CN209996294U - device for accurately measuring optical path difference between front and back surfaces of human cornea - Google Patents

Abstract

device of surface optical path difference around accurate measurement people's eye cornea, reference arm includes collimating mirror, neutral density light filter and speculum, the sample arm includes the second collimating mirror, second mirror and liquid lens, the light that the light source of surveying sent is divided into two tunnel with the light after passing through fiber coupler, way light reachs the second mirror after the second collimating mirror, the light that reflects through the second mirror reachs people's eye cornea measuring area after passing through liquid lens focus, way light is at first through the collimation of collimating mirror, directly arrive speculum through neutral density light filter, speculum is installed at fine setting translation bench, the light that reflects back through takes place to interfere in fiber coupler, then get into the spectrum appearance, the application zooms lens fast and can accurately focus on the front surface and the back surface of cornea, can calculate the optical path difference of cornea front surface and back surface through the distance that reference arm removed.

Description

A device for accurately measuring the optical path difference between the front and rear surfaces of the human cornea

technical field

The utility model belongs to the technical field of optical detection, in particular to a device for accurately measuring the optical path difference between the front and rear surfaces of the cornea.

Background technique

The cornea is the most transparent part of the front of the eye, covering the iris, pupil and anterior chamber, and provides 70% of the refractive power of the eye. A small change in the cornea can cause a large change in the refractive state. shape and optical properties. Accurate measurement of corneal curvature and central corneal thickness (CCT) provides an important basis for early diagnosis of corneal diseases, preoperative screening and postoperative follow-up of corneal refractive surgery, calculation of intraocular lens power, etc. also important.

The prior art solution closest to the technical solution designed in the creation of the present invention is the method for measuring corneal thickness and refractive index adopted in the patent "A Cornea Measurement Method and System" (CN108634928A). It uses the optical coherence tomography system to measure and obtain the optical path L0 from the anterior surface of the cornea to the posterior surface; secondly, move the focusing lens, when the focus of the probe light is located on the anterior and posterior surfaces of the cornea, the signal intensity is the maximum value, and then obtain when the probe light When the focal point is located on the anterior and posterior surfaces of the cornea, the distance between the two positions corresponding to the lens is L1; finally, the refractive index and corneal thickness of the cornea are obtained by using ray tracing technology.

The optical coherence tomography used in the above-mentioned patent is used to obtain the optical path difference from the front surface of the cornea to the back surface. The corresponding frequency, and then the calculated optical path difference is the proportional coefficient k multiplied by the frequency difference. This calculation method is difficult to accurately measure the proportional coefficient k, and there is a certain error; secondly, there is also a certain error in calculating the distance of the focus change of the focusing lens. When moving the lens, it is possible to change the measurement position so that the measurement of the anterior and posterior surfaces of the cornea is not in the same vertical line.

Utility model content

In order to realize the accurate measurement of the thickness and refractive index of the human cornea, the utility model provides a device for measuring the thickness of the center of the cornea and the axial length of the eye, which solves two major problems: the first problem is how to realize the optical path difference between the front and rear surfaces of the cornea. In-body measurement; the second problem is how to change the lens focal length without changing the measurement position.

In order to solve the above-mentioned technical problems, the utility model is realized through the following technical solutions:

A device for accurately measuring the optical path difference between the front and rear surfaces of human cornea, comprising a detection light source, an optical fiber coupler, a reference arm, a sample arm and a spectrometer, the reference arm comprising a first collimating lens, a neutral density filter and a first Reflecting mirror, the sample arm includes a second collimating mirror, a second reflecting mirror and a liquid lens, the light emitted by the detection light source is divided into two paths after passing through the optical fiber coupler, and one light reaches after passing through the second collimating mirror The second reflecting mirror, the light reflected by the second reflecting mirror is focused by the liquid lens and then reaches the cornea measurement area of the human eye; the other light is first collimated by the first collimating mirror, and then directly directed to the first through the neutral density filter. Reflecting mirror, the first reflecting mirror is installed on the fine-tuning translation stage, the light reflected by the first reflecting mirror interferes in the optical fiber coupler, and then enters the spectrometer.

Further, the spectrometer includes a third collimating mirror, a grating, a focusing lens and an e2v line scan camera into which light enters in sequence.

Further, the detection light source is a superluminescent light emitting diode with a center wavelength of 840 nm and a bandwidth of 49 nm.

Further, the aperture of the liquid lens is 2.5mm, the diopter is -5 to 13, and the focusing range is from 5cm to infinity.

Further, the fiber coupler is a 50/50 fiber coupler, which divides the light into two paths of equal intensity.

Further, the fine-tuning translation stage is a one-dimensional manual fine-tuning translation stage.

Compared with the prior art, the beneficial effects of the present utility model are:

The utility model adopts the time-domain optical coherence tomography technology (TD-OCT) to perform high-resolution imaging on the cornea of the human eye, and can accurately focus on the anterior surface and the posterior surface of the cornea by using a fast zoom lens. It can calculate the optical path difference between the anterior surface and the posterior surface of the cornea.

The utility model mainly has two major advantages: the first advantage is that the focusing lens is not moved, and the focal length is changed with a fast zoom lens, which ensures that the measurement position of the human cornea does not change when the focal length is changed; the second advantage is that the front surface of the cornea is The optical path difference of the surface can be directly measured without going to the frequency domain, which avoids the error caused by interpolation and dispersion compensation when converting the frequency domain.

Description of drawings

The accompanying drawings are used to provide a further understanding of the present utility model, and are used to explain the present utility model together with the embodiments of the present utility model, and do not constitute a limitation to the present utility model. In the accompanying drawings:

Fig. 1 is the structural principle diagram of the present utility model;

FIG. 2 is a schematic diagram of the change of the focal length of the liquid lens.

In the picture:

1—detection light source; 2—fiber coupler;

3——First collimating lens; 4——Neutral density filter;

5——The first reflector; 6——The second collimator;

7——Second mirror; 8——Liquid lens;

9—eyes; 10—third collimating mirror;

11 - grating; 12 - focusing lens;

13—e2v line scan camera; 14—computer;

15 - the light reflected by the second mirror; 16 - the light focused on the front surface of the cornea;

17—focusing light on the posterior surface of the cornea; 18—human cornea.

Detailed ways

The preferred embodiments of the present utility model will be described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are only used to illustrate and explain the present utility model, but not to limit the present utility model.

As shown in Figures 1 and 2, a device for accurately measuring the optical path difference between the front and rear surfaces of the cornea described in the present utility model, comprising a central wavelength of 840nm, a superluminescent diode with a bandwidth of 49nm as a detection light source 1, a 50/50 optical fiber coupling 2, a reference arm, a sample arm and a spectrometer, the reference arm includes a first collimating mirror 3, a neutral density filter 4 and a first reflecting mirror 5, and the sample arm includes a second collimating mirror 6, a second reflecting mirror 7 And the liquid lens 8, the light emitted by the detection light source 1 passes through the optical fiber coupler 2 and divides the light into two paths of equal intensity. The light 15 reaches the cornea measurement area of the human eye 9 after being focused by the liquid lens 8; the other light is firstly collimated by the first collimating mirror 3, and then directly directed to the first reflecting mirror 5 through the neutral density filter 4, and the first reflection The mirror 5 is installed on a one-dimensional manual fine-tuning translation stage, and the light reflected by the first mirror 5 interferes in the fiber coupler 2, and then enters the spectrometer. The spectrometer includes a third collimating mirror 10 and a grating 11 that light enters in sequence , focusing lens 12 and e2v line scan camera 13, use Cobra-S800 spectrometer (this spectrometer has very good signal attenuation performance and higher camera sensitivity) to receive the reflected interference signal.

The liquid lens 8 is a D-A-25H liquid lens 8 produced by Brilliantoptics, which has an aperture of 2.5 mm, a diopter of -5 to 13, and a focusing range from 5 cm to infinity.

Finally, it should be noted that the above are only the preferred embodiments of the present utility model, and are not intended to limit the present utility model. Although the present utility model has been described in detail with reference to the embodiments, for those skilled in the art, it is still The technical solutions described in the foregoing embodiments can be modified, or some technical features thereof can be equivalently replaced, but any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present utility model shall be Included within the scope of protection of the present invention.

Claims (6)

1. The device for accurately measuring the optical path difference between the front surface and the rear surface of the human eye cornea is characterized by comprising a detection light source, an optical fiber coupler, a reference arm, a sample arm and a spectrometer, wherein the reference arm comprises a th collimating mirror, a neutral density optical filter and a th reflecting mirror, the sample arm comprises a second collimating mirror, a second reflecting mirror and a liquid lens, light emitted by the detection light source is divided into two paths after passing through the optical fiber coupler, paths of light reach the second reflecting mirror after passing through the second collimating mirror, light reflected by the second reflecting mirror reaches a measurement area of the human eye cornea after being focused by the liquid lens, another paths of light are collimated by the collimating mirror and then directly reach a th reflecting mirror after passing through the neutral density optical filter, an th reflecting mirror is installed on a fine-tuning translation stage, and light reflected by a undergoes interference in the optical fiber coupler and then enters the spectrometer.
2. 2. The apparatus for precisely measuring the optical path difference between the front and back surfaces of the cornea of a human eye according to claim 1, wherein the spectrometer comprises a third collimating mirror, a grating, a focusing lens and an e2v line camera, wherein the third collimating mirror, the grating, the focusing lens and the e2v line camera are sequentially arranged in the spectrometer.
3. 3. The apparatus for accurately measuring the optical path difference between the anterior and posterior surfaces of the cornea of a human eye as claimed in claim 1, wherein the detecting light source is a superluminescent light emitting diode (superluminescent diode) with a central wavelength of 840nm and a bandwidth of 49 nm.
4. 4. The device for accurately measuring the optical path length difference between the anterior and posterior surfaces of the cornea of a human eye according to claim 1, wherein the liquid lens has an aperture of 2.5mm, a diopter of-5 to 13 and a focusing range of 5cm to infinity.
5. 5. The apparatus for accurately measuring the optical path difference between the anterior and posterior surfaces of the cornea of human eye according to claim 1, wherein the optical fiber coupler is 50/50 optical fiber coupler, which splits the light into two paths with equal intensity.
6. 6. The apparatus for accurately measuring the optical path difference between the anterior and posterior surfaces of the cornea of a human eye according to claim 1, wherein the fine adjustment translation stage is a dimension manual fine adjustment translation stage.

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