CN107908015B - A non-invasive human eye intraocular pressure measurement device and method based on optical grating - Google Patents

Abstract

A non-invasive human eye intraocular pressure measurement device and method based on an optical grating, which belongs to the non-invasive human eye intraocular pressure measurement device and method, solves the defects existing in the prior art and meets clinical needs. The soft contact lens of the present invention is composed of an optical grating and a soft contact lens lens, and the optical grating is prepared on the lens of the soft contact lens, so that the optical grating and the soft contact lens are integrated. In the intraocular pressure measurement method of the present invention, the patient wears a contact lens, and then sequentially measures the diffraction spectrum at each moment on the contact lens to obtain the parameters of the optical grating changing with time, including period _j , top line width, line width at the bottom of the line and groove Deep; Finally, recursively calculate the intraocular pressure at each moment and the change value of intraocular pressure at each time period, display and output. The present invention can accurately and rapidly extract the intraocular pressure value dynamically and in real time, and is suitable for clinical 24-hour real-time intraocular pressure monitoring.

Description

A non-invasive human eye intraocular pressure measurement device and method based on optical grating

technical field

The invention belongs to a non-invasive human eye intraocular pressure measurement device and method, and relates to a non-invasive human eye intraocular pressure measurement device and method based on an optical grating, more specifically, to a soft contact lens based on an optical grating and its intraocular pressure measurement method.

Background technique

The optic nerve damage caused by elevated intraocular pressure accompanied by intraocular pressure fluctuations is called glaucoma. It is the world's first irreversible blinding eye disease, which is very harmful to human health. It leads to slow and irreversible damage to the optic nerve. Hard to detect. Elevated intraocular pressure is not the only cause of glaucoma damage. Pathological intraocular pressure fluctuations also play an important role in the development of glaucoma, and the performance is more subtle. It is difficult to control the fluctuation of intraocular pressure in a day. Therefore, it is more important to pay attention to the increase of the absolute value of intraocular pressure and the 24-hour fluctuation of intraocular pressure.

At present, the clinical method used to detect 24-hour intraocular pressure fluctuations is usually measured every 2 hours. This method of representing 24 hours with 12 detection points is not enough to fully reflect the whole process of intraocular pressure fluctuations. In addition, the measurement often needs to be carried out in a sitting position, so it is impossible to know the real situation of the patient in the natural life state, such as: sleep, exercise, etc. Therefore, more research on 24-hour IOP monitoring techniques is necessary.

The existing 24-hour intraocular pressure fluctuation monitoring technology includes invasive measurement methods and non-invasive measurement methods; invasive measurement is to place the sensor directly into the eye, and changes in intraocular pressure cause changes in the distance between the "LC-resonant circuit" capacitor pole pieces. The resonant frequency of the overall circuit is captured by an external receiver to reflect changes and fluctuations in intraocular pressure. Although the invasive measurement method can be directly measured, it will cause irreversible damage to the eyeball. It is usually only used for critical glaucoma patients, and it is not applicable to the measurement of intraocular pressure for the general population.

Compared with the invasive measurement method, the non-invasive measurement method measures intraocular pressure by measuring the deformation of the cornea under pressure changes, which can overcome the defects of the invasive measurement method.

Chinese patent application 102098956 A discloses a sensor contact lens and a measurement method. Multiple sets of electrodes are prepared on the contact lens, and the electrical signals (resistance, current, etc.) and their changes between the electrodes are measured to obtain the corresponding intraocular pressure and its changes. . But its disadvantage is that the repeatability is not good enough, some output signals of the sensor cannot be analyzed, the monitoring accuracy is not high, the sensitivity is not enough, it is difficult to realize multi-point measurement, the output electrical signal can only reflect the pressure fluctuation, and cannot be converted into the real intraocular pressure amplitude, comfortable Poor performance, complex manufacturing process, and high cost; leading to certain limitations in clinical promotion.

Chinese patent application 201410630877.9 discloses a 24-hour intraocular pressure monitoring system based on a fiber grating sensor, which wraps an optical fiber with a Bragg grating in a soft contact lens. Strain causes the period of the grating to change, thereby shifting the wavelength of the light reflected from the grating. According to the change of reflection wavelength, the pressure measurement at the point where the grating is located is realized, and then multi-point measurement is realized. Compared with the intraocular pressure measurement principle of Chinese patent application 102098956 A, the spectral multi-point corneal deformation measurement has incomparable advantages.

Since the thickness of each area of the cornea of the human eye is different, when the intraocular pressure changes, the pressure and change of each area of the cornea are different, and the intraocular pressure at each moment is unique. The existing technology can only obtain the pressure and Pressure change information, so far, there is no report on analyzing the information of intraocular pressure.

For ease of understanding of the present invention, relevant concepts and terms are described below:

The present invention adopts a spatial rectangular coordinate system, as shown in Figure 1, the surface of the grating is an XY plane, the rightward direction is the positive direction of the X axis, the Y axis is along the axis of the grating, and the forward direction is the positive direction of the Y axis; the Z axis is perpendicular to the XY axis The downward direction is the positive direction; the incident point of the incident light on the grating surface is the origin.

The plane formed by the incident light and the reflected light is the incident plane, and the incident angle θ is the angle between the incident light and the normal line (Z axis) of the optical grating surface, and the azimuth angle is the angle between the incident plane and the positive direction of the X-axis.

The ideal grating cross-section is rectangular. Due to the grating preparation process and the deformation of the patient after wearing it, the cross-section deviates from the original surface shape in actual measurement. Therefore, the present invention regards the grating cross-section as any surface shape. For any surface When the grating structure is modeled using the principle of strict coupled wave (RCWA), the grating section is first layered, and the grating surface of each layer is approximated by a rectangular surface, and then the rectangular surface grating is used to The RCWA modeling theory models and calculates each layer, and finally correlates the calculation results of each layer through the electromagnetic field boundary conditions, and then uses the relevant iterative solution algorithm to obtain the spectrum of the entire grating. Without loss of generality, here we take the trapezoidal grating section as an example, as shown in Figure 1, the grating structure is divided into three sub-areas, from top to bottom are incident/reflective area 1, and its longitudinal coordinate z﹤0; grating area 2 , its longitudinal coordinate is 0﹤z﹤H; the transmission area is 3, z﹥H; the period of the trapezoidal grating is Λ, the line width at the top of the line is W, the line width at the bottom of the line is M, the depth of the groove is H, and the width of the bottom of the groove is D , and the sidewall angle is α.

Contents of the invention

The invention provides a soft corneal contact lens based on an optical grating and an intraocular pressure measurement method, which solves the defects in the prior art and meets clinical needs.

A soft contact lens based on an optical grating provided by the present invention is composed of an optical grating and a soft contact lens lens, and is characterized in that:

The optical grating is prepared on the lens of the soft contact lens, so that the optical grating and the soft contact lens are integrated;

The lens material of the soft contact lens is a soft silicon hydrogel material, which is suitable for wearing by humans or animals; the lens of the soft contact lens is spherical in shape, has a diameter of 12 mm to 18 mm, and a thickness of 40 μm to 110 μm. To fit closely with the shape of the patient's eyeball;

The optical grating is parallel stripes arranged periodically, the cross section of the stripes is rectangular or isosceles trapezoidal, the line width at the top of the line is 30nm-15μm, the line width at the bottom of the line is 30nm-15μm, the depth of the groove is 30nm-15μm, and the width of the bottom of the groove is 30nm-15μm, Period Λ is the sum of the line width at the bottom of the line and the bottom width of the groove;

When the strip section is rectangular, the top line width and the bottom line width of the line are the horizontal side length of the rectangle, and the groove depth is the vertical side length of the rectangle; when the strip section is an isosceles trapezoid, the line top line The width is the length of the top side of the isosceles trapezoid, the line width of the bottom of the line is the length of the bottom side of the isosceles trapezoid, and the groove depth is the height of the isosceles trapezoid.

The described soft contact lens based on optical grating is characterized in that:

The soft silicone hydrogel material is a hydrated polymer of methyl methacrylate, ethyl methacrylate or glycerol methacrylate.

The described soft contact lens based on optical grating is characterized in that:

Depositing an optical film with a thickness of 10nm to 50nm on the optical grating, so that the spectrometer can more easily read the diffraction spectrum and characteristic wavelength reflected by the optical grating;

The optical film material can be metal or non-metal, and the refractive index of the non-metal optical film material needs to be greater than that of the corneal contact lens.

The intraocular pressure measurement method based on the soft contact lens provided by the present invention comprises the following steps:

(1) Measure the initial intraocular pressure P ₁ of the patient according to the traditional clinical applanation method; then the patient wears a contact lens and makes it closely fit the shape of the eyeball;

Then the patient carries the spectrum acquisition device, processor and detection light generation device with him, and fixes the optical fiber probe on the head of the patient. The fiber optic probe is connected with the spectrum acquisition device and the detection light generation device through an optical cable, and the spectrum acquisition device and the processor are connected through a data line. ;

The spectrum acquisition device includes a spectrum signal demodulation unit and a spectrum detection unit;

The probing light generating device includes a broadband light source and a spectral signal modulation unit;

(2) Obtain the parameters of the optical grating changing with time:

Measure the diffraction spectrum and characteristic wavelength of any selected point in the optical grating area at different times, and use the spectral library matching method or nonlinear regression method to obtain the corresponding structural parameters of the optical grating over time, including period Λ _j and top line width W _j , line width M _j at the bottom of the line and groove depth H _j ; j=2,...,t-1,t, t≥100, t is an integer;

(3) Recursively calculate the intraocular pressure P _j at each moment and the change value ΔP _j of intraocular pressure at each time period:

In the above formula, the original pressure P ₀ =0 is the pressure difference between the two sides of the soft contact lens exposed to the air when the patient is not wearing it; P ₁ is the intraocular pressure value measured by other conventional equipment when the patient is not wearing it;

Display and output the intraocular pressure at each moment.

Described step (2) can comprise following substep:

(2.1) Project a beam of broadband light emitted by the fiber optic probe to any selected position on the surface of the optical grating on the contact lens at a fixed incident angle and a fixed azimuth angle;

(2.2) Measure the diffracted light reflected by the optical grating for broadband light through the optical fiber probe, and then pass the spectral detection unit (such as a spectrometer) every time T to obtain the diffraction spectrum and the characteristic wavelength of the position point at different times j; 5min≤T ≤120min;

(2.3) According to the diffraction spectrum and characteristic wavelength of the position point at different times j, the processor adopts the spectral library matching method or the nonlinear regression parameter extraction method to obtain the period Λ _j , the top line width W _j , and the bottom line of the optical grating at different times Width M _j and groove depth H _j ;

(2.4) Calculate the change value of period, top line width, line bottom line width or groove depth at the corresponding time ΔQ _j = Q _j -Q ₀ ; Q _j represents period Λ _j , line width at the top of the line W _j , and line width at the bottom of the line M _j or groove depth H _j , Q ₀ represents the period, top line width, line bottom line width or initial value of groove depth: period Λ ₁ , top line width W ₁ , line bottom line width M ₁ and groove depth H ₁ .

In the sub-step (2.3), the processor adopts the spectral library matching method to obtain the period Λ _j , the top line width W _j , and the bottom line width of the optical grating at different times according to the diffraction spectrum and characteristic wavelength of the position point at different times j M _j and groove depth H _j ; including the following process:

(2.3A) First, according to the structure of the optical grating, determine the numerical range of the structural parameters of the optical grating to be tested. The structural parameters include period, line width at the top of the line, line width at the bottom of the line, and groove depth;

The numerical variation range of each structural parameter fluctuates 10% above and below its design value, and the design value of each structural parameter is: line width at the top of the line is 30nm to 15μm, line width at the bottom of the line is 30nm to 15μm, groove depth is 30nm to 15μm, and groove bottom width is 30nm ~15μm, the period Λ is the sum of the line width at the bottom of the line and the bottom width of the groove;

And carry out discretization processing on the numerical variation range of these structural parameters according to the preset step size δ, thereby obtaining a plurality of discrete grid points x _i , i=1, 2, ..., n-1, n, n is Integer; the preset step size δ is 1% to 10% of the numerical variation range of the corresponding structural parameters;

(2.3B) By rigorous coupled wave analysis (RCWA), finite element method (FEM), boundary element method (BEM) or finite time domain difference method (FDTD), according to different combinations of spectral range, incident angle and azimuth angle, Calculate the theoretical spectrum f( _xi |Π) corresponding to each discrete grid point x _i , f( _xi |Π) is expressed in the form of reflectance or transmittance, where Π represents the corresponding measurement configuration combination, Including spectral range, angle of incidence and azimuth;

(2.3C) Store each discrete grid point and its corresponding theoretical spectrum in the spectral library. The entries in the spectral library include the configuration number K, ID number, structural parameters to be measured and theoretical spectra; the configuration number K is the measurement configuration combination The number of elements in K=1,...,m-1,m, m≤5; the ID number is the number of K×i discrete grid points, and the structure parameter to be measured is the structure included in each discrete grid point parameter; the theoretical spectrum is the theoretical spectrum f( _xi |Π) corresponding to each discrete grid point;

(2.3D) Project a beam of broadband light emitted by the fiber optic probe to any selected point on the surface of the optical grating on the contact lens at a fixed incident angle and azimuth angle;

Measure the diffracted light reflected by the optical grating for the broadband light through the optical fiber probe, and obtain the diffraction spectrum y(x ₀ |Π) and the characteristic wavelength λ ₀ of the position point through the spectrometer;

where _x0 represents the true value of grating period, top line width, bottom line width of lines or groove depth on the contact lens;

(2.3E) extracting structural parameters;

Compare the diffraction spectrum y(x ₀ |Π) with the theoretical spectrum in the spectral library, find the minimum value of the root mean square error between the two, and the corresponding structural parameters to be measured are the required set of structural parameters.

During measurement, the patient wears the contact lens of the present invention. If the intraocular pressure changes, the optical (diffraction) grating on the soft contact lens will feel the strain caused by the pressure, causing parameters such as grating period and groove depth to change, so that The spectrum and characteristic wavelengths diffracted by the grating change. Figure 2 shows two theoretical diffraction spectra, its parameters: the incident angle θ and azimuth Ψ are 0, the side wall angle α=90°, the grating periods are 400nm and 500nm respectively, the groove depth is 100nm, and the corresponding characteristics of the corresponding spectra The wavelengths are λ ₁ =0.53 nm and λ ₂ =0.64 nm, respectively. According to the grating diffraction spectrum and the change of characteristic wavelength, based on (fitting error interpolation) spectral library matching method or nonlinear regression and other mathematical methods to obtain the corresponding grating period, line width, groove depth, aspect ratio before and after the change in the grating area Structural parameters such as side wall topography; or direct non-contact measurement of structural parameters and changes of the grating, and then further analysis based on structural parameters and changes over time, rate of change and rate of change, etc., can realize human intraocular pressure and change monitoring .

The present invention adopts the library matching method based on seeking the minimum value of the error for optical diffraction measurement. The method first constructs an error function based on the established spectral library and the obtained measurement spectrum, and then converts the solution of the inverse problem in the diffraction measurement process into the solution of the error The problem of the minimum value of the function, and the structural parameter corresponding to the minimum value is the structural parameter to be measured corresponding to the measured spectrum, and the intraocular pressure value is obtained by further analysis. Although the establishment of the spectral library is a very time-consuming process, fortunately, the whole process of building the library can be carried out offline. Once the spectral library is built, the remaining parameter extraction process is only equivalent to a database query problem, which can ensure that the parameter extraction can be done in a timely manner. It is completed in a relatively short time, so it is suitable for the real-time monitoring application of clinical human eye intraocular pressure.

The library matching method can be realized by rigorous coupled wave analysis (RCWA) method, finite element method (FEM)), boundary element method (BEM), finite time domain difference method (FDTD) and other methods;

The Rigorous Coupled Wave Analysis (RCWA) method shows that:

[1]Li L.Use of Fourier series in the analysis of discontinuousperiodic structures[J].Journal of the Optical Society of America A,1996,13(9):1870-1876;

[2]Li L.Formulation and comparison of two recursive matrix algorithms for modeling layered diffraction gratings[J].Journal of the Optical Society of America A,1996,13(5):1024-1035;

[3] Liu S.Y., Ma Y., Chen X.G., and Zhang C.W., "Estimation of the convergence order of rigorous coupled-wave analysis for binary gratings inoptical critical dimension metrology," Opt.Eng.51(8), 081504(2012) .

Finite Element Method (FEM)) can be seen:

[4]Bao G, Chen Z M, Wu H J.Adaptive finite-element method fordiffraction gratings[J].Journal of the Optical Society of America A,2005,22(6):1106-1114;

[5] Demésy G, Zolla F, Nicolet A. The finite element method as applied to the diffraction by an anisotropic grating [J]. Optics Express, 2007, 15(26): 18090-18102.

The Boundary Element Method (BEM) can see:

[6] Nakata Y, Koshiba M. Boundary-element analysis of plane-wave diffusion from groove-type dielectric and metallic gratings [J]. Journal of the Optical Society of America A, 1990, 7(8): 1494-1502;

[7] Prather D W, Mirotznik M S, Mait J N. Boundary integral methods applied to the analysis of diffractive optical elements [J]. Journal of the Optical Society of America A, 1997, 14(1): 34-43.

The finite time domain difference method (FDTD) can be seen:

[8] Judkins J B, Ziolkowski R W. Finite-difference time-domain modeling of nonperfectly conducting metallic thin-film gradings [J]. Journal of the Optical Society of America A, 1995, 12(9): 1974-1983;

[9] Ichikawa H. Electromagnetic analysis of diffraction gratings by the finite-difference time-domain method [J]. Journal of the Optical Society of America A, 1998, 15(1): 152-157;

[10] Taflove A, Hagness S C. Computational Electrodynamics: The Finite-Difference Time-Domain Method (Third Edition) [M]. London: Artech House, 2005.

The optical diffraction measurement method of the present invention can also adopt a reverse parameter extraction method, and the reverse parameter extraction method can be a nonlinear regression method, because the parameter extraction method based on nonlinear regression needs to call the forward optical characteristic model in each iteration process , and the calculation of the forward characteristic model is a relatively time-consuming process, especially for complex three-dimensional periodic structures, so it is difficult to meet the requirements of the online measurement process.

Nonlinear regression method, it can be seen that:

[11] Gereige I, Robert S, Thiria S, et al. Recognition of diffraction-grating profile using a neural network classifier in optical scatterometry [J]. Journal of the Optical Society of America A, 2008, 25(7): 1661 -1667;

[12] Wei S, Li L. Measurement of photoresist grating profiles based on multiwavelength scatterometry and artificial neural network [J]. Applied Optics, 2008, 47(13): 2524-2532;

[13] Zhang C.W., Liu S.Y., Shi T.L., and Tang Z.R., “Improved model-based infrared reflectrometry for measuring deep trench structures,” J.Opt.Soc.Am.A26(11), 2327–2335(2009).

Compared with the 102098956 A Chinese patent application, the advantage of the present invention is that the spectrum method is used to make the measurement more precise, which can overcome the pathological change information that is difficult to resolve in this patent application; Measurement of any point.

Compared with the 2014106 30877.9 Chinese patent application, (1) the soft contact lens of the present invention can be more closely attached to the cornea, and overcomes the problem that it is difficult to closely attach to the cornea due to the high elasticity of the optical fiber grating in the sensor (2) Utilize the diffraction of light and polarization phenomenon to extract spectral change information in the present invention, the measuring band range that can be used is wide, from short-wave band to long-wave band, depending on the precision difference of measuring signal analysis and selects different wave bands, comparison file utilizes What is more important is the interference effect between the incident light of the input fiber and the reflected light of the Bragg grating, the range of wave bands that can be measured is not as wide as the present invention, and the extracted signals are not as many as the present invention. (3) The present invention can also obtain the change of the geometric size of the grating stripes through other non-contact measurement methods, and then analyze the intraocular pressure and intraocular pressure information. In the prior art, there is no report about directly measuring the geometric size and changes of the grating stripes to analyze the intraocular pressure. (4) The optical grating of the present invention is directly prepared on the soft contact lens lens, and the spectrum and characteristic wavelength changes at any point diffracted by any point on the grating surface of the soft contact lens can be measured to obtain two-dimensional grating change information. One-dimensional information is obtained.

The basic principle of the invention is to project a beam of broadband light onto the surface of the optical grating of the corneal contact lens worn by the measured person, and measure the diffracted light of the grating to obtain the spectrum and spectral changes at different times, and then extract its structure Parameters such as the line width, groove depth, and side wall angle of the grating structure change with time, and further analyze the intraocular pressure values at different times. It can realize the dynamic monitoring of the intraocular pressure of the human eye, and can also obtain the information of the pressure and changes in various regions of the cornea of the eye. The present invention can accurately and rapidly extract the intraocular pressure value dynamically and in real time, and is suitable for clinical 24-hour real-time intraocular pressure monitoring.

Description of drawings

Fig. 1 Structure diagram of contact lens grating sensor;

Fig. 2 Diffraction spectrum and corresponding characteristic wavelengths λ ₁ , λ ₂ ;

Fig. 3 is a schematic flow chart of the intraocular pressure measurement method of the present invention;

Fig. 4 is the measuring system schematic diagram that the present invention adopts;

Fig. 5 is the sub-step flowchart schematic diagram of step (2);

Fig. 6 is a schematic flow chart of sub-step (2.3).

Detailed ways

The present invention will be described in further detail below in conjunction with the accompanying drawings and embodiments.

An embodiment of the contact lens of the present invention is composed of an optical grating and a soft contact lens lens, the optical grating is prepared on the soft contact lens lens, so that the optical grating and the soft contact lens are integrated;

The lens material of the soft contact lens is a hydrated polymer of methyl methacrylate, which is suitable for wearing by humans or animals; the lens of the soft contact lens is spherical in shape, with a diameter of 12 mm and a thickness of 100 μm;

The optical grating is prepared by molding on the surface of the contact lens lens, the optical grating is parallel stripes arranged periodically, the cross section of the stripes is rectangular, the line width at the top of the line and the line width at the bottom of the line are 200nm, the groove depth is 100nm, and the period is 400nm , with a sidewall angle of 90°.

The second embodiment of the contact lens of the present invention is composed of an optical grating and a soft contact lens lens, the optical grating is prepared on the soft contact lens lens, so that the optical grating and the soft contact lens are integrated;

The lens material of the soft contact lens is a hydrated polymer of glycerol methacrylate, which is suitable for wearing by humans or animals; the lens of the soft contact lens is spherical in shape, with a diameter of 12 mm and a thickness of 100 μm;

An optical thin film with a thickness of 15nm is deposited on the optical grating, and the optical thin film material is a metal aluminum film;

The optical grating is prepared by molding on the surface of the contact lens lens, the optical grating is parallel stripes arranged periodically, the cross section of the stripes is rectangular, the line width at the top of the line and the line width at the bottom of the line are 200nm, the groove depth is 100nm, and the period is 400nm , with a sidewall angle of 90°.

The embodiment of the intraocular pressure measurement method based on any of the above-mentioned soft contact lens embodiments, as shown in Figure 3, comprises the following steps:

(1) Measure the initial intraocular pressure P ₁ of the patient according to the traditional clinical applanation method; then the patient wears a contact lens and makes it closely fit the shape of the eyeball;

Then the patient carries the spectrum acquisition device, processor and detection light generation device with him, and fixes the optical fiber probe on the head of the patient. The fiber optic probe is connected with the spectrum acquisition device and the detection light generation device through an optical cable, and the spectrum acquisition device and the processor are connected through a data line. ,As shown in Figure 4;

The spectrum acquisition device includes a spectrum signal demodulation unit and a spectrum detection unit;

The probing light generating device includes a broadband light source and a spectral signal modulation unit;

(2) Obtain the parameters of the optical grating changing with time:

Measure the diffraction spectrum and characteristic wavelength of any selected point in the optical grating area at different times, and use the spectral library matching method or nonlinear regression method to obtain the corresponding structural parameters Q _j of the optical grating over time, including the period Λ _j , the top line of the line Width W _j , bottom line width M _j and groove depth H _j ; j=2,...,t-1,t, t≥100, t is an integer;

As shown in Figure 5, it specifically includes the following sub-steps:

(2.1) Project a beam of broadband light emitted by the fiber optic probe to any selected position on the surface of the optical grating on the contact lens at a fixed incident angle and a fixed azimuth angle;

(2.2) Measure the diffracted light reflected by the optical grating for the broadband light by the optical fiber probe, and then pass the spectrometer at intervals T to obtain the diffraction spectrum and the characteristic wavelength of the position point at different times j, T=30min;

(2.3) According to the diffraction spectrum and characteristic wavelength of the position point at different times j, the processor adopts the spectral library matching method or the nonlinear regression parameter extraction method to obtain the period Λ _j of the optical grating at different times, the line width W _j at the top of the line, and the bottom of the line Line width M _j and groove depth H _j ;

(2.4) Calculate the change value ΔQ _j = Q _j -Q ₀ of the corresponding time period, line width at the top of the line, line width at the bottom of the line or groove depth; Q _j represents the period Λ _j , line width at the top of the line W _j , line at the bottom of the line Width M _j or groove depth H _j , Q ₀ represents the initial value of period, line top line width, line bottom line width or groove depth: period Λ ₁ , line top line width W ₁ , line bottom line width M ₁ and groove depth H ₁ ;

(3) Recursively calculate the intraocular pressure P _i at each moment and the change value ΔP _i of the intraocular pressure at each time period:

In the above formula, the original pressure P ₀ =0 is the pressure difference between the two sides of the soft contact lens exposed to the air when the patient is not wearing it; P ₁ is the intraocular pressure value measured by other conventional equipment when the patient is not wearing it;

Display and output the intraocular pressure at each moment.

As shown in Figure 6, the sub-step (2.3) described in this embodiment includes the following process:

(2.3A) First, according to the structure of the optical grating, determine the numerical range of the structural parameters of the optical grating to be tested. The structural parameters include period, top line width, line bottom line width and groove depth;

The numerical variation range of each structural parameter fluctuates 10% above and below its design value, and the design value of each structural parameter is: top line width 200nm, line bottom line width 200nm, groove depth 100nm, groove bottom width 200nm, period Λ is the line bottom line The sum of the width and the bottom width of the groove is 400nm;

And carry out discretization processing on the numerical variation range of these structural parameters according to the preset step size δ, thereby obtaining a plurality of discrete grid points x _i , i=1, 2, ..., n-1, n, n is Integer; the preset step size δ is 5% of the value variation range of the corresponding structural parameters;

(2.3B) Calculate the theoretical spectrum f(x _i |Π) corresponding to each discrete grid point x _i according to different combinations of spectral range, incident angle and azimuth angle by rigorous coupled wave analysis (RCWA) , where Π represents the corresponding measurement configuration combination, including spectral range, incident angle and azimuth angle; f( _xi |Π) is expressed in the form of reflectance or transmittance;

(2.3C) Store each discrete grid point and its corresponding theoretical spectrum in the spectral library. The entries in the spectral library include the configuration number K, ID number, structural parameters to be measured and theoretical spectra; the configuration number K is the measurement configuration combination The number of elements in , K=1, 2, 3; the ID number is the number of K×i discrete grid points, the structural parameters to be measured are the structural parameters included in each discrete grid point; the theoretical spectrum is the number of each discrete grid point The theoretical spectrum f( _xi |Π) corresponding to the grid point;

(2.3D) Project a beam of broadband light emitted by the fiber optic probe to any selected point on the surface of the optical grating on the contact lens at a fixed incident angle and azimuth angle;

Measure the diffracted light reflected by the optical grating for the broadband light through the optical fiber probe, and obtain the diffraction spectrum y(x ₀ |Π) and the characteristic wavelength λ ₀ of the position point through the spectrometer;

where _x0 represents the true value of grating period, top line width, bottom line width of lines or groove depth on the contact lens;

(2.3E) extracting structural parameters;

Compare the diffraction spectrum y(x ₀ |Π) with the theoretical spectrum in the spectral library, find the minimum value of the root mean square error between the two, and the corresponding structural parameters to be measured are the required set of structural parameters.

Claims (6)

1. a kind of non-intrusion type human eye tonometry equipment based on optical grating, including optical grating and soft corneal contact lens Eyeglass, which is characterized in that further include fibre-optical probe, spectra collection device, processor and detection light generating apparatus；

The optical grating is prepared on soft corneal contact lens eyeglass, so that optical grating and soft corneal contact lens are at one Body；

The soft corneal contact lens lens materials are soft silicon hydrogel material, to be suitble to human or animal to wear；It is described soft The shape of contact lens eyeglass in spherical crown shape, diameter 12mm~18mm, with a thickness of 40 μm~110 μm, with patient's eyeball shape Shape fits closely；

The optical grating is the parallel stripes of periodic arrangement, and striped section is rectangle or isosceles trapezoid, and the width of striped is referred to as Line width, lines top line width 30nm~15 μm, lines bottom line width 30nm~15 μm, groove depth 30nm~15 μm, the bottom of slot are wide 30nm~15 μm are spent, periods lambda is wide the sum of the bottom width with slot of striped lines bottom line；

When striped section is rectangle, line width and lines bottom line width are horizontal sides side length, the groove depth of rectangle at the top of the lines For the vertical edge side length of rectangle；When striped section is isosceles trapezoid, line width is the top margin side of isosceles trapezoid at the top of the lines Long, lines bottom line width is that bottom edge side length, the groove depth of isosceles trapezoid are the height of isosceles trapezoid；

Fibre-optical probe is connect with spectra collection device and detection light generating apparatus by optical cable, and spectra collection device and processor are logical Cross data line connection；

The detection light generating apparatus includes wideband light source and spectral signal modulation unit, for passing through fibre-optical probe to soft angle Optical grating on film contact lense eyeglass emits broadband light；

The spectra collection device includes spectral signal demodulating unit and spectrographic detection unit, for receiving and demodulating optical grating The diffraction light reflected for broadband light.

2. the non-intrusion type human eye tonometry equipment based on optical grating as described in claim 1, it is characterised in that:

The soft silicon hydrogel material is methyl methacrylate, ethyl methacrylate or glyceral methacrylate Hydrated polymer.

3. the non-intrusion type human eye tonometry equipment based on optical grating as claimed in claim 1 or 2, it is characterised in that:

The optical thin film of a layer thickness 10nm~50nm is deposited on the optical grating, so that spectrometer is easier to read light Learn difraction spectrum and characteristic wavelength that optical grating reflection comes out；

The optical film materials be metal or nonmetallic, the refractive index of non-metallic optical thin-film material need to be greater than the angle The refractive index of film contact lense.

4. the tonometry side based on the non-intrusion type human eye tonometry equipment described in claim 1 based on optical grating Method, characterized in that it comprises the following steps:

(1) when patient does not wear, using the initial intraocular pressure P of other conventional equipments measurement patient₁；Then patient wears Corneal Contact Mirror, and be allowed to fit closely with eyeball shape；

Spectra collection device, processor and detection light generating apparatus are carried by patient again, visited in the fixed optical fiber of patients head Head, fibre-optical probe are connect with spectra collection device and detection light generating apparatus by optical cable, and spectra collection device and processor are logical Cross data line connection；

The spectra collection device includes spectral signal demodulating unit and spectrographic detection unit；

The detection light generating apparatus includes wideband light source and spectral signal modulation unit；

(2) parameter that optical grating changes over time is obtained:

Any selected location point different moments difraction spectrum and characteristic wavelength in optical grating region are measured, using spectrum storehouse matching Method or non-linear regression method obtain optical grating and change over time corresponding structural parameters Q_j, including periods lambda_j, lines Top line width W_j, lines bottom line width M_jWith groove depth H_j；J=1 ..., t-1, t, t >=100, t are integer；

(3) the intraocular pressure P at recurrence calculation each moment_jWith the changing value Δ P of every section of time intraocular pressure_j:

ΔP_j=P_j-P₀；

In above formula, j >=2, original pressure P₀=0, when not worn for patient, when soft corneal contact lens two sides exposes in air Pressure difference；P₁When not worn for patient, the intraocular pressure value of other conventional equipment measurements；

Changing value Δ Q_j=Q_j-Q₀；Q_jIndicate periods lambda_j, line width W at the top of lines_j, lines bottom line width M_jOr groove depth H_j, Q₀It indicates The initial value of line width, lines bottom line width or groove depth at the top of period, lines: periods lambda₁, line width W at the top of lines₁, lines bottom line Wide M₁With groove depth H₁；The intraocular pressure at each moment is shown and exported.

5. tonometry method as claimed in claim 4, it is characterised in that:

The step (2) includes following sub-steps:

(2.1) a branch of broadband light that fibre-optical probe issues is projected on contact lens with fixing incidence angle and constant bearing angle Any selected location point in optical grating surface；

(2.2) diffraction light that optical grating reflects broadband light is measured by the fibre-optical probe, then passes through spectrographic detection Unit obtains the difraction spectrum and characteristic wavelength of location point different moments j every time T；5min≤T≤120min；

(2.3) processor is according to the difraction spectrum and characteristic wavelength of location point different moments j, using library of spectra matching process or Nonlinear regression parameter extracting method obtains the periods lambda of different moments optical grating_j, line width W at the top of lines_j, lines bottom line Wide M_jWith groove depth H_j；

(2.4) the changing value Δ Q of corresponding Occasion cycle, lines top line width, lines bottom line width or groove depth is calculated_j=Q_j- Q₀；Q_jIndicate periods lambda_j, line width W at the top of lines_j, lines bottom line width M_jOr groove depth H_j, Q₀Indicate the period, line width at the top of lines, The initial value of lines bottom line width or groove depth: periods lambda₁, line width W at the top of lines₁, lines bottom line width M₁With groove depth H₁。

6. tonometry method as claimed in claim 5, it is characterised in that:

In the sub-step (2.3), processor is according to the difraction spectrum and characteristic wavelength of location point different moments j, using spectrum Storehouse matching method obtains the periods lambda of different moments optical grating_j, line width W at the top of lines_j, lines bottom line width M_jAnd groove depth H_j；Including following processes:

(2.3A) determines optical grating structural parameters numerical value change range to be measured, structure ginseng firstly, according to the structure of optical grating Number includes period, lines top line width, lines bottom line width and groove depth；

The numerical value change range of each structural parameters fluctuates 10% above and below its design value, each design of Structural Parameters value are as follows: lines top Portion line width 30nm~15 μm, lines bottom line width 30nm~15 μm, groove depth 30nm~15 μm, the μ of bottom width 30nm~15 of slot M, periods lambda are the sum of lines bottom line width and the bottom width of slot；

And to the numerical value change range of these structural parameters according to preset step-length δ execute sliding-model control, thus to obtain it is multiple from Dissipate mesh point x_i, i=1,2 ..., n-1, n, n is integer；Preset step-length δ is the 1% of corresponding construction parameter values variation range ~10%；

(2.3B) passes through rigorous couple-wave analysis method (RCWA), finite element method (FEM), Element BEM (BEM) or limited FD―TD method (FDTD) calculates each discrete grid block point x according to spectral region, incidence angle and azimuthal various combination_i Respectively corresponding theoretical spectral f (x_i| Π), f (x_i| Π) it is expressed by way of reflectivity or transmissivity, wherein Π expression pair The measuring configuration combination answered, including spectral region, incidence angle and azimuth；

Each discrete grid block point and its corresponding theoretical spectral are stored into library of spectra by (2.3C), and the entry of library of spectra includes matching Set several K, ID number, structural parameters to be measured and theoretical spectral；Number of the configuration number K for element in measuring configuration combination, K=1 ..., M-1, m, m≤5；ID number is the number of K × i discrete grid block point, and structural parameters to be measured are included by each discrete grid block point Structural parameters；Theoretical spectral is theoretical spectral f (xi | Π) corresponding to each discrete grid block point；

A branch of broadband light that fibre-optical probe issues is projected to contact lens glazing to fix incidence angle and azimuth by (2.3D) Learn any selected location point of grating surface；

The diffraction light that optical grating reflects the broadband light is measured by the fibre-optical probe, position is obtained by spectrometer Difraction spectrum y (the x of point₀| Π) and characteristic wavelength λ₀；

Wherein x₀Indicate the true value of screen periods on contact lens, lines top line width, lines bottom line width or groove depth；

(2.3E) extracts structural parameters；

By difraction spectrum y (x₀| Π) it is compared with the theoretical spectral in library of spectra, find between the two that error mean square root is most Small value, corresponding to structural parameters to be measured is the one group of structural parameters needed.