CN103815868B - Full-eye optical coherence tomography - Google Patents

Abstract

Whole-eye optical coherence tomography, including: swept light source, fiber optic polarizer, first and second optical circulators, first and second broadband polarization beamsplitter prisms in the sample arm, anterior segment scanning imaging optical path and fundus Scanning imaging optical path, the third broadband polarization beamsplitter prism and two reference mirrors in the reference arm, the fourth and fifth broadband polarization beamsplitter prisms at the detection end, the second and third polarization-maintaining optical couplers, the first and second balanced detectors , and function generation cards, data acquisition cards and computers. Based on frequency-swept optical coherence tomography technology, the instrument uses the p-component and s-component of the polarized beam to image the fundus and anterior segment respectively, realizing three-dimensional high-resolution of the whole eye structure on the same system without any device conversion live imaging. The present invention can perform optical path and dispersion matching and scanning settings on the imaging of the anterior segment and the fundus respectively, and can obtain the best image quality and field of view of the imaging of the anterior segment and the fundus at the same time.

Description

Whole-eye optical coherence tomography

technical field

The invention relates to a human eye imaging device and an optical coherence tomography (OCT) technology, in particular to an device which adopts the frequency-sweeping OCT technology and can simultaneously image the whole eye structure.

Background technique

Eye diseases such as short-sightedness, long-sightedness, cataracts and glaucoma can affect the shape and size of the eye. Simultaneous high-resolution imaging of whole-ocular structures is essential in order to examine changes in visual physiology due to ophthalmic diseases. Ultrasound and MRI techniques can achieve whole-eye imaging, but the former is a contact measurement, while the latter is expensive, and their resolution is too low to effectively observe tissue structures. Optical coherence tomography (OCT) technology is a technology that can perform three-dimensional high-resolution non-destructive real-time tomographic imaging of the internal structure of tissues. widely used. At present, OCT has developed time-domain and frequency-domain OCT technologies, and frequency-domain OCT includes spectral domain and frequency-sweeping OCT technologies. The frequency-domain OCT technology can simultaneously acquire all the interference spectrum information in the depth direction of the sample without the axial scanning of the reference arm, and then obtain the structural information through inverse Fourier transform, so it has faster imaging speed and higher detection sensitivity.

In the literature of Dai et al. (C Dai, et al. Optical coherence tomography for whole eye segmentimaging. Optics Express, 2012, 20(6): 6109-6115.) and Chinese invention patent (application number: 201110195189.0), proposed The dual-channel whole-eye OCT imaging system based on spectral domain OCT technology uses two sets of independent light sources, two sets of reference arms, and two sets of detection arms to image the anterior segment and fundus respectively, and only the samples of the two systems The light paths of the arms are combined through a beam splitting prism and share a set of scanning mechanisms. This system has the following disadvantages: 1) The light source is the most expensive device in the OCT system, and the use of two light sources will greatly increase the cost; 2) The dichroic prism used in the sample arm halves the intensity of the illumination light signal from the light source, The intensity of the light signal returned from the sample will be halved again, and the extremely low utilization rate of light energy will reduce the detection sensitivity of the system; 3) Much of the information of the anterior segment is distributed on the nasal side and the temporal side, requiring large-scale scanning and imaging, while the fundus The imaging field of view is extremely limited, and a common set of scanning mechanisms will not be able to perform scanning settings separately according to the requirements of the respective field of view.

In the literature of the J A Izatt group of Duke University (A H Dhalla, et al.Simultaneous swept source optical coherence tomography of the interior segment and retina using coherence revival. Optics Letters,2012,37(11):1883-1885.), A whole-eye imaging system based on frequency-sweeping OCT technology is proposed. The anterior segment and fundus are imaged with the p-component and s-component of the polarized beam in the sample arm, respectively. They matched the fundus imaging optical path with the reference arm optical path, and made the anterior segment imaging optical path mismatch with the reference arm optical path, so that the fundus image and anterior segment image obtained through Fourier inverse transform were not aliased, and the anterior segment image could be eliminated. Conjugation artifacts of section images. The structure of this system is greatly simplified, but there are also shortcomings: 1) The imaging optical path of the anterior segment and the optical path of the reference arm are seriously mismatched, making it difficult to obtain a clear image of the anterior segment; It has a very long coherence length, which means that the light source is required to have a very high wavelength scanning resolution, which brings difficulties to the production of the light source; 2) cannot eliminate the conjugate artifacts of the anterior segment and fundus at the same time; 3) share a set of scanning Institutions, scanning settings cannot be made separately according to the requirements of their respective fields of view.

Contents of the invention

The technical problem of the present invention is to overcome the deficiencies of the prior art, and provide a whole-eye optical coherence tomography imager, based on frequency-sweeping OCT technology, use the p component and s component of the polarized beam to image the fundus and anterior segment respectively, and then Three-dimensional high-resolution results of the whole eye structure are obtained through image reconstruction. Therefore, the present invention can perform optical path and dispersion matching and scanning settings for the imaging of the anterior segment and the fundus respectively, and can obtain the best image quality and field of view of the imaging of the anterior segment and the fundus at the same time.

The technical solution adopted by the present invention to solve the technical problem is: an all-eye optical coherence tomography imager, including: a frequency-sweeping light source, an optical fiber polarizer, a first polarization-maintaining optical coupler, a first optical circulator, a first Lens, first broadband polarization beam splitter, first mirror, first two-dimensional scanner, second lens, second broadband polarization beam splitter, third lens, second mirror, beam expander, second two-dimensional scanning device, the second optical circulator, the fourth lens, the third broadband polarization beam splitter prism, the water box, the first reference mirror, the second reference mirror, the first translation stage, the second translation stage, the fourth broadband polarization beam splitter prism, the first Five broadband polarization beam splitters, the second polarization-maintaining optical coupler, the third polarization-maintaining optical coupler, the first balanced detector, the second balanced detector, the first single-mode polarization-maintaining fiber, the second single-mode polarization-maintaining fiber, the third Single-mode polarization-maintaining optical fiber, fourth single-mode polarization-maintaining optical fiber, fifth single-mode polarization-maintaining optical fiber, sixth single-mode polarization-maintaining optical fiber, seventh single-mode polarization-maintaining optical fiber, function generation card, data acquisition card and computer;

The optical signal sent by the frequency-sweeping light source passes through the optical fiber polarizer, and then is transmitted to the first polarization-maintaining optical coupler by the first single-mode polarization-maintaining optical fiber. port a of the optical circulator, then exits from the port b of the first optical circulator, and enters the sample arm; the other is transmitted to the port d of the second optical circulator through the fourth single-mode polarization-maintaining fiber, and then from the second optical circulator Port e exits and enters the reference arm;

In the sample arm, the light beam emitted from port b of the first optical circulator is transmitted through the third single-mode polarization-maintaining fiber and collimated by the first lens, and then enters the first broadband polarization beam splitter, where the light beam is divided into transmission and reflection Two parts: the transmitted p-polarized light passes through the first mirror, the first two-dimensional scanner, and the beam expander system composed of the second lens and the third lens in sequence, and is focused on the fundus by the anterior segment, and the second broadband polarized light The dichroic prism is located between the second lens and the third lens; the reflected s-polarized light is focused by the third lens after sequentially passing through the second reflector, beam expander, second two-dimensional scanner, and second broadband polarization beam splitter prism on the anterior segment;

In the reference arm, the beam emitted from the port e of the second optical circulator is transmitted through the fifth single-mode polarization-maintaining fiber and collimated by the fourth lens, and then enters the third broadband polarization beam splitter prism, where the beam is divided into transmission and reflection Two parts: after the transmitted p-polarized light passes through the water box, it is vertically incident on the first reference mirror fixed on the first translation stage; the reflected s-polarized light is vertically incident on the second reference mirror fixed on the second translation stage; the water The box is used to balance the dispersion caused by the eyes;

The s-polarized sample light returned from the anterior segment and the p-polarized sample light returned from the fundus respectively return to the port b of the first optical circulator along the original path, and then exit from the port c of the first optical circulator, and are transmitted by the sixth The single-mode polarization-maintaining fiber is transmitted to the fourth broadband polarization beamsplitter prism, where the s-polarized sample light is reflected and the p-polarized sample light is transmitted; the p-polarized reference light returned from the first reference mirror and the The s-polarized reference light returns to the port e of the second optical circulator along the original path, and then exits from the port f of the second optical circulator, and is transmitted to the fifth broadband polarization beam splitter by the seventh single-mode polarization-maintaining optical fiber, Here, the s-polarized reference light is reflected, while the p-polarized reference light is transmitted;

The s-polarized sample light and s-polarized reference light from the fourth and fifth broadband polarization beam splitters, respectively, pass through the second polarization-maintaining optical coupler, and are divided into two parts respectively, and enter the positive and negative receiving ends of the first balanced detector respectively. The p-polarized sample light and the p-polarized reference light from the fourth and fifth broadband polarization beam splitters respectively, after passing through the third polarization-maintaining optical coupler, are respectively divided into two parts and respectively incident on the positive pole and the negative pole of the second balanced detector to receive end;

The frequency-sweeping light source sends out a sampling trigger signal while scanning the wavelength to control the data acquisition card to synchronously collect the interference spectrum signals received by the first and second balance detectors; the scanning drive signal provided by the function generation card and the frequency-sweeping light source send out The sampling trigger signals are synchronized to control the first and second two-dimensional scanners to scan respectively; the signals collected by the data acquisition card are transmitted to the computer for processing.

The frequency-sweeping light source is a near-infrared band wide-spectrum light source.

The front focal point of the second lens coincides with the rear focal point of the third lens, and the two constitute a beam expander system.

The first translation stage moves linearly with the first reference mirror until the p-polarized sample light returned from the fundus and the p-polarized reference light returned from the first reference mirror form interference fringes.

The second translation stage moves linearly with the second reference mirror until the s-polarized sample light returned from the anterior segment and the s-polarized reference light returned from the second reference mirror form interference fringes.

The second and third polarization-maintaining optical couplers are both 2×2 couplers with a splitting ratio of 50:50.

The beneficial effect of the present invention compared with prior art is:

(1) The present invention can simultaneously realize three-dimensional high-resolution imaging of the anterior segment and fundus on the same system without any device conversion;

(2) The present invention can match factors such as the optical path and dispersion between the anterior segment and its reference arm, the fundus and its reference arm, and can perform scanning settings for the anterior segment and fundus imaging respectively, so that the anterior segment and the fundus can be obtained simultaneously. Best image quality and field of view size for fundus imaging;

(3) The present invention adopts frequency-sweeping OCT technology without axial scanning, and the frequency-sweeping rate of the existing frequency-sweeping light source is extremely high (10 ³ KHz order of magnitude or even higher), which can realize real-time imaging, which is beneficial to reduce the imaging time. Image distortion caused by eye movement;

(4) The present invention adopts polarized light interference imaging technology, which has a certain anti-interference effect on environmental stray light.

Description of drawings

Fig. 1 is a schematic diagram of the system structure of the present invention;

Fig. 2 is a schematic diagram of the control system of the present invention.

In the figure: 1. Frequency-sweeping light source, 2. Optical fiber polarizer, 3. The first polarization-maintaining optical coupler, 4. The first optical circulator, 5. The first lens, 6. The first broadband polarization beam splitter, 7. The first mirror, 8. The first two-dimensional scanner, 9. The second lens, 10. The second broadband polarization beam splitter, 11. The third lens, 12. Anterior segment, 13. Fundus, 14. The second mirror , 15. Beam expander, 16. The second two-dimensional scanner, 17. The second optical circulator, 18. The fourth lens, 19. The third broadband polarization beam splitter, 20. Water box, 21-22. The first And the second reference mirror, 23-24. The first and the second translation stage, 25-26. The fourth and the fifth broadband polarization beam splitter, 27-28. The second and the third polarization-maintaining optical coupler, 29-30. The first and second balanced detectors, 31-37. the first to seventh single-mode polarization-maintaining optical fibers, 38. function generator card, 39. data acquisition card, 40. computer.

Detailed ways

The structure of the whole-eye optical coherence tomography proposed by the present invention is shown in Figure 1, including: a frequency-sweeping light source 1, an optical fiber polarizer 2, a first polarization-maintaining optical coupler 3, a first optical circulator 4, and a first lens 5. The first broadband polarization beamsplitter prism 6, the first mirror 7, the first two-dimensional scanner 8, the second lens 9, the second broadband polarization beamsplitter prism 10, the third lens 11, the second reflection mirror 14, beam expander Device 15, second two-dimensional scanner 16, second optical circulator 17, fourth lens 18, third broadband polarization beam splitter prism 19, water box 20, first and second reference mirrors 21-22, first and second Two translation stages 23-24, fourth and fifth broadband polarization beam splitter prisms 25-26, second and third polarization-maintaining optical couplers 27-28, first and second balanced detectors 29-30, first to seventh Single mode polarization maintaining optical fiber 31-37, function generation card 38, data acquisition card 39, computer 40.

The frequency-sweeping light source 1 is a near-infrared band wide-spectrum light source with fast wavelength scanning. The optical signal emitted by it becomes linearly polarized light after passing through the optical fiber polarizer 2, and then is transmitted to the first polarization-maintaining light by the first single-mode polarization-maintaining optical fiber 31. After the coupler 3, it is divided into two paths: one route is transmitted to the port a of the first optical circulator 4 by the second single-mode polarization-maintaining optical fiber 32, and then exits from the port b of the first optical circulator 4 and enters the sample arm; the other route The fourth single-mode polarization-maintaining optical fiber 34 is transmitted to the port d of the second optical circulator 17, and then exits from the port e of the second optical circulator 17 and enters the reference arm.

In the sample arm, the light beam emitted from the port b of the first optical circulator 4 is transmitted by the third single-mode polarization-maintaining fiber 33, collimated by the first lens 5, and then incident on the first broadband polarization beam splitter prism 6. Here the light beam is divided into two parts: transmission and reflection: the transmitted p-polarized light is reflected by the first mirror 7 and the first two-dimensional scanner 8 successively, and then enters the beam expander system composed of the second lens 9 and the third lens 11, The parallel light emitted by the beam expander system is focused on the fundus 13 by the anterior segment 12 , and the first two-dimensional scanner 8 makes the light spot focused on the fundus 13 perform transverse two-dimensional scanning and imaging. Wherein, the front focal point of the second lens 9 coincides with the rear focal point of the third lens 11 to form a beam expander system, and the second broadband polarization beam splitter prism 10 is located between the second lens 9 and the third lens 11 . The reflected s-polarized light passes through the second mirror 14, the beam expander 15, the second two-dimensional scanner 16, and the second broadband polarization beam splitter prism 10 in sequence, and is focused on the anterior segment 12 by the third lens 11, and the second The two-dimensional scanner 16 enables the light spot focused on the anterior segment 12 to perform horizontal two-dimensional scanning and imaging.

In the reference arm, the light beam emitted from the port e of the second optical circulator 17 is collimated by the fourth lens 18 after being transmitted through the fifth single-mode polarization-maintaining fiber 35, and then enters the third broadband polarization beam splitter prism 19, and Here the light beam is divided into transmission and reflection two parts: after the transmitted p-polarized light passes through the water box 20, it is vertically incident on the first reference mirror 21 fixed on the first translation stage 23; the reflected s-polarized light is vertically incident and fixed on the second Second reference mirror 22 on translation stage 24. The water box 20 is used to balance the dispersion caused by the eyes.

The s-polarized sample light returned from the anterior segment 12 and the p-polarized sample light returned from the fundus 13 respectively return to the port b of the first optical circulator 4 along the original path, and then exit from the port c of the first optical circulator 4, And transmitted to the fourth broadband polarization beam splitter 25 by the sixth single-mode polarization-maintaining optical fiber 36, where the s-polarized sample light is reflected, and the p-polarized sample light is transmitted. The p-polarized reference light returned from the first reference mirror 21 and the s-polarized reference light returned from the second reference mirror 22 respectively return to the port e of the second optical circulator 17 along the original path, and then from the second optical circulator 17 Port f of the output port, and transmitted by the seventh single-mode polarization-maintaining fiber 37 to the fifth broadband polarization beam splitter prism 26, where the s-polarized reference light is reflected, and the p-polarized reference light is transmitted.

The s-polarized sample light and s-polarized reference light from the fourth broadband polarization beam splitter 25 and the fifth broadband polarization beam splitter 26 respectively, after passing through the second polarization-maintaining optical coupler 27, are respectively divided into two parts and respectively incident on the first balanced detector The positive and negative receiving ends of the device 29. The p-polarized sample light and p-polarized reference light from the fourth broadband polarization beam splitter 25 and the fifth broadband polarization beam splitter 26 respectively, after passing through the third polarization-maintaining optical coupler 28, are respectively divided into two parts and respectively incident on the second balanced detector The positive and negative receiving ends of the device 30. Both the second polarization-maintaining optical coupler 27 and the third polarization-maintaining optical coupler 28 are 2×2 couplers with a splitting ratio of 50:50.

The first translation stage 23 moves linearly with the first reference mirror 21 until the p-polarized sample light returned from the fundus 13 and the p-polarized reference light returned from the first reference mirror 21 form interference fringes. The second translation stage 24 moves linearly with the second reference mirror 22 until the s-polarized sample light returned from the anterior segment 12 and the s-polarized reference light returned from the second reference mirror 22 form interference fringes.

The control system of the present invention is shown in FIG. 2 . The frequency-sweeping light source 1 sends a sampling trigger signal while performing wavelength scanning, to control the data acquisition card 39 to synchronously collect the interference spectrum signals received by the first balance detector 29 and the second balance detector 30; provided by the function generation card 38 The scanning driving signal is synchronized with the sampling trigger signal sent by the frequency sweeping light source 1, respectively controlling the first two-dimensional scanner 8 and the second two-dimensional scanner 16 to scan; the signal collected by the data acquisition card 39 is transmitted to the computer 40 for processing.

The specific embodiments above are used to explain the present invention, but not to limit the present invention. Within the spirit of the present invention and the protection scope of the claims, any modification and change made to the present invention will fall into the protection scope of the present invention.

Claims (6)

1. full optics of the eye coherence chromatographic imaging instrument, is characterized in that: comprise swept light source (1), the optical fiber polarizer (2), first protects polarisation bonder (3), first optical circulator (4), first lens (5), first wideband polarization Amici prism (6), first reflecting mirror (7), first two-dimensional scanner (8), second lens (9), second wideband polarization Amici prism (10), 3rd lens (11), second reflecting mirror (14), beam expander (15), second two-dimensional scanner (16), second optical circulator (17), 4th lens (18), 3rd wideband polarization Amici prism (19), water box (20), first reference mirror (21), second reference mirror (22), first translation stage (23), second translation stage (24), 4th wideband polarization Amici prism (25), 5th wideband polarization Amici prism (26), second protects polarisation bonder (27), 3rd protects polarisation bonder (28), first balanced detector (29), second balanced detector (30), first single-mode polarization maintaining fiber (31), second single-mode polarization maintaining fiber (32), 3rd single-mode polarization maintaining fiber (33), 4th single-mode polarization maintaining fiber (34), 5th single-mode polarization maintaining fiber (35), 6th single-mode polarization maintaining fiber (36), 7th single-mode polarization maintaining fiber (37), function card (38), data collecting card (39) and computer (40),

The optical signal that swept light source (1) sends is divided into two-way transfer to first guarantor's polarisation bonder (3) by the first single-mode polarization maintaining fiber (31) after the optical fiber polarizer (2) after, one route second single-mode polarization maintaining fiber (32) transfers to the port a of the first optical circulator (4), again from the port b outgoing of the first optical circulator (4), enter sample arm; Another route the 4th single-mode polarization maintaining fiber (34) transfers to the port d of the second optical circulator (17), then from the port e outgoing of the second optical circulator (17), enters reference arm;

In sample arm, from the light beam of the port b outgoing of the first optical circulator (4), after the 3rd single-mode polarization maintaining fiber (33) transmission and the first lens (5) collimation, incident first wideband polarization Amici prism (6), here light beam is divided into transmittance and reflectance two parts: the p polarized light of transmission is successively through the first reflecting mirror (7), after first two-dimensional scanner (8) and the beam-expanding system that is made up of the second lens (9) and the 3rd lens (11), focused on optical fundus (13) by anterior ocular segment (12), second wideband polarization Amici prism (10) is positioned between the second lens (9) and the 3rd lens (11), the s polarized light of reflection, successively after the second reflecting mirror (14), beam expander (15), the second two-dimensional scanner (16) and the second wideband polarization Amici prism (10), is focused in anterior ocular segment (12) by the 3rd lens (11),

In reference arm, from the light beam of the port e outgoing of the second optical circulator (17), after the 5th single-mode polarization maintaining fiber (35) transmission and the 4th lens (18) collimation, incident 3rd wideband polarization Amici prism (19), here light beam is divided into transmittance and reflectance two parts: the p polarized light of transmission is through after water box (20), and vertical incidence is fixed on the first reference mirror (21) on the first translation stage (23); The s polarized light vertical incidence of reflection is fixed on the second reference mirror (22) on the second translation stage (24); Water box (20) falls apart for balancing the color caused by eyes;

The s polarization sample light returned from anterior ocular segment (12) and the p polarization sample light returned from optical fundus (13), the port b of the first optical circulator (4) is back to respectively along former road, again from the port c outgoing of the first optical circulator (4), and transfer to the 4th wideband polarization Amici prism (25) by the 6th single-mode polarization maintaining fiber (36), here s polarization sample light reflects, and p polarization sample light generation transmission; The p polarization reference light returned from the first reference mirror (21) and the s polarization reference light returned from the second reference mirror (22), the port e of the second optical circulator (17) is back to respectively along former road, again from the port f outgoing of the second optical circulator (17), and transfer to the 5th wideband polarization Amici prism (26) by the 7th single-mode polarization maintaining fiber (37), here s polarization reference light reflects, and p polarization reference light generation transmission;

The s polarization sample light come from the 4th wideband polarization Amici prism (25) and the 5th wideband polarization Amici prism (26) respectively and s polarization reference light, after protecting polarisation bonder (27) by second, be divided into two parts separately and the positive pole of incident first balanced detector (29) of difference and negative pole receiving terminal; The p polarization sample light come from the 4th wideband polarization Amici prism (25) and the 5th wideband polarization Amici prism (26) respectively and p polarization reference light, after protecting polarisation bonder (28) by the 3rd, be divided into two parts separately and the positive pole of incident second balanced detector (30) of difference and negative pole receiving terminal;

Send sampling trigger signal while swept light source (1) carries out length scanning, remove the interference spectrum signal that control data capture card (39) synchronous acquisition is received by the first balanced detector (29) and the second balanced detector (30); The scanning drive signal provided by function card (38) is synchronous with the sampling trigger signal that swept light source (1) sends, and controls the first two-dimensional scanner (8) respectively and the second two-dimensional scanner (16) scans; The Signal transmissions that data collecting card (39) collects processes to computer (40).

2. full optics of the eye coherence chromatographic imaging instrument according to claim 1, is characterized in that: described swept light source (1) is near infrared band broad spectrum light source.

3. full optics of the eye coherence chromatographic imaging instrument according to claim 1, is characterized in that: the front focus of described the second lens (9) and the back focus of the 3rd lens (11) coincide, and the two forms a beam-expanding system.

4. full optics of the eye coherence chromatographic imaging instrument according to claim 1, it is characterized in that: described the first translation stage (23) moves linearly with the first reference mirror (21), until the p polarization sample light returned by optical fundus (13) and form interference fringe from the p polarization reference light that the first reference mirror (21) returns.

5. full optics of the eye coherence chromatographic imaging instrument according to claim 1, it is characterized in that: described the second translation stage (24) moves linearly with the second reference mirror (22), until the s polarization sample light returned by anterior ocular segment (12) and form interference fringe from the s polarization reference light that the second reference mirror (22) returns.

6. full optics of the eye coherence chromatographic imaging instrument according to claim 1, is characterized in that: described second and the 3rd protects polarisation bonder (27,28) for having 2 × 2 bonders of 50:50 splitting ratio.