CN201101518Y - Common channel type endoscopic optical coherent chromatography imaging system - Google Patents

Abstract

The utility model discloses a common-channel-type optical endoscopic coherence tomography imaging system. The light emitted from a broadband light source is connected with the port (a) of a first optical circulator, the light emitted from a port (b) reaches a sample through a first collimating lens, a two-dimensional scanning galvanometer, a microobjective, an optical fiber image-transmitting bundle and a Green lens, and the light returning to the port (b) is connected with the port (d) of a second optical circulator through the port (c) of the first optical circulator. The light emitted from the port (e) reaches a reflector arranged on an electric-control translational platform through a second collimating lens and a flat light-splitting sheet. The light returning to the port (e) is shot out from the port (f) of the second optical circulator and then reaches a linear array CCD detector through a third collimating lens, a diffraction grating and an imaging lens. The two-dimensional scanning galvanometer, the electric-control translational platform and the linear array CCD detector are all connected with a control system. Light circulators are adopted to improve the energy utilization rate of the system, and the spectral detection technology is adopted to increase the imaging speed. The imaging quality of the system is free from the environmental impact, the endoscopic sensor is convenient to be processed and installed and the energy utilization rate of the system is high.

Description

Common path endoscopic optical coherence tomography system

technical field

The utility model relates to an endoscopic imaging technology and an optical coherence tomography imaging technology, in particular to a co-channel endoscopic optical coherence tomography imaging system using an optical fiber image transmission bundle as an endoscopic probe.

Background technique

Diagnosis of lesions based only on the morphological changes on the surface of the tissue has great subjectivity and limitations, while the tomographic images inside the tissue can provide more objective basis for the doctor's diagnosis. Many tomography techniques, such as computer tomography (CT), nuclear magnetic resonance (MRI), X-ray, ultrasound, etc., are widely used in clinical diagnosis. However, the above-mentioned techniques can only provide a resolution of 0.1-1 mm, which is far from the level of resolution required to detect tissue abnormalities, such as biological tissue structures in early cancers.

Optical coherence tomography (OCT) is an emerging optical imaging technology that can non-invasively visualize the internal structure, physiological functions and even molecular information of living tissues. It has the high resolution (up to 1-20 μm) required for histopathological analysis, and can perform clinical functions such as early diagnosis of lesions, process monitoring and surgical guidance. OCT also has the advantages of fast imaging speed, no radiation damage, diversified information, moderate price, and good compatibility with existing medical instruments. It is currently an imaging tool that is widely optimistic and can play an important role in clinical medicine. In particular, the endoscopic OCT technology formed by the combination of OCT technology and endoscopic imaging technology can image the tissues and organs inside the living body, which greatly expands the application range of OCT and can provide doctors with more accurate diagnosis basis. Endoscopic OCT has been used in gastrointestinal system, respiratory system, and vascular imaging.

In the existing endoscopic OCT system, such as the Fujimoto group of MIT in the United States (Guillermo J.Tearney, et al., In vivo endoscopic optical biopsy with optical coherence tomography, Science, 276, 2037-2039, 1997), the University of California Chen's group (Tuqiang Xie, et al., Fiber-optic-bundle-based optical coherence tomography, Optics Letters, 30(14), 1803-1805, 2005), etc. generally regard the optical fiber or optical fiber as the optical transmission device of the endoscopic probe The image beam is placed on the sample arm of the interference structure. Due to the irregular structure of the inner cavity of organs in the body, there are inevitably bending and twisting phenomena in the optical fiber or optical fiber image transmission bundle entering it, resulting in changes in the polarization state of the light beam transmitted by the optical fiber or optical fiber image transmission bundle, plus The effects of dispersion caused by them will significantly degrade the imaging quality. Therefore, the above-mentioned factors must be precisely matched in the reference arm, making the composition and adjustment of the system extremely complicated. Moreover, every time the endoscopic probe is replaced, complex operations such as optical path matching, dispersion compensation, and polarization state adjustment with a large travel range are required.

In addition, the reflected light from the end face of the fiber optic bundle will form a background signal on the image plane of the detector, which is an undesired beam that must be deflected from the image plane. Therefore, the end face of the fiber optic bundle must be ground to an inclined plane at an angle of 8° to its axis. . When using a Green lens (GRIN lens, gradient refractive index lens) to focus the output beam, it is also necessary to process the bonding surface of the Green lens and the optical fiber image beam into an inclined surface with an inclination angle of 8°. Accurate positioning complicates the processing and installation process of the optical fiber image beam and the Green lens. The existence of this angle makes the optical path experienced by the light beam different when it is transmitted at different positions of the optical fiber image transmission beam, resulting in uneven interference signal intensity of the entire image plane.

Contents of the invention

In order to overcome the deficiencies of the background technology, the purpose of this utility model is to provide a co-channel endoscopic optical coherence tomography system. The system uses the end-face reflected light of the optical fiber image transmission bundle as the endoscopic probe as the reference light, and it and the signal light from the sample are transmitted through the same optical fiber image transmission bundle, forming a common path and sensing interference structure. The optical path difference between the reference light and the signal light is compensated by another co-path interference structure.

The technical scheme that the utility model solves its technical problem adopts is:

The light emitted by the broadband light source is connected to the port a of the first optical circulator, and the light emitted by the port b of the first optical circulator passes through the first collimator lens, the two-dimensional scanning galvanometer, the microscope objective lens, the optical fiber image transmission bundle and the Green lens in sequence to the sample, the light returned to port b is connected to the second optical circulator port d by the first optical circulator port c; The mirror installed on the electronically controlled translation stage; the light returned to the port e exits the port f of the second optical circulator, and then passes through the third collimator lens, diffraction grating, and imaging lens to the linear CCD detector in sequence; two-dimensional The scanning galvanometer, electronically controlled translation stage and linear array CCD detector are all connected with the control system.

The control system includes an image acquisition card, a computer, a function generator and a stepping motor controller. The linear array CCD detector is connected to the computer through the image acquisition card, and the computer outputs two signals, one of which is connected to the two-dimensional scanning vibrator through the function generator. mirror, and the other path is connected to the electronically controlled translation stage through the stepping motor controller.

The light emitted by the port b of the first optical circulator passes through the first collimator lens, the two-dimensional scanning galvanometer, the microscope objective lens, the optical fiber image transmission bundle and the Green lens in sequence, and then connects the rectangular prism to the sample.

The length of the optical fiber image transmission bundle is greater than 1000mm, the two end faces are processed into planes perpendicular to the axis, and the front end faces are placed on the focal plane of the microscope objective lens.

The transmittance/reflectance of the broadband beam splitting flat plate is close to 62/38.

The reflective mirror is a broadband high reflective mirror, specifically a metal-dielectric film broadband high reflective mirror.

The photosensitive surface of the linear CCD detector is located on the rear focal plane of the imaging lens, and the length direction of the photosensitive surface is perpendicular to the direction of the scribe line of the diffraction grating.

Between the first optical circulator and the broadband light source, the first collimating lens, and the second optical circulator, and between the second optical circulator and the second collimating lens and the third collimating lens, single-mode fiber optic connection.

Compared with background technology, the beneficial effect that the utility model has is:

1. The utility model has the characteristics that the imaging quality is less affected by the environment and the operation is simple: the reference light and the signal light are transmitted through the same optical fiber image transmission beam, and the optical path difference between the two is compensated by another common path interference structure. The whole system is Common path interference structure. Factors such as dispersion and polarization state changes of the optical fiber image transmission bundle, as well as environmental temperature changes and vibrations have little effect on the imaging results, and there is no need to consider matching them, which makes the system configuration and adjustment easier;

2. The utility model can replace and use different endoscopic probes according to the needs, without the need for complex operations such as dispersion matching and polarization state adjustment of the system, and only needs to perform optical path matching in a small stroke range;

3. The utility model has the characteristics of compact structure and safe use: the probe entering the biological cavity only plays the role of signal sensing, and all operations are carried out outside the probe, so that the number of devices inside the probe is reduced to a minimum, and it is convenient to realize the probe The miniaturization makes it easier to enter various organs for imaging; there are no moving parts and driving current inside the probe, and the system has very high safety in use;

4. The utility model simplifies the processing and installation process of the endoscopic probe: the reflected light of the rear end face of the optical fiber image transmission bundle is used as a reference light, so it is not necessary to process the optical fiber image transmission bundle and the end face of the Green lens into an inclination angle of 8° Inclined surface, the installation is also much easier;

5. The utility model has the characteristics of high energy utilization rate: the energy loss of the two optical circulators used is almost negligible, and the energy utilization rate of the system is higher than that of the OCT system using beam splitters.

Description of drawings

Fig. 1 is the system schematic diagram of the present utility model.

Fig. 2 is a schematic diagram of the endoscopic probe used for cavity wall imaging of the present invention.

Fig. 3 is a schematic diagram of the control system of the present invention.

In the figure: 1. Broadband light source, 2. The first optical circulator, 3. The first collimating lens, 4. Two-dimensional scanning galvanometer, 5. Microscopic objective lens, 6. Optical fiber image transmission bundle, 7. Green lens, 8. Right-angle prism, 9. Sample, 10. Second optical circulator, 11. Second collimator lens, 12. Broadband beam splitter, 13. Mirror, 14. Electronically controlled translation stage, 15. Third collimator Lens, 16. Diffraction grating, 17. Imaging lens, 18. Linear array CCD detector, 19. Image acquisition card, 20. Computer, 21. Function generator, 22. Stepper motor controller.

Detailed ways

Below in conjunction with accompanying drawing and embodiment the utility model is described further:

The common path endoscopic optical coherence tomography system proposed by the utility model is shown in Fig. 1, the light emitted by the broadband light source 1 is connected to the port a of the first optical circulator 2, and then emitted to the port b of the first optical circulator 2 The first collimating lens 3 is collimated and incident on the two-dimensional scanning galvanometer 4 in parallel. The reflected light beam is focused by the microscopic objective lens 5 and then coupled into the optical fiber image transmission beam 6. When it is transmitted to the rear end surface, the light beam is divided into retroreflected light and transmitted light. The transmitted light is focused on the sample 9 by a Green lens 7 . The probe used in Figure 1 is a forward-facing endoscopic probe. When it is necessary to image the cavity wall, a side-facing endoscopic probe can be used.

The lateral endoscopic probe is shown in Figure 2, which is formed by bonding the rear end surface of the optical fiber image transmission bundle 6 with a Green lens 7, and the other side of the Green lens 7 with a rectangular prism 8. When using a side-facing endoscopic probe, the light transmitted by the rear end surface of the optical fiber image transmission bundle 6 is focused by the Green lens 7, and then changed direction by the right-angle prism 8, and enters the sample 9 from the side.

In the above two forms of endoscopic probes, the two end faces of the optical fiber image transmission bundle 6 are processed into a plane perpendicular to its axis, and the front end faces are placed on the focal plane of the microscopic objective lens 5 to collect the incident light beam, while the rear end faces are The reference surface of the interference system, together with the sample 9, constitutes an interferometer that is close to a common path and plays a role of signal sensing. Since the optical fiber imaging bundle 6 is not a single-mode fiber, the light beam is transmitted in multiple modes, and only the image formed by the light beam transmitted in the fundamental mode is the real image of the sample. As the length of the optical fiber imaging bundle increases, the image formed by the higher order mode and the image formed by the fundamental mode will be separated in space. When the length of the optical fiber image transmission bundle is about 1000mm, the image formed by the high-order mode can be completely deviated from the display image plane, and only the sample image formed by the fundamental mode is displayed, thus ensuring the system's ability to achieve the sample. Depth of imaging is not affected by multimode transmission. Therefore, the length of the optical fiber image transmission bundle 6 should be greater than 1000mm.

The light reflected or backscattered by the sample 9 and the light reflected by the rear end surface of the optical fiber imaging bundle 6 return to the first optical circulator 2 along the original path, and then exit to the second optical circulator 10 through port c. The light beam emitted from the port e of the second optical circulator 10 is collimated by the second collimator lens 11 , and is divided into reflected light and transmitted light when it is incident on the broadband beam splitter 12 in parallel. The transmitted light is incident on the reflector 13 in parallel, and the reflector 13 is fixed on the electronically controlled translation stage 14 . The transmittance/reflectivity of the broadband beam splitter 12 should be close to 62/38, so that the intensity of the two beams obtained after beam splitting by it matches. In order to make the system have a higher energy utilization rate, the reflector 13 adopts a broadband high-reflectivity mirror, specifically a metal-dielectric film broadband high-reflectance mirror.

After being reflected by the reflector 13 and the broadband beam splitter 12, the light beam returns to the second optical circulator 10 along the original path, exits from the port f to the third collimator lens 15, collimates and enters the diffraction grating 16 in parallel, and after diffraction The dispersed beam is focused by the imaging lens 17 on the image plane of the linear array CCD detector 18 . The length direction of the image plane of the linear array CCD detector 18 is placed perpendicular to the direction of the lines of the diffraction grating 16 . Between the first optical circulator 2 and the broadband light source 1, the first collimating lens 3, the second optical circulator 10, and between the second optical circulator 10 and the second collimating lens 11 and the third collimating lens 15 , with a single-mode fiber connection. The two-dimensional scanning galvanometer 4, the electronically controlled translation stage 14 and the linear array CCD detector 18 are all connected with the control system.

As shown in Figure 3, the control system of the present utility model includes an image acquisition card 19, a computer 20, a function generator 21 and a stepper motor controller 22. The computer 20 controls the linear array CCD detector 18 to collect interference signals through the image acquisition card 19, and inputs the collected signals into the computer 20 for processing and displaying. The computer 20 outputs two control signals: one through the function generator 21 to control the two-dimensional scanning galvanometer 4 to scan horizontally, so as to realize imaging at different positions of the sample 9; one through the stepping motor controller 22 to drive the electronically controlled translation stage 14, It moves axially with the reflector 13 to match the optical path between the signal light and the reference light until the best interference signal appears, realizing the optical alignment between the signal light and the reference light on the outside of the endoscopic probe. Compensation for distance difference.

Line array CCD detector 18, image acquisition card 19 and function generator 21 all can be purchased from the market, they are respectively as the AVIiVA SM2CL linear array CCD detector of U.S. Atmel Company, the PCIe-1430 image acquisition card of U.S. NI Company, and The DS345 function generator of the American STANFORD RESEARCH SYSTEM company. The stepper motor controller 22 and the electronically controlled translation stage 14 are supporting products and can be purchased together, such as the TSA30-C electronically controlled translation stage and the SC3 stepper motor controller of Beijing Zhuoli Hanguang Instrument Co., Ltd.

The common path endoscopic optical coherence tomography method that the utility model proposes, its specific steps are as follows:

1) The electronically controlled translation stage moves axially with the mirror until the best interference signal appears;

2) collect the interference signal by the linear array CCD detector, obtain the signal I(k) distribution of the light intensity with respect to the wavenumber k, and input it into the computer through the image acquisition card;

3) The computer performs one-dimensional Fourier inverse transform on the signal I(k) along the spectrum expansion direction to obtain the signal I(z) distribution of the light intensity with respect to the position z, and I(z) is the image of the sample along the depth direction z;

4) The computer controls the two-dimensional scanning vibrating mirror to scan continuously along the x direction through the function generator, and performs steps 2) and 3) respectively for each point in the x direction, and obtains images of each point along the depth direction z, which can be reconstructed A two-dimensional image of the sample along the x direction and the depth direction z;

5) The two-dimensional scanning galvanometer scans continuously along the y direction, and step 4) is performed once for each scanning step, and the two-dimensional images of the sample along the x direction and the depth direction z corresponding to each scanning step are respectively obtained, by these The image can be reconstructed into a three-dimensional image of the sample.

The above-mentioned specific embodiments are used to explain the utility model, rather than to limit the utility model. Within the spirit of the utility model and the scope of protection of the claims, any modifications and changes made to the utility model fall into the scope of the utility model. scope of protection.

Claims (8)

1. common channel type endoscopic optical coherent chromatography imaging system, it is characterized in that: the light that wideband light source (1) sends meets first optical circulator (2) port a, the light that sends by first optical circulator (2) port b successively through first collimating lens (3), two-dimensional scan galvanometer (4), microcobjective (5), optical fiber image transmission beam (6) and Green lens (7) to sample (9), the light that is back to port b meets second optical circulator (10) port d by first optical circulator (2) port c; The light that sends by second optical circulator (10) port e after second collimating lens (11), broadband beam split plain film (12) to the reflecting mirror (13) that is contained on the electronic control translation stage (14); The light that is back to port e by second optical circulator (10) port f outgoing after, successively through the 3rd collimating lens (1 5), diffraction grating (16), imaging len (17) to line array CCD detector (18); Two-dimensional scan galvanometer (4), electronic control translation stage (14) and line array CCD detector (18) all are connected with control system.

2. common channel type endoscopic optical coherent chromatography imaging according to claim 1 system, it is characterized in that: described control system comprises image pick-up card (19), computer (20), functional generator (21) and controllor for step-by-step motor (22), line array CCD detector (18) connects computer (20) through image pick-up card (19), computer (20) output two paths of signals, one the tunnel connects two-dimensional scan galvanometer (4) through functional generator (21), and another road connects electronic control translation stage (14) through controllor for step-by-step motor (22).

3. common channel type endoscopic optical coherent chromatography imaging according to claim 1 system, it is characterized in that: the described light that is sent by first optical circulator (2) port b behind first collimating lens (3), two-dimensional scan galvanometer (4), microcobjective (5), optical fiber image transmission beam (6) and Green lens (7), connects corner cube prism (8) to sample (9) successively again.

4. common channel type endoscopic optical coherent chromatography imaging according to claim 1 system, it is characterized in that: the length of described optical fiber image transmission beam (6) is greater than 1000mm, two end faces are processed to the plane perpendicular with its axis, and front end face places on the focal plane of microcobjective (5).

5. common channel type endoscopic optical coherent chromatography imaging according to claim 1 system, it is characterized in that: the transmittance/reflectance of described broadband beam split plain film (12) approaches 62/38.

6. common channel type endoscopic optical coherent chromatography imaging according to claim 2 system, it is characterized in that: described reflecting mirror (13) is the broadband high reflection mirror, is specially metal-dielectric film broadband high reflection mirror.

7. common channel type endoscopic optical coherent chromatography imaging according to claim 1 system, it is characterized in that: the photosurface of described line array CCD detector (18) is positioned on the back focal plane of imaging len (17), and the groove direction of the length direction of photosurface and diffraction grating (16) is perpendicular.

8. common channel type endoscopic optical coherent chromatography imaging according to claim 1 system, it is characterized in that: between described first optical circulator (2) and wideband light source (1), first collimating lens (3), second optical circulator (10), and between second optical circulator (10) and second collimating lens (11), the 3rd collimating lens (15), connect with single-mode fiber.

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