CN110680276B - Ophthalmic optical imaging and biological parameter measuring instrument calibration tool and use method thereof - Google Patents
Ophthalmic optical imaging and biological parameter measuring instrument calibration tool and use method thereof Download PDFInfo
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- CN110680276B CN110680276B CN201910871316.0A CN201910871316A CN110680276B CN 110680276 B CN110680276 B CN 110680276B CN 201910871316 A CN201910871316 A CN 201910871316A CN 110680276 B CN110680276 B CN 110680276B
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- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B3/00—Apparatus for testing the eyes; Instruments for examining the eyes
- A61B3/10—Objective types, i.e. instruments for examining the eyes independent of the patients' perceptions or reactions
- A61B3/14—Arrangements specially adapted for eye photography
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- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B3/00—Apparatus for testing the eyes; Instruments for examining the eyes
- A61B3/0016—Operational features thereof
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- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B3/00—Apparatus for testing the eyes; Instruments for examining the eyes
- A61B3/10—Objective types, i.e. instruments for examining the eyes independent of the patients' perceptions or reactions
- A61B3/1005—Objective types, i.e. instruments for examining the eyes independent of the patients' perceptions or reactions for measuring distances inside the eye, e.g. thickness of the cornea
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- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B3/00—Apparatus for testing the eyes; Instruments for examining the eyes
- A61B3/10—Objective types, i.e. instruments for examining the eyes independent of the patients' perceptions or reactions
- A61B3/102—Objective types, i.e. instruments for examining the eyes independent of the patients' perceptions or reactions for optical coherence tomography [OCT]
Abstract
The invention relates to an ophthalmic optical imaging and biological parameter measuring instrument calibration tool and a using method thereof. The calibration tool comprises: a first lens having a first curved surface and a first plane; a second lens having a second curved surface and parallel second and third planes; and the PDMS mold body is internally provided with resolution test microspheres which are uniformly distributed, wherein the first plane and the second plane are attached together, the PDMS mold body is attached to the third plane and a part of the second curved surface, a hollow chamber is arranged between the third plane and the PDMS mold body, the first lens, the second lens, the PDMS mold body and the hollow chamber are symmetrical about a common axis, the curvature radius of the first lens is smaller than that of the second lens, a view field angle scale and a resolution line pair pattern are arranged between the second curved surface and the PDMS mold body, and an image registration fine line is arranged on the third plane.
Description
Technical Field
The application relates to the technical field of instrument detection, in particular to a calibration tool for ophthalmic optical imaging and biological parameter measuring instruments and a using method thereof.
Background
The fundus optical imaging obtains the structural information of human eyes by a two-dimensional or three-dimensional imaging technology, and is widely applied to clinical diagnosis with the advantages of no wound and high precision. The fundus imaging diagnosis device mainly comprises a posterior segment optical coherence tomography scanner, a fundus camera and the like, and an optical coherence tomography scanner with a fundus photographing function, an ophthalmologic optical biological measuring instrument and the like. The maximum measurable field angle of the fundus imaging medical equipment influences the imageable range, and the resolution determines the minimum distinguishable structural size, which are important parameters for representing the measurement and diagnosis capability of the equipment; the depth measurement accuracy is related to the accuracy of thickness measurement of structures below the fundus retina; the measuring accuracy of the eye axis length influences the effect of ophthalmic optical surgery, especially cataract; the signal-to-noise ratio affects the quality of the imaging. These indicators affect the validity and reliability of the final diagnosis result, so a calibration tool or a calibrator is needed to test the imaging device, and further evaluate the measurement accuracy of the field angle, the lateral resolution, the axial resolution, the depth measurement capability, the signal-to-noise ratio and the eye axis length. There is currently no single calibration tool that can detect or calibrate the above parameters of an ophthalmic instrument.
ISO standard 169971 provides a standard and calibration tool for a posterior segment optical coherence tomography scanner, and the parameters involved include resolution, field angle, depth measurement, signal-to-noise ratio, and the like. Fig. 1 is a schematic diagram of the structure of a calibration tool given in ISO standard 169971. As shown in fig. 1, the calibration tool includes a lens 101, a diaphragm 102, a lens barrel 103 having a length of 17mm, a filament 104, a neutral density filter 105, a glass plate 106 having a thickness of 1mm, and a scale 107. The scale of the scale 107 is directly used for detecting the field angle of the OCT instrument. However, the actual OCT imaging scan is not planar, especially when imaging at large field angles. Therefore, the calibration tool given by ISO standard 169971 is only suitable for paraxial small angle detection, and cannot meet the requirement of OCT for field angle detection of tens of degrees. Therefore, in practical detection, the calibration tool is not practical for detecting the OCT parameters, and needs to be improved.
The difficulty of fundus camera equipment detection is analyzed in detail in a paper of fundus camera optical performance detection and solution research in the Chinese medical apparatus information 2017 13 by Li Ning et al. The international standard IS010940 for fundus camera, ophthalmology instrument fundus camera, provides a method for measuring resolution, field angle, etc. by placing a graduated scale at a position 1 meter away from the fundus camera and calculating the field angle from the read length. However, in actual detection, the resolution of the fundus camera to a scale at a distance of 1 meter is low, and image distortion at the edge of the field of view and the resulting blur make it difficult to read the numerical result. The detection method given by IS010940 IS not practical.
CN107647845A "A model eye for fundus examination and its application method" designs a model eye with a lens and an angle scale of field of view and a resolution negative film for fundus camera examination. The view field angle scale and the resolution ratio line are aligned on the negative plate, and the precise alignment of the negative plate and the model eye is difficult to control when the model eye is actually developed, so that the measurement precision of the view field angle is difficult to guarantee; the resolution line pair of the invention can only be used for transverse two-dimensional resolution detection, and cannot detect axial resolution.
Disclosure of Invention
The invention discloses a calibration tool for an ophthalmic optical imaging and biological parameter measuring instrument and a using method thereof, aiming at solving the problem that the existing single calibration tool cannot detect or calibrate parameters such as an angle of view, resolution, depth measurement, eye axial length, signal to noise ratio and the like of the ophthalmic imaging device and the ophthalmic biological parameter measuring instrument.
According to a first aspect of the present invention, there is provided a calibration tool for an ophthalmic optical imaging and bio-parameter measurement instrument, comprising:
a first lens having a first curved surface and a first plane;
a second lens having a second curved surface and parallel second and third planes; and
PDMS mold body, which has resolution test microspheres distributed uniformly,
wherein the first plane and the second plane are attached together, the PDMS mold body is attached to the third plane and a part of the second curved surface, a cavity is arranged between the third plane and the PDMS mold body, and the first lens, the second lens, the PDMS mold body and the cavity are symmetrical about a common axis,
wherein a radius of curvature of the first lens is smaller than a radius of curvature of the second lens,
wherein a field angle scale and a resolution line pair pattern are arranged between the second curved surface and the PDMS mold body, and an image registration fine line is arranged on the third plane.
In an embodiment, the field angle scale and the resolution line pair pattern are formed by forming a groove in the second curved surface or in the PDMS mold body and filling a curable liquid in the groove, wherein a contrast of the curable liquid after curing with respect to the second lens and the PDMS mold body is greater than a preset threshold.
In one embodiment, the effective focal length of the calibration tool is in the range of 8-22 mm.
In one embodiment, the radius of curvature of the second lens is in the range of 7-30 mm.
In an embodiment, the view angle scales are distributed in a petal shape and are symmetric about the center of the third plane, each petal includes a plurality of concentric arcs, two borderlines, and angle bisectors of the borderlines, the number of the concentric arcs is 2-20, the covered angle of view is 2-180 degrees, the angle values of the corresponding angles of view between every two adjacent concentric arcs are equal, and short lines perpendicular to the angle bisectors are arranged on the angle bisectors as view angle subdivision scale lines.
In an embodiment, the resolution line pair pattern is distributed between every two petals of the field angle scale and is symmetrical about a center of the third plane, the resolution line pair pattern comprises a combination of 25lp/mm, 40lp/mm, 60lp/mm, 80lp/mm and 100lp/mm, and a plurality of the combinations are included between every two petals of the field angle scale.
In one embodiment, the third plane has a positioning mark thereon.
In one embodiment, the resolution test microspheres have a diameter in the range of 10nm to 2 μm and the distance between the centers of adjacent microspheres is greater than 2 times the diameter of the microspheres.
In one embodiment, the void chamber is formed at the center of the third plane or the center of the PDMS mold body, and the depth of the void chamber ranges from 300 μm to 3 mm.
According to a second aspect of the present invention, there is provided a method of using the calibration tool described above, comprising:
placing the first curved surface of the calibration tool opposite to the ophthalmic optical imaging and biological parameter measuring instrument to be detected at the measuring position of the calibration tool, adjusting the position and the angle of the calibration tool, and firstly enabling the optical axis of the calibration tool to be superposed with the optical axis of the ophthalmic optical imaging and biological parameter measuring instrument and imaging clearly;
setting the ophthalmic optical imaging and biological parameter measuring instrument to be in a line scanning mode, enabling a scanning preview line of the ophthalmic optical imaging and biological parameter measuring instrument to be consistent with the image registration fine line of the calibration tool in the angles, the x direction and the y direction, and checking a scanning signal of the ophthalmic optical imaging and biological parameter measuring instrument to enable the scanning signal to display the complete length of the image registration fine line;
the center of the view angle scale is coincided with the center of the imaged image, and then the calibration tool is rotated around the optical axis, so that the two view angle scales are respectively parallel to the x direction and the y direction of the imaged image;
combining all xz images obtained from different y positions to obtain an xyz three-dimensional image, and obtaining an xy two-dimensional image through the obtained three-dimensional image;
reading the reading of the field angle ruler of the calibration tool on the xy image to obtain the imaging field angles of the ophthalmic optical imaging and biological parameter measuring instrument in the x direction and the y direction;
reading the minimum resolution line pair capable of being resolved on the xy image to obtain the transverse resolution of the non-central field of view of the ophthalmic optical imaging and biological parameter measuring instrument;
reading the half-height widths of the point spread functions corresponding to the resolution microspheres in the three-dimensional image in the directions of x, y and z to obtain the transverse resolution and the axial resolution of the central field of view area and the non-central field of view area of the ophthalmologic optical imaging and biological parameter measuring instrument at different depths;
obtaining a z-direction depth measurement of the void on an xz image;
reading the distance between the first curved surface and the third plane on the xz image to obtain an eye axis length measurement value; and
and inserting a neutral density filter between the ophthalmic optical imaging and biological parameter measuring instrument and the calibration tool, testing the PDMS mold body, and counting the signal light intensity and the background noise signal of the resolution test microspheres at different depths in the PDMS mold body to obtain a curve of the signal-to-noise ratio changing along with the depth.
Compared with the prior art, the above aspects of the present invention may have the following advantages or beneficial effects:
the single calibration tool covers the functions of detecting multiple parameters such as field angle, resolution, depth measurement, eye axis length, signal to noise ratio and the like, and is simple and convenient to use.
Additional features and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by the practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.
Drawings
The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention and not to limit the invention.
In the drawings, like parts are designated with like reference numerals, and the drawings are schematic and not necessarily drawn to scale.
Fig. 1 is a schematic diagram of the structure of a calibration tool given in ISO standard 169971.
Fig. 2 is a schematic structural diagram of a calibration tool for an ophthalmic optical imaging and biological parameter measuring instrument according to an embodiment of the present invention.
Fig. 3 is an expanded plan view of the rear surface of the second lens according to an embodiment of the present invention.
FIG. 4 is a schematic diagram of a resolution line pair pattern according to an embodiment of the invention.
Fig. 5 is a schematic structural diagram of a calibration tool for an ophthalmic optical imaging and biological parameter measuring instrument according to another embodiment of the present invention.
Detailed Description
The following detailed description of the embodiments of the present invention will be provided with reference to the drawings and examples, so that how to apply the technical means to solve the technical problems and achieve the technical effects can be fully understood and implemented. It should be noted that, as long as there is no conflict, the embodiments and the features of the embodiments of the present invention may be combined with each other, and the technical solutions formed are within the scope of the present invention.
In the following description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the embodiments of the invention. It will be apparent, however, to one skilled in the art that the present invention may be practiced without some of these specific details or with other methods described herein.
As described above, the invention discloses a calibration tool for ophthalmic optical imaging and biological parameter measuring instruments and a use method thereof, wherein the detection range of the calibration tool covers parameters such as field angle, transverse resolution, axial resolution, depth measurement, eye axial length, signal to noise ratio and the like.
Fig. 2 is a schematic structural diagram of a calibration tool for an ophthalmic optical imaging and biological parameter measuring instrument according to an embodiment of the present invention. Wherein, the left half of fig. 2 is a schematic diagram of the overall structure of the calibration tool, and the right half of fig. 2 is an enlarged view of the structure in the oval frame in the left half, so as to more clearly show the structure of the calibration tool. The calibration tool may also be referred to as a simulated eye.
As shown in fig. 2, the calibration tool includes a first lens 201, a second lens 202, and a PDMS (polydimethylsiloxane) mold 203 in this order from front to back (left to right in fig. 2). The first lens 201 is a plano-convex lens, the front surface of which is a curved surface, and the rear surface of which is a first plane 207. The second lens 202 is a plano-convex lens with a truncated spherical cap, and has a front surface formed by a second plane 204 and a rear surface including a third plane 205 and a curved surface portion 206. It is obvious that the first plane 207, the second plane 204 and the third plane 205 are all circular planes, and the three are parallel. Resolution test microspheres 209 which are uniformly distributed are arranged in the PDMS mold body 203. A chamber 210 is provided between the third plane 205 and the PDMS mold body 203.
The first plane 307 and the second plane 204 are attached together and the PDMS mold body 203 is attached to the third plane 205 and a portion of the curved portion 206. The first lens 201, the second lens 202, the PDMS mold body 203, and the chamber 210 are symmetrical about a common axis, which is the horizontal dashed line in fig. 2.
As shown in fig. 2, the radius of curvature of the first lens 201 is smaller than the radius of curvature of the second lens 202, i.e., the first plane 207 is smaller in area than the second plane 204.
In one embodiment, the effective focal length of the calibration tool is in the range of 8-22 mm. For example, the effective focal length of the calibration tool may be 17 mm.
In one embodiment, the radius of curvature of the second lens 202 is in the range of 7-30 mm. For example, the radius of curvature of the second lens 202 is 8.8 mm.
The void 210 between the third plane 205 and the PDMS mold body 203 may be used to test the accuracy of the axial depth small dimension measurement of the device under inspection. The relevant information can be obtained by measuring the depth of the empty chamber 210. In the embodiment shown in fig. 2, the void 210 is formed at the center of the third plane 205. For example, the empty chamber 210 may have a cylindrical shape, a rectangular parallelepiped shape, or the like. The depth of the empty chamber 210 may be selected to have one or more values in the range of 300 μm-3mm, for example 1 mm.
To more clearly show the rear surface of the second lens 202, further reference is now made to fig. 3. Fig. 3 is an expanded plan view of the rear surface of the second lens according to an embodiment of the present invention. As shown in fig. 2 and 3, a field angle scale 208 and a resolution line pair pattern 306 are disposed between the curved surface portion 206 of the second lens 202 and the PDMS mold body 203. In the embodiment shown in fig. 2, the field angle scale 208 and the resolution line pair pattern 306 are formed within the curved portion 206 of the second lens 202. Specifically, the field angle scale 208 and the resolution line pair pattern 306 are formed by forming a groove in the curved surface portion 206 of the second lens 202 and filling a curable liquid in the groove. When the curable liquid cures, a stable field angle scale 208 and resolution line pair pattern 306 are formed. In order to see these patterns, the contrast of the curable liquid after curing with respect to the second lens 202 and the PDMS mold body 203 should be greater than a preset threshold value so that the human eye can see it clearly. The groove can be processed in a laser etching mode, so that the groove can be flexibly arranged, the position precision is high, and the structure is stable.
In fig. 3, in addition to the rear surface of the second lens 202 as a whole, the third plane 205 of the second lens 202 and a part of the field angle scale 208 are also shown enlarged. The invention can detect the accuracy of the measurement of the wide-angle view field angle by designing the view field angle scale on the curved surface, and has more practicability.
As shown in fig. 3, the angular scales 208 of the field of view are distributed in a petal shape and are symmetrical about the center of the third plane 205. Each petal comprises a plurality of concentric arcs 301, two border lines 302, and angular bisectors 303 of the border lines 302.
The concentric arc 301 is a field angle coarse graduation line. The angle values of the corresponding field angles between every two adjacent concentric arcs 301 are equal, and short lines 304, 305 perpendicular to the angular lines are arranged on the angular lines 303 as field angle subdivision graduation lines. The stubs 304, 305 are spaced apart at unequal intervals in length, which facilitates reading registration.
In one embodiment, the number of the concentric arcs 301 may be 2-20, and the covered angle of view may be 2-180 degrees. In a specific embodiment, the number of concentric arcs 301 is 18, and the covered field angle is 72 degrees. At this time, the angle of the corresponding field angle between each two adjacent concentric arcs 301 is 2 degrees. Additionally, 10 short lines 304, 305 are disposed between each two adjacent concentric arcs 301, so that the angle of the corresponding field angle between each two adjacent short lines is 0.2 degrees.
With further reference to fig. 3, a resolution line pair pattern 306 is provided at the blank between each two petals of the field angle scale 208 for measuring the lateral resolution of the non-central field of view. The resolution line pair pattern 306 is also symmetrical about the center of the third plane 205. The resolution line pair pattern 306 includes a combination of 25lp/mm, 40lp/mm, 60lp/mm, 80lp/mm, and 100lp/mm, and a plurality of the combinations are included between each two petals of the field angle scale 208. FIG. 4 is a schematic diagram of a resolution line pair pattern according to an embodiment of the invention.
In an embodiment, further referring to fig. 3, an image registration fine line 310 is disposed on the third plane 205 of the second lens 202 for registration of the fundus preview image and the scanned image. The diameter of the fine image registration wire 310 may be 50-200 μm, preferably 100 μm. Also disposed on the third plane 205 are a field center inner ring 308, a field center outer ring 309, and a locator mark 307. The orientation marker 307 facilitates fast finding the orientation of the calibration tool based on its correspondence with the image.
Fig. 5 is a schematic structural diagram of a calibration tool for an ophthalmic optical imaging and biological parameter measuring instrument according to another embodiment of the present invention. Wherein, the left half part of fig. 5 is a schematic diagram of the whole structure of the calibration tool, and the right half part of fig. 5 is an enlarged view of the two structures in the circle frame and the oval frame in the left half part, so as to more clearly show the structure of the calibration tool.
Similar to the embodiment shown in fig. 2, the calibration tool shown in fig. 5 comprises: a first lens 501, a second lens 502 and a PDMS mold body 503. The first lens 501 is a plano-convex lens, the front surface of which is a curved surface, and the rear surface of which is a first plane 507. The second lens 502 is a plano-convex lens with a truncated spherical cap, and has a front surface formed by a second plane 504 and a rear surface including a third plane 505 and a curved surface portion 506. Resolution test microspheres 509 are uniformly distributed in the PDMS mold body 503.
One difference between the embodiment shown in fig. 5 and the embodiment shown in fig. 2 is that in the embodiment shown in fig. 5, the field angle scale 508 and the resolution line pair pattern (not shown) are formed within the PDMS mold body 503. Specifically, the field angle scale 508 and the resolution line pair pattern are formed by forming grooves in the PDMS mold body 503 and filling the grooves with a curable liquid. When the curable liquid is cured, a stable field angle scale 508 and resolution line pair pattern are formed. Similarly, the contrast of the curable liquid after curing with respect to the second lens 502 and the PDMS mold 503 should be greater than a predetermined threshold to be visible to human eyes.
Another difference between the embodiment shown in FIG. 5 and the embodiment shown in FIG. 2 is that in the embodiment shown in FIG. 5, the void 510 is formed in the center of the PDMS mold body 503.
Other features of the embodiment shown in fig. 5 are similar to those of the embodiment shown in fig. 2 and will not be described again here.
It should be noted that, although in the embodiment shown in fig. 2, the field angle scale 208, the resolution line pair pattern 306 and the empty chamber 210 are all formed in the second lens 202, and in the embodiment shown in fig. 5, the field angle scale 508, the resolution line pair pattern and the empty chamber 510 are all formed in the PDMS mold body 503, the present invention may also be implemented in a scheme in which the field angle scale, the resolution line pattern and the empty chamber are formed in different components. For example, the field angle scale and the resolution line pattern are formed in the second lens, and the cavities are both formed in the PDMS mold body.
The specific structure of the calibration tool for ophthalmic optical imaging and bio-parameter measurement instrument according to the present invention has been described. It will be apparent to those skilled in the art that the various numbers/numbers described above are not limiting, but are exemplary and variations can be made.
The following describes in detail the method of use of the calibration tool for ophthalmic optical imaging and bio-parameter measurement instruments according to the present invention, comprising the following steps.
The first step, the first curved surface of the calibration tool is placed at the measurement position of the ophthalmology optical imaging and biological parameter measuring instrument just opposite to the to-be-detected, the position and the angle of the calibration tool are adjusted, and the optical axis of the calibration tool is superposed with the optical axis of the ophthalmology optical imaging and biological parameter measuring instrument and clearly imaged.
And a second step of setting the ophthalmic optical imaging and biological parameter measuring instrument to be in a line scanning mode, enabling a scanning preview line of the ophthalmic optical imaging and biological parameter measuring instrument to be consistent with the image registration fine line of the calibration tool in the angles, the x direction and the y direction, and checking a scanning signal of the ophthalmic optical imaging and biological parameter measuring instrument to enable the scanning signal to display the complete length of the image registration fine line.
And thirdly, enabling the center of the view angle scale to coincide with the center of the imaged image, and then rotating the calibration tool around the optical axis to enable the two view angle scales to be parallel to the x direction and the y direction of the imaged image respectively.
And fourthly, combining all xz images obtained from different y positions to obtain an xyz three-dimensional image, and obtaining an xy two-dimensional image through the obtained three-dimensional image.
And fifthly, reading the reading of the field angle ruler of the calibration tool on the xy image to obtain the imaging field angles of the ophthalmic optical imaging and biological parameter measuring instrument in the x direction and the y direction.
And sixthly, reading the minimum resolution line pair capable of being resolved on the xy image to obtain the transverse resolution of the non-central field of view of the ophthalmic optical imaging and biological parameter measuring instrument.
And seventhly, reading the full widths at half maximum of the point spread functions corresponding to the resolution microspheres on the three-dimensional image in the directions of x, y and z to obtain the transverse resolution and the axial resolution of the central field of view area and the non-central field of view area of the ophthalmologic optical imaging and biological parameter measuring instrument at different depths.
And eighthly, obtaining a z-direction depth measurement value of the empty chamber on the xz image.
And ninthly, reading the distance between the first curved surface and the third plane on the xz image to obtain an eye axis length measurement value.
And step ten, inserting a neutral density filter between the ophthalmologic optical imaging and biological parameter measuring instrument and the calibration tool, testing the PDMS mold body, and counting the signal light intensity and the background noise signal of the resolution test microspheres at different depths in the PDMS mold body to obtain a curve of the signal-to-noise ratio changing along with the depth.
The calibration tool for the ophthalmology optical imaging and biological parameter measuring instrument has the advantages that the detection range covers parameters such as an angle of view, transverse resolution, axial resolution, depth measurement, axial length of an eye, signal to noise ratio and the like, and the tool is multipurpose and can be used for detecting and calibrating the ophthalmology optical imaging and biological parameter measuring instrument such as a posterior segment optical coherence tomography scanner and the like. At present, no calibration tool can detect or calibrate and detect two parameters or even more parameters of axial resolution and depth measurement of the ophthalmic optical imaging equipment at home, and the calibration tool according to the invention can realize the measurement of the parameters.
It is to be understood that the disclosed embodiments of the invention are not limited to the particular process steps or materials disclosed herein, but rather, are extended to equivalents thereof as would be understood by those of ordinary skill in the relevant art. Reference in the specification to "an embodiment" means that a particular feature, or characteristic described in connection with the embodiment is included in at least one embodiment of the invention. Thus, the appearances of the phrase or "an embodiment" in various places throughout this specification are not necessarily all referring to the same embodiment.
Furthermore, the described features or characteristics may be combined in any other suitable manner in one or more embodiments. In the above description, certain specific details are provided, such as thicknesses, amounts, etc., to provide a thorough understanding of embodiments of the invention. One skilled in the relevant art will recognize, however, that the invention may be practiced without one or more of the specific details, or with other methods, components, materials, and so forth.
While the above examples are illustrative of the principles of the present invention in one or more applications, it will be apparent to those of ordinary skill in the art that various changes in form, usage and details of implementation can be made without departing from the principles and concepts of the invention. Accordingly, the invention is defined by the appended claims.
Claims (10)
1. A calibration tool for ophthalmic optical imaging and biological parameter measurement instruments, comprising:
a first lens having a first curved surface and a first plane;
a second lens having a second curved surface and parallel second and third planes; and
PDMS mold body, which has resolution test microspheres distributed uniformly,
wherein the first plane and the second plane are attached together, the PDMS mold body is attached to the third plane and a part of the second curved surface, a cavity is arranged between the third plane and the PDMS mold body, and the first lens, the second lens, the PDMS mold body and the cavity are symmetrical about a common axis,
wherein a radius of curvature of the first lens is smaller than a radius of curvature of the second lens,
wherein a field angle scale and a resolution line pair pattern are arranged between the second curved surface and the PDMS mold body, and an image registration fine line is arranged on the third plane.
2. The calibration tool of claim 1, wherein the field angle scale and the resolution line pair pattern are formed by forming grooves in the second curved surface or in the PDMS mold body and filling the grooves with a curable liquid, wherein a contrast of the curable liquid after curing with respect to the second lens and the PDMS mold body is greater than a preset threshold.
3. The calibration tool of claim 1, wherein the effective focal length of the calibration tool is in the range of 8-22 mm.
4. The calibration tool of claim 1, wherein the radius of curvature of the second lens is in the range of 7-30 mm.
5. The calibration tool of claim 1, wherein the view angle scales are distributed in a petal shape and are symmetric about the center of the third plane, each petal comprises a plurality of concentric arcs, two borderlines, and angle divisions of the borderlines, the number of the concentric arcs is 2-20, the covered angle of view is 2-180 degrees, the angle value of the corresponding angle of view between each two adjacent concentric arcs is equal, and short lines perpendicular to the angle divisions are arranged on the angle divisions as the angle of view subdivision graduation lines.
6. The calibration tool of claim 5, wherein the resolution line pair pattern is distributed between every two petals of the field angle scale and is symmetrical about a center of the third plane, the resolution line pair pattern comprises a combination of 25lp/mm, 40lp/mm, 60lp/mm, 80lp/mm, and 100lp/mm, and the field angle scale comprises a plurality of the combinations between every two petals.
7. The calibration tool of claim 1, wherein the third plane has a locator mark thereon.
8. The calibration tool of claim 1, wherein the resolution test microspheres have a diameter in the range of 10nm to 2 μ ι η and the center-to-center spacing of adjacent microspheres is greater than 2 times the microsphere diameter.
9. The calibration tool of claim 1, wherein the void chamber is formed at the center of the third plane or the center of the PDMS mold body, and the depth of the void chamber ranges from 300 μ ι η to 3 mm.
10. A method of using the calibration tool of any of claims 1-9, comprising:
placing the first curved surface of the calibration tool opposite to the ophthalmic optical imaging and biological parameter measuring instrument to be detected at the measuring position of the ophthalmic optical imaging and biological parameter measuring instrument, adjusting the position and the angle of the calibration tool, and firstly enabling the optical axis of the calibration tool to be superposed with the optical axis of the ophthalmic optical imaging and biological parameter measuring instrument and imaging clearly;
setting the ophthalmic optical imaging and biological parameter measuring instrument to be in a line scanning mode, enabling a scanning preview line of the ophthalmic optical imaging and biological parameter measuring instrument to be consistent with the image registration fine line of the calibration tool in the angles, the x direction and the y direction, and checking a scanning signal of the ophthalmic optical imaging and biological parameter measuring instrument to enable the scanning signal to display the complete length of the image registration fine line;
the center of the view angle scale is coincided with the center of the imaged image, and then the calibration tool is rotated around the optical axis, so that the two view angle scales are respectively parallel to the x direction and the y direction of the imaged image;
combining all xz images obtained from different y positions to obtain an xyz three-dimensional image, and obtaining an xy two-dimensional image through the obtained three-dimensional image;
reading the reading of the field angle ruler of the calibration tool on the xy image to obtain the imaging field angles of the ophthalmic optical imaging and biological parameter measuring instrument in the x direction and the y direction;
reading the minimum resolution line pair capable of being resolved on the xy image to obtain the transverse resolution of the non-central field of view of the ophthalmic optical imaging and biological parameter measuring instrument;
reading the half-height widths of the point spread functions corresponding to the resolution microspheres in the three-dimensional image in the directions of x, y and z to obtain the transverse resolution and the axial resolution of the central field of view area and the non-central field of view area of the ophthalmologic optical imaging and biological parameter measuring instrument at different depths;
obtaining a z-direction depth measurement of the void on an xz image;
reading the distance between the first curved surface and the third plane on the xz image to obtain an eye axis length measurement value; and
and inserting a neutral density filter between the ophthalmic optical imaging and biological parameter measuring instrument and the calibration tool, testing the PDMS mold body, and counting the signal light intensity and the background noise signal of the resolution test microspheres at different depths in the PDMS mold body to obtain a curve of the signal-to-noise ratio changing along with the depth.
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| CN112826439A (en) * | 2020-12-31 | 2021-05-25 | 重庆贝奥新视野医疗设备有限公司 | Ophthalmic optics coherence tomography instrument measuring device |
| CN113848042B (en) * | 2021-10-09 | 2023-08-29 | 深圳市资福医疗技术有限公司 | Optical resolution detection system of capsule endoscope |
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