A method and device for measuring eye axis based on variable-focus OCT

Abstract

The invention discloses an axial length measurement method and device based on variable-focus OCT. The method comprises: before acquisition, the posterior segment optical path adjustment module is used to make the posterior segment optical path in a reference position, and the device self-check before axial length measurement is completed; during acquisition, the first reference arm light beam is matched with the anterior segment optical path, the posterior segment optical path adjustment module is adjusted, the second reference arm light beam is matched with the posterior segment optical path, and the sample arm light beam is focused on the cornea and retina in sequence by using a variable-focus liquid lens; and the cornea and retina are rapidly and focused on to achieve rapid imaging. According to the OCT imaging results of the cornea and retina and the displacement of the posterior segment optical path adjustment module, the axial length of the eye to be measured is measured. The axial length measurement device is used to implement the axial length measurement method, and can achieve rapid focused imaging of the cornea and retina to be measured. The invention uses the interference signals of the two reference arms to quickly calibrate the reference position of the posterior segment reference arm before each axial length measurement, so as to improve the accuracy of axial length measurement.

Description

Technical Field

[0001] The present invention relates to the field of eye axis measurement equipment in medical device technology, and in particular to an eye axis measurement method and device based on variable focus OCT (Optical Coherence Tomography). Technical Background

[0002] Among various ophthalmic examinations, axial length is a key factor in measuring the degree of myopia. Currently, the technologies for measuring axial length mainly include ultrasonic biometry (A-type ultrasonic measuring instrument) and optical biometry. A-ultrasound needs to contact the corneal surface during measurement, which can easily cause discomfort to the subject, and the pressure of the probe on the cornea can also cause errors in axial length measurement.

[0003] Optical Coherence Tomography (OCT) technology uses the interference signal of back-reflected light from biological tissues to acquire cross-sectional images of the anterior and posterior segments of the human eye with micron-level resolution. With its advantages of non-contact measurement, real-time performance, high sensitivity and high resolution, it provides a more accurate measurement basis for clinical ophthalmic biometry. At present, there are some axial length measurement methods and devices based on OCT technology. These methods can realize axial length measurement, but still have the following disadvantages: in the axial length measurement systems and methods disclosed in patent documents 202121905127.X, 202010202763.X, etc., the optical paths of the front and back segments of the sample arm are shared, and there is only one reference arm. The device can only rely on the switching of the optical delay line to obtain the images of the front and back segments of the eye to be measured in time. The speed of the optical path switching will cause interference with eye movement, thereby causing errors in the axial length measurement results; in the axial length measurement systems and methods disclosed in patent documents 202011037937.8, etc., the anterior and posterior segments of the sample arm adopt a common path design. When a zoom lens is not used, only the anterior segment of the eye can be focused and imaged. The posterior segment of the eye is not focused and can only be blurred. The position of the retinal pigment epithelium cannot be accurately determined, affecting the accuracy of the axial length measurement. In particular, the above-mentioned axial length measurement methods based on OCT technology all have a disadvantage, that is, the calculation formula of the axial length includes the displacement of the optical delay line. Due to the slight movement of the optomechanical components during the optical installation or use of the device, the initial reference position of the optical delay line is different, which will introduce calculation errors in the measurement of the axial length. Summary of the invention

[0004] In view of the shortcomings of the prior art, the present invention proposes a method and device for measuring the axial length of the eye based on variable-focus OCT. The present invention can quickly alternately focus on the anterior and posterior segments of the eye, further achieving rapid and clear imaging of the anterior and posterior segments of the eye, and proposes a reference arm optical path calibration method, which helps to improve the accuracy of axial length measurement.

[0005] The objective of the present invention is achieved through the following technical solutions:

[0006] 1. A method for measuring eye axis based on variable-focus OCT

[0007] S1: Before the acquisition begins, the axial length measurement device is self-checked using the posterior segment optical path adjustment module, and after the self-check, the posterior segment optical path adjustment module is calibrated to be in the reference position for axial length measurement;

[0008] S2: adjusting the eye axis measurement device to make the iris image clear, so that the anterior segment OCT image appears at the imaging focus position of the first OCT image display frame, and the focal length of the variable focus liquid lens is recorded as the first focal length;

[0009] S3: the posterior segment optical path adjustment module moves along the optical axis until the posterior segment OCT image appears at a preset pixel position of the second OCT image display frame, and the displacement of the posterior segment optical path adjustment module is recorded;

[0010] S4: the variable-focus liquid lens traverses within the preset focal length range until the posterior segment OCT image is clear, and the focal length of the variable-focus liquid lens is recorded and recorded as the second focal length;

[0011] S5: The variable-focus liquid lens switches between the first focal length and the second focal length to alternately acquire two-dimensional OCT images of the anterior segment and the posterior segment of the eye;

[0012] S6: Calculate the axial length of the eye to be tested based on the two-dimensional OCT images of the anterior segment and the posterior segment of the eye to be tested and the displacement of the posterior segment optical path adjustment module.

[0013] The S1 is specifically:

[0014] Adjust the optical path adjustment module at the posterior eye node so that the first reference arm beam and the second reference arm beam in the reference arm beam splitting module form an interference signal in the optical fiber coupler, and the spectrometer camera detects and collects the interference image. At this time, the position of the optical path adjustment module at the posterior eye node is used as the reference position for eye axis measurement.

[0015] The S2 is specifically:

[0016] Adjust the eye axis measurement device and use the iris imaging optical path to preliminarily locate the position of the cornea to be measured. When the iris image is clear, the front surface of the cornea to be measured is exactly at the focal position of the eye contact objective lens. At this time, the anterior segment OCT image appears at the imaging focal position of the first OCT image display frame. Then move the position of the corneal tomographic section of the eye to be measured up and down to make a central light column caused by the strong reflection of the corneal vertex appear in the first OCT image display frame. At this time, the focal length of the variable focus liquid lens is recorded as the first focal length.

[0017] The S3 is specifically:

[0018] The posterior segment optical path adjustment module moves along the optical axis from the reference position until the posterior segment OCT image appears at the preset pixel position of the second OCT image display frame. The optical path of the second reference arm light beam matches the optical path of the sample arm light beam in the posterior segment information acquisition mode, and the displacement of the posterior segment optical path adjustment module at this time is recorded.

[0019] The S6 is specifically:

[0020] According to the two-dimensional OCT images of the anterior segment and posterior segment of the eye to be tested, the pixel positions of the anterior surface of the cornea and the retinal pigment epithelial cell layer of the eye to be tested are obtained, and then according to the displacement of the optical path adjustment module of the posterior segment, the distance between the anterior surface of the cornea of ​​the eye to be tested and the retinal pigment epithelial cell layer is calculated and used as the axial length of the eye to be tested.

[0021] In the S6, the two-dimensional OCT images of the anterior segment and the posterior segment of the eye to be tested are combined into the OCT two-dimensional imaging result of the eye to be tested, and the pixel positions of the anterior surface of the cornea and the retinal pigment epithelial cell layer of the eye to be tested are obtained after image processing of the OCT two-dimensional imaging result of the eye to be tested using a boundary recognition method; the distance between the vertex of the anterior surface of the cornea of ​​the eye to be tested and the zero optical path difference position is recorded as d1, the distance between the retinal pigment epithelium and the zero optical path difference position is recorded as d2, and the displacement of the optical path adjustment module of the posterior segment is recorded as d3, then the axial length D of the eye to be tested satisfies D=d2-d1+d3+d4.

[0022] 2. An eye axis measurement device based on variable-focus OCT

[0023] The device includes an OCT main module, an OCT sample arm module, an OCT reference arm module, an iris imaging module and a fixation module; the sample arm light beam emitted from the OCT main module is incident on the OCT sample arm module, the reference arm light beam emitted from the OCT main module is incident on the OCT reference arm module, the OCT sample arm module is connected to the iris imaging module and the fixation module respectively, and the OCT sample arm module measures the eye to be tested;

[0024] The OCT main module includes a broadband light source, a fiber coupler and a spectrometer, wherein the spectrometer is composed of a spectrometer collimator, a reflective grating, a spectrometer focusing lens and a spectrometer camera; the first input end of the fiber coupler is connected to the broadband light source, the second input end of the fiber coupler is connected to the spectrometer collimator, the spectrometer collimator is sequentially connected to the reflective grating and the spectrometer focusing lens and then connected to the spectrometer camera, the first output end of the fiber coupler emits a sample arm beam, and the second output end of the fiber coupler emits a reference arm beam, that is, the first output end of the fiber coupler is connected to the sample arm collimator of the OCT sample arm module, and the second output end of the fiber coupler is connected to the polarization controller of the OCT reference arm module.

[0025] The OCT sample arm module comprises a sample arm collimator, a sample arm zoom module, a second dichroic mirror, an eye lens and an infrared illumination light source; the sample arm light beam emitted by the OCT main body module is incident on the sample arm collimator, and the sample arm light beam after passing through the sample arm collimator is incident on the eye to be tested after being reflected by the sample arm zoom module and the second dichroic mirror and transmitted by the eye lens along the optical axis, and an infrared illumination light source is installed on the side of the eye lens;

[0026] The light emitted by the infrared illumination light source is reflected by the cornea of ​​the eye to be tested to form an iris imaging beam, and the iris imaging beam is incident on the iris imaging module after being sequentially transmitted through the eye contact lens and the second dichroic mirror along the optical axis;

[0027] The fixation beam emitted by the fixation module is incident on the sample arm zoom module, and the fixation beam after passing through the sample arm zoom module is incident on the second dichroic mirror. The fixation beam reflected by the second dichroic mirror is then incident on the eye to be tested after being transmitted through the eyepiece objective lens.

[0028] The infrared illumination light source includes but is not limited to using two or more infrared point light sources, and evenly distributed on both sides of the eyepiece objective lens.

[0029] The sample arm zoom module includes a liquid variable focus lens, a scanning galvanometer and a first dichroic mirror; the sample arm light beam after passing through the sample arm collimator is incident on the second dichroic mirror after being reflected by the scanning galvanometer, reflected by the first dichroic mirror and transmitted by the liquid variable focus lens along the optical axis; in the anterior segment information acquisition mode, the refractive power of the liquid variable focus lens is 0D, the sample arm light beam reflected from the first dichroic mirror 18 is still emitted as a parallel light beam after being transmitted through the liquid variable focus lens, and then is reflected by the second dichroic mirror 20 and converged on the human cornea through the eye contact objective lens; in the posterior segment information acquisition mode, the rear focus of the liquid variable focus lens coincides with the front focus of the eye contact objective lens, the sample arm light beam reflected back from the first dichroic mirror enters the liquid variable focus lens as a parallel light beam, and the sample arm light beam after being transmitted through the liquid variable focus lens is then emitted as a parallel light beam at the eye contact objective lens and enters the eye to be tested, and finally converges on the retina through the human eye lens.

[0030] The sample arm zoom module comprises a liquid variable focus lens, a scanning galvanometer, a first dichroic mirror and a sample arm relay lens; the sample arm light beam after passing through the sample arm collimator is incident on the second dichroic mirror after being transmitted through the liquid variable focus lens, reflected through the scanning galvanometer, reflected through the first dichroic mirror and transmitted through the sample arm relay lens along the optical axis; in an anterior segment information acquisition mode, the rear focus of the liquid variable focus lens and the front focus of the sample arm relay lens coincide with each other, so that the sample arm light beam reflected through the second dichroic mirror enters the eye-receiving objective lens in the form of parallel light, and then converges on the cornea of ​​the eye to be tested through the eye-receiving objective lens, thereby realizing the acquisition of anterior segment information; in a posterior segment information acquisition mode, the rear focus of the sample arm relay lens and the front focus of the eye-receiving objective lens coincide with each other, so that the sample arm light beam transmitted through the eye-receiving objective lens is incident on the eye to be tested in the form of parallel light, and the eye to be tested itself converges the sample arm light beam on the retina, thereby realizing the acquisition of posterior segment information.

[0031] The OCT reference arm module includes a polarization controller, a reference arm collimator and a reference arm beam splitting module. The reference arm beam emitted by the OCT main module is incident on the polarization controller, and the reference arm beam passing through the polarization controller is incident on the reference arm beam splitting module after passing through the reference arm collimator. The reference arm beam splitting module splits the reference arm beam into a first reference arm beam and a second reference arm beam. The optical path of the first reference arm beam matches the optical path of the sample arm beam in the anterior segment information acquisition mode, and the optical path of the second reference arm beam matches the optical path of the sample arm beam in the posterior segment information acquisition mode.

[0032] The reference arm beam splitting module comprises a beam splitting prism, a reference arm first focusing lens, a reference arm first reflecting mirror, a reference arm second focusing lens and a reference arm second reflecting mirror;

[0033] The reference arm light beam passing through the reference arm collimator is incident on the dichroic prism to be reflected and transmitted, the reference arm light beam transmitted through the dichroic prism is used as the first reference arm light beam, and the reference arm light beam reflected through the dichroic prism is used as the second reference arm light beam, the first reference arm light beam is converged by the first focusing lens of the reference arm and incident on the first reflecting mirror of the reference arm to be reflected, and the optical path of the first reference arm light beam matches the optical path of the sample arm light beam in the anterior segment information acquisition mode; the second reference arm light beam is converged by the second focusing lens of the reference arm and incident on the second reflecting mirror of the reference arm to be reflected, the second focusing lens of the reference arm and the second reflecting mirror of the reference arm as a whole serve as a posterior segment optical path adjustment module, the posterior segment optical path adjustment module is moved along the optical axis to achieve the optical path matching of the second reference arm light beam and the sample arm light beam in the posterior segment information acquisition mode.

[0034] The reference arm beam splitting module includes a reference arm second reflector and a reference arm third reflector. The reference arm light beam passing through the reference arm collimator is incident on the reference arm third reflector. The reference arm light beam reflected by the reference arm third reflector serves as the first reference arm light beam. The optical path of the first reference arm light beam matches the optical path of the sample arm light beam in the anterior segment of the eye information acquisition mode. The central opening of the reference arm third reflector is used. The reference arm light beam passing through the central hole of the reference arm third reflector and then incident on the reference arm second reflector serves as the second reference arm light beam. The reference arm second reflector serves as a posterior segment optical path adjustment module. The posterior segment optical path adjustment module is moved along the optical axis to achieve optical path matching of the second reference arm light beam and the sample arm light beam in the posterior segment of the eye information acquisition mode.

[0035] The second dichroic mirror is a long-wave pass dichroic mirror, which transmits the iris imaging beam emitted by the infrared illumination light source, reflects the sample arm beam and the fixation beam; the iris imaging light path shares the same light path with the OCT sample arm after passing through the second dichroic mirror.

[0036] The first dichroic mirror is a short-wave pass dichroic mirror, which transmits the fixation light beam emitted by the fixation light source and reflects the OCT sample arm light beam; the fixation light path shares the same light path with the OCT sample arm after passing through the first dichroic mirror.

[0037] The iris imaging module includes an iris imaging camera, an iris imaging focusing lens and an iris imaging diverging lens;

[0038] The light emitted by the infrared illumination light source is reflected by the cornea of ​​the eye to be tested to form an iris imaging beam, and the iris imaging beam is transmitted through the eyepiece objective lens, the second dichroic mirror, the iris imaging divergent lens and the iris imaging focusing lens in sequence along the optical axis before entering the iris imaging camera;

[0039] The fixation module includes a fixation light source and a fixation lens. The fixation light beam emitted by the fixation light source is sequentially transmitted through the fixation lens, the first dichroic mirror, the sample arm zoom module, reflected by the second dichroic mirror and transmitted by the eye contact lens, and then focused on the retina of the eye to be tested.

[0040] A displacement stage is provided under the posterior segment optical path adjustment module, and the displacement stage is, but is not limited to, a manual displacement stage or an electric displacement stage.

[0041] The second focusing lens and the second reflecting mirror of the reference arm are used as optical path calibration devices through the adjustment of the optical path adjustment module after the eye during self-check before the device collects data, and are used as the second reference arm optical path during the device collects data.

[0042] Compared with some existing methods and devices for measuring eye axis based on variable-focus OCT, the beneficial effects of the present invention are as follows:

[0043] (1) In order to solve the calculation error caused by the displacement of optomechanical components during the installation or use of the optical path in the existing axial length measurement methods, the reference position calibration method proposed in the present invention can calibrate the reference position of the optical path adjustment module of the posterior segment of the eye, that is, calibrate the reference position of the optical path of the second reference arm, adjust the optical path of the posterior segment of the eye according to the reference position, and then calculate the axial length according to the displacement of the optical path adjustment device, thereby eliminating the axial length calculation error.

[0044] (2) For devices that only focus on the anterior segment of the eye and only have a relatively blurred imaging result of the posterior segment of the eye, the exact position of the retinal pigment epithelium cannot be determined, which affects the accuracy of axial length measurement. In order to address this shortcoming of the prior art, the present invention can quickly focus the anterior segment of the eye and the posterior segment of the eye through a variable-focus liquid lens, obtain clear two-dimensional tomographic imaging results, and further improve the accuracy of axial length measurement.

[0045] (3) In particular, there is a common shortcoming in the existing OCT-based axial length measurement devices, that is, the calculation formula for the axial length includes the displacement of the optical delay line. If the displacement of the optomechanical components occurs during the installation or use of the optical path, calculation errors will be introduced into the axial length measurement. In view of this shortcoming of the prior art, the present invention adopts a reference arm beam splitting module to split the reference arm light beam into a first reference arm light beam and a second reference arm light beam. By adjusting the optical path adjustment module at the posterior node of the eye, the two reference arms are interfered before each acquisition. The reference position of the optical path adjustment device is calibrated based on the interference signals of the two reference arms, so as to avoid the axial length calculation error introduced by the displacement of the optomechanical components during the installation or use of the optical path.

[0046] In summary, in response to the deficiencies in the prior art, the present invention proposes an axial length measurement method and device based on variable-focus OCT, which can quickly focus on the anterior segment and posterior segment of the eye, further achieving fast and clear imaging of the anterior segment and posterior segment of the eye, and proposes a reference position calibration method, which can quickly calibrate the reference position of the posterior segment optical path before each axial length measurement, thereby helping to improve the accuracy of axial length measurement. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 is a schematic diagram of a device according to an embodiment of the present invention;

[0048] Figure 2 This is a schematic diagram of the sample arm focusing on the anterior segment of the eye according to an embodiment of the present invention;

[0049] Figure 3 This is a schematic diagram of the sample arm focusing on the posterior segment of the eye according to an embodiment of the present invention;

[0050] Figure 4 A schematic diagram of an embodiment of a sample arm of the present invention;

[0051] Figure 5A schematic diagram of an embodiment of a reference arm of the present invention;

[0052] Figure 6 Schematic diagram of OCT two-dimensional tomography results of the cornea and retina to be tested in the present invention.

[0053] In the figure: 1- broadband light source; 2- fiber coupler; 3- polarization controller; 4- reference arm collimator; 5- beam splitter; 6- reference arm first focusing lens; 7- reference arm first reflector; 8- reference arm second focusing lens; 9- reference arm second reflector; 11- spectrometer collimator; 12- reflective grating; 13- spectrometer focusing lens; 14- spectrometer camera; 15- sample arm collimator; 16- variable focus liquid lens; 17- scanning galvanometer; 18- first dichroic mirror; 19- sample arm relay lens; 20- second dichroic mirror; 21- eyepiece objective lens; 22- infrared illumination light source; 23- iris imaging divergent lens; 24- iris imaging focusing lens; 25- iris imaging camera; 26- fixation lens; 27- fixation light source; 28- eye to be tested; 29- reference arm third reflector. DETAILED DESCRIPTION

[0054] The specific implementation of the present invention will be described in detail below in conjunction with the accompanying drawings, which form a part of this document. It should be noted that these descriptions and examples are only exemplary and cannot be understood as limiting the scope of the present invention. The scope of protection of the present invention is defined by the attached claims, and any changes based on the claims of the present invention are within the scope of protection of the present invention.

[0055] To facilitate understanding of the embodiments of the present invention, each operation is described as a plurality of discrete operations; however, the order of description does not represent the order of implementing the operations.

[0056] Embodiments of the present invention are as follows:

[0057] like Figure 1 As shown, it includes an OCT main body module, an OCT sample arm module, an OCT reference arm module, an iris imaging module and a fixation module;

[0058] The sample arm beam emitted from the OCT main module is incident on the OCT sample arm module, and the reference arm beam emitted from the OCT main module is incident on the OCT reference arm module. The OCT sample arm module is connected to the iris imaging module and the fixation module respectively, and the OCT sample arm module measures the eye to be measured 28;

[0059] The OCT main module includes a broadband light source 1, a fiber coupler 2 and a spectrometer, wherein the spectrometer is composed of a spectrometer collimator 11, a reflective grating 12, a spectrometer focusing lens 13 and a spectrometer camera 14; the first input end of the fiber coupler 2 is connected to the broadband light source 1, the second input end of the fiber coupler 2 is connected to the spectrometer collimator 11, the spectrometer collimator 11 is sequentially connected to the reflective grating 12 and the spectrometer focusing lens 13 and then connected to the spectrometer camera 14, the first output end of the fiber coupler 3 emits a sample arm beam, and the second output end of the fiber coupler 3 emits a reference arm beam, that is, the first output end of the fiber coupler 3 is connected to the sample arm collimator 15 of the OCT sample arm module, and the second output end of the fiber coupler 3 is connected to the polarization controller 3 of the OCT reference arm module.

[0060] The OCT sample arm module includes a sample arm collimator 15, a sample arm zoom module, a second dichroic mirror 20, an eye lens 21 and an infrared illumination light source 22; the sample arm light beam emitted from the first output end of the fiber coupler 3 in the OCT main body module is incident on the sample arm collimator 15, and the sample arm light beam after passing through the sample arm collimator 15 is incident on the eye to be tested 28 after being reflected by the sample arm zoom module and the second dichroic mirror 20 and transmitted by the eye lens 21 along the optical axis, and the infrared illumination light source 22 is installed on the side of the eye lens 21;

[0061] The light emitted by the infrared illumination light source 22 is reflected by the cornea of ​​the eye to be tested 28 to form an iris imaging beam, and the iris imaging beam is incident on the iris imaging module after being transmitted by the eye-receiving objective lens 21 and the second dichroic mirror 20 in sequence along the optical axis;

[0062] The fixation beam emitted by the fixation module is incident on the sample arm zoom module, and the fixation beam after passing through the sample arm zoom module is incident on the second dichroic mirror 20. The fixation beam reflected by the second dichroic mirror 20 is then transmitted through the eye contact lens 21 and then incident on the eye to be tested 28.

[0063] An embodiment of the OCT sample arm module of the present invention is as follows Figure 2 As shown, the sample arm zoom module includes a liquid variable focus lens 16, a scanning galvanometer 17, a first dichroic mirror 18 and a sample arm relay lens 19; the sample arm light beam after passing through the sample arm collimator 15 is incident on the second dichroic mirror 20 after being sequentially transmitted along the optical axis by the liquid variable focus lens 16, reflected by the scanning galvanometer 17, reflected by the first dichroic mirror 18 and transmitted by the sample arm relay lens 19;

[0064] In the anterior segment information acquisition mode, the rear focus of the liquid variable focus lens 16 coincides with the front focus of the sample arm relay lens 19, so that the sample arm light beam reflected by the second dichroic mirror 20 enters the eye lens 21 in the form of parallel light, and then converges on the cornea of ​​the eye to be tested 28 through the eye lens 21, so as to realize the acquisition of the anterior segment information. Figure 2 As shown; in the posterior segment information acquisition mode, the rear focus of the sample arm relay lens 19 coincides with the front focus of the eye lens 21. At this time, the refractive power of the variable focus liquid lens 16 is 0D, so that the sample arm light beam transmitted through the eye lens 21 is incident on the eye to be tested 28 in the form of parallel light. The eye to be tested 28 itself converges the sample arm light beam on the retina to realize the acquisition of the posterior segment information of the eye, as shown in FIG. Figure 3 After returning along the original optical path, the sample arm beam carrying the anterior segment information and the sample arm beam carrying the posterior segment information are alternately transmitted from the first output end of the optical fiber coupler 2 to the spectrometer camera 14.

[0065] like Figure 4 As shown, another embodiment of the OCT sample arm module of the present invention is that the sample arm zoom module includes a liquid variable focus lens 16, a scanning galvanometer 17 and a first dichroic mirror 18; the sample arm light beam after passing through the sample arm collimator 15 is incident on the second dichroic mirror 20 after being reflected by the scanning galvanometer 17, reflected by the first dichroic mirror 18 and transmitted by the liquid variable focus lens 16 along the optical axis;

[0066] In the anterior segment information acquisition mode, the refractive power of the liquid variable focus lens 16 is 0D, and the sample arm light beam reflected from the first dichroic mirror 18 is still emitted as a parallel light beam after being transmitted through the liquid variable focus lens 16, and then is reflected by the second dichroic mirror 20 and converged on the human cornea through the eye contact objective lens 21; in the posterior segment information acquisition mode, the liquid variable focus lens 16 adjusts the focal length so that the rear focus of the liquid variable focus lens 16 coincides with the front focus of the eye contact objective lens 21, forming a Keplerian telescope system, and the sample arm light beam reflected from the first dichroic mirror 18 enters the liquid variable focus lens 16 as a parallel light beam, and the sample arm light beam after being transmitted through the liquid variable focus lens 16 is then emitted at the eye contact objective lens 21 in the form of a parallel light beam and enters the eye to be tested 28, and finally converges on the retina through the human eye lens; by synchronizing the focal length switching of the liquid variable focus lens 16 with the acquisition of the spectrometer camera 14, fast focusing and alternating acquisition of OCT images of the whole eye can be achieved.

[0067] The fixation beam emitted by the fixation module is incident on the first dichroic mirror 18 , and the fixation beam transmitted through the first dichroic mirror 18 and the sample arm beam reflected through the first dichroic mirror 18 share a common optical path.

[0068] The infrared illumination light source includes but is not limited to using two or more infrared point light sources, and evenly distributed on both sides of the eyepiece objective lens.

[0069] The light emitted by the infrared illumination light source 22 is reflected by the cornea of ​​the eye to be tested 28 to form an iris imaging beam, and the iris imaging beam is incident on the iris imaging module after being transmitted by the eye-receiving objective lens 21 and the second dichroic mirror 20 in sequence along the optical axis;

[0070] The OCT reference arm module includes a polarization controller 3, a reference arm collimator 4 and a reference arm beam splitting module. The reference arm beam emitted from the second output end of the optical fiber coupler 3 in the OCT main module is incident on the polarization controller 3. The reference arm beam passing through the polarization controller 3 is incident on the reference arm beam splitting module after passing through the reference arm collimator 4. The reference arm beam is split into a first reference arm beam and a second reference arm beam in the reference arm beam splitting module. The optical path of the first reference arm beam matches the optical path of the sample arm beam in the anterior segment information acquisition mode. The first reference arm beam and the sample arm beam carrying the anterior segment information generate a sample arm anterior segment weak coherence interference signal at the optical fiber coupler 2. The anterior segment OCT image is obtained after the interference signal is received by the spectrometer camera 14. The optical path of the second reference arm beam matches the optical path of the sample arm beam in the posterior segment information acquisition mode. The second reference arm beam and the sample arm beam carrying the posterior segment information generate a sample arm posterior segment weak coherence interference signal at the optical fiber coupler 2. The posterior segment OCT image is obtained after the interference signal is received by the spectrometer camera 14.

[0071] like Figure 1 As shown, the reference arm beam splitting module includes a beam splitting prism 5, a reference arm first focusing lens 6, a reference arm first reflecting mirror 7, a reference arm second focusing lens 8 and a reference arm second reflecting mirror 9;

[0072] The reference arm light beam passing through the reference arm collimator 4 is incident on the dichroic prism 5 for reflection and transmission. The reference arm light beam transmitted through the dichroic prism 5 is used as the first reference arm light beam, and the reference arm light beam reflected by the dichroic prism 5 is used as the second reference arm light beam. The first reference arm light beam is converged by the reference arm first focusing lens 6 and is incident on the reference arm first reflecting mirror 7 for reflection. The optical path of the first reference arm light beam matches the optical path of the sample arm light beam in the anterior segment information acquisition mode. The second reference arm light beam is converged by the reference arm second focusing lens 8 and is incident on the reference arm second reflecting mirror 9 for reflection. The reference arm second focusing lens 8 and the reference arm second reflecting mirror 9 as a whole serve as a posterior segment optical path adjustment module. The posterior segment optical path adjustment module is moved along the optical axis to achieve optical path matching between the second reference arm light beam and the sample arm light beam in the posterior segment information acquisition mode.

[0073] The iris imaging module includes an iris imaging camera 25, an iris imaging focusing lens 24 and an iris imaging diverging lens 23; the light emitted by the infrared illumination light source 22 is reflected by the cornea of ​​the eye to be tested 28 to form an iris imaging beam, and the iris imaging beam is transmitted along the optical axis through the eye contact lens 21, the second dichroic mirror 20, the iris imaging diverging lens 23 and the iris imaging focusing lens 24 in sequence, and then enters the iris imaging camera 25;

[0074] The second dichroic mirror 20 is a long-wave pass dichroic mirror, which transmits the iris imaging beam emitted by the infrared illumination light source 22, reflects the sample arm beam and the fixation beam; the iris imaging light path shares the same light path with the OCT sample arm after passing through the second dichroic mirror.

[0075] The fixation module includes a fixation light source 27 and a fixation lens 26. The fixation light beam emitted by the fixation light source 27 is sequentially transmitted through the fixation lens 26, the first dichroic mirror 18, the sample arm focusing lens 19, reflected by the second dichroic mirror 20 and transmitted by the eye contact lens 21, and then focused on the retina of the eye to be tested through the eye to be tested 28.

[0076] The first dichroic mirror 18 is a short-wave pass dichroic mirror, which transmits the fixation light beam emitted by the fixation light source 27 and reflects the OCT sample arm light beam; the fixation light path shares the same light path with the OCT sample arm after passing through the first dichroic mirror.

[0077] A translation stage is arranged under the posterior segment optical path adjustment module, and the translation stage includes but is not limited to a manual translation stage or an electric translation stage.

[0078] When the reference arm second focusing lens 8 and the reference arm second reflecting mirror 9 are self-checked before the device collects data, the self-check is achieved by moving the reference arm second focusing lens 8 and the reference arm second reflecting mirror 9 on a displacement stage.

[0079] During the eye axis measurement process, the broadband light source 1 emits an OCT beam, which is split by the fiber coupler 2, passes through the polarization controller 3, enters the reference arm, is collimated by the reference arm collimator, enters the beam splitter prism as a parallel beam, and is split into the first reference arm beam and the second reference arm beam, which are respectively passed through the reference arm first focusing lens 6 and the reference arm second focusing lens 8 and converged on the reference arm first reflector 7 and the reference arm second reflector 9. On the other hand, the original light path returns to the fiber coupler 2 after being reflected by the reflector; the other path passes through the sample arm collimator 15 and enters the liquid variable focus lens 16 as a parallel light beam. In the anterior segment information acquisition mode, the rear focus of the variable focus lens coincides with the front focus of the relay lens, so that the parallel light beam emitted by the sample arm collimator 15 passes through the liquid variable focus lens 16, the scanning galvanometer 17, the first dichroic mirror 18, and the relay lens 19, and then enters the eye lens 21 as a parallel light beam after being reflected by the second dichroic mirror and converges on the cornea of ​​the eye to be tested 28, forming the first sample arm light beam carrying the anterior segment information of the eye to be tested and returns to the fiber coupler 2, and forms an anterior segment weak coherent interference signal with the first reference arm light beam, and finally It is then received by the spectrometer and its camera; in the posterior segment of the eye information acquisition mode, the refractive power of the variable focus lens is 0D, and the parallel light beam emitted by the sample arm collimator 15 passes through the variable focus lens, and is still reflected by the scanning galvanometer 17 and the first dichroic mirror 18 as a parallel light beam, and then enters the sample arm relay lens 19. At this time, the rear focus of the sample arm relay lens 19 coincides with the front focus of the eye lens 21, and the sample arm light beam enters the eye to be tested 28 as a parallel light beam, passes through the human eye lens and converges on the retina, forming a second sample arm light beam carrying the posterior segment of the eye to be tested. The light returns to the fiber coupler 2, and forms a posterior segment weak coherent interference signal with the second reference arm light beam, and is finally received by the spectrometer and its camera. In addition, in the posterior segment of the eye information acquisition mode, the convergence degree of the sample arm light beam is changed by adjusting the refractive power of the variable focus lens, so that under different diopter conditions of human eyes, the second sample arm light beam can converge on the retina of the human eye.

[0080] During the axial length measurement process, the fixation light source 27 is approximately a point light source after passing through the internal aperture diaphragm. After passing through the fixation lens, a parallel visible light beam is formed and transmitted through the first dichroic mirror 18. The rear focus of the sample arm relay lens 19 in the sample arm coincides with the front focus of the eye contact lens 21. After passing through the sample arm relay lens 19 and the eye contact lens 21, the light beam is focused on the retina of the eye to be measured 28 to maintain the stability of the line of sight of the eye to be measured 28.

[0081] During the axial length measurement process, the infrared illumination light source 22 emits an illumination beam to illuminate the anterior segment of the eye to be measured 28, and the visual signal carrying the anterior segment of the eye is transmitted through the eye-receiving objective lens 21, the second dichroic mirror 20, the iris imaging divergent lens 23, and the iris imaging focusing lens 24 in sequence, and finally converges on the target surface of the iris imaging camera 25 to obtain the iris imaging result of the eye to be measured 28 in real time.

[0082] like Figure 5 As shown, another embodiment of the OCT reference arm module of the present invention is that the reference arm beam splitting module includes a reference arm second reflector 9 and a reference arm third reflector 29, and the reference arm third reflector 29 is a reflector with a hole in the middle, and the diameter of the hole is equal to the diameter of the exit spot of the reference arm collimator 4. times, to ensure that the light intensity of the first reference arm beam and the second reference arm beam is equal, the reference arm beam passing through the reference arm collimator 4 is incident on the reference arm third reflector 29, the reference arm beam reflected by the reference arm third reflector 29 is used as the first reference arm beam, and the optical path of the first reference arm beam matches the optical path of the sample arm beam in the anterior segment information acquisition mode; the central opening of the reference arm third reflector 29, the reference arm beam passing through the central hole of the reference arm third reflector 29 and incident on the reference arm second reflector 9 is used as the second reference arm beam, that is, the reference arm beam reflected by the reference arm second reflector 9, the reference arm second reflector 9 is used as the posterior segment optical path adjustment module, the posterior segment optical path adjustment module is moved along the optical axis, and the optical path of the second reference arm beam matches the optical path of the sample arm beam in the posterior segment information acquisition mode. Before the start of the axial measurement, the first reference arm beam and the second reference arm beam are interfered by moving the reference arm second reflector 9, and the optical path of the axial measurement is self-checked using the interference signal of the double reference arms, so that the posterior segment optical path adjustment module is in the zero optical path reference position.

[0083] The method of the present invention comprises the following steps:

[0084] S1: Before the acquisition begins, the axial length measurement device is self-checked using the posterior segment optical path adjustment module, and after the self-check, the posterior segment optical path adjustment module is calibrated to be in the reference position for axial length measurement;

[0085] S1 is specifically:

[0086] The optical path adjustment module of the posterior eye section is adjusted so that the first reference arm beam and the second reference arm beam in the reference arm beam splitting module form an interference signal in the optical fiber coupler 2, and the spectrometer camera 14 detects and collects the interference image. At this time, the position of the optical path adjustment module of the posterior eye section is used as the reference position for eye axis measurement. When the reference arm beam splitting module is composed of a beam splitter prism 5, a first focusing lens 6 of the reference arm, a first reflector 7 of the reference arm, a second focusing lens 8 of the reference arm, and a second reflector 9 of the reference arm, the optical path adjustment module of the posterior eye section is adjusted so that the interference image is located at a zero optical path difference position. At this time, the first reference arm beam and the second reference arm beam are respectively propagated along their respective optical paths and then reflected back to the beam splitter prism by the reflector. The optical path of the first reference arm beam is equal to the optical path of the second reference arm beam, and the optical path difference d4 of the two reference arms is zero. When the reference arm beam splitting module is composed of the reference arm second reflector 9 and the reference arm third reflector 29, the optical path adjustment module of the rear eye section is adjusted to make the first reference arm light beam and the second reference arm light beam interfere with each other. Due to the limitation of the thickness of the reflector, the interference image is no longer located at the zero optical path difference position. A suitable interference position is selected for calibration. According to the set interference envelope peak position, the optical path difference between the two reference arms at this time is recorded as d4.

[0087] S2: Adjust the axial length measuring device to make the iris image clear, so that the anterior segment OCT image appears at the imaging focus position of the first OCT image display frame. At this time, the focal length of the variable focus liquid lens 16 is recorded as the first focal length; in the OCT system in which the anterior segment and the posterior segment of the eye are imaged alternately, the anterior segment and the posterior segment OCT images are distinguished by odd and even frames, the odd frames correspond to the anterior segment of the eye, and the even frames correspond to the posterior segment of the eye; therefore, in the imaging software, two image display frames of odd and even frames are usually set, where the anterior segment of the eye appears in the odd imaging frame (i.e., the first OCT image display frame), and the posterior segment of the eye will appear in the even imaging frame (i.e., the second OCT image display frame).

[0088] S2 is specifically:

[0089] Adjust the eye axis measurement device and use the iris imaging optical path to preliminarily locate the corneal position of the eye to be tested 28. The iris imaging optical path and the anterior segment OCT optical path are confocal. When the iris image is clear, the front surface of the cornea of ​​the eye to be tested is exactly located at the focal position of the eye-viewing objective lens 21. At this time, the anterior segment OCT image appears at the imaging focal position (i.e., the preset pixel position) of the first OCT image display frame. Then move the corneal section position of the eye to be tested up and down, so that a central light column caused by strong reflection from the corneal vertex appears in the first OCT image display frame. At this time, the focal length of the variable-focus liquid lens 16 is recorded as the first focal length.

[0090] S3: the posterior segment optical path adjustment module moves along the optical axis until the posterior segment OCT image appears at a preset pixel position of the second OCT image display frame, and the displacement of the posterior segment optical path adjustment module is recorded;

[0091] S3 is specifically:

[0092] The posterior segment optical path adjustment module moves along the optical axis from the reference position until the posterior segment OCT image appears at the preset pixel position of the second OCT image display frame. The optical path of the second reference arm light beam matches the optical path of the sample arm light beam in the posterior segment information acquisition mode, and the displacement of the posterior segment optical path adjustment module at this time is recorded.

[0093] S4: The variable-focus liquid lens 16 traverses within a preset focal length range until the posterior segment OCT image is clear, and the focal length of the variable-focus liquid lens 16 is recorded and recorded as a second focal length; when the variable-focus liquid lens is at the second focal length, the posterior segment information acquisition mode is performed.

[0094] S5: The variable-focus liquid lens switches between the first focal length and the second focal length to alternately acquire two-dimensional OCT images of the anterior segment and the posterior segment of the eye;

[0095] S6: Calculate the axial length of the eye to be tested based on the two-dimensional OCT images of the anterior segment and the posterior segment of the eye to be tested 28 and the displacement of the posterior segment optical path adjustment module.

[0096] S6 is specifically:

[0097] According to the two-dimensional OCT images of the anterior segment and posterior segment of the eye 28 to be tested, the pixel positions of the anterior surface of the cornea and the retinal pigment epithelial cell layer of the eye 28 to be tested are obtained, and then according to the displacement of the optical path adjustment module of the posterior segment, the distance between the anterior surface of the cornea of ​​the eye 28 to be tested and the retinal pigment epithelial cell layer is calculated and used as the axial length of the eye 28 to be tested.

[0098] like Figure 6 As shown, in S6, the two-dimensional OCT images of the anterior segment and the posterior segment of the eye to be tested 28 are merged into the OCT two-dimensional imaging result of the eye to be tested 28, and the pixel positions of the anterior surface of the cornea and the retinal pigment epithelial cell layer of the eye to be tested 28 are obtained after image processing of the OCT two-dimensional imaging result of the eye to be tested 28 using a boundary recognition method; the distance between the vertex of the anterior surface of the cornea of ​​the eye to be tested 28 and the zero optical path difference position is d1, the distance between the retinal pigment epithelium and the zero optical path difference position is d2, and the displacement of the posterior segment optical path adjustment module is d3, then the axial length D of the eye to be tested 28 satisfies D=d2-d1+d3+d4.

[0099] When the reference arm beam splitting module includes the beam splitting prism 5, the reference arm first focusing lens 6, the reference arm first reflector 7, the reference arm second focusing lens 8 and the reference arm second reflector 9, that is, when zero optical path calibration is performed, d4 ​​= 0; when the reference arm beam splitting module includes the reference arm second reflector 9 and the reference arm third reflector 29, d4 ≠0.

Claims

1. A method for measuring eye axis based on variable focus OCT, characterized in that: The following steps are involved: S1: Before the acquisition begins, the axial length measurement device is self-checked using the posterior segment optical path adjustment module, and after the self-check, the posterior segment optical path adjustment module is calibrated to be in the reference position for axial length measurement; S2: adjusting the eye axis measurement device so that the iris image is clear, and the anterior segment OCT image appears at the imaging focus position of the first OCT image display frame, and the focal length of the variable focus liquid lens (16) is recorded as the first focal length; S3: the posterior segment optical path adjustment module moves along the optical axis until the posterior segment OCT image appears at a preset pixel position of the second OCT image display frame, and the displacement of the posterior segment optical path adjustment module is recorded; S4: the variable-focus liquid lens (16) traverses within a preset focal length range until the posterior segment OCT image is clear, and the focal length of the variable-focus liquid lens (16) is recorded and recorded as a second focal length; S5: The variable-focus liquid lens switches between the first focal length and the second focal length to alternately acquire two-dimensional OCT images of the anterior segment and the posterior segment of the eye; In the anterior segment information collection mode, the rear focus of the variable focus liquid lens (16) and the front focus of the sample arm relay lens (19) coincide with each other, so that the sample arm light beam reflected by the second dichroic mirror (20) enters the eye contact lens (21) in the form of parallel light, and then converges on the cornea of ​​the eye to be tested (28) through the eye contact lens (21), thereby realizing the collection of the anterior segment information; in the posterior segment information collection mode, the rear focus of the sample arm relay lens (19) and the front focus of the eye contact lens (21) coincide with each other, so that the sample arm light beam transmitted by the eye contact lens (21) enters the eye to be tested (28) in the form of parallel light, and the eye to be tested (28) converges the sample arm light beam on the retina, thereby realizing the collection of the posterior segment information; S6: calculating the axial length of the eye to be tested based on the two-dimensional OCT images of the anterior segment and the posterior segment of the eye to be tested (28) and the displacement of the posterior segment optical path adjustment module; The S1 is specifically: The optical path adjustment module at the posterior eye section is adjusted so that the first reference arm light beam and the second reference arm light beam in the reference arm beam splitting module form an interference signal in the optical fiber coupler (2), and the spectrometer camera (14) detects and collects the interference image. At this time, the position of the optical path adjustment module at the posterior eye section is used as the reference position for measuring the eye axis.

2. The method for measuring eye axis based on variable focus OCT according to claim 1, characterized in that: The S2 is specifically: The eye axis measuring device is adjusted, and the corneal position of the eye to be tested (28) is preliminarily located using the iris imaging optical path. When the iris image is clear, the front surface of the cornea of ​​the eye to be tested is exactly located at the focal position of the eye contact objective lens (21). At this time, the anterior segment OCT image appears at the imaging focal position of the first OCT image display frame. The corneal section position of the eye to be tested is then moved up and down, so that a central light column caused by strong reflection from the corneal vertex appears in the first OCT image display frame. At this time, the focal length of the variable focus liquid lens (16) is recorded as the first focal length.

3. The method for measuring eye axis based on variable focus OCT according to claim 1, characterized in that: The S3 is specifically: The posterior segment optical path adjustment module moves along the optical axis from the reference position until the posterior segment OCT image appears at the preset pixel position of the second OCT image display frame. The optical path of the second reference arm light beam matches the optical path of the sample arm light beam in the posterior segment information acquisition mode, and the displacement of the posterior segment optical path adjustment module at this time is recorded.

4. The method for measuring eye axis based on variable focus OCT according to claim 1, characterized in that: The S6 is specifically: Based on the two-dimensional OCT images of the anterior segment and posterior segment of the eye to be tested (28), the pixel positions of the anterior surface of the cornea and the retinal pigment epithelial cell layer of the eye to be tested (28) are obtained, and then based on the displacement of the posterior segment optical path adjustment module, the distance between the anterior surface of the cornea of ​​the eye to be tested (28) and the retinal pigment epithelial cell layer is calculated and used as the axial length of the eye to be tested (28).

5. An eye axis measurement device based on variable focus OCT for implementing the eye axis measurement method according to any one of claims 1 to 4, characterized in that: It comprises an OCT main body module, an OCT sample arm module, an OCT reference arm module, an iris imaging module and a fixation module; the sample arm beam emitted from the OCT main body module is incident on the OCT sample arm module, the reference arm beam emitted from the OCT main body module is incident on the OCT reference arm module, the OCT sample arm module is connected to the iris imaging module and the fixation module respectively, and the OCT sample arm module measures the eye to be measured (28); The OCT sample arm module comprises a sample arm collimator (15), a sample arm zoom module, a second dichroic mirror (20), an eyepiece objective lens (21) and an infrared illumination light source (22); the sample arm light beam emitted by the OCT main body module is incident on the sample arm collimator (15), and the sample arm light beam after passing through the sample arm collimator (15) is incident on the eye to be tested (28) after being reflected by the sample arm zoom module and the second dichroic mirror (20) and transmitted by the eyepiece objective lens (21) along the optical axis in sequence; an infrared illumination light source (22) is installed on the side of the eyepiece objective lens (21); The light emitted by the infrared illumination light source (22) is reflected by the cornea of ​​the eye to be tested (28) to form an iris imaging light beam, and the iris imaging light beam is incident on the iris imaging module after being sequentially transmitted through the eyepiece objective lens (21) and the second dichroic mirror (20) along the optical axis; The fixation light beam emitted by the fixation module is incident on the sample arm zoom module, the fixation light beam after passing through the sample arm zoom module is incident on the second dichroic mirror (20), the fixation light beam reflected by the second dichroic mirror (20) is then transmitted through the eye contact objective lens (21) and then incident on the eye to be tested (28).

6. The eye axis measurement device based on variable focus OCT according to claim 5, characterized in that: The sample arm zoom module comprises a variable focus liquid lens (16), a scanning galvanometer (17) and a first dichroic mirror (18); the sample arm light beam after passing through the sample arm collimator (15) is sequentially reflected by the scanning galvanometer (17), reflected by the first dichroic mirror (18) and transmitted by the variable focus liquid lens (16) along the optical axis, and then incident on the second dichroic mirror (20); in an anterior segment information collection mode, the refractive power of the variable focus liquid lens (16) is 0D, and the sample arm light beam reflected from the first dichroic mirror 18 is still at 0D after being transmitted through the variable focus liquid lens (16). The parallel light beam is emitted, and then reflected by the second dichroic mirror 20 and converged on the human cornea through the eyepiece objective lens (21); in the posterior segment information collection mode, the rear focus of the variable focus liquid lens (16) coincides with the front focus of the eyepiece objective lens (21), and the sample arm light beam reflected from the first dichroic mirror (18) enters the variable focus liquid lens (16) as a parallel light beam. After being transmitted through the variable focus liquid lens (16), the sample arm light beam is emitted from the eyepiece objective lens (21) as a parallel light beam and enters the eye to be tested (28), and finally converges on the retina through the human eye lens.

7. The eye axis measurement device based on variable focus OCT according to claim 5, characterized in that: The sample arm zoom module comprises a variable focus liquid lens (16), a scanning galvanometer (17), a first dichroic mirror (18) and a sample arm relay lens (19); the sample arm light beam after passing through the sample arm collimator (15) is sequentially transmitted along the optical axis through the variable focus liquid lens (16), reflected by the scanning galvanometer (17), reflected by the first dichroic mirror (18) and transmitted by the sample arm relay lens (19), and then incident on the second dichroic mirror (20).

8. The eye axis measurement device based on variable focus OCT according to claim 5, characterized in that: The OCT reference arm module comprises a polarization controller (3), a reference arm collimator (4) and a reference arm beam splitting module. The reference arm beam emitted by the OCT main body module is incident on the polarization controller (3). The reference arm beam passing through the polarization controller (3) is incident on the reference arm beam splitting module after passing through the reference arm collimator (4). The reference arm beam splitting module splits the reference arm beam into a first reference arm beam and a second reference arm beam. The optical path of the first reference arm beam matches the optical path of the sample arm beam in an anterior segment information collection mode. The optical path of the second reference arm beam matches the optical path of the sample arm beam in a posterior segment information collection mode.

9. The eye axis measurement device based on variable focus OCT according to claim 8, characterized in that: The reference arm beam splitting module comprises a reference arm second reflector (9) and a reference arm third reflector (29); the reference arm light beam passing through the reference arm collimator (4) is incident on the reference arm third reflector (29); the reference arm light beam reflected by the reference arm third reflector (29) serves as a first reference arm light beam; the optical path of the first reference arm light beam matches the optical path of the sample arm light beam in an anterior segment information collection mode; the reference arm third reflector (29) has a central opening; the reference arm light beam passing through the central hole of the reference arm third reflector (29) and then incident on the reference arm second reflector (9) serves as a posterior segment optical path adjustment module; the posterior segment optical path adjustment module is moved along the optical axis to achieve optical path matching of the second reference arm light beam with the optical path of the sample arm light beam in an posterior segment information collection mode.

Images