CN110013212B - Multi-parameter and multi-functional eye measurement instrument based on optical coherence tomography - Google Patents

Abstract

The invention provides a multi-parameter and multifunctional eye measuring instrument based on optical coherence tomography; the measuring instrument disclosed by the invention has the advantages of simple structure, reasonable design, convenience in optical path regulation and control, realization of conversion between the time domain and the frequency domain of the OCT reference arm optical path, capability of enabling a single device to have multiple imaging functions, capability of greatly improving the performance of the device, capability of meeting common ophthalmic measurement requirements, convenience for a doctor to obtain parameters of each part of a measured eye, and capability of saving the purchase cost, maintenance cost and operation training cost of the corresponding device and management cost of the device.

Description

Multi-parameter and multi-functional eye measurement instrument based on optical coherence tomography

The invention belongs to the technical field of ophthalmic examination instruments, and in particular relates to a multi-parameter and multi-functional eye measuring instrument based on optical coherence tomography.

Background technique

Optical coherence tomography (OCT) is an emerging imaging technology. Since its emergence in 1991, with the deepening of research, this technology has the advantages of non-invasive and non-destructive in vivo, high resolution, and quantitative evaluation. Its working principle is to use the principle of low-coherence interference combined with confocal scanning to perform high-resolution tomographic scanning on the microstructure inside biological tissues or other scattering media, and reconstruct the image of the sample under test through a computer. With the development of corresponding software algorithms, it has been widely used in clinical applications such as blood flow imaging and eye detection. Among them, in terms of eye detection, due to the superior resolution of OCT, OCT has become the "gold standard" for eye detection.

Currently, OCT is divided into two categories: time domain TD-OCT and frequency domain SD-OCT. The working principle of TD-OCT is that the light emitted by a low-coherence light source is divided into two beams of light at the fiber coupler. One beam of reference light is directed to the reference arm and reflected back from the plane mirror. The other beam of measurement light is directed to the sample and scattered back through the sample. The reflected reference beam and the backscattered light generated by the measurement beam on the sample interfere with each other at the fiber coupler. The photoelectric sensor then receives and processes this interference signal, and finally obtains a tomographic image of the sample through computer processing. By scanning the longitudinal reference arm, the longitudinal information (depth direction) inside the sample can be acquired point by point. Due to the limitations of this scanning mechanism, the axial line scanning speed (A-line) of TD-OCT is generally limited to 2-4kHz, which greatly limits the imaging speed of TD-OCT.

Different from the working principle of TD-OCT system, SD-OCT replaces the photoelectric sensor with a spectrometer at the light receiving end, and no longer needs a longitudinal scanning reference arm, thereby increasing the scanning speed and stability. Specifically, the interference spectrum data received by the spectrometer is analyzed through Fourier inverse transform, and finally the longitudinal information of the measured material is obtained, and the image data is collected and analyzed by computer. The design of this system realizes the effective conversion of the two optical paths through the time domain and frequency domain optical path change devices, achieves multi-parameter detection of various parts of the eye, and realizes the multi-function of the measuring instrument.

At present, the ophthalmic examination instruments on the market are all aimed at a certain eye parameter target, such as measuring the axial length of the eye, using a single TD-OCT or SD-OCT to image the retina, etc. They can meet clinical needs in single target imaging. However, if multiple targets need to be imaged, multiple examination instruments need to be equipped. With the in-depth study of ophthalmic diseases, some diseases are related to multiple parts of the eye, that is, when ophthalmic diseases occur, there is a certain need for morphological and structural imaging of multiple parts.

Therefore, traditional ophthalmic examination instruments that target a single target are difficult to meet actual needs through a single examination item, and multiple testing devices are required to test patients. This not only increases the purchase cost of the testing instrument, but also increases the maintenance cost of the machine, the training cost of related personnel, and so on.

Summary of the invention

The purpose of the present invention is to provide a multi-parameter, multi-functional eye measuring instrument to address the deficiencies of existing ophthalmic examination instruments, which can measure multiple parameters at one time, including multiple anterior segments, retina, axial length and other parameters.

In order to achieve the above technical objectives, the technical solution of the present invention is as follows: a multi-parameter, multi-functional eye measuring instrument based on optical coherence tomography, comprising a light source, a light coupler, a reference arm, a sample arm, a detector and a processor;

The light source is used to provide an initial light beam;

The optical fiber coupler is used to split the initial light beam into two parts, which enter the reference arm and the sample arm respectively, and receive the light beams returned by the reference arm and the sample arm;

The reference arm comprises a frequency domain module and a time domain module arranged in parallel, the frequency domain module comprises a collimator and a frequency domain zero optical path position changing device, and the time domain module comprises a collimator and a time domain optical delay line device;

The sample arm is used to scan the eye to be tested;

The detector is used to receive the interference pattern formed by the interference of the light beams returned by the reference arm and the sample arm, and convert it into an electrical signal; it includes a spectrometer and a photoelectric sensor arranged in parallel;

The processor is used to receive the electrical signal and generate an image.

The eye measuring instrument of the present invention is provided with a frequency domain zero optical path position changing device and a time domain optical delay line device in parallel on the sample arm and the detector, as well as a spectrometer and a photoelectric sensor; thereby, the light beam emitted by the light source can be selected to adopt the frequency domain optical path or the frequency domain optical path. Specifically, the frequency domain optical path is as follows: the light emitted by the light source is divided into two parts by the optical fiber coupler, one of which enters the reference arm, and the light beam entering the reference arm can enter the frequency domain module through the frequency domain zero optical path position changing device, and finally the light returned by the reflector interferes with the light returned by the sample arm, so as to be detected and imaged by the spectrometer; the time domain optical path is as follows: the light emitted by the light source is divided into two parts by the optical fiber coupler, one of which enters the reference arm, and the light beam entering the reference arm can enter the time domain module through the optical delay line device, and finally the light returned by the reflector interferes with the light returned by the sample arm, so as to be detected and imaged by the photoelectric detector and the processor.

In this way, the time domain OCT module can be used to measure the axial length of the eye, while the frequency domain OCT module can be used to image the eye, so as to realize the examination of multiple parts of the eye.

Furthermore, the frequency domain zero optical path position changing device comprises: a collimating lens and a movable plane mirror, which has a simple structure and is convenient for adjusting the optical path.

Preferably, the movable plane mirror comprises a motor-driven guide rail and a plane mirror located on the guide rail.

The time domain optical delay line device is mainly used to quickly change the optical path of the reference arm. Preferably, the time domain optical delay line device includes a circular turntable and a plurality of reflectors fixed on the turntable at a certain angle. The structure is simple and the optical path can be adjusted accordingly.

Furthermore, the light source is a laser light source with a central wavelength of 840nm, a bandwidth of 49nm, and an average power of 20mW. The use of near-infrared light waves can reduce tissue scattering to achieve a greater imaging depth; the narrow bandwidth can ensure that the image is not affected by the inevitable movement of the eye such as micro-saccades.

Furthermore, the sample arm includes a collimator, a fast scanning galvanometer, a slow scanning galvanometer, and a first lens group and a second lens group. After the light enters, it passes through the collimator, the fast scanning galvanometer, the slow scanning galvanometer in sequence, and then enters the first lens group or the second lens group. The first lens group is a divergent lens group, and the second lens group is a condenser lens group. The first lens group and the second lens group can be switched. The first lens group is a divergent lens group, so that the scanning light is a parallel light before entering the eye, and then it can be focused on the fundus after passing through the light system of the eye, so that the fundus can be imaged; the second lens group is a condenser lens group, so that the parallel light entering can be focused on the anterior chamber of the eye through the first lens group, so as to image the anterior chamber of the eye. In this way, by switching the first lens group and the second lens group, the entire device can image both the fundus and the anterior chamber of the eye, so that more information can be obtained.

Preferably, the first lens group includes two mutually parallel focusing lenses, and the two focusing lenses form a 4f system, which has a simple structure and is convenient for optical path control.

Preferably, the second lens group consists of a focusing lens, which is convenient for focusing and system optical path control.

Preferably, the spectrometer comprises a collimating lens, a grating, a focusing lens and a CMOS linear array camera.

The measuring instrument of the present invention has a simple structure and a reasonable design, and is convenient for optical path regulation and control, so as to realize the conversion between the time domain and the frequency domain of the optical path of the OCT reference arm, so that a single device has multiple imaging functions, which greatly improves the performance of the device and can meet common ophthalmic measurement needs, such as anterior chamber imaging, fundus retinal imaging, axial length measurement, blood flow imaging, etc., thereby facilitating doctors to obtain the parameters of measuring various parts of the eye, saving the purchase cost, maintenance cost, and corresponding equipment operation training cost, and equipment management cost.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a schematic diagram of the structure of a multi-parameter, multi-functional eye measuring instrument based on optical coherence tomography provided by an embodiment of the present invention;

2 is a schematic structural diagram of a frequency domain zero optical path position changing device according to an embodiment of the present invention;

FIG. 3 is a schematic diagram of the structure of a time domain optical delay line device according to an embodiment of the present invention.

Detailed ways

The technical solution of the present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

1 , a multi-parameter, multi-functional eye measuring instrument based on optical coherence tomography includes a light source 1, a fiber coupler 2, a reference arm, a sample arm, a detector and a processor.

The reference arm includes a frequency domain module and a time domain module arranged in parallel, the frequency domain module includes a collimator 3 and a frequency domain zero optical path position changing device 5, as shown in FIG2, the frequency domain zero optical path position changing device 5 is a movable plane mirror, including a motor-driven guide rail 51 and a plane mirror 52 located on the guide rail, and the plane mirror 52 is moved by the movement of the motor-driven guide rail 51 to change the length of the reference arm, so that the length of the reference arm is consistent with the length of the sample arm to be measured. The time domain module includes a collimator 3 and a time domain optical delay line device 4, wherein the structure of the time domain optical delay line device 4 is shown in FIG3; it includes a circular turntable 41, and a plurality of reflectors 42 fixed on the turntable 41 at a certain angle; the reflectors 42 rotate with the turntable 41, and the position of the light hitting the reflectors 42 changes during the rotation, thereby changing the length of the reference arm.

The sample arm includes a collimating mirror 3, a fast scanning galvanometer 6, a slow scanning galvanometer 7, and a switchable first lens group and a second lens group, wherein the first lens group is a diverging lens group, and the second lens group is a focusing lens group, wherein the first lens group is composed of two mutually parallel focusing lenses 8, and the two focusing lenses 8 form a 4f system; the second lens group is composed of a focusing lens 8; the detector includes a spectrometer and a photoelectric sensor 9 arranged in parallel, wherein the spectrometer includes a collimating mirror 3, a grating 10, a focusing lens 8 and a CMOS linear array camera 11; the processor is a computer 12.

By arranging parallel frequency domain zero optical path position changing device 5 and time domain optical delay line device 4, as well as spectrometer and photoelectric sensor 9 on the sample arm and detector respectively, the light beam emitted by the light source can choose to use frequency domain optical path or frequency domain optical path.

The optical path of the frequency domain OCT of the measuring instrument of the embodiment of the present invention is that the light source 1 emits a beam of light and enters the fiber coupler 2 to be divided into two, one beam enters the reference arm, and enters the frequency domain zero optical path position changing device. Specifically, it is converted into a beam of parallel light through a fiber collimator 3, and then the parallel light hits a movable plane mirror 52. Due to the mobility of the plane mirror 52, the system can adjust the position of the plane mirror according to different imaging targets (such as imaging the anterior chamber of the eye or imaging the fundus), and then adjust the arm length of the reference arm to match the target to be imaged in the optical path. After the light entering the reference arm is reflected on the reflector 52, it returns to the fiber coupler 2 along the original path. Another beam of light enters the sample arm, passes through the slow scanning galvanometer 6, then passes through the fast scanning galvanometer 7, and then passes through the lens group that matches the target - the first lens group or the second lens group, and is focused and scanned on the imaging target. The scanning light is reflected in the tissue and returns along the original path, and interferes with the light returned from the reference arm in the fiber coupler 2, and then enters the detector part, that is, a spectrometer composed of a collimating lens 3, a grating 10, a focusing lens 8 and a CMOS linear array camera 11. The optical signal is converted into an electrical signal, and the final signal is transmitted to the electronic computer 12 for imaging.

The time domain OCT optical path of the measuring instrument of the embodiment of the present invention is as follows: the light source 1 emits a beam of light which enters the optical fiber coupler 2 and is split into two. One beam enters the reference arm and enters the time domain optical delay line device 4. Specifically, it passes through the collimator 3 and enters the optical delay line device 4, and then returns along the original path and enters the optical fiber coupler 2. The other beam of light enters the sample arm, passes through the slow scanning galvanometer 6, and then passes through the fast scanning galvanometer 7, and then passes through the lens group matching the target - the first lens group or the second lens group, and is focused and scanned on the imaging target. The scanning light is reflected in the tissue and returns along the original path, and interferes with the light returned from the reference arm in the optical fiber coupler 2, and then enters the photoelectric sensor part. The optical signal is converted into an electrical signal by the photoelectric sensor 9, and the final signal is transmitted to the electronic computer 12 for imaging.

The light source of the OCT system determines the performance level that can be achieved, and the central wavelength determines the longitudinal resolution and the detection depth that the system can achieve. Therefore, the light source 1 of the measuring instrument of this embodiment preferably uses a laser light source with a central wavelength of 840nm and a bandwidth of 49nm customized by the research team, and an average power of 20mW, so that the axial resolution is <12μm, which makes it possible to achieve high-sensitivity detection and fast image acquisition in the human eye. At the same time, the use of near-infrared light waves can reduce tissue scattering to achieve a greater imaging depth; the narrow bandwidth range can ensure that the image is not affected by the inevitable movement of the eye itself, such as micro-saccades of the eye.

At the same time, in this embodiment, a switchable first lens group and a second lens group are provided, the first lens group is a divergent lens group, so that the scanning light is parallel light before entering the eye, and then can be focused on the fundus after passing through the light system of the eye, so that the fundus can be imaged; the second lens group is a condenser lens group, so that the entering parallel light can be focused on the anterior chamber of the eye through the first lens group, so as to image the anterior chamber of the eye. In this way, by switching the first lens group and the second lens group, the entire device can image both the fundus and the anterior chamber of the eye, so that more information can be obtained.

In this way, the eye measuring instrument of the embodiment of the present invention has both time domain OCT and frequency domain OCT modules, and has an optional first lens group and a second lens group, which can focus and image the fundus and the anterior segment of the eye respectively. In this way, the frequency domain module can be used to obtain the structural information of the eye, such as the anterior chamber structure information and the retinal structure information, and can be introduced through the corresponding imaging algorithm, so as to image the blood flow. The imaging of the anterior chamber and fundus is performed by changing the length of the reference arm in the frequency domain and the corresponding focusing lens to image the target. The time domain system is used to measure the axial length of the eye, which basically covers the important parameters in ophthalmic examination.

Furthermore, the measuring instrument of the present invention has a simple structure by optimizing the design of the components of each structure, which is convenient for adjusting the optical focusing of different imaging parts and the corresponding optical path of the reference arm. The measuring instrument of the embodiment of the present invention has fast scanning and short time consumption, which is convenient for doctors to obtain the parameters of measuring various parts of the eye, saving the purchase cost, maintenance cost, and operation training cost of the corresponding equipment and the management cost of the equipment.

According to the disclosure and teaching of the above description, those skilled in the art to which the present invention belongs may also make changes and modifications to the above embodiments. Therefore, the present invention is not limited to the specific embodiments disclosed and described above, and some modifications and changes to the present invention should also fall within the scope of protection of the claims of the present invention. In addition, although some specific terms are used in this specification, these terms are only for the convenience of description and do not constitute any limitation to the present invention.

Claims (10)

1. The multi-parameter and multi-functional eye measuring instrument based on optical coherence tomography is characterized by comprising a light source, an optical fiber coupler, a reference arm, a sample arm, a detector and a processor;

the light source is used for providing an initial light beam;

the optical fiber coupler is used for dividing the initial light beam into two parts, respectively entering the reference arm and the sample arm, and receiving the light beams returned by the reference arm and the sample arm;

the reference arm comprises a frequency domain module and a time domain module which are arranged in parallel, the frequency domain module comprises a collimating mirror and a frequency domain zero optical path position changing device, and the time domain module comprises a collimating mirror and a time domain optical delay line device;

the sample arm is used for scanning the eye to be detected;

the detector is used for receiving interference formed by interference of light beams returned by the reference arm and the sample arm and converting the interference into an electric signal; the detector comprises a spectrometer and a photoelectric sensor which are arranged in parallel;

the processor is used for receiving the electric signals and imaging;

wherein the axial resolution of the light source is <12 μm.

2. The eye measurement instrument according to claim 1, wherein the frequency domain zero optical path position changing means comprises: a collimating lens and a movable plane mirror.

3. The eye measurement instrument according to claim 2, wherein the movable mirror comprises a motor driven rail and a mirror positioned on the rail.

4. The eye measurement instrument according to claim 1, wherein the time domain optical delay line device comprises a circular turntable, and a plurality of mirrors fixed at an angle to the turntable.

5. The eye measurement instrument according to claim 1, wherein the light source is a laser light source with a center wavelength of 840nm and a bandwidth of 49nm, and the average power is 20mW.

6. The eye measurement instrument according to claim 1, wherein the sample arm comprises a collimator lens, a fast scanning galvanometer, a slow scanning galvanometer, a first lens group and a second lens group, and light rays sequentially pass through the collimator lens, the fast scanning galvanometer, the slow scanning galvanometer and then enter the first lens group or the second lens group after entering, wherein the first lens group is a condensing lens group, the second lens group is a diverging lens group, and the first lens group and the second lens group are switchable.

7. The eye measurement instrument according to claim 6, wherein the first lens group comprises two focusing lenses parallel to each other, and the two focusing lenses form a 4f system.

8. The eye measurement instrument according to claim 6, wherein the second lens group is comprised of a focusing lens.

9. The eye measurement instrument according to claim 1, wherein the spectrometer comprises a collimating lens, a grating, a first focusing lens, and a CMOS line camera.

10. The eye measurement instrument according to claim 1, wherein the processor is a terminal device having a memory function.