CN114343564B

CN114343564B - OCT imaging device in ultra-large range and imaging method thereof

Info

Publication number: CN114343564B
Application number: CN202210262931.3A
Authority: CN
Inventors: 任秋实; 胡毅成; 黄智宇; 周传清
Original assignee: Peking University; Peking University Shenzhen Graduate School
Current assignee: Peking University; Peking University Shenzhen Graduate School
Priority date: 2022-03-17
Filing date: 2022-03-17
Publication date: 2022-05-17
Anticipated expiration: 2042-03-17
Also published as: CN114343564A

Abstract

The invention discloses an ultra-large range OCT imaging device and an imaging method thereof. The invention is based on the optical fiber beam splitter, and can realize the simultaneous imaging of the anterior segment and the posterior segment of the eye by only utilizing a sweep frequency light source, a detector and a data acquisition card; a 1 Xn optical fiber beam splitter is utilized to generate a plurality of sample arm branches, and the optical path difference between different sample arm branches and the same reference arm is set to be different values, so that interference signals generated by different sample arm branches are positioned in different frequency ranges, and the purpose that the same detector simultaneously detects the interference signals of the anterior segment and the posterior segment of the eye is realized; the axial imaging range and the transverse imaging range of the OCT imaging device are enlarged by designing a sample arm light path; according to the invention, a distance measurement light source and an optical fiber type electric attenuator are added as position detection modules, so that the problem of inaccurate alignment is solved, the field curvature aberration can be effectively reduced, the imaging quality of the edge field is improved, and the image distortion caused by eyeball shake can be effectively eliminated.

Description

OCT imaging device in ultra-large range and imaging method thereof

Technical Field

The invention relates to the human eye optical imaging technology, in particular to an ultra-wide range OCT imaging device and an imaging method thereof.

Background

Optical Coherence Tomography (OCT) is a major component of contemporary ophthalmic care and can provide high resolution cross-sectional images of ocular structures. However, since the first reports of OCT, typical anterior segment OCT systems do not image the posterior segment of the eye well, such as the retina and choroid; in contrast, typical posterior segment OCT systems do not image the anterior segment of the eye well, such as the cornea and the lens. Due to this physical separation in imaging capabilities, the use of OCT as a comprehensive scanner for the entire eye is limited.

The whole-eye OCT system can capture OCT images of the posterior segment and the anterior segment of the eye simultaneously or sequentially to generate a true whole-eye image. In the Fan et al literature (Fan S, Li L, Li Q, et al, Dual band Dual focal optical coherence tomography for imaging the porous eye segment [ J ]. Biomedical optical coherence tomography, 2015, 6(7): 2481-2493.), a Dual band Dual focal spectral domain optical coherence tomography system was developed that can be used for in vivo 2D/3D imaging of the entire segment of the eye, including the entire anterior segment of the eye and the retina. The system has two OCT channels centered at 840 nm and 1050 nm at two different wavelength bands for imaging the retina and the anterior segment of the eye, respectively. Coaxial scanning is performed by combining two probe beams. The disadvantage of this system is insufficient imaging depth of the anterior segment; the structure is complicated, a plurality of lasers are needed, the cost is high, and the debugging is difficult. In recent decades, with the continuous progress of electronic technology, swept-frequency OCT based on a swept-frequency light source brings about a leap in scanning speed and imaging depth, and a novel OCT apparatus has entered the swept-frequency era at present.

Patent application No. CN201410243150.5 proposes a multifunctional ophthalmic frequency domain OCT that uses a galvanometer to separate the optical paths of the anterior segment and fundus oculi, achieving a fast switching function. However, the system is not simple in light path design, various in devices, complex in debugging, limited by the influence of frequency domain OCT, and not fast enough in imaging speed.

The patent with application number CN201810440088.7 proposes an optical interference imaging system of swept-frequency OCT, which uses a swept-frequency light source to achieve a faster imaging depth than frequency-domain OCT, but its optical path is single and cannot achieve both anterior ocular segment and fundus imaging.

Disclosure of Invention

In order to solve the problems of single measurement performance, slow running speed and small scanning field of view of the existing ophthalmology OCT measurement instrument, the invention provides an OCT imaging device with an ultra-large range and an imaging method thereof.

An object of the present invention is to provide an ultra-wide range OCT imaging apparatus.

The ultra-wide range OCT imaging apparatus of the invention comprises: the device comprises a sweep frequency light source, an optical fiber beam splitter, an interpolation clock module, a data acquisition card, a computer, a distance measurement light source, an optical fiber type electric attenuator, a wavelength division multiplexer, a general optical fiber coupler, a sample arm, an electric delay line, an equipartition optical fiber coupler, a balance photoelectric detector, a low-pass filter, a radio frequency attenuator and a master control module; the output end of the sweep frequency light source is connected to the input end of the optical fiber beam splitter through an optical fiber; the output end of the optical fiber beam splitter is respectively connected to the light beam input end of the interpolation clock module and one input end of the wavelength division multiplexer through optical fibers, and the output end of the interpolation clock module is connected to the external clock end of the data acquisition card through a radio frequency cable; the data acquisition card is connected to the computer through a data bus; the distance measuring light source is connected with the input end of the optical fiber type electric attenuator through an optical fiber; the output end of the optical fiber type electric attenuator is connected to the other input end of the wavelength division multiplexer; the output end of the wavelength division multiplexer is connected to a first port of the universal optical fiber coupler through an optical fiber, a second port of the universal optical fiber coupler is connected to the sample arm through an optical fiber, a third port of the universal optical fiber coupler is connected to one end of the electric delay line through an optical fiber, a fourth port of the universal optical fiber coupler is connected to a first port of the equal-division optical fiber coupler through an optical fiber, and the light-splitting ratio of the universal optical fiber coupler is set arbitrarily; the other end of the electric delay line is connected to a second port of the equipartition optical fiber coupler, and the electric delay line is used as a reference arm; the third and fourth ports of the equipartition optical fiber coupler are respectively connected to the balanced photoelectric detector through optical fibers; the balance photoelectric detector is connected to the low-pass filter through a radio frequency cable; the low-pass filter is connected with the radio frequency attenuator through a radio frequency cable; the radio frequency attenuator is connected to the signal end of the data acquisition card through a radio frequency cable; the synchronous trigger signal end of the sweep frequency light source is connected to the signal input end of the interpolation clock module through a radio frequency cable; the synchronous trigger signal end of the sweep frequency light source is connected to the master control module; the master control module is connected to a trigger port of the data acquisition card through a radio frequency cable;

the sample arm comprises a 1 xn optical fiber beam splitter and n paths of sample arm branches, a second port of the universal optical fiber coupler is connected to an input end of the 1 xn optical fiber beam splitter, n output ends of the 1 xn optical fiber beam splitter are respectively connected with the n paths of sample arm branches, light from the second port of the universal optical fiber coupler is divided into n paths through the 1 xn optical fiber beam splitter, and each path of sample arm branch meets the set requirement of optical path difference, namely different sample arm branches and a reference arm have different optical path differences, so that the interference signal frequencies of different sample arm branches and the reference arm are in different frequency band ranges; the master control module is connected to the scanning galvanometers of each sample arm branch through signal lines, and n is a natural number not less than 2;

the sweep frequency light source sends out a synchronous trigger signal T1 which is respectively connected to the interpolation clock module and the master control module and used as a reference clock signal thereof, so that the interpolation clock signal T2 output by the interpolation clock module, the trigger signal T3 generated by the master control module and the interference signal T4 carrying sample information output by the radio frequency attenuator are synchronous;

the frequency sweeping light source sends a beam of broadband light to the optical fiber beam splitter, and the broadband light is respectively transmitted to the interpolation clock module and the wavelength division multiplexer through a set proportion; the interpolation clock module obtains a complete interpolation clock signal T2 and transmits the complete interpolation clock signal T2 to the data acquisition card; the distance measuring light source emits laser to be transmitted to the optical fiber type electric attenuator; the optical fiber type electric attenuator adjusts the optical power of the laser entering the wavelength division multiplexer; the wavelength division multiplexer combines the broadband light emitted by the sweep frequency light source and the laser emitted by the ranging light source and inputs the combined beam to the universal optical fiber coupler; the universal optical fiber coupler transmits a part of light to the sample arm through the second port according to the set optical power proportion; irradiating the sample through a sample arm, wherein the sample is irradiated to generate scattered light; the scattered light is received by the sample arm and returns to the second port of the universal fiber coupler; the scattered light generated by the sample is transmitted to the averaging optical fiber coupler through the fourth port of the universal optical fiber coupler; the universal optical fiber coupler transmits the other part of light to the electric delay line through a third port; the electric delay line is used as a reference arm, the optical path difference of the reference arm is adjusted, and light with the optical path adjusted by the electric delay line is used as reference light and transmitted to the equipartition optical fiber coupler; the scattered light and the reference light interfere at the equipartition optical fiber coupler, and the interference light carries sample information; the equalizing optical fiber coupler equally divides the interference light and then transmits the interference light to the balance photoelectric detector; the balance photoelectric detector converts the interference light from an optical signal into an electric signal and transmits the electric signal to the low-pass filter; after high-frequency noise is suppressed by the low-pass filter, the high-frequency noise is transmitted to the radio frequency attenuator, the amplitude of an electric signal is adjusted by the radio frequency attenuator to meet the acquisition range of the data acquisition card, and an interference signal T4 is output; the master control module generates a trigger signal T3 according to a synchronous trigger signal T1 output by the sweep frequency light source and transmits the trigger signal to the data acquisition card to control the working time sequence of the whole OCT imaging device; the master control module generates control signals to control each path of sample arm branch to carry out synchronous scanning; the data acquisition card acquires an interference signal T4 which is output by the radio frequency attenuator and carries sample information according to a trigger signal T3; the data acquisition card transmits the interference signal T4 to the computer, and the computer analyzes the interference signal T4 to obtain a three-dimensional full-eye structure diagram and a blood flow diagram of the sample in an ultra-large field of view.

The interpolation clock module comprises: the Mach-Zehnder interferometer (MZI) optical path, the interpolation clock photoelectric detector, the first filter, the radio frequency amplifier, the second filter, the interpolation clock control module, the frequency multiplication clock module and the electronic switch; the optical fiber beam splitter splits a part of light beams emitted from the sweep frequency light source to an MZI optical path; an MZI optical path with an electric adjustable optical path difference generates an interference spectrum with a set frequency band, the range of the frequency band is 1 MHz-10 GHz, and the interference spectrum is input to an interpolation clock photoelectric detector; the interpolation clock photoelectric detector changes the interference spectrum into an initial interpolation clock signal, and the initial interpolation clock signal is changed into an interpolation clock signal with relatively consistent amplitude after sequentially passing through the first filter, the radio frequency amplifier and the second filter; the interpolation clock control module controls the frequency multiplication clock module to generate a base frequency clock signal, and the frequency is 0.1 MHz-100 MHz; the synchronous trigger signal end of the sweep frequency light source is connected to the interpolation clock control module, and the synchronous trigger signal T1 is transmitted to the interpolation clock control module; the interpolation clock control module carries out time sequence control according to a synchronous trigger signal T1 output by the sweep frequency light source, namely, according to the difference of the output spectrum duty ratio of the sweep frequency light source, the interpolation clock control module controls the electronic switch to output a base frequency clock signal generated by the frequency doubling clock module for the part without spectrum output; for the part with the spectrum output, controlling the electronic switch to output an interpolation clock signal generated by a second filter; the baseband clock signal and the interpolated clock signal generated by the second filter are combined together in a time sequence with or without spectral output to form a complete interpolated clock signal T2.

The n sample arm branches include: m paths of posterior eye sections and n-m paths of anterior eye sections, wherein m is a natural number, m is more than or equal to 0 and less than or equal to n, and n is a natural number more than or equal to 2.

Each posterior eye segment optical path comprises: the device comprises a first polarization controller, a first collimator, a first zoom lens, a first scanning galvanometer, a first lens and a second lens; one output end of the 1 Xn optical fiber beam splitter is connected to the first collimator through an optical fiber jumper, and a first polarization controller is arranged on the optical fiber jumper of which the output end is connected to the first collimator; the first lens and the second lens are arranged in a confocal manner to form a 4F system; the light beam passes through a first polarization controller, and interference signals of a posterior eye segment light path and a reference arm are adjusted to be maximized; the light beam is changed into parallel light after passing through the first collimator, the diopter of the incident light beam is adjusted through the first zoom lens, and then the incident light beam is transmitted to the first scanning galvanometer; the first scanning galvanometer is a two-dimensional scanning galvanometer, a pivot point is positioned on a focal plane of the first lens, and the first scanning galvanometer scans light beams according to a control signal generated by the master control module and irradiates the light beams to the posterior segment of the eye after passing through the first lens and the second lens; the imaging area of each posterior segment of the eye is different by adjusting the included angle between each posterior segment of the eye light path and the optical axis of the eye, and the field range of the whole posterior segment of the eye is enlarged.

Each anterior ocular segment optical path comprises: the second polarization controller, the second collimator, the second zoom lens, the second scanning galvanometer and the third lens; one output end of the 1 xn optical fiber beam splitter is connected to the second collimator through an optical fiber jumper, and a second polarization controller is arranged on the output end of the 1 xn optical fiber beam splitter through the optical fiber jumper connected to the second collimator; the light beam passes through a second polarization controller to adjust the interference signal of the anterior ocular segment light path so as to maximize the interference signal; the light beam is changed into parallel light after passing through a second collimator, the diopter of the incident light beam is adjusted through a second zoom lens, and then the incident light beam is transmitted to a second scanning galvanometer; the second scanning galvanometer is a two-dimensional scanning galvanometer, a pivot point is positioned on a focal plane of the third lens, and the second scanning galvanometer scans light beams according to a control signal generated by the master control module and irradiates the light beams to anterior segment of eyes after passing through the third lens; by adjusting the offset between the optical fiber jumper at the output end of the 1 Xn optical fiber beam splitter and the optical axis of the second collimator, different optical paths of the anterior segment of the eye and the optical axis of the second collimator have different offsets, so that different anterior segment regions of the eye are imaged, and the field range of the whole anterior segment imaging is enlarged.

And adjusting the optical fiber jumper corresponding to each path of posterior-segment optical path or anterior-segment optical path to enable the optical fiber jumper to meet the set length requirement, so that each path of sample arm branch and the reference arm meet the set optical path difference. And the master control module is connected to the scanning galvanometers of all paths of sample arm branches through signal lines.

The anterior segment light is focused on the anterior segment, i.e., the cornea and the crystalline lens; the light of the optical path of the posterior segment of the eye is focused on the posterior segment of the eye, namely the fundus.

The fixation lamp light path sequentially comprises a dichroic mirror, a lens and a display screen and is positioned on an eye optical axis; the dichroic mirror has high reflectivity to the wavelength of the swept-frequency light source and high transmittance to the wavelength generated by the display screen.

Furthermore, the invention also comprises an angle adjusting module which can flexibly adjust the incident beam angle of each path of sample arm branch; the angle adjusting module comprises a sample arm supporting plate, a first guide rail, a second guide rail and i lens sliding blocks; the sample arm supporting plate is a flat plate, and the surface of the sample arm supporting plate is respectively provided with a first guide rail and a second guide rail; the first guide rail and the second guide rail are both partial annular groove guide rails, the circular rings where the first guide rail and the second guide rail are located are concentric, and the samples are located in the circle centers and occupy the same proportion of the circular rings; the bottom ends of the i lens sliding blocks are respectively embedded into the first guide rail and the second guide rail and can slide along the first guide rail and the second guide rail, and the direction of the lens sliding blocks is along the radial direction of the circular ring where the first guide rail and the second guide rail are located; one lens sliding block is provided with one path of sample arm branch, i lens sliding blocks respectively correspond to i paths of sample arm branches, and i is a natural number less than or equal to n; the closer the slide block is to the circle center, the smaller the transverse size is; compare in rectangle slider, the advantage is that two camera lens sliders can be close to, and angular adjustment's scope is bigger. The bottom surface of the lens sliding block is respectively provided with a cylinder and a partial annular column, the cylinder and the partial annular column are respectively embedded into the grooves of the first guide rail and the second guide rail, and the curvature of the partial annular column is consistent with that of the guide rail; the cylinder and the part of the annular column slide in the first guide rail and the second guide rail to realize the sliding of the lens sliding block, and the part of the annular column is characterized in that the curvatures of the front surface and the rear surface of the part of the annular column are the same as the curvature of the groove of the second guide rail, so that the smoothness and the stability during sliding are ensured.

Another object of the present invention is to provide an ultra-wide range OCT imaging method.

The invention discloses an ultra-wide range OCT imaging method, which comprises the following steps:

1) the OCT imaging device is connected with:

the output end of the sweep frequency light source is connected to the input end of the optical fiber beam splitter through an optical fiber; the output end of the optical fiber beam splitter is respectively connected to the light beam input end of the interpolation clock module and one input end of the wavelength division multiplexer through optical fibers, and the output end of the interpolation clock module is connected to the external clock end of the data acquisition card through a radio frequency cable; the data acquisition card is connected to the computer through a data bus; the distance measuring light source is connected with the input end of the optical fiber type electric attenuator through an optical fiber; the output end of the optical fiber type electric attenuator is connected to the other input end of the wavelength division multiplexer; the output end of the wavelength division multiplexer is connected to a first port of the universal optical fiber coupler through an optical fiber, a second port of the universal optical fiber coupler is connected to the sample arm through an optical fiber, a third port of the universal optical fiber coupler is connected to one end of the electric delay line through an optical fiber, a fourth port of the universal optical fiber coupler is connected to a first port of the equal-division optical fiber coupler through an optical fiber, and the light-splitting ratio of the universal optical fiber coupler is set arbitrarily; the other end of the electric delay line is connected to a second port of the equipartition optical fiber coupler; the third and fourth ports of the equipartition optical fiber coupler are respectively connected to the balanced photoelectric detector through optical fibers; the balance photoelectric detector is connected to the low-pass filter through a radio frequency cable; the low-pass filter is connected with the radio frequency attenuator through a radio frequency cable; the radio frequency attenuator is connected to the signal end of the data acquisition card through a radio frequency cable; the synchronous trigger signal end of the sweep frequency light source is connected to the signal input end of the interpolation clock module through a radio frequency cable; the synchronous trigger signal end of the sweep frequency light source is connected to the master control module; the master control module is connected to a trigger port of the data acquisition card through a radio frequency cable;

the second port of the general optical fiber coupler is connected to the input end of the 1 xn optical fiber beam splitter, n output ends of the 1 xn optical fiber beam splitter are respectively connected with n paths of sample arm branches, and light from the second port of the general optical fiber coupler is divided into n paths through the 1 xn optical fiber beam splitter; the master control module is connected to each path of sample arm branch through a signal line, and n is a natural number not less than 2;

2) position correction is carried out, and the positions of images of different sample arm branches are further corrected, so that mutual crosstalk is avoided;

3) the sweep frequency light source sends out a synchronous trigger signal T1 which is respectively connected to the interpolation clock module and the master control module and used as a reference clock signal thereof, so that the interpolation clock signal T2 output by the interpolation clock module, the trigger signal T3 generated by the master control module and the interference signal T4 carrying sample information output by the radio frequency attenuator are synchronous;

4) the frequency sweeping light source sends a beam of broadband light to the optical fiber beam splitter, and the broadband light is respectively transmitted to the interpolation clock module and the wavelength division multiplexer through a set proportion; the interpolation clock module obtains a complete interpolation clock signal T2 and transmits the complete interpolation clock signal T2 to the data acquisition card;

5) the distance measuring light source emits laser to be transmitted to the optical fiber type electric attenuator; the optical fiber type electric attenuator adjusts the optical power of the laser entering the wavelength division multiplexer; the wavelength division multiplexer combines the broadband light emitted by the sweep frequency light source and the laser emitted by the ranging light source and inputs the combined beam to the universal optical fiber coupler; the universal optical fiber coupler transmits a part of light to the sample arm through the second port according to the set optical power proportion; irradiating the sample through a sample arm, wherein the sample is irradiated to generate scattered light;

6) the scattered light is received by the sample arm and returns to the second port of the universal fiber coupler; the scattered light generated by the sample is transmitted to the averaging optical fiber coupler through the fourth port of the universal optical fiber coupler; the universal optical fiber coupler transmits the other part of light to the electric delay line through a third port; the electric delay line is used as a reference arm, the optical path difference of the reference arm is adjusted, and light with the optical path adjusted by the electric delay line is used as reference light and transmitted to the equipartition optical fiber coupler;

7) the scattered light and the reference light interfere at the equipartition optical fiber coupler, and the interference light carries sample information; the equalizing optical fiber coupler evenly divides the interference light and then transmits the interference light to the balance photoelectric detector; the balance photoelectric detector converts the interference light from an optical signal into an electric signal and transmits the electric signal to the low-pass filter; after high-frequency noise is suppressed by the low-pass filter, the high-frequency noise is transmitted to the radio frequency attenuator, the amplitude of an electric signal is adjusted by the radio frequency attenuator to meet the acquisition range of the data acquisition card, and an interference signal T4 is output;

8) the master control module generates a trigger signal T3 according to a synchronous trigger signal T1 output by the sweep frequency light source and transmits the trigger signal to the data acquisition card to control the working time sequence of the whole OCT imaging device; (ii) a The data acquisition card acquires an interference signal T4 which is output by the radio frequency attenuator and carries sample information according to the trigger signal T3; the data acquisition card transmits the interference signal T4 to the computer;

9) the master control module outputs control signals to control each path of sample arm branch to synchronously scan the sample until data acquisition of all scanning points is completed;

10) and (4) analyzing the interference signal T4 by the computer to obtain a three-dimensional full-eye structure chart and a blood flow chart of the sample with the ultra-large field of view.

In step 2), a distance measuring light source and an optical fiber type electric attenuator are used for correcting the working distance position, and the positions of the images of different sample arm branches are further corrected, and the method comprises the following steps:

a) turning off a sweep frequency light source, turning on a distance measurement light source, placing a reflector at a rated working distance of the OCT imaging device, wherein the reflector is used for simulating a cornea, turning off the sweep frequency light source, turning on the distance measurement light source, recording a signal generated by interference between the surface of the reflector and a reference arm at the moment, converting the signal into a depth value z1, and calculating the position of the reference arm as a first position at the moment;

b) placing a model eye in the test position;

c) keeping the sweep frequency light source turned off and the ranging light source turned on, observing a signal generated by interference of the anterior corneal surface of the model eye and the reference arm, and enabling a corresponding depth value to be a second depth z2, wherein the working distance is adjusted to enable z2= z1, and the tested model eye is at a rated working distance; if z1< z2, which indicates that the distance between the tested model eye and the OCT imaging device is larger than the rated working distance, the distance should be reduced; if z1> z2, indicating that the distance between the model eye under test and the OCT imaging apparatus is less than the nominal working distance, the distance should be increased;

d) the sweep frequency light source and the distance measurement light source are simultaneously turned on, and the optical path difference of the reference arm is adjusted, so that the signals generated by the interference of different sample arm branches and the reference arm cannot generate frequency aliasing, namely, in a preview image, the anterior segment image and the posterior segment image of the model eye obtained by different sample arms are respectively positioned at different depths, and the anterior segment image and the posterior segment image are not crossed.

In step 10), the computer analyzes the interference signal T4 to obtain a whole-eye structure chart and a blood flow chart of the sample, and comprises the following steps:

i. obtaining interference signals corresponding to different sample arm branches by a successive band-pass filtering method, wherein the frequency range of the band-pass filtering is set according to the size of the optical path difference between the sample arm and the reference arm;

performing interpolation, dispersion compensation and refractive index correction on each group of interference signals respectively;

according to original data of the multiple paths of anterior ocular segment optical paths and the multiple paths of posterior ocular segment optical paths, splicing an anterior ocular segment structure chart and a posterior ocular segment structure chart with large visual fields, then combining optical path differences of reference arms during imaging of the anterior ocular segment and the posterior ocular segment, splicing to form a three-dimensional whole-eye structure chart with an ultra-large visual field range, and performing data processing on the three-dimensional whole-eye structure chart to obtain a blood flow chart;

extracting various biological data of the eyeball from the three-dimensional whole eye structure chart, wherein the biological data comprises the thickness of the retina, the curvature of the cornea, the angle of the eye, the thickness of the cornea, the depth of the anterior chamber, the thickness of the crystalline lens, the length of the axis of the eye, the angle of the eye and the like.

The invention has the advantages that:

(1) the whole-eye OCT imaging device based on the optical fiber beam splitter method can realize simultaneous imaging of the anterior segment and the posterior segment of the eye by only utilizing one sweep frequency light source, one detector and one acquisition card, and compared with a multi-light-source scheme, the invention greatly reduces the hardware cost; in addition, the OCT imaging device has better stability and simpler processing and assembly due to the use of the all-fiber;

(2) utilizing the advantage of long coherence length of a swept source, utilizing a 1 x n fiber beam splitter to generate a plurality of paths of sample arm branches, and setting optical path differences between different sample arm branches and the same reference arm to different values, so that interference signals generated by different sample arm branches are positioned in different frequency ranges; the frequency range of the interference signal equivalent to the posterior segment of the eye and the frequency range of the interference signal equivalent to the anterior segment of the eye have a larger interval, so that the interference signals of the anterior segment of the eye and the posterior segment of the eye can be simultaneously detected by the same detector;

(3) because the optical structure of human eyes is more complex, the difference of different individuals is larger, and the aberration is larger, the ophthalmic OCT imaging device, especially the posterior segment OCT imaging device, faces the problem of smaller scanning field range; according to the technical scheme, the sample arms of the two posterior segment optical paths of the eye are incident to the eye ground at different angles, so that the imaging field range of the eye ground OCT imaging device can be remarkably enlarged, the observation of the structural information and the blood flow information of the peripheral area of the optic disc is facilitated, and the method has an important effect on the early screening of chronic diseases such as diabetes, hypertension and the like; according to the technical scheme, the sample arms of the two anterior ocular segment optical paths are horizontally shifted by a certain distance to realize three-dimensional imaging of different xy areas, so that the imaging field range of the anterior ocular segment OCT imaging device can be remarkably enlarged; the axial imaging range and the transverse imaging range of the OCT imaging device are enlarged by designing a sample arm light path;

(4) the traditional clock module only directly outputs interference signals of the MZI interferometer and then collects the interference signals by using a signal channel of a data collection card; according to the technical scheme, the intensity is homogenized by shaping and filtering interference signals of the MZI interferometer, and then fundamental frequency filling is carried out on places where the shaped MZI interference signals are zero according to scanning clock signals of a frequency sweeping light source; finally, the signal can be directly input to an external clock port of the data acquisition card, and the problem that the frequency of the external clock signal of the acquisition card is zero and collapses is solved;

(5) by adding a distance measurement light source and an optical fiber type electric attenuator and sharing an OCT imaging device, a set of position detection module based on time domain OCT is formed, for example, a light source with a wavelength different from that of a sweep light source is added, and a position detection function can be realized by using a balance photoelectric detector without adding another photoelectric detector, namely, the distance from the last lens of the OCT imaging device to the front surface of the cornea in actual work is detected, so that the problem of inaccurate alignment can be solved, the field curvature aberration can be effectively reduced, and the imaging quality of a marginal field of view is improved; in addition, interference signals generated by the position detection module can be used as a reference standard for large-field image registration, and image distortion caused by eye shake can be effectively eliminated.

Drawings

FIG. 1 is a block diagram of the structure of an ultra-wide range OCT imaging apparatus of the present invention;

FIG. 2 is a block diagram of the interpolation clock module of the ultra-large range OCT imaging apparatus of the present invention;

FIG. 3 is an optical path diagram of a first embodiment of a sample arm of the ultra-wide range OCT imaging apparatus of the present invention;

FIG. 4 is an optical path diagram of a second embodiment of a sample arm of the ultra-large range OCT imaging apparatus of the present invention;

FIG. 5 is an optical path diagram of a third embodiment of a sample arm of the ultra-large range OCT imaging apparatus of the present invention;

FIG. 6 is an optical path diagram of a fourth embodiment of the sample arm of the ultra-large range OCT imaging apparatus of the present invention;

fig. 7 is a schematic diagram of an angle adjustment module of an embodiment of the multi-beam polarization OCT imaging device of the present invention, in which (a) is a top view and (b) is a cross-sectional view of a lens slider along a line a-a in fig. (a).

Detailed Description

The invention will be further elucidated by means of specific embodiments in the following with reference to the drawing.

As shown in fig. 1, the ultra-wide range OCT imaging apparatus of the present embodiment includes: the device comprises a sweep frequency light source, an optical fiber beam splitter, an interpolation clock module, a data acquisition card, a computer, a distance measurement light source, an optical fiber type electric attenuator, a wavelength division multiplexer, a general optical fiber coupler, a sample arm, an electric delay line, an equipartition optical fiber coupler, a balance photoelectric detector, a low-pass filter, a radio frequency attenuator and a master control module; the output end of the sweep frequency light source is connected to the input end of the optical fiber beam splitter through an optical fiber, and the wavelength scanning range of the sweep frequency light source is 1000nm-1100 nm; the output end of the optical fiber beam splitter is respectively connected to the light beam input end of the interpolation clock module and one input end of the wavelength division multiplexer through optical fibers, and the output end of the interpolation clock module is connected to the external clock end of the data acquisition card through a radio frequency cable; the data acquisition card is connected to the computer through a data bus; the distance measuring light source is connected with the input end of the optical fiber type electric attenuator through an optical fiber, and the working wavelength is 1550 nm; the output end of the optical fiber type electric attenuator is connected to the other input end of the wavelength division multiplexer; the output end of the wavelength division multiplexer is connected to a first port of the universal optical fiber coupler through an optical fiber, and the splitting ratio is 10: 90 or 20: 80, the second port of the universal optical fiber coupler is connected to the sample arm through an optical fiber, the third port of the universal optical fiber coupler is connected to one end of the electric delay line through an optical fiber, the fourth port of the universal optical fiber coupler is connected to the first port of the equal-division optical fiber coupler through an optical fiber, and the splitting ratio of the two output ends of the equal-division optical fiber coupler, namely the second port and the third port, is 50: 50, the optical power ratio output by the two output ends of the general optical fiber coupler is set randomly; the other end of the electric delay line is connected to a second port of the equipartition optical fiber coupler; the third and fourth ports of the equipartition optical fiber coupler are respectively connected to the balanced photoelectric detector through optical fibers; the balance photoelectric detector is connected to the low-pass filter through a radio frequency cable; the low-pass filter is connected with the radio frequency attenuator through a radio frequency cable; the radio frequency attenuator is connected to the signal end of the data acquisition card through a radio frequency cable; the synchronous trigger signal end of the sweep frequency light source is connected to the signal input end of the interpolation clock module through a radio frequency cable; the synchronous trigger signal end of the sweep frequency light source is connected to the master control module; the master control module is connected to a trigger port of the data acquisition card through a radio frequency cable; and the master control module is also connected to each scanning galvanometer of the sample arm branch through a signal line.

As shown in fig. 2, the interpolation clock module includes a Mach-Zehnder interferometer (MZI) optical path, an interpolation clock photodetector, a first filter, a radio frequency amplifier, a second filter, an interpolation clock control module, a frequency multiplication clock module, and an electronic switch, where the Mach-Zehnder interferometer (MZI) optical path is electrically adjustable in optical path difference; the fiber beam splitter splits a part of light beams emitted from the sweep frequency light source to an MZI optical path; an MZI optical path with an electric adjustable optical path difference generates an interference spectrum of a set frequency band and inputs the interference spectrum to an interpolation clock photoelectric detector; the interpolation clock photoelectric detector changes the interference spectrum into an initial interpolation clock signal, and the initial interpolation clock signal is changed into an interpolation clock signal with relatively consistent amplitude after sequentially passing through the first filter, the radio frequency amplifier and the second filter; the interpolation clock control module controls the frequency multiplication clock module to generate a base frequency clock signal, and the frequency is 0.1 MHz-100 MHz; the synchronous trigger signal end of the sweep frequency light source is connected to the interpolation clock control module, and the synchronous trigger signal T1 is transmitted to the interpolation clock control module; the interpolation clock control module carries out time sequence control according to a synchronous trigger signal T1 output by the sweep frequency light source, namely, according to the difference of the output spectrum duty ratio of the sweep frequency light source, the interpolation clock control module controls the electronic switch to output a base frequency clock signal generated by the frequency doubling clock module for the part without spectrum output; for the part with the spectrum output, controlling the electronic switch to output an interpolation clock signal generated by a second filter; the baseband clock signal and the interpolated clock signal generated by the second filter are combined together in a time sequence with or without spectral output to form a complete interpolated clock signal T2.

The ultra-wide range OCT imaging method of the embodiment comprises the following steps:

1) the OCT imaging apparatus is connected, as shown in figure 1;

2) position correction is carried out by adopting a distance measuring light source and an optical fiber type electric attenuator:

a) turning off the sweep frequency light source, turning on the distance measurement light source, preferably adopting a sweep frequency laser for the distance measurement light source, and preferably selecting the wavelength of 1200-1600 nm; placing a reflector at a rated working distance, wherein the reflector is used for simulating a cornea, recording an interference signal generated by interference between the surface of the reflector and a reference arm at the moment, converting the interference signal into a first depth z1, and converting the position of the reference arm into a first position z 11;

b) placing a model eye in the test position;

c) keeping the sweep frequency light source turned off and the ranging light source turned on, observing interference signals of the cornea front surface of the model eye and the reference arm, taking the corresponding depth value as a second depth z2, and adjusting the working distance to ensure that z2= z1, wherein the tested model eye is at the rated working distance; if z1< z2, which indicates that the distance between the tested model eye and the OCT imaging device is greater than the rated working distance, the distance should be reduced, and the distance between the tested model eye and the OCT imaging device refers to the distance between the back surface of the last imaging lens of the OCT imaging device and the front surface of the cornea of the tested model eye; if z1> z2, indicating that the distance between the model eye under test and the OCT imaging apparatus is less than the nominal working distance, the distance should be increased;

d) the sweep frequency light source and the distance measurement light source are both opened, and the optical path difference of the reference arm is adjusted, so that the interference signals of different sample arms cannot generate frequency aliasing, namely, in a preview image, the anterior segment and the posterior segment of the model eye obtained by different sample arms are respectively positioned at different depths, and do not intersect; assuming that the depth value of the corneal surface output by the detection module corresponding to the interference signal of the reference arm is the third depth z3 when the reference arm moves to the third position z33, z33-z11= z3-z1 should be satisfied; if not, the actual working distance needs to be adjusted to meet the requirement; taking the sample arm of the large-view-field full-eye OCT imaging device based on the 1 x 3 optical fiber beam splitter method as an example, assuming that the optical path difference between the first posterior segment optical path and the reference arm is 0mm, the optical path difference between the second posterior segment optical path and the reference arm is 5mm, and the optical path difference between the anterior segment optical path and the reference arm is 10 mm; the first position signal output by the detection module is generated by the interference of the light returned by the front surface of the cornea and the light returned by the reference arm, so that when the eye is positioned at the rated working distance, the position signal output by the detection module is just positioned at the position corresponding to the optical path difference of 10 mm; in addition, the detection module can also output a second position signal and a third position signal which are respectively generated by the interference of the first eye posterior segment optical path and the reference arm and the interference of the second eye posterior segment optical path and the reference arm; however, the reflected light beam of the fundus oculi is very weak, and the second position signal and the third position signal are very weak in the preview image, so that the first position signal is suitable for being used for making a judgment standard of the working distance; the first position signal, the second position signal and the third position signal have the further advantage of facilitating large-field splicing and jitter elimination of data of different channels;

5) the distance measuring light source emits laser to be transmitted to the optical fiber type electric attenuator; the optical fiber type electric attenuator adjusts the optical power of the laser entering the wavelength division multiplexer; the wavelength division multiplexer combines the broadband light emitted by the sweep frequency light source and the laser emitted by the ranging light source and inputs the combined beam to the universal optical fiber coupler; the universal optical fiber coupler transmits a small part of light to the sample arm through the second port according to the optical power ratio of 2: 98; irradiating the sample through a sample arm, wherein the sample is irradiated to generate scattered light;

7) the scattered light and the reference light interfere at the equipartition optical fiber coupler, and the interference light carries sample information; the equalizing optical fiber coupler equally divides the interference light and then transmits the interference light to the balance photoelectric detector; the balanced photoelectric detector converts the interference light from an optical signal into an electric signal and transmits the electric signal to the low-pass filter; after high-frequency noise is suppressed by the low-pass filter, the high-frequency noise is transmitted to the radio frequency attenuator, the amplitude of an electric signal is adjusted by the radio frequency attenuator to meet the acquisition range of the data acquisition card, and an interference signal T4 is output;

8) the master control module generates a trigger signal T3 according to a synchronous trigger signal T1 output by the sweep frequency light source and transmits the trigger signal to the data acquisition card to control the working time sequence of the whole OCT imaging device; the data acquisition card acquires an interference signal T4 which is output by the radio frequency attenuator and carries sample information according to the trigger signal T3; the data acquisition card transmits the interference signal T4 to the computer;

9) the master control module is used for respectively generating control signals S1, S2. cndot. Sn to the scanning galvanometers of the n paths of sample arm branches and controlling the scanning galvanometers of each path of sample arm branch;

10) and (3) analyzing the interference signal T4 by the computer to obtain a three-dimensional full-eye structure chart and a blood flow chart of the sample in the ultra-large field range:

The sample arm comprises a 1 xn optical fiber beam splitter and n paths of sample arm branches, light from the second port of the universal optical fiber coupler is divided into n paths of sample arm branches through the 1 xn optical fiber beam splitter, and each path of sample arm branch meets the set optical path difference requirement, so that different sample arm branches and the reference arm have different optical path differences, and the interference signal frequency of different sample arm branches and the reference arm is in different frequency band ranges.

Example one

As shown in fig. 3, in this embodiment, two posterior-segment optical paths and one anterior-segment optical path are adopted, and are divided into 3 sample arm branches by a 1 × 3 optical fiber beam splitter 9001, and each output end of the 1 × 3 optical fiber beam splitter is respectively connected to one posterior-segment optical path or one anterior-segment optical path; the splitting ratio of the 1 × 3 optical fiber splitter 9001 is 40:30:30, 40% of ports provide for anterior ocular segment optical paths, and 30% of ports provide for two posterior ocular segment optical paths respectively.

Each path of the posterior eye optical path comprises a first polarization controller 902, a first collimator 903, a first zoom lens 904, a first scanning galvanometer 905, a first lens 906 and a second lens 907; one output end of the 1 xn optical fiber beam splitter is connected to the first collimator through an optical fiber jumper, and a first polarization controller is arranged on an optical fiber of which the output end is connected to the first collimator; the first lens and the second lens are arranged in a confocal manner to form a 4F system, and the 4F system with the beam shrinkage ratio of 2-3 is preferred; the light beam passes through a first polarization controller, and interference signals of a sample arm and a reference arm of a posterior segment optical path are adjusted to be maximized; the light beam is changed into parallel light after passing through the first collimator, the diopter of the incident light beam is adjusted through the first zoom lens, and then the incident light beam is transmitted to the first scanning galvanometer; the first scanning galvanometer is a two-dimensional scanning galvanometer, a pivot point is positioned on a focal plane of the first lens, and the first scanning galvanometer scans light beams according to a control signal generated by the master control module and irradiates the light beams to the posterior segment of the eye after passing through the first lens and the second lens; by adjusting the included angle between each path of posterior segment optical path and the optical axis of the eyes, the imaging areas of each path of posterior segment optical path are different, and the field range of the whole posterior segment imaging is increased. The included angle degree between the first posterior ocular segment optical path and the optical axis of the eye is preferably 20-45 degrees. The degree of an included angle between the second posterior segment of the eye and the optical axis of the eye is preferably-20 to-45 degrees.

Each anterior ocular segment optical path includes a second polarization controller 912, a second collimator 913, a second zoom lens 914, a second scanning galvanometer 915, and a third lens 916; one output end of the 1 xn optical fiber beam splitter is connected to the second collimator through an optical fiber jumper, and a second polarization controller is arranged on the optical fiber of which the output end is connected to the second collimator; the light beam passes through a second polarization controller to adjust the interference signal of the anterior ocular segment light path so as to maximize the interference signal; the light beam is changed into parallel light after passing through a second collimator, the diopter of the incident light beam is adjusted through a second zoom lens, and then the incident light beam is transmitted to a second scanning galvanometer; the second scanning galvanometer is a two-dimensional scanning galvanometer, a pivot point is positioned on a focal plane of the third lens, and the second scanning galvanometer scans light beams according to a control signal generated by the master control module, reflects the light beams by the dichroic mirror 916, and irradiates the light beams to anterior segment of eyes after passing through the third lens.

And adjusting the optical fiber jumper corresponding to each path of posterior-segment optical path or anterior-segment optical path to enable the optical fiber jumper to meet the set length requirement, so that each path of sample arm branch and the reference arm meet the set optical path difference.

The fixation lamp light path sequentially comprises a dichroic mirror 917, a lens 918 and a display screen 919, and is positioned on an eye optical axis; the dichroic mirror has high reflectivity to the wavelength of the swept-frequency light source and high transmittance to the wavelength generated by the display screen. The light of the display screen is transmitted through the dichroic mirror through the lens and then reaches the eyeball to be tested through the third lens 916.

The optical fiber jumpers corresponding to the posterior segment optical paths and the anterior segment optical paths of each path of eyes meet the length requirement: when the optical path difference between the reference arm and the first eye posterior segment optical path is zero, the optical path difference between the second eye posterior segment optical path and the reference arm needs to be larger than 3mm, namely the maximum measuring range during the imaging of the eye posterior segment is preferably 4mm-8 mm; the optical path difference between the anterior ocular segment and the reference arm needs to be more than 6mm, and preferably 8mm-16 mm.

Example two

As shown in fig. 4, in this embodiment, two optical paths of the posterior segment of the eye and two optical paths of the anterior segment of the eye are adopted, and are divided into 4 sample arm branches by a 1 × 4 optical fiber beam splitter 9002, each output end of the 1 × 4 optical fiber beam splitter is respectively connected to one optical path of the posterior segment of the eye or the optical path of the anterior segment of the eye, and the splitting ratio of the 1 × 4 optical fiber beam splitter 9002 is preferably 25:25:25: 25. In the present embodiment, the two anterior ocular segment optical paths share the second collimator 913, the second zoom lens 914, the second scanning galvanometer 915, and the third lens 916. The included angle degree between the first posterior ocular segment optical path and the optical axis of the eye is preferably 20-45 degrees. The degree of an included angle between the second posterior segment of the eye and the optical axis of the eye is preferably-20 to-45 degrees.

The optical fiber jumper wires corresponding to each path of posterior segment optical path and each path of anterior segment optical path meet the length requirement: when the optical path difference between the reference arm and the first eye posterior segment optical path is zero, the optical path difference between the second eye posterior segment optical path and the reference arm needs to be larger than 3mm, namely the maximum measuring range during the imaging of the eye posterior segment is preferably 4mm-8 mm; the optical path difference between the first anterior ocular segment optical path and the reference arm needs to be larger than 6mm, and preferably 8mm-16 mm; the optical path difference between the second anterior ocular segment optical path and the reference arm needs to be more than 20mm, and preferably 24mm-32 mm. The other steps are the same as those of the first embodiment.

EXAMPLE III

As shown in fig. 5, in this embodiment, a path of optical path at the posterior eye section and a path of optical path at the anterior eye section are adopted, and are divided into 2 paths of sample arm branches by a first 1 × 2 optical fiber beam splitter 9003, and two output ends of the first 1 × 2 optical fiber beam splitter 9003 are respectively connected to the path of optical path at the posterior eye section and the path of optical path at the anterior eye section. The angle between the posterior segment optical path and the optical axis of the eye is preferably-20 to-45 degrees or +20 to +45 degrees.

The optical fiber jumper wires corresponding to the posterior segment optical path and the anterior segment optical path meet the length requirement: when the optical path difference between the reference arm and the eye posterior segment optical path is zero, the optical path difference between the eye anterior segment optical path and the reference arm needs to be larger than 3mm, and preferably 4mm-8 mm. The other steps are the same as those of the first embodiment.

Example four

As shown in fig. 6, in this embodiment, two eye posterior segment optical paths are adopted, and are divided into 2 sample arm branches by a second 1 × 2 optical fiber splitter 9004, and two output ends of the second 1 × 2 optical fiber splitter 9004 are respectively connected to the two eye posterior segment optical paths. The included angle between the first posterior segment optical path of the eye and the optical axis of the eye is preferably 40 degrees; the angle between the second posterior ocular segment and the optical axis of the eye is preferably-40 °.

The optical fiber jumpers corresponding to the two eye posterior segment optical paths meet the length requirement: when the optical path difference between the reference arm and the first eye posterior segment optical path is zero, the optical path difference between the second eye posterior segment optical path and the reference arm needs to be larger than 3mm, namely the maximum measuring range when the eye posterior segment is imaged is preferably 4mm-8 mm. The other steps are the same as those of the first embodiment.

As shown in fig. 7, the angle adjustment module includes a sample arm support plate 1, a first guide rail 2, a second guide rail 3, and two lens sliders 4; the sample arm support plate 1 is a flat plate, and the surface of the sample arm support plate 1 is respectively provided with a first guide rail 2 and a second guide rail 3; the first guide rail 2 and the second guide rail 3 are both partially circular groove guide rails, the circular rings of the first guide rail 2 and the second guide rail 3 are concentric O, and the samples are positioned at the circle centers and occupy the same proportion of the circular rings; the bottom ends of the two lens sliders 4 are respectively embedded into the first guide rail 2 and the second guide rail 3 and can slide along the first guide rail 2 and the second guide rail 3, and the direction of the lens sliders 4 is along the radial direction of a ring where the first guide rail 2 and the second guide rail 3 are located; one sample arm branch is arranged on one lens sliding block 4, and the two lens sliding blocks 4 respectively correspond to the two sample arm branches; the cross section of the sliding block is a polygon CDEHG, the adjacent vertex angle is not a right angle, and the characteristic is that the angle EFG is an obtuse angle and the angle FGC is an obtuse angle; compared with a rectangular sliding block, the lens adjusting mechanism has the advantages that the two lens sliding blocks can be closer, and the angle adjustment range is larger. The bottom surface of the lens sliding block 4 is respectively provided with a cylinder 5 and a partial annular column 6, the cylinder 5 and the partial annular column 6 are respectively embedded into the grooves of the first guide rail 2 and the second guide rail 3, and the curvature of the partial annular column is consistent with that of the guide rail; the cylinder 5 and the part of the annular column 6 slide in the first guide rail 2 and the second guide rail 3 to realize the sliding of the lens sliding block 4, and the part of the annular column 6 is characterized in that the curvatures of the front surface and the rear surface are the same as the curvature of the groove of the second guide rail 3, so that the smoothness and the stability during sliding are ensured.

Finally, it is noted that the disclosed embodiments are intended to aid in further understanding of the invention, but those skilled in the art will appreciate that: various substitutions and modifications are possible without departing from the spirit and scope of the invention and the appended claims. Therefore, the invention should not be limited to the embodiments disclosed, but the scope of the invention is defined by the appended claims.

Claims

1. An ultra-large range Optical Coherence Tomography (OCT) imaging apparatus, the ultra-large range OCT imaging apparatus comprising: the device comprises a sweep frequency light source, an optical fiber beam splitter, an interpolation clock module, a data acquisition card, a computer, a distance measurement light source, an optical fiber type electric attenuator, a wavelength division multiplexer, a general optical fiber coupler, a sample arm, an electric delay line, an equipartition optical fiber coupler, a balance photoelectric detector, a low-pass filter, a radio frequency attenuator and a master control module; the output end of the sweep frequency light source is connected to the input end of the optical fiber beam splitter through an optical fiber; the output end of the optical fiber beam splitter is respectively connected to the light beam input end of the interpolation clock module and one input end of the wavelength division multiplexer through optical fibers, and the output end of the interpolation clock module is connected to the external clock end of the data acquisition card through a radio frequency cable; the data acquisition card is connected to the computer through a data bus; the distance measuring light source is connected with the input end of the optical fiber type electric attenuator through an optical fiber; the output end of the optical fiber type electric attenuator is connected to the other input end of the wavelength division multiplexer; the output end of the wavelength division multiplexer is connected to a first port of the universal optical fiber coupler through an optical fiber, a second port of the universal optical fiber coupler is connected to the sample arm through an optical fiber, a third port of the universal optical fiber coupler is connected to one end of the electric delay line through an optical fiber, a fourth port of the universal optical fiber coupler is connected to a first port of the equal-division optical fiber coupler through an optical fiber, and the light-splitting ratio of the universal optical fiber coupler is set arbitrarily; the other end of the electric delay line is connected to a second port of the equipartition optical fiber coupler, and the electric delay line is used as a reference arm; the third and fourth ports of the equipartition optical fiber coupler are respectively connected to the balanced photoelectric detector through optical fibers; the balance photoelectric detector is connected to the low-pass filter through a radio frequency cable; the low-pass filter is connected with the radio frequency attenuator through a radio frequency cable; the radio frequency attenuator is connected to the signal end of the data acquisition card through a radio frequency cable; the synchronous trigger signal end of the sweep frequency light source is connected to the signal input end of the interpolation clock module through a radio frequency cable; the synchronous trigger signal end of the sweep frequency light source is connected to the master control module; the master control module is connected to a trigger port of the data acquisition card through a radio frequency cable;

the sample arm comprises a 1 xn optical fiber beam splitter and n paths of sample arm branches, a second port of the universal optical fiber coupler is connected to an input end of the 1 xn optical fiber beam splitter, n output ends of the 1 xn optical fiber beam splitter are respectively connected with the n paths of sample arm branches, light from the second port of the universal optical fiber coupler is divided into n paths through the 1 xn optical fiber beam splitter, and each path of sample arm branch meets the set requirement of optical path difference, namely different sample arm branches and a reference arm have different optical path differences, so that the interference signal frequencies of different sample arm branches and the reference arm are in different frequency band ranges; the master control module is connected to each path of sample arm branch through a signal line, and n is a natural number not less than 2;

the frequency sweeping light source sends a beam of broadband light to the optical fiber beam splitter, and the broadband light is respectively transmitted to the interpolation clock module and the wavelength division multiplexer through a set proportion; the interpolation clock module obtains a complete interpolation clock signal T2 and transmits the complete interpolation clock signal T2 to the data acquisition card; the distance measuring light source emits laser to be transmitted to the optical fiber type electric attenuator; the optical fiber type electric attenuator adjusts the optical power of the laser entering the wavelength division multiplexer; the wavelength division multiplexer combines the broadband light emitted by the sweep frequency light source and the laser emitted by the ranging light source and inputs the combined beam to the universal optical fiber coupler; the universal optical fiber coupler transmits a part of light to the sample arm through the second port according to the set optical power proportion; irradiating the sample through a sample arm, wherein the sample is irradiated to generate scattered light; the scattered light is received by the sample arm and returns to the second port of the universal fiber coupler; the scattered light generated by the sample is transmitted to the averaging optical fiber coupler through the fourth port of the universal optical fiber coupler; the universal optical fiber coupler transmits the other part of light to the electric delay line through a third port; the electric delay line is used as a reference arm, the optical path difference of the reference arm is adjusted, and light with the optical path adjusted by the electric delay line is used as reference light and transmitted to the equipartition optical fiber coupler; the scattered light and the reference light interfere at the equipartition optical fiber coupler, and the interference light carries sample information; the equalizing optical fiber coupler equally divides the interference light and then transmits the interference light to the balance photoelectric detector; the balance photoelectric detector converts the interference light from an optical signal into an electric signal and transmits the electric signal to the low-pass filter; after high-frequency noise is suppressed by the low-pass filter, the high-frequency noise is transmitted to the radio frequency attenuator, the amplitude of an electric signal is adjusted by the radio frequency attenuator to meet the acquisition range of the data acquisition card, and an interference signal T4 is output; the master control module generates a trigger signal T3 according to a synchronous trigger signal T1 output by the sweep frequency light source and transmits the trigger signal to the data acquisition card to control the working time sequence of the whole OCT imaging device; the master control module generates control signals to control each path of sample arm branch to carry out synchronous scanning; the data acquisition card acquires an interference signal T4 which is output by the radio frequency attenuator and carries sample information according to the trigger signal T3; the data acquisition card transmits the interference signal T4 to the computer, and the computer analyzes the interference signal T4 to obtain a three-dimensional full-eye structure diagram and a blood flow diagram of the sample in an ultra-large field of view.

2. The ultra-wide range OCT imaging device of claim 1, wherein the interpolation clock module comprises: the Mach-Zehnder interferometer with the electric adjustable optical path difference comprises an MZI optical path, an interpolation clock photoelectric detector, a first filter, a radio frequency amplifier, a second filter, an interpolation clock control module, a frequency multiplication clock module and an electronic switch; the optical fiber beam splitter splits a part of light beams emitted from the sweep frequency light source to an MZI optical path; an MZI optical path with an electric adjustable optical path difference generates an interference spectrum of a set frequency band and inputs the interference spectrum to an interpolation clock photoelectric detector; the interpolation clock photoelectric detector changes the interference spectrum into an initial interpolation clock signal, and the initial interpolation clock signal is changed into an interpolation clock signal with relatively consistent amplitude after sequentially passing through the first filter, the radio frequency amplifier and the second filter; the interpolation clock control module controls the frequency multiplication clock module to generate a base frequency clock signal; the synchronous trigger signal end of the sweep frequency light source is connected to the interpolation clock control module, and the synchronous trigger signal T1 is transmitted to the interpolation clock control module; the interpolation clock control module carries out time sequence control according to a synchronous trigger signal T1 output by the sweep frequency light source, namely, according to the difference of the output spectrum duty ratio of the sweep frequency light source, the interpolation clock control module controls the electronic switch to output a base frequency clock signal generated by the frequency doubling clock module for the part without spectrum output; for the part with the spectrum output, controlling the electronic switch to output an interpolation clock signal generated by a second filter; the baseband clock signal and the interpolated clock signal generated by the second filter are combined together in a time sequence with or without spectral output to form a complete interpolated clock signal T2.

3. The ultra-wide range OCT imaging device of claim 1, wherein said n sample arm branches comprise: m paths of posterior eye sections and n-m paths of anterior eye sections, wherein m is a natural number, m is more than or equal to 0 and less than or equal to n, and n is a natural number more than or equal to 2.

4. The ultra-wide range OCT imaging device of claim 3, wherein each posterior segment of the eye path comprises: the device comprises a first polarization controller, a first collimator, a first zoom lens, a first scanning galvanometer, a first lens and a second lens; one output end of the 1 Xn optical fiber beam splitter is connected to the first collimator through an optical fiber jumper, and a first polarization controller is arranged on the optical fiber jumper of which the output end is connected to the first collimator; the first lens and the second lens are arranged in a confocal manner to form a 4F system; the light beam passes through a first polarization controller, and interference signals of a posterior eye segment light path and a reference arm are adjusted to be maximized; the light beam is changed into parallel light after passing through the first collimator, the diopter of the incident light beam is adjusted through the first zoom lens, and then the incident light beam is transmitted to the first scanning galvanometer; the first scanning galvanometer is a two-dimensional scanning galvanometer, a pivot point is positioned on a focal plane of the first lens, and the first scanning galvanometer scans light beams according to a control signal generated by the master control module and irradiates the light beams to the posterior segment of the eye after passing through the first lens and the second lens; the imaging area of each posterior segment of the eye is different by adjusting the included angle between each posterior segment of the eye light path and the optical axis of the eye, and the field range of the whole posterior segment of the eye is enlarged.

5. The ultra-wide range OCT imaging device of claim 3, wherein each anterior ocular segment optical path comprises: the second polarization controller, the second collimator, the second zoom lens, the second scanning galvanometer and the third lens; one output end of the 1 xn optical fiber beam splitter is connected to the second collimator through an optical fiber jumper, and a second polarization controller is arranged on the output end of the 1 xn optical fiber beam splitter through the optical fiber jumper connected to the second collimator; the light beam passes through a second polarization controller to adjust the interference signal of the anterior ocular segment light path so as to maximize the interference signal; the light beam is changed into parallel light after passing through a second collimator, the diopter of the incident light beam is adjusted through a second zoom lens, and then the incident light beam is transmitted to a second scanning galvanometer; the second scanning galvanometer is a two-dimensional scanning galvanometer, a pivot point is positioned on a focal plane of the third lens, and the second scanning galvanometer scans light beams according to a control signal generated by the master control module and irradiates the light beams to anterior segment of eyes after passing through the third lens; by adjusting the offset between the optical fiber jumper at the output end of the 1 Xn optical fiber beam splitter and the optical axis of the second collimator, different optical paths of the anterior segment of the eye and the optical axis of the second collimator have different offsets, so that different anterior segment regions of the eye are imaged, and the field range of the whole anterior segment imaging is enlarged.

6. The apparatus of claim 1, further comprising a fixation lamp light path, said fixation lamp light path comprising a dichroic mirror, a lens and a display screen, in that order, positioned on the optical axis of the eye.

7. The ultra-wide range OCT imaging device of claim 1, further comprising an angle adjustment module comprising a sample arm support plate, a first rail, a second rail, and i lens slides; the sample arm supporting plate is a flat plate, and the surface of the sample arm supporting plate is respectively provided with a first guide rail and a second guide rail; the first guide rail and the second guide rail are both partial annular groove guide rails, the circular rings where the first guide rail and the second guide rail are located are concentric, and the samples are located at the circle centers of the circular rings and occupy the same proportion of the circular rings; the bottom ends of the i lens sliding blocks are respectively embedded into the first guide rail and the second guide rail and can slide along the first guide rail and the second guide rail, and the direction of the lens sliding blocks is along the radial direction of the circular ring where the first guide rail and the second guide rail are located; one lens sliding block is provided with one path of sample arm branch, i lens sliding blocks respectively correspond to i paths of sample arm branches, and i is a natural number less than or equal to n; the closer the lens slide block is to the circle center, the smaller the transverse size is; the bottom surface of the lens sliding block is respectively provided with a cylinder and a partial annular column, the cylinder and the partial annular column are respectively embedded into the grooves of the first guide rail and the second guide rail, and the curvature of the partial annular column is consistent with that of the guide rail; the sliding of the lens sliding block is realized by the sliding of the cylinder and the part annular column in the first guide rail and the second guide rail, and the curvature of the front surface and the rear surface of the part annular column is the same as that of the groove of the second guide rail.

8. An imaging method of the ultra-wide range OCT imaging device of claim 1, comprising the steps of:

1) the OCT imaging device is connected with:

2) position correction is carried out, and the positions of the images of the arm branches of different samples are further corrected, so that mutual crosstalk is avoided;

4) the frequency sweeping light source sends a beam of broadband light to the optical fiber beam splitter, and the broadband light is respectively transmitted to the interpolation clock module and the wavelength division multiplexer through a set proportion; the interpolation clock module obtains a complete interpolation clock signal T2 and transmits the signal to the data acquisition card;

7) the scattered light and the reference light interfere at the equipartition optical fiber coupler, and the interference light carries sample information; the equalizing optical fiber coupler equally divides the interference light and then transmits the interference light to the balance photoelectric detector; the balance photoelectric detector converts the interference light from an optical signal into an electric signal and transmits the electric signal to the low-pass filter; after high-frequency noise is suppressed by the low-pass filter, the high-frequency noise is transmitted to the radio frequency attenuator, the amplitude of an electric signal is adjusted by the radio frequency attenuator to meet the acquisition range of the data acquisition card, and an interference signal T4 is output;

8) the master control module generates a trigger signal T3 according to a synchronous trigger signal T1 output by the sweep frequency light source, transmits the trigger signal to a data acquisition card and controls the working time sequence of the whole OCT imaging device; the data acquisition card acquires an interference signal T4 which is output by the radio frequency attenuator and carries sample information according to the trigger signal T3; the data acquisition card transmits the interference signal T4 to the computer;

9) the master control module outputs control signals to control each path of sample arm branch to synchronously scan the samples until data acquisition of all scanning points is completed;

9. The imaging method of claim 8, wherein in step 2), position correction is performed using a ranging light source and a fiber-optic motorized attenuator, and further the position of the images of the different sample arm branches is corrected, comprising the steps of:

b) placing a model eye in the test position;

c) keeping the sweep frequency light source turned off and the ranging light source turned on, observing a signal generated by interference of the anterior corneal surface of the model eye and the reference arm, and enabling a corresponding depth value to be a second depth z2, wherein the working distance is adjusted to enable z2= z1, and the tested model eye is at a rated working distance; if z1< z2, which indicates that the distance between the tested model eye and the OCT imaging device is larger than the rated working distance, the distance should be reduced; if z1> z2 indicates that the distance between the tested model eye and the OCT imaging device is less than the rated working distance, the distance should be increased;