CN116965771B - Optical microscopic system for intraocular pressure measurement - Google Patents

Abstract

The present invention provides an optical microscopy system for intraocular pressure measurement, which relates to the field of optical measurement technology; it includes a spatial optical sensing unit, a light transmission unit, an intraocular pressure sensor, a spectrum collection unit and a spectrum demodulation unit; wherein the spatial optical sensing unit is connected to the spectrum collection unit; the spectrum collection unit and the spectrum demodulation unit are connected through a transmission link; a Fabry-Perot microcavity is arranged on the intraocular pressure sensor; the broadband light emitted by the spatial optical sensing unit is vertically incident on the Fabry-Perot microcavity through the light transmission unit to obtain interference broadband light; the interference broadband light is transmitted to the spectrum collection unit; the spectrum collection unit converts the interference broadband light into a digital spectrum, and then transmits the digital spectrum to the spectrum demodulation unit; the spectrum demodulation unit obtains intraocular pressure according to the digital spectrum. The present invention completes the incident broadband light and the reception of the interference broadband light by cooperating with the spatial optical sensing unit, the light transmission unit and the intraocular pressure sensor, and reduces the optical components.

Description

An optical microscope system for measuring intraocular pressure

Technical Field

The invention relates to the technical field of optical measurement, and in particular to an optical microscope system for measuring intraocular pressure.

Background Art

Glaucoma is one of the three major causes of blindness in the human eye. It is extremely harmful and is the world's leading irreversible blinding disease. Intraocular pressure refers to the pressure exerted on the eyeball wall by the contents of the eyeball. Under normal circumstances, human intraocular pressure should be within the range of 10-21 mmHg. High intraocular pressure is considered an important risk factor for glaucoma. Therefore, intraocular pressure is an important indicator for determining treatment goals and evaluating treatment effects and prognosis in clinical practice.

At present, the main method of measuring intraocular pressure in clinical practice is to measure the patient's immediate intraocular pressure through instruments. The detection instruments mainly include applanation tonometer, jet tonometer, etc. Among them, applanation tonometer is currently considered the "gold standard" for measuring intraocular pressure, but this method has a complicated measurement process, and has the disadvantages of requiring surface anesthesia before measurement, dripping sodium fluorescein on the cornea during measurement, and the measurement value is affected by the central thickness of the cornea. Compared with the applanation tonometer, the jet tonometer simplifies the process of measuring intraocular pressure and does not require surface anesthesia and sodium fluorescein. However, the jet tonometer also has many problems such as its impact airflow can cause eye discomfort to patients, and the instrument is expensive and not portable.

In addition, there are many studies on miniature intraocular pressure sensors based on different principles. The common characteristics of these studies are: 1. The sensor is separated from the detection equipment, and the sensing method is non-contact; 2. The sensor area and volume are tiny, ranging from hundreds of microns to several millimeters; 3. The sensor is in contact with the eye structure, and is attached to the eyeball or implanted inside the eyeball.

According to the sensing principle, the proposed micro intraocular pressure sensors are mainly classified into three types: electrical sensing, microfluidic sensing, and optical sensing. Chen et al. designed an intraocular pressure sensor based on contact lenses, which is sensitive to pressure based on the capacitance value. The frequency of the LC oscillator formed by the capacitor and the inductor also changes with the change of , and the reading device is a large network analyzer. Agaoglu et al. used microfluidic chips to realize intraocular pressure detection, and implanted the artificial lens with integrated microfluidic chips into the eyeball using cataract surgery technology. As the intraocular pressure fluctuates, the position of the liquid-gas interface of the artificial lens is displaced, and the intraocular pressure value can be obtained by monitoring the position of the interface. Electrical sensing is limited by circuit structure and materials, and it is difficult to achieve submillimeter size, and the reading device is large and expensive. Microfluidic sensing is limited by the strict requirements for airtightness and the indirect sensing principle of taking pictures and reading, which makes miniaturization encounter bottlenecks. The volume of optical sensors is generally smaller than that of electrical sensors and microfluidic sensors, so it has become the main research direction of implantable sensors.

The existing optical measurement solutions are all based on the Fabry–Pérot interference structure. Lee's team used silicon nitride as a flexible sensing membrane and silicon as a shell to reduce the size of the sensor to about 1 mm, with a detection accuracy of 1.3 mmHg. Kim's team made further optimizations based on Lee's work and added ANN artificial intelligence to the demodulation algorithm, which increased the accuracy to 0.1 mmHg. The size of both sensors is millimeter-level, and the manufacturing process is etching and assembly. This poses a great challenge to mass production and minimally invasive implantation. In addition, the above team used a slit lamp, a professional equipment for ophthalmic testing, as a basis, and modified and expanded it to provide a desktop broadband light source input interface and an output interface to a large spectrometer. The overall system is complicated, with poor portability and high cost.

In view of this, it is particularly important to provide a non-contact optical microscopy system with a simple structure.

Summary of the invention

The technical problem to be solved by the present invention is: in order to solve the problem of the overall redundancy of the optical detection equipment used for intraocular pressure measurement in the prior art, the present invention provides an optical microscopy system for intraocular pressure measurement, which optimizes the optical path, reduces the optical components, simplifies the structure of the optical microscopy system, and solves the problem of the overall redundancy of the optical detection equipment used for intraocular pressure measurement in the prior art.

The technical solution adopted by the present invention to solve the technical problem is:

An optical microscopy system for intraocular pressure measurement includes a spatial optical sensing unit, a light transmission unit, an intraocular pressure sensor, a spectrum collection unit, and a spectrum demodulation unit; wherein:

The spatial optical sensing unit is connected to the spectrum collection unit;

The spectrum acquisition unit is connected to the spectrum demodulation unit via a transmission link 1;

The intraocular pressure sensor is provided with a Fabry-Perot microcavity;

The broadband light emitted by the spatial optical sensing unit is vertically incident on the Fabry-Perot microcavity through the light transmission unit to obtain interference broadband light;

The interference broadband light passes through the light transmission unit and the spatial optical sensing unit and is then transmitted to the spectrum collection unit;

After the spectrum acquisition unit converts the interference broadband light into a digital spectrum, the digital spectrum is transmitted to the spectrum demodulation unit;

The spectrum demodulation unit obtains intraocular pressure according to the digital spectrum.

Optionally, the spatial optical sensing unit includes a broadband light source, a fiber circulator and a fiber collimator; wherein the broadband light source and the fiber circulator, the fiber circulator and the fiber collimator, and the fiber circulator and the spectrum collection device are all connected through optical fibers; the broadband light source is used to emit the broadband light; the broadband light is sequentially input into the light transmission unit through the fiber circulator and the fiber collimator; the interference broadband light sequentially passes through the light transmission unit, the fiber collimator, and the fiber circulator and is then transmitted to the spectrum collection unit.

Optionally, the wavelength range of the broadband light is 750nm-950nm.

Optionally, it also includes a microscopic imaging positioning unit; the microscopic imaging positioning unit is connected to the spectral demodulation unit via a transmission link 2; the indication light emitted by the microscopic imaging positioning unit is incident on the Fabry-Perot microcavity via the light transmission unit to obtain reflected indication light; the reflected indication light is received and imaged by the microscopic imaging positioning unit after passing through the light transmission unit to obtain a real-time image, and the real-time image is transmitted to the spectral demodulation unit.

Optionally, the microscopic imaging positioning unit includes a CCD camera and an indicator light source; the indicator light source is used to emit the indicator light; and the CCD camera is signal-connected to the spectrum demodulation unit.

Optionally, the light transmission unit includes a lens group and an objective lens sequentially arranged along the light path.

Optionally, the spectrum acquisition unit includes an optical dispersion conversion module, an embedded module and a power driving module; wherein the power driving module supplies power to the optical dispersion conversion module under the control of the embedded module; the optical dispersion conversion module converts the interference broadband light of different wavelengths into an electrical signal through a diffraction effect, and transmits the electrical signal to the embedded module; the embedded module is used to digitize the electrical signal to obtain the digital spectrum.

Optionally, the spectral demodulation unit includes at least one central processor.

Optionally, the spectrum demodulation unit acquires intraocular pressure according to the digital spectrum, comprising the following steps:

S1: Determine the position of the optical microscope system;

S2: reading the digital spectrum to obtain original spectrum data;

S3: extracting the maximum value of the original spectrum data, comparing the maximum value with a preset threshold, and determining whether the maximum value is not less than the preset threshold. If so, proceed to step S4, otherwise proceed to step S1;

S4: performing spectrum interpolation processing on the original spectrum data and performing FFT filtering to restore the spectrum data of the interference broadband light;

S5: using a peak-finding algorithm to separate the spectral data of the interference broadband light into peaks, and obtaining the central wavelength position of the spectral data of the interference broadband light;

S6: Obtaining intraocular pressure through the central wavelength position.

Optionally, the preset threshold is 50% of the mirror reflected light intensity when the broadband light is vertically incident on the plane reflector.

The beneficial effects of the present invention are:

The optical microscopy system for intraocular pressure measurement provided by the present invention achieves the incident broadband light and the reception of the interference broadband light by cooperating with the spatial optical sensing unit, the light transmission unit and the intraocular pressure sensor, measures the intraocular pressure based on the Fabry–Pérot interference structure, reduces the optical components while ensuring the accuracy of the intraocular pressure measurement result, simplifies the structure of the optical microscopy system, and solves the problem of overall complexity of the optical detection equipment for intraocular pressure measurement in the prior art.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention is further described below in conjunction with the accompanying drawings and embodiments.

FIG1 is a schematic diagram of the structure of an optical microscope system for measuring intraocular pressure in the present invention;

FIG2 is a schematic diagram of the structure of the spectrum acquisition unit 4 in the present invention;

FIG3 is a schematic diagram of a process of performing spectrum demodulation by a spectrum demodulation unit in the present invention;

FIG4 is a diagram of raw spectrum data read by a demodulation system in a specific embodiment of the present invention;

FIG5 is a diagram of interference spectrum data restored by a demodulation system in a specific embodiment of the present invention;

FIG6 is a diagram of interference spectrum data under different pressures in a specific embodiment of the present invention;

FIG. 7 is a linear fitting result of the central wavelength corresponding to the interference spectrum peak and the applied pressure.

In the figure: 1-spatial optical sensing unit; 11-broadband light source; 12-fiber circulator; 13-fiber collimator; 2-light transmission unit; 21-lens group; 22-objective lens; 3-intraocular pressure sensor; 4-spectral acquisition unit; 41-light dispersion conversion module; 42-embedded module; 43-power drive module; 5-spectral demodulation unit; 6-microscopic imaging positioning unit; 61-CCD camera; 62-indicator light source; 7-transmission link one; 8-transmission link two.

DETAILED DESCRIPTION

The present invention is now further described in detail. The embodiments described below are exemplary and intended to be used to explain the present invention, but cannot be understood as limiting the present invention. All other embodiments obtained by ordinary technicians in this field without creative work based on the embodiments of the present invention belong to the scope of protection of the present invention.

In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

In order to solve the problem of the complexity of the overall system of the optical detection equipment used for intraocular pressure measurement in the prior art, the present invention provides an optical microscopy system for intraocular pressure measurement, as shown in Figure 1, the optical microscopy system includes a spatial optical sensing unit 1, a light transmission unit 2, an intraocular pressure sensor 3, a spectrum acquisition unit 4 and a spectrum demodulation unit 5; wherein the spatial optical sensing unit 1 is connected to the spectrum acquisition unit 4 through an optical fiber; the spectrum acquisition unit 4 is connected to the spectrum demodulation unit 5 through a transmission link 7, and the transmission link 7 is a transmission link for digital electrical signals, and the transmission implementation method can be a wired transmission technology or a wireless transmission technology; it is worth noting that the wired transmission technology includes but is not limited to serial port, USB, Ethernet, CAN, HDMI, DisplayPort, etc. ort, etc.; wireless transmission technologies include but are not limited to WIFI, Bluetooth, 2.4G, NFC, etc.; a Fabry-Perot microcavity is arranged on the intraocular pressure sensor 3; during operation, the broadband light emitted by the spatial optical sensing unit 1 is vertically incident on the Fabry-Perot microcavity, i.e., the F-P resonant cavity, on the intraocular pressure sensor 3 through the light transmission unit 2, enters the cavity of the Fabry-Perot microcavity, is reflected by multiple surfaces and interferes, and obtains interference broadband light; the obtained interference broadband light passes through the light transmission unit 2 and the spatial optical sensing unit 1 in turn and is then transmitted to the spectrum acquisition unit 4; the spectrum acquisition unit 4 converts the interference broadband light into a digital spectrum and transmits the digital spectrum to the spectrum demodulation unit 5; the spectrum demodulation unit 5 obtains the liquid environment pressure outside the Fabry-Perot microcavity on the intraocular pressure sensor 3, i.e., the intraocular pressure, according to the digital spectrum.

The optical microscopy system for intraocular pressure measurement provided by the present invention achieves the incident broadband light and the reception of the interference broadband light through the cooperation of the spatial optical sensing unit 1, the light transmission unit 2 and the intraocular pressure sensor 3, measures the intraocular pressure based on the Fabry–Pérot interference structure, reduces the optical components while ensuring the accuracy of the intraocular pressure measurement result, simplifies the structure of the optical microscopy system, and solves the problem of overall complexity of the optical detection equipment for intraocular pressure measurement in the prior art.

The intraocular pressure sensor 3 in the present invention is preferably manufactured using two-photon femtosecond laser 3D printing technology, and its structure contains an optical Fabry-Pérot interference cavity, i.e., a Fabry-Perot microcavity, the outer reflective surface of the cavity is a thin film sensitive to external pressure changes, and the inner reflective surface of the cavity is a rigid structure, which is not affected by external pressure; by using two-photon femtosecond laser 3D printing technology, the precision manufacturing of Fabry-Pérot structure intraocular pressure sensors sensitive to pressure changes can be achieved in batches at sub-millimeter sizes; the present invention preferably uses the F-P resonant cavity, i.e., the outer reflective surface of the Fabry-Perot microcavity, to be opposite and parallel to the inner reflective surface of the cavity in the intraocular pressure sensor 3. The intraocular pressure sensor 3 can use an existing intraocular pressure sensor with a Fabry-Perot microcavity, such as the intraocular pressure sensor described in the patent with application number 2022104328698.

The spatial optical sensing unit 1 in the present invention comprises a broadband light source 11, a fiber circulator 12 and a fiber collimator 13; wherein the broadband light source 11 and the fiber circulator 12, the fiber circulator 12 and the fiber collimator 13, and the fiber circulator 12 and the spectrum collection device 4 are all connected via optical fibers; the broadband light source 11 is used to emit broadband light; the broadband light is sequentially input into the light transmission unit 2 through the fiber circulator 12 and the fiber collimator 13; the interference broadband light is sequentially transmitted through the light transmission unit 2, the fiber collimator 13, and the fiber circulator 12 and then transmitted to the spectrum collection unit 4.

Specifically, the broadband light emitted by the broadband light source 11 is input to the first port of the optical fiber circulator 12 through the optical fiber, and then output from the second port of the optical fiber circulator 12, and input to the optical fiber collimator 13 through the optical fiber; the optical fiber collimator 13 is fixed at a position perpendicular to the optical axis of the light transmission unit 2, so that the broadband light is collimated by the optical fiber collimator 13, and then vertically incident on the Fabry-Perot microcavity of the intraocular pressure sensor 3 through the light transmission unit 2. The broadband light enters the cavity of the Fabry-Perot microcavity, is reflected by multiple surfaces and interferes, and obtains interfering broadband light; the obtained interfering broadband light passes through the light transmission unit 2, enters the optical fiber collimator 13 and the optical fiber circulator 12 in sequence, and then is output from the third port of the optical fiber circulator 12, and is transmitted to the spectrum acquisition unit 4 through the optical fiber.

The optical microscopy system for intraocular pressure measurement provided by the present invention comprises a broadband light source 11, a fiber circulator 12, a fiber collimator 13, a light transmission unit 2 and a Fabry-Perot microcavity of an intraocular pressure sensor 3 to form a transmission route for broadband light, and a Fabry-Perot microcavity structure of the intraocular pressure sensor 3, a light transmission unit 2, a fiber collimator 13, a fiber circulator 12 and a spectrum acquisition unit 4 to form a transmission route for interference broadband light, so that the transmission of broadband light and interference broadband light can be completed with fewer components.

The wavelength range of the broadband light is preferably 750nm-950nm. The light in this wavelength range is invisible to the human eye, will not cause discomfort to the patient, and will not cause the patient to produce protective actions such as blinking and rotating the eyeball. In addition, the light in this wavelength range is not absorbed by the cornea and has good penetrability. Most of the energy can directly reach the intraocular pressure sensor 3 in the eye. It is worth noting that the excitation of broadband light can be, but is not limited to, LED semiconductor infrared light sources, thermal radiation infrared light sources, gas discharge infrared light sources, laser infrared light sources, liquid crystal infrared light sources, etc.

Furthermore, the present invention preferably includes a microscopic imaging positioning unit 6 for measuring intraocular pressure; the microscopic imaging positioning unit 6 is connected to the spectral demodulation unit 5 via a transmission link 8, which is a transmission link for digital signals, and the transmission implementation method may be a wired transmission technology or a wireless transmission technology; it is worth noting that wired transmission technologies include but are not limited to serial ports, USB, Ethernet, CAN, HDMI, DisplayPort, etc.; wireless transmission technologies include but are not limited to WIFI, Bluetooth, 2.4G, NFC, etc.; during operation, the indicator light emitted by the microscopic imaging positioning unit 6 is incident on the Fabry-Perot microcavity of the intraocular pressure sensor 3 through the light transmission unit 2 to obtain reflected indicator light; the reflected indicator light is received and imaged by the microscopic imaging positioning unit 6 after passing through the light transmission unit 2 to obtain a real-time image, and the real-time image is transmitted to the spectral demodulation unit 5, and the position of the intraocular pressure sensor 3 is monitored by the spectral demodulation unit 5, so as to monitor the position where the indicator light is irradiated on the intraocular pressure sensor 3.

Furthermore, the present invention preferably has the same transmission optical path of the indicator light and the broadband light in the light transmission unit 2, that is, the indicator light and the broadband light in the light transmission unit 2 are spatially in the same straight line, thereby ensuring that the incident positions of the indicator light and the broadband light on the intraocular pressure sensor 3 are the same, and then the incident position of the broadband light on the intraocular pressure sensor 3 can be monitored by monitoring the incident position of the indicator light on the intraocular pressure sensor 3, thereby facilitating the operator to adjust the position of the spatial optical sensing unit 1 according to the obtained real-time image.

Furthermore, it is preferred to display the real-time image on a corresponding visual screen so as to intuitively monitor the position of the intraocular pressure sensor 3 .

Specifically, the preferred microscopic imaging positioning unit 6 of the present invention includes a CCD camera 61 and an indication light source 62; the indication light source 62 is used to emit indication light; wherein the indication light source 62 is fixed at a position perpendicular to the optical axis of the light transmission unit 2, and the emission direction of the indication light emitted by the indication light source 62 is perpendicular to the optical axis of the light transmission unit 2; the CCD camera 61 is coaxially arranged with the light transmission unit 2; and the CCD camera 61 is signal-connected with the spectral demodulation unit 5.

During operation, the indicator light emitted by the indicator light source 62 passes through the light transmission unit 2 and is vertically incident on the Fabry-Perot microcavity of the intraocular pressure sensor 3 and then reflected to form reflected indicator light; the reflected indicator light passes through the light transmission unit 2 and is received and imaged by the CCD camera 61 to obtain a real-time image; and the real-time image is transmitted to the spectral demodulation unit 5 to monitor the position of the intraocular pressure sensor 3.

In the present invention, the indicating light source 62, the light transmission unit 2, and the Fabry-Perot microcavity of the intraocular pressure sensor 3 constitute a transmission route for the indicating light, and the Fabry-Perot microcavity, the light transmission unit 2, and the CCD camera constitute a transmission route for the reflected indicating light, thereby realizing the monitoring of the position of the intraocular pressure sensor 3.

As shown in FIG1 , the broadband light and interference broadband light, as well as the indicator light and reflected indicator light in the present invention, share a light transmission unit 2 for light transmission. Without adding any additional optical elements, the position of the intraocular pressure sensor 3 and the measurement of the intraocular pressure can be monitored at the same time. This can improve the accuracy of intraocular pressure measurement without adding any optical elements, thereby helping to further simplify the structure of the optical microscope system.

To facilitate the transmission of light, the light transmission unit 2 in the present invention includes a lens group 21 and an objective lens 22 arranged in sequence along the optical path; wherein the lens group 21 and the objective lens 22 form a coaxial structure; the lens group 21 may include two or more lenses, and the two or more lenses respectively reflect or transmit the indicator light and the broadband light respectively to realize the transmission of broadband light, interference broadband light, indicator light and reflected indicator light; the lenses in the lens group 21 can be processed by coating or other methods to make them selectively transparent, that is, the same lens can reflect light in certain specific wavelength ranges and transmit light in certain specific wavelength ranges, so that the indicator light, reflected indicator light, broadband light and interference broadband light can be transmitted separately through the lens group 21 at the same time; and the reflectivity and transmittance of each lens to light in different wavelength ranges can be selected according to the requirements of the optical path; or, each lens can also be set to reflect or transmit light in different wavelength ranges in different areas.

Specifically, after the indicator light enters the lens group 21, it is reflected and incident on the objective lens 22, and the objective lens 22 focuses the indicator light onto the surface of the intraocular pressure sensor 3; the indicator light is reflected to form reflected indicator light; the objective lens 22 collects the reflected indicator light, and the reflected indicator light is received by the CCD camera 61 and imaged after passing through the lens group 21.

After the broadband light enters the lens group 21, it is reflected and incident on the objective lens 22. The objective lens 22 focuses the broadband light on the Fabry-Perot microcavity on the intraocular pressure sensor 3 to generate interference broadband light. The objective lens 22 collects the interference broadband light, which is input into the fiber collimator 13 after passing through the lens group 21.

In the present invention, the objective lens 22 preferably focuses the indicator light and the broadband light vertically to the same point on the intraocular pressure sensor 3 at the same time, and collects the returned reflected indicator light and the interfering broadband light at the same time.

The present invention preferably sets the spatial optical sensing unit 1, the light transmission unit 2 and the microscopic imaging positioning unit 6 as a whole, and uses a multi-dimensional displacement stage to carry the whole, so that the position and angle of the focusing spot of the objective lens 22 on the intraocular pressure sensor 3 can be precisely adjusted by the multi-dimensional displacement stage. It is worth noting that "multi-dimensional" includes but is not limited to front and back, left and right, up and down, pitch and yaw. The adjustment method includes but is not limited to manual adjustment, electric adjustment, pneumatic adjustment, hydraulic adjustment, etc.

The present invention integrates the microscopic imaging positioning unit 6, the spatial optical sensing unit 1 and the light transmission unit 2 into one, so that the optical microscopic system for intraocular pressure measurement has good structural stability, high sensing reliability, small size, high portability and low cost.

Furthermore, the present invention preferably integrates the broadband light source 11, the optical fiber circulator 12, the spectrum collection unit 4 and the driving circuit of the indicator light source 62 into one chassis. The whole machine is powered by an external power supply or an internal battery, and the two power supply modes can be switched at will.

As shown in Figure 2, the spectrum acquisition unit 4 in the present invention includes an optical dispersion conversion module 41, an embedded module 42 and a power driving module 43; wherein the power driving module 43 supplies power to the optical dispersion conversion module 41 under the control of the embedded module 42; the optical dispersion conversion module 41 converts interference broadband light of different wavelengths into electrical signals through the diffraction effect, and transmits the electrical signals to the embedded module 42; the embedded module 42 is used to digitize the electrical signals to obtain a digital spectrum.

Specifically, the power driving module 43 is controlled by the embedded module 42, and is used to supply power to the optical dispersion conversion module 41, and realizes the photoelectric conversion of different speeds of the optical dispersion conversion module 41 by adjusting the power supply frequency; the optical dispersion conversion module 41 distinguishes light of different wavelengths in space through the diffraction effect, and then converts the light of different wavelengths into electrical signals of corresponding intensities; the diffraction effect preferably used by the optical dispersion conversion module 41 of the present invention is the second-order diffraction effect; after the interference broadband light is dispersed by two-order diffraction, the light of different wavelengths is obviously distinguished in space, and the light at different spatial positions is converted into electrical signals of corresponding intensities through photoelectric conversion, which effectively improves the accuracy of demodulation of the external liquid environment pressure based on the change of the central wavelength position; the embedded module 42 captures the electrical signal, digitizes it, and obtains a digital spectrum.

The embedded module 42 in the present invention can control the power drive module 43 to adjust the frequency of supplying power to the optical dispersion conversion module 41, thereby realizing the measurement of different rates of the interference broadband light energy spectrum and meeting the measurement rate requirements in different medical environments.

The spectral demodulation unit 5 in the present invention is used, on the one hand, to monitor in real time the position of the intraocular pressure sensor 3 in the image formed by the area array CCD camera 61, so that the operator can adjust the irradiation position of the indicator light in time; on the other hand, it is used to obtain the digital spectrum and find the central wavelength corresponding to the spectrum peak, and obtain the pressure of the external liquid environment, i.e., the intraocular pressure, in real time through the correspondence between the central wavelength position and the pressure; and can also give the operator feedback on whether the broadband light is aligned with the intraocular pressure sensor 3 and operational suggestions for multi-dimensional calibration adjustment according to the quality of the real-time spectrum. It is worth noting that the evaluation criteria of the spectrum quality include but are not limited to light intensity, free spectral range, signal-to-noise ratio and frequency domain transformation results. The forms of feedback and suggestions include but are not limited to sound, text, graphics, indicator lights, vibration and a combination of various media above.

To achieve the above functions, the spectrum demodulation unit 5 in the present invention includes at least one central processing unit, and the demodulation step is executed in the central processing unit in the form of a program or instruction, and the program or instruction is stored in a permanent memory and can be called by the central processing unit at any time. It is worth noting that the central processing unit includes but is not limited to CPU, MCU, MPU, DSP, FPGA and ASIC, etc. The permanent memory includes but is not limited to programmable ROM, Flash ROM, CD, floppy disk, hard disk, etc.

The invention realizes a detection and demodulation method of a Fabry-Pérot structure intraocular pressure sensor based on an embedded system and a non-contact optical microscopic detection system.

As shown in FIG3 , the spectrum demodulation unit 5 in the present invention obtains intraocular pressure according to the digital spectrum, including the following steps:

S1: Determine the position of the optical microscope system;

S2: read the digital spectrum and obtain the original spectrum data;

S3: extract the maximum value of the original spectrum data, compare the maximum value with the preset threshold, and determine whether the maximum value is not less than the preset threshold. If so, proceed to step S4, otherwise proceed to step S1;

S4: Perform spectral interpolation processing on the original spectral data and perform FFT filtering to restore the spectral data of the interfering broadband light;

S5: using a peak-finding algorithm to separate the spectral data of the interference broadband light into peaks, and obtaining the central wavelength position of the spectral data of the interference broadband light;

S6: Obtain intraocular pressure by the central wavelength position.

According to the sensing principle of the F-P resonant cavity, when the reflectivity of the two reflective surfaces is less than 4%, most of the light vertically incident into the F-P resonant cavity will be transmitted from the other side, and only the light reflected for the first and second time will maintain the same order of magnitude in energy. Therefore, the F-P resonant cavity composed of such low-reflectivity reflective surfaces can simplify multi-beam interference to double-beam interference; therefore, the expression for the intensity of the reflected interference light is:

Where: I _FP is the intensity of the reflected interference light, I ₀ is the intensity of the incident light, R ₁ and R ₂ are the reflectivity of the two surfaces respectively, n is the refractive index of the medium between the two reflecting surfaces, L is the distance between the two reflecting surfaces, and λ is the wavelength of light within the spectral range of the light source.

If one of the reflection surfaces of the F-P resonant cavity is a pressure-sensitive film, the film will deform axially under the action of pressure. At this time, the cavity length L of the F-P resonant cavity will be shortened by ΔL. A phase deviation ΔΦ related to the change in cavity length will be introduced into the interference spectrum, and its calculation formula is as follows:

Where n is the refractive index of the medium between the two reflecting surfaces, λ is the wavelength of light within the spectral range of the light source, and ΔL is the change in the length of the resonant cavity; in the interference spectrum, it is manifested as a wavelength shift corresponding to the peak of the entire spectrum.

According to the theory of solid mechanics, the center of the square diaphragm will undergo axial deformation under the action of static pressure. The relationship between the maximum axial deformation ΔL of the diaphragm and the static pressure P is as follows:

Where: υ is the Poisson's ratio of the diaphragm, E is the Young's modulus of the diaphragm, t is the thickness of the diaphragm, and α is the side length of the diaphragm.

From the above formula, we can see that the change in pressure is linearly related to the maximum axial deformation of the diaphragm, ΔL, and the maximum axial deformation of the diaphragm is also linearly related to the wavelength shift corresponding to the spectral peak. Therefore, the system can demodulate the change in the corresponding pressure through the drift of the wavelength corresponding to the spectral peak.

Specifically, after preliminarily determining the position of the optical microscope system, the spectral demodulation unit 5 reads the digital spectrum output by the spectral acquisition unit 4 to obtain original spectral data; extracts the maximum value of the original spectral data, and compares the maximum value with the preset threshold value. If the maximum value is less than the original threshold value, the spectral demodulation program will determine that the broadband light is not vertically incident on the intraocular pressure sensor 3. At this time, the preferred system prompts the operator to adjust the spatial position of the broadband light focus by adjusting the multi-dimensional displacement stage and combining the real-time image obtained by the microscopic imaging positioning unit 6, and re-determine the position of the optical microscope system until the maximum value of the read original spectral data is greater than or equal to the preset threshold value. At this time, the system will determine that the broadband light has been vertically incident on the intraocular pressure sensor 3, and then restore the spectral data of the interference broadband light by performing spectral interpolation processing on the original spectral data and performing FFT filtering; then use the peak-finding algorithm to separate the spectral data of the interference broadband light, obtain the central wavelength position of the spectral data of the interference broadband light, and obtain the central wavelength of the interference spectrum peak of the real-time F-P resonant cavity, and then obtain the pressure of the external liquid environment at this time, that is, the intraocular pressure, according to the corresponding relationship between the central wavelength and the pressure.

The spectrum demodulation unit 5 in the present invention is used to demodulate the received digital spectrum; according to the characteristics of the system, when the broadband light is vertically incident on the plane reflector, the system will receive the strongest mirror reflected light. Since the surface of the intraocular pressure sensor is rougher than the reflector, the received interference broadband light intensity can only reach 50% of the mirror reflected light intensity, so 50% of the maximum value of the mirror reflected light intensity is set as the preset threshold, that is, the preferred preset threshold of the present invention is 50% of the mirror reflected light intensity when the broadband light is vertically incident on the plane reflector.

For ease of understanding, the present invention describes the complete working process of the optical microscope system for intraocular pressure measurement as follows:

The indication light emitted by the indication light source 62 is reflected by the lens group 21, and after entering the objective lens 22, it is focused on the surface of the intraocular pressure sensor 3 and reflected. The return light is received by the area array CCD camera 61 through the objective lens 22 and the lens group 21, and the generated image is transmitted to the screen of the host computer (spectral demodulation unit 5) in real time; the multi-dimensional displacement stage is adjusted to make the intraocular pressure sensor 3 appear in the center of the field of view of the area array CCD camera 61.

At this time, the broadband light emitted by the broadband light source 11 enters from the first port of the optical fiber circulator 12, is output from the second port of the optical fiber circulator 12, enters the optical fiber collimator 13, is reflected by the lens group 21, is focused by the objective lens 22, and vertically enters the F-P resonant cavity of the intraocular pressure sensor 3. The broadband light enters the cavity and is reflected by multiple surfaces and interferes. The formed interference broadband light is collected by the objective lens 22, reflected by the lens group 21, enters the optical fiber collimator 13, is input from the second port of the optical fiber circulator 13, is output from the third port of the optical fiber circulator 13, and finally enters the spectrum acquisition unit 4.

The interference broadband light enters the spectrum collection unit 4 , and the optical dispersion conversion module 41 and the embedded module 42 convert the energy spectrum of the interference broadband light into a digital spectrum and transmit it to the spectrum demodulation unit 5 .

The spectrum demodulation unit 5 demodulates the received digital spectrum. The present invention uses a computer as the spectrum demodulation unit 5. After the obtained original spectrum data is subjected to spectrum interpolation, FFT filtering, threshold setting, peak search algorithm, threshold peak separation, and searching for wavelength coordinates corresponding to a single spectrum peak, the central wavelength of the interference spectrum peak of the real-time F-P resonant cavity and the pressure corresponding to the external liquid environment at this time, i.e., the intraocular pressure, are obtained, thereby realizing rapid non-contact optical detection demodulation of the intraocular pressure.

In a specific implementation of the present invention, the measurement process is:

1) placing the intraocular pressure sensor 3 in a pressure-controllable liquid container, and positioning the intraocular pressure sensor 3 using the microscopic imaging positioning unit 6; setting the single pressurization amount to 3.75 mmHg, pressurizing from 3.75 mmHg to 37.5 mmHg, and performing steps 2 to 4 after each pressurization;

2) Read the digital spectrum output by the spectrum acquisition unit 4 to obtain the original spectrum data, as shown in FIG4 ;

3) Interpolate the original spectral data and perform FFT filtering to restore the interference spectral data generated by the F-P resonant cavity of the intraocular pressure sensor under this pressure, as shown in FIG5 ;

4) Using a peak-finding algorithm to perform threshold peak separation on the interference spectrum data, record the coordinates of the maximum value of a single spectrum peak, that is, obtain the central wavelength position of the spectrum peak under this pressure;

5) The position of the central wavelength of the spectrum peak under each pressure and the data of the corresponding pressure are linearly fitted to obtain the sensing sensitivity of the intraocular pressure sensor 3, and then the corresponding pressure, i.e., the intraocular pressure, can be obtained according to the position of the central wavelength of the spectrum peak and the sensing sensitivity.

The specific linear fitting process is shown in FIG7 . The fitting result is a linear function of the center wavelength position (y) of the spectrum peak with respect to the pressure (x): y=0.03263x+752.97241. The slope of the linear function is the sensing sensitivity of the intraocular pressure sensor 3 .

The interference spectrum data detected and restored by the intraocular pressure sensor 3 under different pressures are shown in FIG6 .

As shown in Figure 7, the test experiment obtained that the sensing sensitivity of the intraocular pressure sensor 3 is 32.63pm/mmHg. In addition, this embodiment tests the demodulation accuracy of the system. When the intraocular pressure sensor is at a fixed pressure, the pressure demodulation accuracy of the demodulation system is controlled within the range of ±1.5mmHg.

Based on the above ideal embodiments of the present invention, the relevant staff can make various changes and modifications without departing from the technical concept of the present invention through the above description. The technical scope of the present invention is not limited to the contents of the specification, and its technical scope must be determined according to the scope of the claims.

Claims (7)

1. An optical microscopy system for measuring intraocular pressure, characterized in that it comprises a spatial optical sensing unit (1), a light transmission unit (2), an intraocular pressure sensor (3), a spectrum acquisition unit (4) and a spectrum demodulation unit (5); wherein: The spatial optical sensing unit (1) is connected to the spectrum collection unit (4); The spectrum acquisition unit (4) is connected to the spectrum demodulation unit (5) via a transmission link 1 (7); The intraocular pressure sensor (3) is provided with a Fabry-Perot microcavity; The broadband light emitted by the spatial optical sensing unit (1) is vertically incident on the Fabry-Perot microcavity through the light transmission unit (2), thereby obtaining interference broadband light; The interference broadband light passes through the light transmission unit (2) and the spatial optical sensing unit (1) and is then transmitted to the spectrum collection unit (4); The spectrum acquisition unit (4) converts the interference broadband light into a digital spectrum and transmits the digital spectrum to the spectrum demodulation unit (5); The spectrum demodulation unit (5) obtains intraocular pressure according to the digital spectrum; The spatial optical sensing unit (1) comprises a broadband light source (11), an optical fiber circulator (12), and an optical fiber collimator (13); wherein the broadband light source (11) and the optical fiber circulator (12), the optical fiber circulator (12) and the optical fiber collimator (13), and the optical fiber circulator (12) and the spectrum collection unit (4) are all connected via optical fibers; the broadband light source (11) is used to emit the broadband light; the broadband light is sequentially transmitted through the optical fiber circulator (12) and the optical fiber collimator (13) and input into the light transmission unit (2); the interference broadband light is sequentially transmitted through the light transmission unit (2), the optical fiber collimator (13), and the optical fiber circulator (12) and then transmitted to the spectrum collection unit (4); It also includes a microscopic imaging positioning unit (6); the microscopic imaging positioning unit (6) is connected to the spectral demodulation unit (5) via a second transmission link (8); the indicator light emitted by the microscopic imaging positioning unit (6) is incident on the Fabry-Perot microcavity via the light transmission unit (2) to obtain reflected indicator light; the reflected indicator light is received by the microscopic imaging positioning unit (6) after passing through the light transmission unit (2) to obtain a real-time image, and the real-time image is transmitted to the spectral demodulation unit (5); The wavelength range of the broadband light is 750nm-950nm. 2. The optical microscope system for intraocular pressure measurement according to claim 1, characterized in that the microscopic imaging positioning unit (6) comprises a CCD camera (61) and an indicator light source (62); the indicator light source (62) is used to emit the indicator light; and the CCD camera (61) is signal-connected to the spectral demodulation unit (5). 3. The optical microscope system for intraocular pressure measurement according to claim 1, characterized in that the light transmission unit (2) comprises a lens group (21) and an objective lens (22) arranged in sequence along the light path. 4. The optical microscopy system for intraocular pressure measurement according to claim 1, characterized in that the spectrum acquisition unit (4) comprises a light dispersion conversion module (41), an embedded module (42) and a power drive module (43); wherein the power drive module (43) supplies power to the light dispersion conversion module (41) under the control of the embedded module (42); the light dispersion conversion module (41) converts the interference broadband light of different wavelengths into an electrical signal through a diffraction effect, and transmits the electrical signal to the embedded module (42); the embedded module (42) is used to digitize the electrical signal to obtain the digital spectrum. 5. The optical microscopy system for intraocular pressure measurement according to claim 1, characterized in that the spectral demodulation unit (5) comprises at least one central processing unit. 6. The optical microscope system for intraocular pressure measurement according to claim 5, characterized in that the spectral demodulation unit (5) acquires intraocular pressure according to the digital spectrum comprising the following steps: S1: Determine the position of the optical microscope system; S2: reading the digital spectrum to obtain original spectrum data; S3: extracting the maximum value of the original spectrum data, comparing the maximum value with a preset threshold, and determining whether the maximum value is not less than the preset threshold. If so, proceed to step S4, otherwise proceed to step S1; S4: performing spectrum interpolation processing on the original spectrum data and performing FFT filtering to restore the spectrum data of the interference broadband light; S5: using a peak-finding algorithm to separate the spectral data of the interference broadband light into peaks, and obtaining the central wavelength position of the spectral data of the interference broadband light; S6: Obtaining intraocular pressure through the central wavelength position. 7. The optical microscope system for intraocular pressure measurement according to claim 6, characterized in that the preset threshold is 50% of the mirror reflected light intensity when the broadband light is vertically incident on the plane reflector.