CN1539376A - Longitudinal scanning method and device in optical coherence tomography system - Google Patents

Abstract

The invention relates to a longitudinal scanning method and a device thereof in an optical coherence tomography system. The method adopts a prism system composed of a movable prism group and a stationary prism group in the longitudinal scanning device, and drives the movable prism group with a micro-displacement device to realize high-speed and high-precision linear longitudinal scanning; the device includes a light source, Optical fiber, fiber optic coupler, lens, etc., also includes a prism system and a micro-displacement device composed of a movable prism group and a static prism group. The movable prism group and the static prism group are respectively composed of multiple small reflection prisms, plane Composed of mirrors and apertures. The present invention has the advantages of compact structure, simple structure, good symmetry, and high-speed scanning; and the prism can be processed by the traditional optical element processing method, so that the processing precision is high, and the prism angle error can be controlled within 1". The device can avoid errors caused by beam dispersion.

Description

Longitudinal scanning method and device in optical coherence tomography system

1. Technical field

The invention relates to optical coherence tomography technology, in particular to a high-speed longitudinal scanning method and device thereof in an optical coherence tomography system.

2. Background technology

There are mainly three types of tomographic imaging technologies that have developed relatively maturely: Computed tomography, Ultrasonic imaging and Nuclear magnetic resonance imaging. These three technologies have their own characteristics. For example, in terms of damage to the human body when they are used in human body examinations, although the dose of X-rays used for diagnosis has been reduced a lot in these years, there are still many data showing that there are relatively serious problems. Small damage effects may increase the probability of human infection of some diseases such as cancer, leukemia and cataract. However, the vast majority of data indicate no toxic effects at the diagnostic doses used today in ultrasound or the relatively strong magnetic fields in MRI. However, these three tomographic imaging techniques cannot fully meet the requirements of scientific research and clinical diagnosis for real-time, non-invasive, and high-resolution imaging (the resolution of these three tomographic images is about 100 μm to 1 mm).

In 1991, David Huang of the Massachusetts Institute of Technology (MIT) applied the principles of low-coherence reflectometry and confocal microscopy to the field of biomedical tomography, and proposed optical coherence tomography ( Optical Coherence Tomography), in the past ten years of development, optical coherence tomography (OCT) has attracted the attention of scientific and engineering researchers for its advantages of non-destructive imaging, high imaging resolution, simple system structure, and low cost. .

Optical coherence tomography (OCT) can be used in many areas where other imaging techniques have potential shortcomings, especially in providing reference data for delicate surgical procedures. For example, in brain surgery, traditional biopsy is very dangerous, and other imaging techniques have many limitations due to their low resolution; another example is the diagnosis of early retinal diseases, which require micron-scale imaging Technology, so far, there is no more suitable imaging technique than optical coherence tomography (OCT).

The basic principle of optical coherence tomography (OCT) is to make the backscattered light of the organism to be measured on the signal arm interfere with the reference light reflected by the total mirror on the reference arm through a fiber-optic Michelson interferometer. The information of the organism to be measured can be obtained by detecting the interference signal. The to-and-fro movement of the total mirror of the reference arm along the direction of the optical axis realizes the scanning of the depth direction of the organism to be measured, that is, the longitudinal scanning, and the horizontal scanning of the organism to be measured is realized by moving the signal arm along the direction perpendicular to the optical axis. Since the light source uses a low-coherence light source and its coherence length is short, the interference phenomenon can only occur when the difference between the length of the reference arm and the signal arm is within the coherence length. Therefore, the longitudinal resolution of the imaging of the organism to be measured depends on the coherence length of the light l _c :

${\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 4</span>}\mathrm{<span\; class="notranslate">\; ln</span>}\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; \&pi;</span>}}\frac{{\mathrm{<span\; class="notranslate">\; \&lambda;</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}{\mathrm{<span\; class="notranslate">\; \&Delta;\&lambda;</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>$

Among them, λ ₀ is the center wavelength, and Δλ is the bandwidth of the light source (Bandwidth FWHM). Since the optical signal is round-trip, the imaging longitudinal resolution is half of that of _lc . For example, when using a superluminescent diode (SLD) with a center wavelength of 830nm and a bandwidth of 25nm, the longitudinal resolution of imaging is 12 μm. If image restoration technology is used, the resolution can be improved to the order of microns or even submicrons.

The key components in an optical coherence tomography (OCT) system can be classified into three parts: light source, interferometer and scanning device.

The light source must meet three basic conditions: near-infrared spectrum, short coherence length, and high irradiance. Optical coherence tomography (OCT) requires a long-wave light source due to the short average scattering length at higher light frequencies (blue light or higher), but at 2 μm or longer, the absorption coefficient of water increases, so only Select a band with a wavelength below 1.8 μm. On the other hand, if the wavelength is shorter, the resolution is higher. Correspondingly, if the wavelength increases, in order to maintain the same resolution, the bandwidth of the light source must increase with the trend of the power of 2. Therefore, in order to facilitate the selection of the light source, the Try to choose a short-wave light source. However, due to the large absorption coefficient of hemoglobin below 700nm, and considering the relationship between the scattering length, the wavelength of the light source is generally selected around 850nm.

The interferometer is based on the structure of the Michelson interferometer. The optical coherence tomography (OCT) system usually uses the optical fiber structure. Although the optical fiber connection makes the optical path flexible and simplifies a lot, it also brings the limitation of the system efficiency. Due to the use of What is used is a broadband light source, so the dispersion of the fiber will greatly reduce the longitudinal resolution.

The longitudinal scanning speed and resolution of the scanning device are equally important in optical coherence tomography (OCT). For high-resolution imaging systems, the slight movement of the organism to be measured may cause image blurring, so only by increasing the scanning speed can this disadvantage be overcome. The existing vertical scanning technologies can be roughly divided into the following six types:

1. The stepper motor drives the mirror to realize scanning. Advantages: linearity, convenient control, and low price; Disadvantages: slow speed, poor positioning accuracy during reciprocating motion.

2. Realize scanning with piezoelectric crystal. Advantages: high speed, approximate linearity, convenient control, low price; Disadvantages: small displacement, fragile crystal.

3. Stretch the optical fiber to realize scanning. Advantages: simple structure, convenient control, and low price; Disadvantages: nonlinearity, changes in the polarization state of the beam.

4. Realize scanning with rotating prism. Advantages: high speed, convenient control, and low price; Disadvantages: nonlinearity, low duty cycle, and dispersion of light beams passing through prisms.

5. Optical delay line realizes scanning. Advantages: high speed, approximately linear; Disadvantages: certain duty cycle, complex structure.

6. Realize scanning with spiral mirror. Advantages: high speed, linearity, simple structure, reflective type; Disadvantages: difficult to guarantee processing accuracy.

It can be seen that each of these vertical scanning technologies has its own advantages and disadvantages, among which the stepping motor drives the mirror to realize the scanning is the first generation of vertical scanning technology, which has been replaced by many other technologies.

Optical delay line is the most used method to realize vertical scanning at present. Its structure is relatively complicated, and the vertical scanning is realized through the angular swing of the galvanometer. Therefore, it can only approximate linearity at small angles.

Longitudinal scanning with a spiral mirror has the advantages of high speed, linearity, and simple structure. Because it is a direct reflection type element, the beam has no dispersion problem, but the traditional optical element processing method cannot be used, so mechanical processing methods have to be used. Due to its structural characteristics, the required processing tools must be configured separately, and it is difficult to polish the required optical surface, that is, it is difficult to achieve micron-level precision.

Utilizing the electrostrictive effect of piezoelectric ceramics, it is possible to achieve submicron-level positioning accuracy and micro-displacement with nanometer-level resolution. Although there are also disadvantages of hysteresis, the reason for the hysteresis is the difference between the dielectric constant of the medium and the electric field strength. Therefore, if the method of directly controlling the electric polarization intensity is used, the hysteresis phenomenon of piezoelectric ceramics can be effectively solved in the open-loop state, and the piezoelectric ceramics can also be solved by adding a micro-displacement sensor to achieve closed-loop control. hysteresis phenomenon. However, the existing piezoelectric/electrostrictive ceramics can only achieve a displacement from a few microns to more than one hundred microns, and the displacement is relatively small. For example, the use of piezoelectric/electrostrictive ceramics to drive mirrors cannot meet the requirements of optical coherence tomography. (OCT) system needs to meet the requirement of 2mm to 3mm longitudinal scan depth.

3. Contents of the invention

The purpose of the present invention is to overcome the defects of the above-mentioned existing longitudinal scanning technology, provide a method and device for longitudinal scanning in the optical coherence tomography system, and solve the problem that the existing micro-displacement drive mirror cannot meet the requirements of optical technology. The coherence tomography system needs to meet the requirement of longitudinal scanning depth of 2mm to 3mm, and can directly use the high-precision traditional optical element processing method to process the required optical prism, so as to realize high-speed and high-precision linear scanning, thereby improving the accuracy of measurement .

The purpose of the present invention is achieved through the following technical solutions:

The method for longitudinal scanning in the optical coherence tomography system of the present invention adopts a prism system composed of a movable prism group and a stationary prism group, which is used in the longitudinal scanning device of the optical coherence tomography system of the present invention, and then uses a micro-displacement device The movable prism group in the driving prism system realizes high-speed and high-precision longitudinal scanning by the translational movement of high-precision micro-displacement devices such as piezoelectric/electrostrictive ceramics.

The longitudinal scanning device in the optical coherence tomography system of the present invention includes components such as light source, optical fiber, optical fiber coupler, lens, data acquisition system, data terminal, etc., the light source is connected with the optical fiber, the optical fiber is connected with the optical fiber coupler, and the optical fiber coupler is They are respectively connected to two optical fibers, that is, the light passing through the fiber coupler is divided into two beams of light and enters the two optical fibers respectively, and the light beam drawn from one optical fiber enters the two lenses to achieve collimation and focusing before reaching the organism to be measured. According to the present invention The device also includes a prism system composed of a stationary prism group and a movable prism group and a micro displacement device for driving the movable prism group, the stationary prism group is placed behind a collimator lens, and the movable prism group in the prism system It is fixed on the micro-displacement device and placed behind the stationary prism group. The movable prism group and the stationary prism group must be used in pairs.

The movable prism group and the static prism group in the prism system of the device are respectively composed of a plurality of small reflective prisms, plane reflectors and light holes. The structure of the prism system varies with the structural parameters of the movable prism group and the static prism group. The specific structural parameters of the movable prism group and the stationary prism group include: the length, width and height of each small reflective prism; the length and width of the prism group; the number of small reflective prisms in the length direction of the prism group; the width of the prism group The number of small reflective prisms in the direction; the position of the light hole; whether there is a plane reflector and the position of the plane reflector.

Compared with the prior art, the present invention has the following advantages:

1. The prism system adopted in the present invention is assembled from many small reflective prisms. Therefore, traditional optical element processing methods can be used to process the prisms. The processing accuracy is high, and the prism angle error can be controlled within 1 ".

2. The present invention uses high-precision micro-displacement devices such as piezoelectric/electrostrictive ceramics to drive the movable prism group in the prism system. Because piezoelectric/electrostrictive ceramics have a very high response speed (tens of microseconds), just because Its response speed is fast, and the speed of its electromechanical coupling effect is very fast, and it is too late to exchange heat with the outside world, so there is no heating problem, and it can achieve high-speed, no mechanical friction, and no noise longitudinal scanning.

3. The piezoelectric/electrostrictive ceramic micro-displacement device used in the present invention is generally small in size, and used in conjunction with the prism system of the present invention, it has the advantages of compact structure and small volume.

4. The structure of the movable prism group in the prism system adopted by the present invention is simple and the symmetry is good, so the unstable factors in the movement are reduced, and the measurement accuracy is further improved.

5. The prism system used in the present invention is a total reflection element, which avoids the dispersion problem.

4. Description of drawings

Fig. 1 is a schematic diagram of the connection of the prism system of the present invention used in an optical coherence tomography system.

FIG. 2 is a structural schematic diagram of a movable prism group with 4×4 regions paired with FIG. 3 in the prism system of the present invention.

FIG. 3 is a schematic structural diagram of a stationary prism group with 4×4 regions in the prism system of the present invention.

FIG. 4 is a schematic structural diagram of a movable prism group with 6×6 regions paired with FIG. 5 in the prism system of the present invention.

Fig. 5 is a schematic structural diagram of a stationary prism group with 6*6 regions in the prism system of the present invention.

FIG. 6 is a structural schematic diagram of a movable prism group with 4×4 regions paired with FIG. 7 in the prism system of the present invention.

FIG. 7 is a schematic structural diagram of a static prism group with 4×4 regions and two light holes in the prism system of the present invention.

Fig. 8 is a two-dimensional equivalent light path diagram of the prism system used in the present invention.

5. Specific implementation

Below in conjunction with accompanying drawing, the present invention will be further described through embodiment. But the content of the present invention is not limited to the content involved in the embodiment.

The longitudinal scanning method in the optical coherence tomography system of the present invention adopts a prism system composed of a movable prism group 112 and a stationary prism group 111, which is used in the longitudinal scanning device of the optical coherence tomography system, and then uses piezoelectric/electrostrictive The ceramic micro-displacer 113 drives the movable prism group 112 in the prism system, and high-speed and high-precision linear longitudinal scanning is realized through the translational movement of the piezoelectric/electrostrictive ceramic micro-displacer 113 .

Referring to Fig. 1, the longitudinal scanning device in the optical coherence tomography system of the present invention includes components such as light source 11, optical fibers 12, 14, 15, optical fiber coupler 13, lenses 16, 17, data acquisition system 115, data terminal 116, etc. The light source 11 is connected with the optical fiber 12, the optical fiber 12 is connected with the optical fiber coupler 13, and the optical fiber coupler 13 is respectively connected with the optical fiber 14 and the optical fiber 15, that is, the light passing through the optical fiber coupler is divided into two bundles of light and enters the optical fiber 14 and the optical fiber 15 respectively, The light beam drawn by the optical fiber 14 enters the lens 16 and the lens 17 to achieve collimation and focusing, and then reaches the organism 18 to be measured. According to the present invention, the device also includes a prism composed of a movable prism group 112 and a stationary prism group 111. system, and the piezoelectric/electrostrictive ceramic micro-displacement device 113 used to drive the movable prism group 112, the light beam drawn by the optical fiber 15 enters the collimating lens 110, and the stationary prism group 111 is placed at the rear of the collimating lens 110, which can The movable prism group 112 is fixed on the micro-displacement device 113 and placed behind the static prism group, and the movable prism group and the static prism group must be used in pairs.

The scanning process is as follows: the light beam emitted from the light source 11 is coupled into the optical fiber 12, the light beam enters the 2×2 fiber coupler 13 after passing through the optical fiber 12, and then is divided into two beams and enters the optical fiber 14 and the optical fiber 15 respectively.

The first beam of light is collimated by the lens 16 after being transmitted by the optical fiber 14, and then focused on the organism 18 to be measured by the lens 17, and the backscattered light of the organism 18 to be measured is collected by the lens 17 and transmitted to the lens 16 for focusing and coupling Enter the optical fiber 14, then enter the 2×2 fiber coupler 13 through the optical fiber 14, and transmit to the detector 114. The whole body 19 composed of the optical fiber 14 , the lens 16 and the lens 17 is moved in the direction of the arrow in the figure to realize the transverse scanning of the biological object 18 to be tested.

The second beam of light is collimated by the collimating lens 110 after being transmitted through the optical fiber 15, and then enters the stationary prism group 111 of the prism system, and after being reflected back and forth between the stationary prism group 111 and the movable prism group 112 of the prism system, it is then passed by the prism system The stationary prism group 111 in the prism exits, and the outgoing beam is still collected by the collimator lens 110 , coupled into the optical fiber 15 , and then transmitted to the detector 114 through the 2×2 optical fiber coupler 13 . The piezoelectric/electrostrictive ceramic 113 translates the movable prism group 112 in the prism system in the direction of the arrow in the figure to realize longitudinal scanning.

The detector 114 converts the interference optical signal of the two beams of light into an electrical signal, enters the data acquisition system 115, and finally enters the data terminal 116 for processing to obtain a tomographic image.

The structure of the prism system designed by the present invention varies with structural parameters, and Fig. 2, Fig. 3, Fig. 4, Fig. 5, Fig. 6 and Fig. 7 are exactly the structures of the movable prism group and the stationary prism group under different structural parameters , the black part in the figure represents the reflective film coated, the white line above the black part is an auxiliary line for highlighting the three-dimensional structure, without any physical meaning; the white part represents the light hole without the reflective film, and the white part above The black lines are auxiliary lines for highlighting the three-dimensional structure, without any physical meaning.

The specific structural parameters of the prism system include: length d _i , width d′ _i and height h _i (wherein the subscript i represents the number of each small reflective prism) of each small reflective prism; length l and width of the prism group w; the number N _i of small reflective prisms in the length direction of the prism group; the number N _w of small reflective prisms in the width direction of the prism group; the position of the light hole; whether there is a plane mirror and the position of the plane mirror.

Different examples in Fig. 2, Fig. 3, Fig. 4, Fig. 5, Fig. 6 and Fig. 7 illustrate that the structural parameters can be selected as required.

Figure 2 is a movable prism group used in conjunction with Figure 3, and Figure 3 is a stationary prism group, both prism groups can be regarded as having 4×4 areas, and each area can place a small reflective prism or a plane reflector , can also be used as a light hole, wherein the length and width of each area are the length and width of each small reflective prism, that is, d _i =d' _i =d (wherein the i subscript represents each small reflective prism prism number), the height of each small reflective prism is _hi =d; the length l=4d of the prism group, the width w=4d; the number N l of the small reflective prisms in the length direction of the prism group N _l =l/d =4; the number N w of the small reflective prisms in the width direction of the prism group N _w =w/d=4; the position of the light passing hole is the 31 area in Fig. 3, which is the incident and exit window of the light beam; the position of the plane reflector In the 316 area in Figure 3.

Fig. 4 is a movable prism group used in conjunction with Fig. 5, and Fig. 5 is a stationary prism group, both prism groups can be regarded as having 6 × 6 areas, and each area can place a small reflective prism or a plane reflector , can also be used as a light hole, wherein the length and width of each area are the length and width of each small reflective prism, that is, d _i =d' _i =d (wherein the i subscript represents each small reflective prism prism number), the height of each small reflective prism is _hi =d; the length l=6d of the prism group, the width w=6d; the number N _l =l/d of the small reflective prisms in the length direction of the prism group =6; the number N w of the small reflective prisms in the width direction of the prism group N _w =w/d=6; the position of the light passing hole is the 51 area among Fig. 5, which is the incident and exit window of the light beam; the position of the plane reflector In the 536 area in Figure 5.

Fig. 6 is a movable prism group used in conjunction with Fig. 7, and Fig. 7 is a stationary prism group, both prism groups can be regarded as having 4 × 4 areas, and each area can place a small reflective prism or a plane reflector , can also be used as a light hole, wherein the length and width of each area are the length and width of each small reflective prism, that is, d _i =d' _i =d (wherein the i subscript represents each small reflective prism prism number), the height of each small reflective prism is _hi =d; the length l=4d of the prism group, the width w=4d; the number N l of the small reflective prisms in the length direction of the prism group N _l =l/d =4; the number N w of the small reflective prisms in the width direction of the prism group N _w =w/d=4; the position of the light passing hole is the 71 area and the 716 area in Fig. 7, which are respectively the incident and exit windows of the light beam; there is no flat mirror.

In FIG. 8 , through the two-dimensional equivalent structures of the movable prism group 112 and the stationary prism group 111 , the value of the required structural parameters of the prism system can be deduced. For the convenience of component processing, the length, width and height of each small reflective prism are chosen to be equal, that is, d _i =d' _i =h _i =d.

After being incident, the light beam is reflected multiple times between the movable prism group 112 and the stationary prism group 111, and finally passes through the plane reflector 83 of the stationary prism group to make the light beam return along the original optical path. When the movable prism group 112 is displaced by Δx, the optical path difference of the light beam is

                                          

Wherein N is the number of small reflective prisms of the movable prism group 112, the displacement Δx of the movable prism group 112 is determined by the displacement of the micro-displacer, using piezoelectric/electrostrictive ceramics as the micro-displacer, the displacement The optical path difference is usually around Δx=100μm, and N=16 prisms are used, then the optical path difference will reach about Δl=3.2mm, which can fully meet the requirements of the longitudinal scanning depth of 2mm to 3mm in the optical coherence tomography system.

When selecting the value of the length, width and height d _i =d' _i =h _i =d of each small reflective prism, it is necessary to consider the value range of the traditional optical element processing method that can process the prism with high precision, here select d= 10mm. After such values are taken, it can be seen that the length l=N×d=16×10=160mm of the two-dimensional equivalent structure of the movable prism group 112, and the width is the width w=d=10mm of a small reflective prism.

In Fig. 2, the movable prism group 112 is a three-dimensional structure that the two-dimensional equivalent structure of the movable prism group 112 shown in Fig. 8 is spatially arranged into, and this three-dimensional structure can effectively reduce the size of the prism group, Improve the symmetry of element, as the small reflective prism number N=16 of movable prism group, the length of each small reflective prism is d=10mm, so the three-dimensional structure shown in Fig. 2 only needs to get the prism group length direction The number of small reflective prisms and the number of small reflective prisms in the width direction of the prism group are equal N _l = N _w = 4, and the number of small reflective prisms N = N _l * N _w = 16 can be realized. And the length and width of the movable prism group are l=w=4d=40mm.

In this way, the three-dimensional structure used in the present invention integrates the movable prism group from length l=160mm and width w=10mm into a structure with equal length and width, that is, l=w=40mm. The simplification of this structure plays an important role in improving the stability of the vibration process of the movable prism group, especially the movable prism group needs to vibrate at a frequency greater than 100 Hz, so the improvement of its symmetry will effectively improve the stability of the movement.

Now use the prism system shown in Figure 2 and Figure 3 to describe the transmission process of the light beam in the prism system. The small reflective prism 21 is reflected on the small reflective prism 22, and the light beam is reflected on the small reflective prism 32 of the stationary prism group through the small reflective prism 22, then reflected to the small reflective prism 33, and then reflected by the small reflective prism 33 to The small reflective prism 23 of the movable prism group is reflected to the small reflective prism 24, and then reflected to the small reflective prism 34 of the stationary prism group. Because the directions of the small reflective prism 34 and the small reflective prism 35 are different, the light beam After being reflected by the small reflective prism 34 to the small reflective prism 35, it will be reflected on the small reflective prism 25 of the next row of prisms in the movable prism group, thereby repeating the previous reflection process, finally by the plane of the stationary prism group The reflector 316 returns the light beam along the original path to the incident light hole 31 and then exits. Its specific reflection process is described by the numbers of the light holes, small reflective prisms and plane mirrors in the movable prism group and the stationary prism group: 31→21→22→32→33→23→24→34→35 →25→26→36→37→27→28→38→39→29→210→310→311→211→212→312→313→213→214→314→315→215→216→316→216→215 →315→314→214→213→313→312→212→211→311→310→210→29→39→38→28→27→37→36→26→25→35→34→24→23→33 →32→22→21→31.

Although the structure of the movable prism group _shown in Fig _. 2 is _glued together by N _l = N _w = 4; But when using the traditional optical element processing method, it can be processed and glued as three prisms. The first prism to be processed is a 10mm×40mm prism composed of small reflective prism 21, small reflective prism 28, small reflective prism 29, and small reflective prism 216; the second prism to be processed is Combination of small reflective prism 22, small reflective prism 27, small reflective prism 210, small reflective prism 215, small reflective prism 23, small reflective prism 26, small reflective prism 211, and small reflective prism 214 The prism of the 20mm * 40mm that becomes; The 3rd prism that needs processing is the prism of 10mm * 40mm that is combined by small reflective prism 24, small reflective prism 25, small reflective prism 212, small reflective prism 213. The shape and size of the first prism to be processed and the third prism to be processed are the same and can be processed in batches.

Although the structure of the static prism group shown in _{Fig .} 3 is made up of 4× ₄ =16 regions of N _l =N _w =4; 1, 1 plane mirror and 1 light hole, but when using traditional optical element processing methods, it can be processed and glued as 8 prisms and 1 plane mirror. Among them, the shape and size of 6 prisms to be processed are all the same, that is, small reflective prism 34; small reflective prism 35; small reflective prism 312; small reflective prism 313; small reflective prism 38; small reflective prism 39 have the same shape and size and can be processed in batches; the 7th prism to be processed is a 10mm× 40mm prism; the eighth prism to be processed is a 10mm×40mm prism composed of small reflective prism 33, small reflective prism 36, small reflective prism 311, and small reflective prism 314; The processed prism has the same shape and size as the eighth prism to be processed, and can be processed in batches. Then process a flat reflector with a size of 10mm×10mm, and glue it on the position of area 316.

Claims (4)

1, the method for longitudinal scanning in a kind of optical coherence tomography system, it is characterized in that adopting a kind of prism system that constitutes by movable prism group (112) and stationary prism group (111) to be used in the longitudinal scan device of optical coherence tomography system, utilize the movable prism group (112) in micro positioner (113) the driving prism system again, realize the longitudinal scanning of high-speed, high precision by the translational motion of micro positioner.

2, longitudinal scan device in a kind of optical coherence tomography system, include light source (11), optical fiber (12), (14), (15) and fiber coupler (13), lens (16), (17), data collecting system (115), data terminal components and parts such as (116), light source (11) is connected with optical fiber (12), optical fiber (12) is connected with fiber coupler (13), fiber coupler (13) is connected with optical fiber (15) with optical fiber (14) respectively, promptly be divided into two-beam and enter optical fiber (14) and optical fiber (15) respectively through the light of fiber coupler, the light beam of being drawn by optical fiber (14) enters lens (16) and lens (17), arrive organism to be measured (18) again, it is characterized in that said device also comprises one by the prism system of movable prism group (112) and stationary prism group (111) formation and in order to drive the micro positioner (113) of movable prism group (112), the light beam of being drawn by optical fiber (15) enters collimating lens (110), stationary prism group (111) places collimating lens (110) rear, movable prism group (112) is fixed on the micro positioner, and placing stationary prism group rear, movable prism group and stationary prism group must be used in pairing.

3,, it is characterized in that movable prism group (112) and the stationary prism group (111) in the said prism system is made of a plurality of little reflection-type prisms, plane mirror and light hole respectively again according to the described device of claim 2.

4, according to claim 2 or 3 described devices, the structure that it is characterized in that said prism system has difference with movable prism group and stationary prism group structural parameters different, and its concrete structure parameter comprises: the prismatical length of each little reflection-type, width and height; The length of prism group and width; The prismatical number of little reflection-type of prism group length direction; The prismatical number of little reflection-type of prism group width; The position of light hole; The position whether plane mirror and plane mirror are arranged.

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