector is also disposed at one end of the third sub-cavity, the camera is disposed at the other end of the third sub-cavity, and another of the double-cemented focusing lenses is disposed in the third sub-cavity.

[0021] Furthermore, the white light spectrometer can process interference light signals in the 810nm-850nm band and has a diffraction limit of less than 8m.

[0022] The energy efficiency of the volume phase holographic grating is not less than 70%, the wavelength range is 790nm-910nm, the center wavelength is 850nm±10nm, and the diffraction angle corresponding to the center wavelength is 49.1°±0.3°.

[0023] In a second aspect, the present invention also provides a white light spectroscopic interference optical system, comprising: a white light source, a circulator, a probe, and the aforementioned white light spectroscopic interference spectrometer;

[0024] The white light source is connected to the input end of the circulator via an optical fiber; the input and output ends of the circulator are connected to the probe; the probe is used to project a portion of the split white light onto a reference surface, which is reflected to form a reference light, and to project another portion onto the surface of the object to be measured, which is reflected to form a measurement light, and to combine the reference light and the measurement light to form an interference light signal; the output end of the circulator is connected to the white light spectrometer, and the circulator is used to transmit the white light emitted by the white light source to the probe, receive the interference light signal returned by the probe, and send the received interference light signal to the white light spectrometer.

[0025] Furthermore, the camera has a pixel size of 4μm, an image plane size of 2048×1200 pixels, a frame rate of 159.4 fps when transmitting the entire image plane, a transmission rate of 3424.66 fps when transmitting an image plane of 2048×10 pixels, and a spectral response rate of not less than 40% in the near-infrared band.

[0026] Furthermore, the probe includes a gradient refractive index lens and a reflecting prism;

[0027] The gradient refractive index lens is fixedly connected to the optical fiber at the input and output ends of the circulator through a sleeve. The reflecting prism is disposed in the output optical path of the gradient refractive index lens, and an anti-reflection coating is also disposed in the reflected optical path of the reflecting prism.

[0028] Furthermore, the gradient refractive index lens has a pitch of 0.23P, an error range of ±5μm, a diameter of 1.8±0.2 mm, a length of 4.35±0.2 mm, and an end face with a tilt angle of 8±0.5°; the antireflective coating has a reflectivity of 30%±5%.

[0029] The white-light spectroscopic interferometry spectrometer of this invention employs a volume-phase holographic grating, which has higher diffraction efficiency compared to reflective gratings. To address the problem of the volume-phase holographic grating's polarization insensitivity leading to the inability to receive interference signals, a polarizer is added to the optical path structure in combination with the volume-phase holographic grating. This filters out light of one polarization state while improving diffraction efficiency. Furthermore, two cemented doublet focusing lenses are used to focus the light separated by the grating. This invention solves the technical problem of poor imaging quality caused by low precision and low energy efficiency in related spectrometers. Attached Figure Description

[0030] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings:

[0031] Figure 1 This is a schematic diagram of the optical path structure of a white light spectrometer in related technologies;

[0032] Figure 2 This is a schematic diagram of the structure of a white light spectrophotometer according to an embodiment of the present invention;

[0033] Figure 3 This is a schematic diagram of the optical path structure of a white light spectrometer according to an embodiment of the present invention;

[0034] Figure 4 Figure 1 shows the design and performance of a volume phase holographic grating; Figure 2 shows the structural diagram of the volume phase holographic grating, and Figure 3 shows the energy efficiency diagram of the volume phase holographic grating.

[0035] Figure 5 This is the interference light signal received by the white light spectrometer of this invention without the addition of a polarizer;

[0036] Figure 6 This is the interference light signal received by the white light spectrometer in an embodiment of the present invention after adding a polarizer;

[0037] Figure 7 It is the RMS plot of a white light spectrophotometer in the wavelength range of 810 nm-855 nm in related technologies;

[0038] Figure 8 The RMS plot of the white light spectrometer in the wavelength range of 810 nm-855 nm is an embodiment of the invention.

[0039] Figure 9 This is a dot plot of a white light spectroscopic interferometer according to an embodiment of the present invention;

[0040] Figure 10 This is a schematic diagram of the structure of a white light beam-splitting interference optical system according to an embodiment of the present invention.

[0041] The above figures include the following reference numerals:

[0042] 1—Inlet; 2—Polarizer; 3—Cemented collimating lens; 4—Volume phase holographic grating; 5—Cemented focusing lens; 6—Camera; 7—Mirror; 8—Housing; 9—First sub-cavity; 10—Second sub-cavity; 11—Third sub-cavity. Detailed Implementation

[0043] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0044] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0045] Unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps described in these embodiments do not limit the scope of this application. It should also be understood that, for ease of description, the dimensions of the various parts shown in the drawings are not drawn to actual scale. Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters in the following drawings denote similar items; therefore, once an item is defined in one drawing, it need not be further discussed in subsequent drawings.

[0046] See Figure 2 and Figure 3 This application provides a white light spectrometer, including: an entrance port 1, a collimation component, a diffraction component, a focusing component, and a camera 6;

[0047] The light inlet 1 is connected to the incident optical fiber, which is used to provide the interference light signal to be analyzed.

[0048] The diffraction component includes a polarizer 2 and a volume phase holographic grating 4; the collimation component includes a cemented collimating lens 3 arranged coaxially; and the focusing component includes at least one cemented focusing lens 5 arranged coaxially.

[0049] The polarizer 2 and the cemented collimating lens 3 are coaxially arranged and both are located on the first optical path. The first optical path is a straight optical path from the light inlet 1 toward the volume phase holographic grating 4. The angle between the first optical path and the volume phase holographic grating 4 is 48.5°-49.5°.

[0050] The cemented focusing lenses 5 are all located on the second optical path, which is the optical path between the volume phase holographic grating 4 and the camera 6. The angle between the incident end of the second optical path and the volume phase holographic grating 4 is 48°-50°. The camera 6 is located at the exit end of the second optical path. The light emitted by the volume phase holographic grating 4 is focused onto the image plane of the camera 6 by the cemented focusing lenses 5.

[0051] In this embodiment of the invention, the cemented collimating lens 3 is collimated using a cemented doublet achromatic lens. Due to its coaxial structure, it is easier to assemble and adjust compared to off-axis parabolic mirrors in related technologies.

[0052] The volume phase holographic grating 4 has an energy efficiency of not less than 70%, a wavelength range of 790nm-910nm, a center wavelength of 850nm±10nm, and a diffraction angle corresponding to the center wavelength of 49.1°±0.3°.

[0053] The polarizer 2 is disposed between the light inlet 1 and the cemented doublet achromatic lens.

[0054] The energy efficiency of reflective gratings in related technologies is too low, only 20%-40%. Therefore, when measuring non-cooperative targets with weak surface reflection, the measurement peak may be submerged by noise. Therefore, this invention replaces the reflective grating with a volume phase holographic grating (VPH grating), as follows: Figure 4 As shown, the volume phase holographic grating 4 is designed with a center wavelength of 840 nm and a wavelength range of 790 nm to 890 nm, with a diffraction angle of 49.1° corresponding to the center wavelength. By periodically modulating the refractive index of the internal material, the diffraction efficiency of the grating can be improved, thereby increasing the energy efficiency of the spectrometer system and reducing energy dissipation. In the range of 810 nm to 850 nm, the energy efficiency of the volume phase holographic grating 4 is above 70%.

[0055] However, the diffraction efficiency of the volume-phase holographic grating 4 for both s and p polarized light is related to its structural parameters. When the incident angle satisfies the Bragg condition, its parameters are designed so that the diffraction efficiency for both polarized states is approximately the same, meaning it lacks polarization selectivity. In contrast, a reflective grating is only sensitive to one polarization state. Therefore, when using the volume-phase holographic grating 4, the light received on the image plane is a superposition of two polarized states. The mutual interference between these two polarization states reduces the contrast of the interference light, and may even result in no interference signal being received at all. Figure 5 As shown, although interference light still exists, no grayscale fluctuation signal generated by the interference can be received at all.

[0056] To address the problem of the volume-phase holographic grating 4 being insensitive to polarization and thus unable to receive interference signals, this invention adds a polarizer 2 to the optical path structure for use in conjunction with the volume-phase holographic grating 4. This improves diffraction efficiency while filtering out light of one polarization state. Figure 6 As shown, the contrast of the received interference light is better after adding polarizer 2.

[0057] In this embodiment of the invention, the focusing assembly includes two cemented focusing lenses 5, and the cemented focusing lenses 5 are double cemented focusing lenses.

[0058] This invention uses two cemented doublet focusing lenses combined to focus the light separated by the grating, resulting in less aberration for light in the spectral range of 810 nm-850 nm compared to optical spectrometers in related technologies. Figure 7 and Figure 8 It can be seen that the diffraction limit of the optical path structure of the present invention is less than 8 μm, which is lower than the diffraction limit of 12 μm in the related technology. Moreover, the RMS is close to the diffraction limit in the wavelength range of 810 nm-850 nm. Therefore, the imaging quality is improved compared with the related technology.

[0059] Furthermore, to verify that the spectrometer of this invention can still achieve a wavelength resolution of 0.02 nm near the center wavelength, the embodiments of this invention used Zemax software to analyze its spot plots near 825 nm, 830 nm, and 835 nm. The results obtained are as follows. Figure 9 As shown, the spectrometer of this invention can still distinguish light with a wavelength difference of 0.02 nm near the center wavelength of 830 nm, thus its wavelength resolution meets the requirements.

[0060] As an optional embodiment, a reflector 7 is provided between two cemented doublet focusing lenses to redirect the second optical path so that the reflected second optical path faces the end closer to the light inlet.

[0061] By incorporating the reflector 7, the size of the spectrometer can be reduced, making the spectrometer structure of this invention more compact and efficient, and easier to use and carry.

[0062] See Figure 2 The white light spectrometer of the present invention further includes an optical cavity disposed within a quadrilateral housing 8. The housing 8 includes three first sides and one second side. The three first sides correspond to the first optical path, the second optical path before reflection, and the second optical path after reflection, respectively. The size of the second side does not exceed that of the first side. The light inlet 1 and the camera 6 are distributed at both ends of the second side.

[0063] The optical cavity includes a first sub-cavity 9, a second sub-cavity 10, and a third sub-cavity 11.

[0064] The light inlet 1 is located at one end of the first sub-cavity 9, and the volume phase holographic grating 4 is located at the other end of the first sub-cavity 9; along the first direction from the light inlet 1 to the volume phase holographic grating 4, the polarizer 2 and the doublet achromatic lens are arranged coaxially in sequence.

[0065] The volume phase holographic grating 4 is also disposed at one end of the second sub-cavity 10, the reflector 7 is disposed at the other end of the second sub-cavity 10, and a double cemented focusing lens is disposed in the second sub-cavity 10. The angle between the reflector 7 and the volume phase holographic grating 4 is 0°±2°.

[0066] The reflector 7 is also disposed at one end of the third sub-cavity 11, the camera 6 is disposed at the other end of the third sub-cavity 11, and another double-cemented focusing lens is disposed in the third sub-cavity 11.

[0067] On the other hand, such as Figure 10 As shown in the figure, this application embodiment also provides a white light spectroscopic interferometry optical system, including: a white light source, a circulator, a probe, and the white light spectroscopic interferometry spectrometer of the above embodiment.

[0068] The white light source is connected to the input end of the circulator via an optical fiber; the input and output ends of the circulator are connected to the probe; the probe is used to project a portion of the split white light onto a reference surface, which is reflected to form a reference light, and to project another portion onto the surface of the object to be measured, which is reflected to form a measurement light, and to combine the reference light and the measurement light to form an interference light signal; the output end of the circulator is connected to the white light spectrometer, and the circulator is used to transmit the white light emitted by the white light source to the probe, receive the interference light signal returned by the probe, and send the received interference light signal to the white light spectrometer.

[0069] This system includes the aforementioned white light spectroscopic interferometry spectrometer; therefore, this white light spectroscopic interferometry optical system encompasses all the technical effects of the spectrometer described in the above embodiments. Since the technical effects of the spectrometer have already been described in detail above, they will not be repeated here.

[0070] In this embodiment of the invention, the camera 6 used has a pixel size of 4μm, an image plane size of 2048×1200 pixels, a frame rate of 159.4 fps when transmitting the entire image plane, a transmission rate of 3424.66 fps when transmitting an image plane of 2048×10 pixels, and a spectral response rate of not less than 40% in the near-infrared band.

[0071] The probe includes a gradient refractive index lens and a reflecting prism; the gradient refractive index lens is fixedly connected to the optical fiber at the input and output ends of the circulator through a sleeve, and the reflecting prism serves as a reference surface and is disposed in the output optical path of the gradient refractive index lens. An anti-reflection coating is also disposed in the reflected optical path of the reflecting prism.

[0072] In this embodiment of the invention, the gradient refractive index lens in the probe has a pitch of 0.23P, an error range of ±5μm, a diameter of 1.8±0.2 mm, a length of 4.35±0.2 mm, and an end face tilt angle of 8±0.5°, which can prevent reflected light from mixing with the reflected light signal and interfering with the signal. The surface of the reflecting prism is coated with a 30%±5% anti-reflection film, with a transmittance-to-reflection ratio of 7:3, which is beneficial for measuring targets with low surface reflectivity.

[0073] The probe of this invention is small in size, making it suitable for measurements in confined spaces.

[0074] For ease of description, spatial relative terms such as "above," "on top of," "on the upper surface of," "above," etc., are used herein to describe the spatial positional relationship of a device or feature as shown in the figures to other devices or features. It should be understood that spatial relative terms are intended to encompass different orientations in use or operation beyond the orientation of the device as described in the figures. For example, if the device in the figures were inverted, a device described as "above" or "on top of" other devices or structures would subsequently be positioned as "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below." The device may also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used herein will be interpreted accordingly.

[0075] Furthermore, it should be noted that the use of terms such as "first" and "second" to define components is merely for the purpose of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore cannot be construed as limiting the scope of protection of this application.

[0076] The above are merely preferred embodiments of this application and are not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A white light spectrophotometer with interferometric cross-section, characterized in that, include: Light inlet, collimating assembly, diffraction assembly, focusing assembly, and camera; The light inlet is connected to the incident optical fiber, which is used to provide the interference light signal to be analyzed. The diffraction component includes a polarizer and a volume phase holographic grating, the collimation component includes a cemented collimating lens arranged coaxially, and the focusing component includes at least one cemented focusing lens arranged coaxially. The polarizer and the cemented collimating lens are coaxially arranged and both are located on the first optical path. The first optical path is a straight optical path from the light inlet to the volume phase holographic grating. The angle between the first optical path and the volume phase holographic grating is 48.5°-49.5°. The cemented focusing lenses are all located on the second optical path, which is the optical path between the volume phase holographic grating and the camera. The angle between the incident end of the second optical path and the volume phase holographic grating is 48°-50°. The camera is set at the exit end of the second optical path. The light output by the volume phase holographic grating is focused on the image plane of the camera by the cemented focusing lenses.

2. The white light spectrometer according to claim 1, characterized in that, The cemented collimating lens is a cemented doublet achromatic lens, and the focusing assembly includes two cemented focusing lenses, which are cemented doublet focusing lenses.

3. The white light spectrometer according to claim 2, characterized in that, The polarizer is disposed between the light inlet and the cemented doublet achromatic lens.

4. The white light spectrometer according to claim 2, characterized in that, It also includes a reflector, which is disposed between the two cemented doublet focusing lenses to deflect the second light path so that the reflected second light path is directed toward the end closer to the light inlet.

5. The white light spectrometer according to claim 4, characterized in that, It also includes an optical cavity, which is disposed in a quadrilateral housing; The quadrilateral shell includes three first sides and one second side. The three first sides correspond to the first optical path, the second optical path before reflection, and the second optical path after reflection, respectively. The size of the second side does not exceed that of the first side. Both the light inlet and the camera are located on the second side.

6. The white light spectrometer according to claim 5, characterized in that, The optical cavity includes a first sub-cavity, a second sub-cavity, and a third sub-cavity; The light inlet is located at one end of the first sub-cavity, and the volume phase holographic grating is located at the other end of the first sub-cavity; along the first direction pointing from the light inlet to the volume phase holographic grating, the polarizer and the cemented doublet achromatic lens are arranged coaxially in sequence; The volume phase holographic grating is also disposed at one end of the second sub-cavity, the reflector is disposed at the other end of the second sub-cavity, and one of the double cemented focusing lenses is disposed in the second sub-cavity. The angle between the reflector and the volume phase holographic grating is 0°±2°. The reflector is also disposed at one end of the third sub-cavity, the camera is disposed at the other end of the third sub-cavity, and another of the double-cemented focusing lenses is disposed in the third sub-cavity.

7. The white light spectrometer according to claim 1, characterized in that, The white light spectrometer can process interference light signals in the 810nm-850nm band and has a diffraction limit of less than 8m. The energy efficiency of the volume phase holographic grating is not less than 70%, the wavelength range is 790nm-910nm, the center wavelength is 850nm±10nm, and the diffraction angle corresponding to the center wavelength is 49.1°±0.3°.

8. A white light beam-splitting interferometry optical system, characterized in that, include: A white light source, a circulator, a probe, and a white light spectrometer as described in any one of claims 1 to 7; The white light source is connected to the input end of the circulator via an optical fiber; the input and output ends of the circulator are connected to the probe; the probe is used to project a portion of the split white light onto a reference surface, which is reflected to form a reference light, and to project another portion onto the surface of the object to be measured, which is reflected to form a measurement light, and to combine the reference light and the measurement light to form an interference light signal; the output end of the circulator is connected to the white light spectrometer, and the circulator is used to transmit the white light emitted by the white light source to the probe, receive the interference light signal returned by the probe, and send the received interference light signal to the white light spectrometer.

9. The white light beam-splitting interferometry optical system according to claim 8, characterized in that, The camera has a pixel size of 4μm, an image plane size of 2048×1200 pixels, a frame rate of 159.4 fps when transmitting the entire image plane, a transmission rate of 3424.66 fps when transmitting an image plane of 2048×10 pixels, and a spectral response rate of not less than 40% in the near-infrared band.

10. The white light beam-splitting interferometry optical system according to claim 8, characterized in that, The probe includes a gradient refractive index lens and a reflecting prism; The gradient refractive index lens is fixedly connected to the optical fiber at the input and output ends of the circulator through a sleeve. The reflecting prism is disposed in the output optical path of the gradient refractive index lens, and an anti-reflection coating is also disposed in the reflected optical path of the reflecting prism.

11. The white light beam-splitting interferometry optical system according to claim 10, characterized in that, The gradient refractive index lens has a pitch of 0.23P, an error range of ±5μm, a diameter of 1.8±0.2 mm, a length of 4.35±0.2 mm, and an end face with a tilt angle of 8±0.5°; the antireflective coating has a reflectivity of 30%±5%.

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