CN110477849B - Self-calibration optical coherent scanner and sampling method - Google Patents
Self-calibration optical coherent scanner and sampling method Download PDFInfo
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- CN110477849B CN110477849B CN201910798897.XA CN201910798897A CN110477849B CN 110477849 B CN110477849 B CN 110477849B CN 201910798897 A CN201910798897 A CN 201910798897A CN 110477849 B CN110477849 B CN 110477849B
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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]
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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
Abstract
The invention discloses a self-calibration optical coherence scanner and a sampling method, comprising an objective lens, a secondary sensor module and a sampling module, wherein the objective lens is configured and arranged to focus light of a target path, and the secondary sensor module is used for obtaining an OCT image signal which is resolved by another time compared with that obtained by a fixed sensor; a light source module; the objective lens, the main sensor, the auxiliary sensor module and the light source module are respectively positioned on the four light splitting branches of the beam splitter. The light source module generates light, the light is reflected after irradiating a sample, and the light enters the main sensor module and the auxiliary sensor module after passing through the beam splitter. The invention has the advantages of automatically overcoming sample movement and improving imaging accuracy.
Description
Technical Field
The invention relates to an optical coherent scanning device, in particular to a self-calibration optical coherent scanner and a sampling method.
Background
To form a three-dimensional (3D) tomogram of the eye by means of Optical Coherence Tomography (OCT), it is conventional: a plurality of OCT images arranged in a line (e.g., an a-scan) and/or layer (e.g., a B-scan) relative to one another within a volume of an eye to be scanned are recorded and subsequently aligned relative to one another to form a tomogram. However, after the eye moves, the resulting 3D tomogram shows movement-induced artifacts. These artifacts reduce the quality of the 3D tomogram, since, for example, the geometry, contour or height profile of the eye or of individual parts thereof (such as the cornea) is reproduced in the tomogram in a lower-quality manner. Prior art As Chinese patent publication No. CN105050483B, an apparatus for optical coherence tomography of the eye and a method for optical coherence tomography of the eye are disclosed, the apparatus comprising a camera system configured to capture a time resolved camera image of the eye; and an OCT image acquisition unit configured to acquire a time-resolved OCT image of the eye. The measurement axis of the OCT image acquisition unit and the measurement axis of the camera system are aligned along a common measurement axis of the device using a beam splitter. The apparatus further comprises a control unit configured to determine time-resolved movement data from the time-resolved camera images, the movement data being indicative of a movement of the eye relative to a measurement axis of the apparatus. The control unit is further configured to transform at least a portion of the OCT image based on the movement data and generate a tomogram from the OCT image.
Disclosure of Invention
The invention aims to provide a self-calibration optical coherence scanner and a sampling method which can automatically overcome sample movement and improve imaging accuracy in the prior art.
The technical scheme adopted by the invention for solving the technical problems is as follows: a self-calibrating optical coherence scanner comprising an objective lens configured and arranged to focus light of a target path, further containing a secondary sensor module for obtaining another time-resolved OCT image signal acquired compared to the primary sensor;
the light source module is used for providing light with different wavelengths, so that the main sensor module and the auxiliary sensor module respectively obtain image signals with different detection depths;
the objective lens, the main sensor, the auxiliary sensor module and the light source module are respectively positioned on the four light splitting branches of the beam splitter. The light source module generates light, the light is reflected after irradiating a sample, and the light enters the main sensor module and the auxiliary sensor module after passing through the beam splitter. The light source module generates light waves with different wavelengths in different time periods, for example, the main sensor receives a sample signal of a first time period, and the sub-sensor module detects stored image signals of other time periods in a second time period. Thereby alternating the operation of the two sensors between acquiring new signals and verifying the acquired data.
In order to optimize the technical scheme, the adopted measures further comprise: the light source module comprises a main light source and a secondary light source; the light on the beam splitter is projected between the main light source and the auxiliary light source through the light source switcher. The main light source and the secondary light source are tunable light sources, and the light source switcher is used for rapidly switching the light sources from one wavelength to another wavelength after the main sensor or the secondary sensor completes one period of scanning. Taking the example of layer-by-layer penetration and lengthened wavelength, during the nth period, the XY adjusting mirror and the Z-axis semi-transparent mirror are in proper positions, and the main sensor obtains and stores the sampling signal of the wavelength under the main light source during the nth period. And in the (n + 1) th period, converting the wavelength of the secondary light source into the wavelength of the secondary light source in the n-1 period, and comparing and checking the image signal obtained by the secondary sensor with the image signal of the main sensor in the wavelength of the primary light source in the n-1 period. If the two wavelengths are different, the checking times are increased so as to filter out singular values, keep stable values and set the wavelengths of the main light source and the secondary light source in an iterative mode. The filtering and retaining logic can be selected from an averaging method, an intercepting method and the like in the existing sampling method according to the precision will, and is not described in detail. When a scanning image is acquired, due to the special characteristic that the sample position is not static, the data of a certain scanning stage is a non-target area. Therefore, under the condition of self-checking measurement by the device, a relatively accurate scanning overall image set can be obtained. The sub-sensor module comprises a sub-sensor and a Z-axis semi-transparent mirror positioned at the front end of the sub-sensor. The Z-axis half-lens is adjusted to enable the beam splitter to generate phase difference between the reference signal light and the optical signal from the objective lens, so that the detection effect and efficiency are improved. And the projection position of the sample can be adjusted more flexibly by combining the XY adjusting mirror. When the objective lens is small, such as an endoscope-like structure or optical fiber detection, the XY adjusting mirror can be omitted and the image can be adjusted by a computer program. A focusing mirror for adjusting the light beam emitted by the light source module is arranged between the light source module and the beam splitter; the central axis of the focusing lens and the objective lens are overlapped on the light path. The design is a light source single lens arrangement mode. A main focusing mirror is arranged between the main light source and the light source switcher; an auxiliary focusing mirror is arranged between the auxiliary light source and the light source switcher; the central axes of the main focusing lens, the auxiliary focusing lens and the objective lens are overlapped on the light path. The design is a light source double-lens arrangement mode. The housing construction of the device is well known in the art and can be readily assembled by one of ordinary skill in the art without undue experimentation and without recitation.
A self-calibrating optical coherence scanner, employing the scanner of claim 1, comprising the steps of,
1) initial data filling step: the wavelength D0 is used as a light source, the main sensor acquires a scanning signal, and data filling of a period T0 is completed;
2) a scanning step: in a period Tn, taking a wavelength Dn as a light source, and acquiring a scanning signal Pn by a main sensor;
3) checking and scanning: in the period Tn +1, taking the wavelength Dn-1 as a light source, and acquiring a scanning contrast signal Qn +1 by the auxiliary sensor;
4) a checking treatment step: comparing the scanning comparison signal Qn +1 with the scanning signal Pn-1, if the scanning comparison signal Qn +1 is the same as or meets the data filtering requirement, checking and storing the result, and if the scanning comparison signal Qn +1 is different from the scanning comparison signal Pn-1, repeating the steps 3) and 4) during the next period of measurement. By adopting the mode, the image signals obtained by mutual verification on the two sensors in different scanning periods can be eliminated, and the error measurement caused by factors such as eye movement and the like can be eliminated. The data filtering requirement is a principle of sample comparison, including but not limited to a majority principle or an average farthest principle and a maximum value interception principle.
The invention also comprises a secondary sensor module which is used for obtaining another time-resolved OCT image signal acquired by a comparison and calibration sensor; the light source module is used for providing light with different wavelengths, so that the main sensor module and the auxiliary sensor module respectively obtain image signals with different detection depths; the objective lens, the main sensor, the auxiliary sensor module and the light source module are respectively positioned on the four light splitting branches of the beam splitter. The light source module generates light, the light is reflected after irradiating a sample, and the light enters the main sensor module and the auxiliary sensor module after passing through the beam splitter. The light source module generates light waves with different wavelengths in different time periods, for example, the main sensor receives a sample signal of a first time period, and the sub-sensor module detects stored image signals of other time periods in a second time period. Thereby alternating the operation of the two sensors between acquiring new signals and verifying the acquired data. Therefore, the invention has the advantages of automatically overcoming sample movement and improving imaging accuracy.
Drawings
Fig. 1 is a schematic diagram of an optical path structure in embodiment 1 of the present invention;
fig. 2 is a schematic diagram of an optical path structure in embodiment 2 of the present invention;
FIG. 3 is a schematic view of the measurement results before correction in example 1 of the present invention;
fig. 4 is a schematic diagram of the corrected measurement result in embodiment 1 of the present invention.
Detailed Description
The present invention will be described in further detail with reference to the following examples.
The reference numbers illustrate: the device comprises a light source module 1, a main light source 11, an auxiliary light source 12, a light source switcher 13, a focusing mirror 2, a main focusing mirror 21, an auxiliary focusing mirror 22, a beam splitter 3, a main sensor 4, an auxiliary sensor module 5, an auxiliary sensor 51, a Z-axis semi-transparent mirror 52, an XY adjusting mirror 6, an objective lens 7 and a sample 8.
Example 1: referring to fig. 1, 3, 4, a self-calibrating optical coherence scanner and sampling method includes an objective lens 7 configured and arranged to focus light of a target path, which also contains a secondary sensor module 5 for obtaining another time-resolved OCT image signal acquired over the primary sensor 4;
the light source module 1 is used for providing light with different wavelengths, so that the main sensor 4 and the auxiliary sensor module 5 respectively obtain image signals with different detection depths;
the objective lens 7, the main sensor 4, the sub sensor module 5 and the light source module 1 are respectively positioned on four light splitting branches of the beam splitter 3. The light source module 1 generates light, which is reflected after illuminating the sample 8, and enters the main sensor 4 and the sub sensor module 5 after passing through the beam splitter 3. The light source module 1 generates light waves with different wavelengths in different time periods, for example, the main sensor 4 receives a sample signal of a first time period, and the sub-sensor module 5 detects a stored image signal of another time period in a second time period. Thereby alternating the operation of the two sensors between acquiring new signals and verifying the acquired data. The light source module 1 comprises a main light source 11 and a secondary light source 12; the light projection on the beam splitter 3 is realized between the main light source 11 and the sub-light source 12 via the light source switch 13. The primary and secondary light sources 11, 12 are tunable light sources, and the light source switch 13 functions to rapidly switch the light sources from one wavelength to another after the primary sensor 4 or the secondary sensor 51 completes one period of scanning. Taking the example of layer-by-layer penetration and wavelength lengthening, at the nth period, the XY adjusting mirror 6 and the Z-axis semi-transparent mirror 52 are in proper positions, and the main sensor 4 obtains and stores the sampling signal of the wavelength at the nth period under the main light source 11. And in the (n + 1) th period, the wavelength of the secondary light source 12 is switched to the wavelength of the n-1 period, and the image signal obtained by the secondary sensor 51 is compared with the image signal of the primary sensor 4 in the wavelength of the primary light source 11 in the n-1 period for verification. If not, the number of checks is increased to filter out singular values, retain stable values, and the wavelengths of the main light source 11 and the sub-light source 12 are iteratively set. The filtering and retaining logic can be selected from an averaging method, an intercepting method and the like in the existing sampling method according to the precision will, and is not described in detail. When a scanning image is acquired, the data of a certain scanning stage is a non-target area due to the special characteristic that the position of the sample 9 is not static. Therefore, under the condition of self-checking measurement by the device, a relatively accurate scanning overall image set can be obtained. The sub sensor module 5 includes a sub sensor 51 and a Z-axis half mirror 52 at the front end thereof. The detection effect and efficiency are improved by adjusting the Z-axis half-mirror 52 to generate a phase difference between the reference signal light from the beam splitter 3 and the optical signal from the objective lens 7. The projection position of the sample 9 can be adjusted more flexibly by combining the XY adjusting mirror 6. When the objective lens 7 is small, such as an endoscope-like structure or an optical fiber type detection, the XY adjustment mirror 6 can be omitted and the image can be adjusted by a computer program. A focusing mirror 2 for adjusting the light beam emitted by the light source module 1 is arranged between the light source module 1 and the beam splitter 3; the focusing lens 2 and the central axis of the objective lens 7 are overlapped on the light path. The design is a light source single lens arrangement mode. The housing construction of the device is well known in the art and can be readily assembled by one of ordinary skill in the art without undue experimentation and without recitation. The scanner is adopted, and comprises the following steps,
1) initial data filling step: the main sensor 4 acquires a scanning signal by taking the wavelength D0 as a light source to complete data filling of a period T0;
2) a scanning step: in a period Tn, the main sensor 4 acquires a scanning signal Pn by taking a wavelength Dn as a light source;
3) checking and scanning: in the period Tn +1, the wavelength Dn-1 is taken as a light source, and the auxiliary sensor module 5 acquires a scanning contrast signal Qn + 1;
4) a checking treatment step: comparing the scanning comparison signal Qn +1 with the scanning signal Pn-1, if the scanning comparison signal Qn +1 is the same as or meets the data filtering requirement, checking and storing the result, and if the scanning comparison signal Qn +1 is different from the scanning comparison signal Pn-1, repeating the steps 3) and 4) during the next period of measurement. By adopting the mode, the image signals obtained by mutual verification on the two sensors in different scanning periods can be eliminated, and the error measurement caused by factors such as eye movement and the like can be eliminated. The data filtering requirement is a principle of sample comparison, including but not limited to a majority principle or an average farthest principle and a maximum value interception principle.
The wavelength of light emitted from the light source module 1 is preferably in the range of 1.1 to 1.7 micrometers, and more preferably about 1.2 micrometers. Light emitted by the light source module 1 is split into a target path and a reference path by the beam splitter 3. Light of the target path is projected through the XY-adjusted mirror 6 to the sample 8 through the objective lens 7, then reflected from the sample 8, and returned to the beam splitter 3 through the objective lens 7. The Z-axis half mirror 52 is movable in the Z direction by a drive mechanism, and light from the beam splitter 3 is reflected back to the main sensor 4, and the other part of the light passes through the Z-axis half mirror 52 and reaches the sub sensor 51. The light reaching the main sensor 4 is phase-shifted and therefore has more information. The light reaching the main sensor 4 and the sub-sensor 51 is coupled with different wavelengths of the light source module 1 according to different periods, so that images with different depths can be obtained, image signals obtained by mutual verification on the two sensors in different scanning periods can be obtained, and wrong measurement caused by factors such as eye movement is eliminated.
Example 2: referring to fig. 2, the present embodiment is different from embodiment 1 only in the structure of the light source module 1.
A main focusing mirror 21 is arranged between the main light source 11 and the light source switcher 13; a secondary focusing mirror 22 is arranged between the secondary light source 12 and the light source switcher 13; the central axes of the primary focusing mirror 21, the secondary focusing mirror 22 and the objective lens 7 are overlapped on the light path. The design is a light source double-lens arrangement mode.
While the invention has been described in connection with a preferred embodiment, it is not intended to limit the invention, and it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the spirit and scope of the invention.
Claims (2)
1. Self-calibrating optical coherence scanner comprising an objective lens (7) configured and arranged to focus light of a target path, characterized in that: the system also comprises a secondary sensor module (5) for obtaining another time-resolved OCT image signal acquired by the comparison main sensor (4);
the light source module (1) is used for providing light with different wavelengths, so that the main sensor (4) and the auxiliary sensor module (5) respectively obtain image signals with different detection depths;
the objective lens (7), the main sensor (4), the auxiliary sensor module (5) and the light source module (1) are respectively positioned on four light splitting branches of the beam splitter (3);
the light source module (1) comprises a main light source (11) and a secondary light source (12); the projection of light on the beam splitter (3) is realized between the main light source (11) and the auxiliary light source (12) through a light source switcher (13), the auxiliary sensor module (5) comprises an auxiliary sensor (51) and a Z-axis semi-transparent mirror (52) positioned at the front end of the auxiliary sensor module, and a focusing mirror (2) used for adjusting light beams emitted by the light source module (1) is arranged between the light source module (1) and the beam splitter (3); the central axes of the focusing mirror (2) and the objective lens (7) are overlapped on a light path, and a main focusing mirror (21) is arranged between the main light source (11) and the light source switcher (13); a secondary focusing mirror (22) is arranged between the secondary light source (12) and the light source switcher (13); the central axes of the main focusing mirror (21), the auxiliary focusing mirror (22) and the objective lens (7) are overlapped on the light path, the scanner is adopted, and the method comprises the following steps,
1) initial data filling step: the wavelength D0 is used as a light source, the main sensor (4) acquires a scanning signal, and data filling of a period T0 is completed;
2) a scanning step: in a period Tn, a main sensor (4) acquires a scanning signal Pn by taking a wavelength Dn as a light source;
3) checking and scanning: in the period Tn +1, the wavelength Dn-1 is taken as a light source, and the auxiliary sensor module (5) acquires a scanning contrast signal Qn + 1;
4) a checking treatment step: comparing the scanning comparison signal Qn +1 with the scanning signal Pn-1, if the scanning comparison signal Qn +1 is the same as or meets the data filtering requirement, checking and storing the result, and if the scanning comparison signal Qn +1 is different from the scanning comparison signal Pn-1, repeating the steps 3) and 4) during the next period of measurement.
2. The self-calibrating optical coherence scanner of claim 1, wherein: the data filtering requirement is a principle of sampling comparison, including but not limited to a majority principle or an average farthest principle, and a maximum value interception principle.
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2007039267A2 (en) * | 2005-10-05 | 2007-04-12 | Carl Zeiss Meditec Ag | Optical coherence tomography for eye-length measurement |
| CN102753086A (en) * | 2010-01-29 | 2012-10-24 | 佳能株式会社 | Ophthalmologic imaging apparatus |
| CN104318541A (en) * | 2014-11-19 | 2015-01-28 | 深圳市斯尔顿科技有限公司 | Method for processing ophthalmology OCT images |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2007039267A2 (en) * | 2005-10-05 | 2007-04-12 | Carl Zeiss Meditec Ag | Optical coherence tomography for eye-length measurement |
| CN102753086A (en) * | 2010-01-29 | 2012-10-24 | 佳能株式会社 | Ophthalmologic imaging apparatus |
| CN104318541A (en) * | 2014-11-19 | 2015-01-28 | 深圳市斯尔顿科技有限公司 | Method for processing ophthalmology OCT images |
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