CN112245045B - Oral cavity scanning device based on optical coherence tomography principle - Google Patents
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Abstract
The invention discloses an oral cavity scanning device based on an optical coherence tomography principle. The method is based on the optical coherence tomography principle, detects interference spectrum signals generated by convergence of backscattered light of tissues at different depths and reference beams, and realizes parallel detection of depth information through inverse Fourier transform. The invention combines the longitudinal chromatography capability and the transverse scanning function, and provides the oral cavity scanning device for reconstructing a digital three-dimensional model of the oral cavity with complete data and high resolution in real time under the non-ionizing radiation and non-invasive conditions. Compared with the traditional impression technology, the invention realizes complete digitization, saves material cost and operation time, improves the comfort of patients and the quality of models, and the digitized models are convenient to store, transmit and analyze. The invention has the beneficial effects which are not possessed by the existing digital oral impression technology.
Description
Technical Field
The invention relates to the technical field of biomedical treatment and optical imaging, in particular to an oral cavity scanning device based on an optical coherence tomography principle.
Background
In the clinical diagnosis and treatment of orthodontic treatment, model analysis is one of the important examination methods for diagnosing malocclusion. The orthodontic model is the accurate duplication of the shapes of teeth, dental arches, tooth sockets, basic bones, palatal caps and the like and the occlusion relation of upper and lower teeth of a patient, and comprises a working model and a memory model. The working model can be used for model measurement and analysis and tooth arrangement tests and is a carrier for manufacturing various correction devices. The memory model is a record of the dental condition of the patient at some stages before and after the correction, can be used for contrast observation in the treatment process, and is an important component of case display and an important legal basis in judicial identification after the treatment is finished. In view of this, the memory model is required to be accurately manufactured and stored for a long time.
In the traditional model making, firstly, impression materials such as alginate or silicon rubber are adopted to make a female die of the structure in the oral cavity of a patient, namely an impression technology; then pouring the model material such as plaster into the stamp mould to obtain the model completely consistent with the shape of the inner face of the oral cavity. Because the traditional model is complicated in manufacturing steps, the quality of the model is influenced by various factors such as the operation of a doctor, the compliance of a patient, the deformation of an impression material and a plaster material and the like, and the original appearance of the oral tissue is difficult to accurately restore. Furthermore, in the traditional impression taking process, the tray in place may cause nausea and discomfort, tooth sensitivity, and even dyspnea in the patient (BMC Oral health.2014Jan 30; 14: 10.). After the model is prepared, the transportation, storage and analysis of the model are limited due to the heavy weight, large volume, fragility, friction resistance and poor visualization of the traditional plaster model (ortho Craniofac Res.2015May; 18(2): 65-76).
With the development of the digital oral diagnosis and treatment mode, the digital oral impression is used as the premise and the basis of digital diagnosis and treatment, the defects of the traditional plaster model are overcome, and the plaster model is widely applied to the advantages of easy storage, high precision, convenient measurement and the like. The digital oral impression technique is divided into an indirect method and a direct method. Indirect, i.e., extraoral optical impression, obtains impression data by scanning either a plaster positive or a fine negative. However, this method still requires the steps of making an impression, reproducing a plaster model, etc., and cannot be fully digitalized. The process of manufacturing the gypsum male die is complex and needs a long time; scanning the impression, although relatively simple, is prone to data loss in narrow portions deep in the impression; die deformation, defects, temperature and humidity effects, etc. can all affect the accuracy of the digitized die (J Prosthodot. 2016Jun; 25(4): 282-7.). The direct method is an intraoral optical impression, and a probing optical scanning probe is adopted to directly scan and measure the tooth body and related soft and hard tissues in the oral cavity of a patient so as to obtain a digital model in real time. Compared with the traditional mode of taking the impression and the mode of scanning outside the mouth, the digital intraoral impression does not need to use impression materials and trays and cast plaster models, thereby avoiding the problems of nausea and discomfort caused by the tray contacting with the soft palate, angular stomatitis caused by the tray stimulation, mistaken suction of impression materials by patients and the like, and improving the comfort level and diagnosis and treatment safety of the patients; errors caused by shrinkage or deformation of impression materials, expansion of the plaster model and the like are avoided, the model accuracy is improved, and the cost and the operation time are saved. In addition, the data storage mode of the oral cavity digital model is convenient, and the problem of the requirement of the traditional plaster model on the physical storage space is solved; doctors can quickly access the three-dimensional diagnosis information, data sharing is conveniently realized through a network, and the risk of damage of the traditional plaster model in the transmission process is avoided; the scanned oral cavity digital model has good three-dimensional visualization effect, can be directly connected with other digital image data, is expected to realize the complete digitization of orthodontic diagnosis design, and improves the diagnosis and treatment efficiency (J promthodon Res.2020 Apr; 64(2): 109-113.).
The aim of orthodontic treatment is balance, stability and beauty, after malocclusion is treated, not only can the dental crowns be arranged orderly, but also the craniofacial shapes and functions of the dental jaws need to obtain new balance and coordination relationship. Therefore, in the clinical diagnosis and treatment process of orthodontic treatment, complete three-dimensional information of the tooth body and the periodontal tissue of a patient is required to be matched with the formulation of a diagnosis and treatment scheme. However, in both the traditional model taking method and the digital mouth impression technology, the obtained dental model only contains the structure of the dental crown, and three-dimensional image information such as the dental root, the alveolar bone and the like cannot be displayed. The oral cbct (cone beam Computed tomography) image reconstruction model may contain complete three-dimensional information of oral structures, but its scanning accuracy is relatively low, and multiple repeated scans at different cycles of orthodontic treatment may cause ionizing radiation damage to the patient. The scholars propose that CBCT data are reconstructed in three dimensions to obtain an independent tooth model containing tooth root information, and then the independent tooth model is registered with a dentition model reconstructed by digital intraoral scanning to reconstruct a full dentition and jaw model with clearly displayed tooth crowns and tooth roots (J Craniofac Surg.2018Nov; 29(8): 2241-. Although the method solves the problems of dental crown scanning precision and dental crown root integral imaging to a certain extent, the alignment and registration process of the intraoral scanning model and the CBCT reconstruction model is easy to have overlapping deviation, and the ionizing radiation injury risk still exists. In view of the current situation, there is an urgent need to develop an apparatus and method for reconstructing an intra-oral digital model with complete data and high resolution by using non-ionizing radiation.
Disclosure of Invention
The invention provides an oral cavity scanning device and method based on an optical coherence tomography principle, which are characterized in that a reference beam and backscattered light of tissues at different depths are interfered, and a digital oral cavity three-dimensional model with complete data and high resolution is reconstructed in real time under the conditions of non-ionizing radiation and non-invasion by acquiring and processing interference signals. Considering that the time-domain optical coherence tomography system needs to move the reflective mirror when acquiring the tomography signal, the mechanical movement mode limits the imaging speed and the imaging quality, and the relative bulkiness of the mechanical device reduces the portability of the device and the stability of the system. Therefore, the embodiment of the invention is established based on a Fourier domain optical coherence tomography system, comprises a spectral domain optical coherence tomography system and a frequency scanning source optical coherence tomography system, does not need to carry out axial mechanical scanning, all backward scattering light and reference light are converged to generate interference spectrum signals together, and depth information is obtained through Fourier inverse transformation of the interference spectrum, so that parallel detection of the depth information is realized, and the imaging speed, the sensitivity and the signal-to-noise ratio are improved.
The purpose of the invention is realized by at least one of the following technical solutions.
An oral cavity scanning device based on an optical coherence tomography principle comprises a three-dimensional scanning module, an anti-fog and moisture-proof module, a drainage port, a control port and a data processing port;
the three-dimensional scanning module comprises a light source, a first beam splitter, a second beam splitter, a first lens, a second lens, a third lens, a plane reflector, a high-speed scanning galvanometer, a deflection angle monitoring component, a light penetrating plate, a delay line component, a color photographic system and a detection component; the antifogging and moisture-insulating module comprises a wind-heat heating device and a negative-pressure saliva sucking device;
the negative pressure saliva suction device is connected with the drainage port and drains the saliva sucked by the negative pressure to the drainage component connected with the outside; parts of components in the three-dimensional scanning module and the antifogging and moisture-insulating module are connected with an external control assembly through a control port;
irradiating light emitted by a light source to a first beam splitter, and splitting the light into a reference beam and a sampling beam; the reference beam is collimated by a first lens and then reflected from the plane mirror back to the first beam splitter; the sampling light beam is collimated by the second lens, reflected by the high-speed scanning galvanometer and focused by the third lens in sequence, and reaches the internal tissues of the oral cavity through the light penetrating plate; the backward scattering light from tissues with different depths and the returned reference beam are converged and interfered in the detection assembly through the first beam splitter, longitudinal chromatographic capacity is obtained based on a low coherence interference principle, transverse scanning is realized through a high-speed scanning galvanometer, a three-dimensional image of an internal tissue structure of the oral cavity is reconstructed through a data processing assembly which is connected with the data processing port through the outside, and an image of a scanning area is displayed in real time through the display assembly.
Further, the oral scanning device includes, but is not limited to, a handheld design.
Further, the wind-heat heating device comprises a humidity monitoring assembly, a fan, a heating assembly, an air duct and an air outlet; the humidity monitoring component monitors the humidity of the scanning area in real time and transmits the monitoring result to the heating component; the heating component heats the air from the fan in a feedback manner according to the humidity information, and the hot air reaches the scanning area through the air channel and the air outlet, so that the influence of the fog generated by mouth breathing on the scanning precision is reduced to the greatest extent;
the negative-pressure saliva sucking device comprises a negative-pressure generating device, a valve, a drainage channel and a filter; the negative pressure generating device generates negative pressure, saliva is drained through the drainage channel, and the influence of the high-light-reflection characteristic of the enamel surface wetted by the saliva on the scanning precision is reduced to the greatest extent.
Furthermore, the light source, the high-speed scanning galvanometer, the fan, the heating assembly and the negative pressure generating device are all connected with the control assembly through control ports;
a drainage channel in the negative pressure saliva suction device is connected with a drainage port, and the negative pressure saliva is drained to an externally connected drainage assembly;
the information collected by the deflection angle monitoring assembly, the color photographic system and the detection assembly is connected with the data processing assembly through the data processing port, and the data processing assembly is connected with the display assembly and is used for processing and displaying the camera shooting result and the three-dimensional reconstructed digital intra-oral model in real time.
Furthermore, the second beam splitter is arranged between the first beam splitter and the second lens, backward scattered light from tissues with different depths returns through the original optical path, before the backward scattered light reaches the first beam splitter, part of light beams are reflected by the second beam splitter, pass through the delay line assembly, and the scanning area in the oral cavity is monitored in real time by the color photographic system; on one hand, the surface appearance characteristics of teeth, gum and the like can be captured, processed by the data processing assembly and integrated with the three-dimensional data collected at the same time to obtain a true color digital model; on the other hand, the method can be compared with a three-dimensional scanning result synchronously displayed by an external display component in real time, and when a blind area or a data sparse area is found, secondary supplementary scanning is carried out on the area in time, so that the real-time performance and flexibility of scanning are improved.
Further, the light source is a low coherence light source; when the oral cavity scanning device is built based on a spectral domain optical coherence tomography system, the light source is a broadband light source, including but not limited to a super-radiation light-emitting diode; when the oral cavity scanning device is built on the basis of a swept source optical coherence tomography system, the light source is a broadband swept source, and the output wavelength is scanned at a high speed along with time;
the high-speed scanning galvanometer changes the deflection angle of the high-speed scanning galvanometer under the driving signal of the control assembly, so that the reflection angle of the sampling light beam is changed, and transverse scanning is realized;
the deflection angle monitoring component records the deflection angle of the high-speed scanning galvanometer in real time, so that the transverse two-dimensional coordinate information is obtained in real time.
Further, when the oral cavity scanning device is built based on a spectral domain optical coherence tomography system, the detection assembly consists of a grating and a linear array CCD camera; when the oral scanning apparatus is built on a swept source optical coherence tomography system, the detection component is a balanced detector, which acts as a balanced receiver by subtraction of two optical input signals, thereby eliminating common mode noise and extracting small variations in the signal path from the noise floor of the interference.
Further, the delay line assembly includes, but is not limited to, a mirror group, and the optical path is adjusted to enable the sampling beam to reach the color photographic system and the detection assembly at the same time, so as to realize real-time monitoring.
Further, the valve is designed by adopting a check valve, so that backflow of the drainage saliva is prevented;
the filter is used for filtering solid impurities in the sucked saliva and preventing the solid impurities from blocking the drainage channel.
The method is based on the optical coherence tomography principle, detects interference spectrum signals generated by convergence of backscattered light of tissues at different depths and reference beams, and realizes parallel detection of depth information through inverse Fourier transform. The invention combines the longitudinal chromatography capability and the transverse scanning function, and provides the oral cavity scanning device for reconstructing a digital three-dimensional model of the oral cavity with complete data and high resolution in real time under the non-ionizing radiation and non-invasive conditions.
Compared with the prior art, the invention has the following beneficial effects:
1. compared with the traditional impression technology, the invention realizes complete digitization, saves material cost and operation time, improves the comfort of patients and the quality of models, and the digitized models are convenient to store, transmit and analyze. The invention has the beneficial effects which are not possessed by the existing digital oral impression technology.
2. Compared with the existing digital oral impression technology, the digital oral impression model is based on the optical coherence tomography principle, has longitudinal tomography capability, and provides a digital oral three-dimensional model with more complete data for oral clinical diagnosis and treatment. The currently common intraoral scanning devices are an iTero intraoral scanner and a 3shape intraoral scanner, both of which are constructed based on the confocal microscopic imaging principle, and although the scanning resolution is high, the imaging depth is limited by optical scattering.
3. Compared with medical imaging technologies such as CBCT and the like, the invention adopts a non-ionizing radiation broadband light source and realizes high-resolution imaging by utilizing the low coherence characteristic of the light source. While medical imaging techniques such as CBCT can achieve imaging of deep tissue structures, the resolution is low. In addition, the present invention has the characteristic of non-ionizing radiation imaging, and the CBCT uses three-dimensional cone-beam X-ray scanning, although the average radiation dose of a single CBCT examination is relatively small, if CBCT examination is performed for a plurality of times at different stages of orthodontic treatment, the risk of ionizing radiation damage to the patient is increased, which is contrary to the principle of radiation protection.
4. Compared with the technology of combining the digital intraoral impression with the CBCT, the method avoids the overlapping deviation which can occur in the registration and alignment process of the CBCT reconstruction model and the intraoral scanning model. The present invention does not risk ionizing radiation damage.
5. The anti-fog moisture-insulation module comprises an air heating device and a negative-pressure saliva suction device, and the influence of fog generated by mouth breathing and the high-light-reflection characteristic of the enamel surface wetted by saliva on the scanning precision is reduced to the greatest extent.
6. The present invention includes, but is not limited to, a handheld design. The design of the handle follows the principle of ergonomics, so that the operator has the maximum use efficiency. The design of the probe follows the protection principle, and the diagnosis and treatment safety and the comfort of a patient are improved while the scanning quality is ensured.
Drawings
FIG. 1 is a schematic structural diagram of an oral cavity scanning device based on the principle of optical coherence tomography according to this embodiment;
FIG. 2 is a port connection diagram of an oral cavity scanning device based on the optical coherence tomography principle according to the present embodiment;
FIG. 3 is a schematic diagram of the transverse scanning of the oral cavity scanning device based on the optical coherence tomography in the present embodiment;
fig. 4 is a longitudinal tomographic schematic diagram of the oral cavity scanning device based on the optical coherence tomography principle according to the present embodiment, wherein fig. 4a is a longitudinal tomographic interference diagram of the oral cavity scanning device based on the optical coherence tomography principle according to the present embodiment; FIG. 4b is a schematic diagram of an inverse Fourier transform of a longitudinal tomographic interferogram of the oral cavity scanning device based on the optical coherence tomography principle according to the present embodiment; FIG. 4c is a schematic diagram of the inverse Fourier transform of the longitudinal tomographic deconvolution interferogram of the oral cavity scanning device based on the optical coherence tomography principle according to the present embodiment; FIG. 4d is a schematic diagram of the inverse Fourier transform of the longitudinal tomographic deconvolution differential interferogram of the oral cavity scanning device based on the optical coherence tomography principle according to the present embodiment; fig. 4e is a longitudinal tomographic schematic diagram of the oral cavity scanning device based on the optical coherence tomography principle according to the embodiment.
Detailed Description
The technical solution in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.
Example (b):
an oral cavity scanning device based on the principle of Optical Coherence Tomography (OCT) is shown in fig. 1 and comprises a three-dimensional scanning module 3, an anti-fog and moisture-insulation module 4, a drainage port 28, a control port 29 and a data processing port 30;
the three-dimensional scanning module 3 comprises a light source 5, a first beam splitter 6, a second beam splitter 15, a first lens 7, a second lens 9, a third lens 12, a plane mirror 8, a high-speed scanning galvanometer 10, a deflection angle monitoring component 11, a light penetration plate 13, a delay line component 16, a color photographic system 17 and a detection component 18; the antifogging and moisture-insulating module 4 comprises a wind-heat heating device and a negative-pressure saliva sucking device;
as shown in fig. 2, the negative pressure saliva sucking device is connected with the drainage port 28, and drains the saliva sucked by the negative pressure to the drainage assembly 31 connected externally; parts of the components in the three-dimensional scanning module 3 and the antifogging and moisture-insulating module 4 are connected with an external control assembly 32 through a control port 29;
light emitted by the light source 5 is irradiated to the first beam splitter 6, and is split into a reference beam and a sampling beam; the reference beam is collimated by a first lens 7 and reflected from a plane mirror 8 back to the first beam splitter 6; the sampling light beams are collimated by the second lens 9, reflected by the high-speed scanning galvanometer 10 and focused by the third lens 9 in sequence, and reach the internal tissues of the oral cavity through the light penetration plate 13; the backward scattering light from tissues with different depths and the returned reference beam are converged and interfered in the detection component 18 through the first beam splitter 6, the longitudinal chromatography capacity is obtained based on the low coherence interference principle, the transverse scanning is realized through the high-speed scanning galvanometer 10, the three-dimensional image of the internal tissue structure of the oral cavity is reconstructed through the data processing port 30 and the data processing component 33 which is externally connected, and the image of the scanning area is displayed in real time through the display component 34.
In the embodiment, the oral cavity scanning device is designed in a handheld mode, the shape of the oral cavity scanning device is divided into a handle 1 and a probe 2, the handle 1 is located at the rear end of the probe 2 and is perpendicular to the probe, the joint is in an arc shape, and the handle 1 and the probe form an integrated structure; the handle 1 is designed by adopting ergonomics, so that excessive pressure on hands is avoided, and hand spasm, numbness or fatigue caused by local blood circulation disorder is prevented; by holding the handle 1, the back tooth area can be conveniently scanned by virtue of the working length of the probe 2; when the anterior tooth area is scanned, if the working length of the probe 2 influences that the wrist is in a straight state, the scanning can be performed through the arc-shaped connection part of the holding handle 1 and the rear end of the probe 2;
the probe 2 is a part which extends into the oral cavity for three-dimensional scanning, the surface is smooth, and the corners are designed in a circular arc shape, so that the soft and hard tissues of the oral cavity are prevented from being damaged; the front end of the probe 2 is designed to be an inclined surface, which on one hand helps to reduce the volume of the probe and on the other hand facilitates the separation of lips, cheeks and tongue from the tooth and gum surface, preventing the interference of the probe with the scanning process.
The light-transmitting plate 13 is disposed on the lower side of the front end of the probe 2 to provide a light-transmitting window for the sampling beam.
As shown in fig. 1, the wind-heat heating device includes a humidity monitoring assembly 19, a fan 20, a heating assembly 21, an air duct 22, and an air outlet 23; the humidity monitoring component 19 monitors the humidity of the scanning area in real time and transmits the monitoring result to the heating component 21; the heating component 21 heats the wind from the fan in a feedback manner according to the humidity information, the hot wind reaches the scanning area through the wind channel 22 and the wind outlet 23, and the influence of the fog generated by mouth breathing on the scanning precision is reduced to the maximum extent;
the negative-pressure saliva sucking device comprises a negative-pressure generating device 24, a valve 25, a drainage channel 26 and a filter 27; the negative pressure generating device 24 generates negative pressure, and the saliva is drained through the drainage channel 26, so that the influence of the high-reflectivity characteristic of the enamel surface wetted by the saliva on the scanning precision is reduced to the greatest extent.
As shown in fig. 2, the light source 5, the high-speed scanning galvanometer 10, the fan 20, the heating assembly 21 and the negative pressure generating device 24 are all connected with the control assembly 32 through a control port 29;
a drainage channel 26 in the negative pressure saliva suction device is connected with a drainage port 28 and drains the saliva sucked by negative pressure to an externally connected drainage assembly 31;
the information collected by the deflection angle monitoring component 11, the color photographic system 17 and the detection component 18 is connected with the data processing component 33 through the data processing port 30, the data processing component 33 is connected with the display component 34, and the shooting result and the three-dimensional reconstructed digital intra-oral model are processed and displayed in real time for a doctor to refer and compare in real time and are beneficial to communication with patients and family members thereof.
The second beam splitter 15 is arranged between the first beam splitter 6 and the second lens 9, the backward scattered light from tissues with different depths returns through an original optical path, before the backward scattered light reaches the first beam splitter 6, part of light beams are reflected by the second beam splitter 15, pass through the delay line assembly 16, and the scanning area in the oral cavity is monitored in real time by the color photographic system 17; on one hand, the surface appearance characteristics of teeth, gum and the like can be captured, processed by the data processing component 33 and integrated with the three-dimensional data collected at the same time to obtain a true color digital model; on the other hand, the three-dimensional scanning result synchronously displayed by the external display component 34 can be compared in real time, and when a blind area or a data sparse area is found, secondary supplementary scanning is performed on the area in time, so that the real-time performance and flexibility of scanning are improved.
The light source 5 is a low-coherence light source; when the oral cavity scanning device is built based on a spectral domain optical coherence tomography system, the light source 5 is a broadband light source, including but not limited to a super-radiation light-emitting diode; when the oral cavity scanning device is built on the basis of a swept source optical coherence tomography system, the light source 5 is a broadband swept source, and the output wavelength is scanned at a high speed along with time;
the high-speed scanning galvanometer 10 changes the deflection angle thereof under the driving signal of the control assembly 32, thereby changing the reflection angle of the sampling light beam and realizing transverse scanning;
as shown in fig. 3, in this embodiment, when the high-speed scanning galvanometer 10 is at different deflection angles, the sampling light beam collimated by the second lens 9 enters the high-speed scanning galvanometer 10 at different angles, and is reflected to the third lens 12 at different reflection angles, and finally is focused to different positions of the two-dimensional plane of the internal structure XOY of the oral cavity, so as to implement transverse scanning. The deflection angle monitoring component 11 records the deflection angle information of the high-speed scanning galvanometer 10 in real time, transmits the deflection angle information to the data processing component 33 through the data processing port 30, and can obtain the real-time image information of the XOY two-dimensional plane after data processing.
The deflection angle monitoring component 11 records the deflection angle of the high-speed scanning galvanometer 10 in real time, so that the transverse two-dimensional coordinate information is obtained in real time;
when the oral cavity scanning device is built based on a spectral domain optical coherence tomography system, the detection component 18 consists of a grating and a linear array CCD camera; when the oral scanning apparatus is built on a swept source optical coherence tomography system, the detection assembly 18 is a balanced detector that acts as a balanced receiver by subtracting two optical input signals, thereby eliminating common mode noise and extracting small variations in the signal path from the noise floor of the interference.
The delay line assembly 16 includes, but is not limited to, a mirror group, and the optical path is adjusted to allow the sampling beam to reach the color camera system 17 and the detection assembly 18 simultaneously, so as to realize real-time monitoring.
The valve 25 adopts a check valve design to prevent backflow of the drainage saliva;
the filter 27 serves to filter solid impurities in the sucked saliva, preventing them from clogging the drainage channel.
As shown in fig. 4, the detection component 18 collects interference signals of the reference beam and the sampling beam in real time, and transmits the acquired discrete light intensity information of the whole spectrum domain to the data processing component 33 through the data processing port 30. The detected light intensity is a function of the wave number k, and the data processing component 33 converts the data from the variable space with respect to wave number (as shown in fig. 4 a) to the variable space with respect to depth (as shown in fig. 4 b) by inverse fourier transform, and obtains the longitudinal tomographic capability in the Z-axis direction based on the principle of low coherence interference, as shown in fig. 4 e.
However, as shown in FIG. 4b, the detected light intensity contains intrinsic DC and AC components in addition to the interference of the backscattered light from tissues at different depths in the mouth with the return light of the reference beam. The intrinsic direct current component refers to the contribution of the returning light of the reference beam to the intensity of the detected light, and the alternating current component is generated by the mutual interference of tissue layers with different depths of the internal structure of the oral cavity, and the intensity of the alternating current component is weak relative to the intrinsic direct current component. By eliminating the interference of the above-mentioned dc component and ac component, a real image can be recovered, and the applicable methods include, but are not limited to, the following schemes:
1. the interference of the dc and ac components is removed by the data processing component 33, as shown in fig. 4c and 4d, the deconvolution sharpens the peaks, and the deconvolved differential interferogram is subjected to an inverse fourier transform to produce a sharp one-dimensional image.
2. The control elements for the reference light path and the sampling light path are added on the basis of the device shown in fig. 1, the sampling light path and the reference light path are respectively blocked, signals of inherent direct current components and alternating current components can be respectively obtained, and then the signals are subtracted from the detection light intensity through the data processing component 33.
3. On the basis of the device shown in fig. 1, a second signal acquisition channel is symmetrically added, and the interference of inherent direct current components and alternating current components is eliminated by making a difference value between signals of the two channels.
The data processing component 33 analyzes data transmitted through the data processing port 30 in real time, combines two-dimensional information of an XOY plane with one-dimensional information in the Z-axis direction to obtain three-dimensional structural characteristics of the internal tissue of the oral cavity, integrates the three-dimensional structural characteristics with data such as surface morphology and the like synchronously captured by the color photographic system 17, reconstructs the three-dimensional digital model which truly reflects the internal tissue structure of the oral cavity, and displays the three-dimensional digital model in real time through the display component 34.
The above-mentioned embodiments are only examples of the present invention, but the present invention is not limited by the above-mentioned embodiments, and any other changes, modifications, substitutions, combinations, and simplifications which do not depart from the spirit and principle of the present invention should be regarded as equivalent substitutions and are included in the scope of the present invention.
Claims (6)
1. An oral cavity scanning device based on optical coherence tomography principle, characterized in that: the device comprises a three-dimensional scanning module (3), an anti-fog and moisture-proof module (4), a drainage port (28), a control port (29) and a data processing port (30);
the three-dimensional scanning module (3) comprises a light source (5), a first beam splitter (6), a second beam splitter (15), a first lens (7), a second lens (9), a third lens (12), a plane mirror (8), a high-speed scanning galvanometer (10), a deflection angle monitoring component (11), a light penetrating plate component (13), a delay line component (16), a color photographic system (17) and a detection component (18); the antifogging and moisture-insulating module (4) comprises a wind-heat heating device and a negative-pressure saliva sucking device;
the negative pressure saliva suction device is connected with the drainage port (28) and drains the saliva sucked by the negative pressure to an externally connected drainage assembly (31); parts of components in the three-dimensional scanning module (3) and the anti-fog moisture-proof module (4) are connected with an external control assembly (32) through a control port (29);
light emitted by the light source (5) is irradiated to the first beam splitter (6) and is split into a reference beam and a sampling beam; the reference beam is collimated by a first lens (7) and then reflected from a plane mirror (8) back to the first beam splitter (6); the sampling light beams are collimated by the second lens (9), reflected by the high-speed scanning galvanometer (10) and focused by the third lens (9) in sequence, and reach the internal tissues of the oral cavity through the light penetration plate (13); backward scattered light from tissues with different depths and a returned reference beam are converged and interfered in a detection assembly (18) through a first beam splitter (6), longitudinal chromatographic capacity is obtained based on a low coherence interference principle, transverse scanning is realized through a high-speed scanning galvanometer (10), a three-dimensional image of an internal tissue structure of an oral cavity is reconstructed through a data processing port (30) and a data processing assembly (33) connected with the external, and an image of a scanning area is displayed in real time through a display assembly (34);
the wind-heat heating device comprises a humidity monitoring component (19), a fan (20), a heating component (21), an air duct (22) and an air outlet (23); the humidity monitoring component (19) monitors the humidity of the scanning area in real time and transmits the monitoring result to the heating component (21); the heating component (21) heats air from the fan in a feedback manner according to the humidity information, and hot air reaches a scanning area through the air channel (22) and the air outlet (23), so that the influence of fog generated by mouth breathing on scanning precision is reduced to the maximum extent;
the negative-pressure saliva sucking device comprises a negative-pressure generating device (24), a valve (25), a drainage channel (26) and a filter (27); the negative pressure generating device (24) generates negative pressure, saliva is drained through the drainage channel (26), and the influence of the high-reflectivity characteristic of the enamel surface wetted by the saliva on the scanning precision is reduced to the maximum extent;
the light source (5), the high-speed scanning galvanometer (10), the fan (20), the heating assembly (21) and the negative pressure generating device (24) are all connected with the control assembly (32) through a control port (29);
a drainage channel (26) in the negative pressure saliva suction device is connected with a drainage port (28) and drains the saliva sucked by negative pressure to an externally connected drainage assembly (31);
the information collected by the deflection angle monitoring component (11), the color photographic system (17) and the detection component (18) is connected with a data processing component (33) through a data processing port (30), the data processing component (33) is connected with a display component (34), and a shooting result and a three-dimensional reconstructed digital intra-oral model are processed and displayed in real time;
the second beam splitter (15) is arranged between the first beam splitter (6) and the second lens (9), backward scattered light from tissues with different depths returns through an original optical path, before the backward scattered light reaches the first beam splitter (6), partial light beams are reflected by the second beam splitter (15), pass through the delay line assembly (16), and a color photographic system (17) monitors a scanning area in the oral cavity in real time; on one hand, the surface appearance characteristics of teeth, gum color and the like can be captured, processed by the data processing component (33), and integrated with the three-dimensional data collected at the same time to obtain a true color digital model; on the other hand, the method can be compared with a three-dimensional scanning result synchronously displayed by an external display component (34) in real time, and when a blind area or a data sparse area is found, secondary supplementary scanning is carried out on the area in time, so that the real-time performance and flexibility of scanning are improved.
2. An oral scanning device based on the principle of optical coherence tomography according to claim 1, wherein: the oral cavity scanning device is of a handheld design.
3. An oral scanning device based on the principle of optical coherence tomography according to claim 1, wherein: the light source (5) is a low-coherence light source; when the oral cavity scanning device is built based on a spectral domain optical coherence tomography system, the light source (5) is a broadband light source; when the oral cavity scanning device is built based on a sweep-frequency source optical coherence tomography system, the light source (5) is a broadband sweep-frequency light source, and the output wavelength is scanned at high speed along with time;
the high-speed scanning galvanometer (10) changes the deflection angle thereof under the driving signal of the control assembly (32), thereby changing the reflection angle of the sampling light beam and realizing transverse scanning;
the deflection angle monitoring component (11) records the deflection angle of the high-speed scanning galvanometer (10) in real time, so that the transverse two-dimensional coordinate information is obtained in real time.
4. An oral scanning device based on the principle of optical coherence tomography according to claim 1, wherein: when the oral cavity scanning device is built on the basis of a spectral domain optical coherence tomography system, the detection assembly (18) consists of a grating and a linear array CCD camera; when the oral scanning apparatus is built on a swept source optical coherence tomography system, the detection assembly (18) is a balanced detector that acts as a balanced receiver by subtraction of two optical input signals, thereby eliminating common mode noise and extracting small variations in the signal path from the noise floor of the interference.
5. An oral scanning device based on the principle of optical coherence tomography according to claim 1, wherein: the delay line assembly (16) comprises a reflector group, and the sampling light beams simultaneously reach the color photographic system (17) and the detection assembly (18) by adjusting the optical distance, so that real-time monitoring is realized.
6. An oral scanning device based on the principle of optical coherence tomography according to claim 1, wherein: the valve (25) is designed as a check valve to prevent backflow of the drainage saliva;
the filter (27) is used for filtering solid impurities in the sucked saliva and preventing the solid impurities from blocking the drainage channel.
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