CN100415158C - Method for expanding dynamic range in tomography of optical coherent - Google Patents

Method for expanding dynamic range in tomography of optical coherent Download PDF

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CN100415158C
CN100415158C CN 200610053328 CN200610053328A CN100415158C CN 100415158 C CN100415158 C CN 100415158C CN 200610053328 CN200610053328 CN 200610053328 CN 200610053328 A CN200610053328 A CN 200610053328A CN 100415158 C CN100415158 C CN 100415158C
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oct
dynamic range
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CN1915164A (en )
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丁志华
杨亚良
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浙江大学
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Abstract

本发明公开了一种扩展光学相干层析成像(OCT)动态范围的方法,该方法以提出的动态范围扩展方法在谱域OCT中的应用为实施例,在采用线聚焦照明方式面阵CCD探测器探测的并行谱域OCT系统的探测臂处,使用一块具有较高分光比的分光板对干涉光谱信号进行分光,分别由面阵CCD探测器来采集光谱信号并经一维傅立叶变换后,得到两幅不同曝光量的OCT图像。 The present invention discloses a method of extending optical coherence tomography (OCT) dynamic range, the dynamic range expansion method applied to the method proposed in the spectral domain OCT in an embodiment, the employed illumination line focus detection area CCD at parallel probe arms spectral domain OCT system is detected, with the use of a high splitting ratio of the beam splitter to the spectral interference spectrum signals, respectively, by the area CCD detector to acquire a spectroscopic signal dimensional Fourier transform and dried to give OCT images of two different exposure amounts. 然后用基于人眼灰度识别特性的数字图像合成方法,把这两幅OCT图像合成为一幅动态范围扩展了的OCT图像。 Followed by human eyes gradation digital image synthesis method based on identifying characteristics, these two OCT images into an extended dynamic range of the OCT image. 该方法具有很强的可移植性,可应用在不同的OCT系统结构和探测方式中,且不额外增加图像采集时间。 This method has very portable, can be used in different system configuration and the OCT probe, the image acquisition time without extra. 本发明具有扩展动态范围效果显著、成本节省和算法简单等特点。 The present invention has an expanded dynamic range effect is remarkable, cost savings and simple algorithm and so on.

Description

一种扩展光学相干层析成像动态范围的方法技术领域本发明涉及一种扩展光学相干层析成像动态范围的方法,尤其涉及一种基于人眼灰度识别特性的数字图像合成方法来扩展光学相干层析成像动态范围的方法。 An extended dynamic range optical coherence tomography TECHNICAL FIELD The present invention relates to a method for optical coherence tomography extended dynamic range, in particular, it relates to a digital gradation image synthesis method based on the identifying characteristic of the human eye to extend optical coherence tomography method of dynamic range. 背景技术光学相干层析成像(Optical Coherence Tomography,简称OCT)是近年发展起来的层析成像技术,能实现对活体内部的组织结构与生理功能进行非接触、 无损伤、高分辨率成像,因而在生物医学领域和临床诊断上得到广泛应用,在材料科学和基础研究中也将发挥重要作用。 BACKGROUND ART Optical coherence tomography (Optical Coherence Tomography, referred to as OCT) is developed in recent years tomography, can be realized on the organization structure and physiological function inside a living body non-contact, non-invasive, high-resolution imaging, thus widely used in clinical diagnostics and biomedical fields on, it will also play an important role in materials science and basic research. 在基于点探测器的OCT系统中,OCT图像动态范围的典型值在60〜100dB 之间,有的甚至高达120dB以上。 Based on the point in the OCT probe system, a typical value of OCT image dynamic range between 60~100dB, and some even as high as more than 120dB. 但在基于面阵探测器的并行OCT系统中,由于面阵探测器像素单元尺度受限,图像动态范围很难达到点探测OCT系统的水平。 However, in a parallel OCT systems based on flat panel detector, since the surface of the detector pixel array unit scale limited dynamic range image point detection is difficult to achieve the level of OCT system. 以CCD探测器为例,目前科学级CCD在常温下的动态范围仅为70dB左右, 在冷却条件下其动态范围能扩展至80~100dB,但成本大大增加。 A CCD detector as an example, the current scientific grade CCD at room temperature is only about 70dB dynamic range, the dynamic range can be extended to 80 ~ 100dB under cooling conditions, but the cost is greatly increased. 普通型CCD 的动态范围更小,仅为60dB左右,甚至更低。 Normal CCD dynamic range is smaller, only about 60dB, even lower. 因此,利用面阵CCD探测信号时,往往会因其动态范围受限而影响样品信号的提取。 Thus, when using a CCD area array detection signal, the dynamic range is limited because often affect the extracted sample signal. 一些OCT动态范围扩展的方法被人们提了出来,包括软件和硬件的方法。 Some OCT dynamic range expansion method been put forward, including software and hardware approach. 软件的方法有:以分贝为单位的对数变换、正弦变换和通信领域的p原理变换(Mawtransform)等,其中对数变换图像显示方法被广泛采用。 The method of the software are: in decibels logarithmic transformation, sine transformation P transforms the principles and communications (Mawtransform) and the like, wherein the image display logarithmic transformation methods are widely used. 硬件方法目前只是针对点探测器的OCT系统,如采用非线性增益放大器,对探测信号进行动态范围压縮,然后采样。 The method currently only hardware point detectors for OCT system, such as the non-linear gain amplifier, the detection signal dynamic range compression, and then sampled. 非线性增益曲线可以是上述软件方法里提到的任何一种变换。 Linear gain curve may be any conversion method mentioned in the above software. 直接扩展探测器的动态范围也是一条可行之路。 Direct extension of the dynamic range of the detector is a practical way. 如A. Dubois等在论文"Three-dimensional cellular-level imaging using flill-field optical coherence tomography " (Physics in medicine and biology, 49, 1227-1234, 2004)里,把像素数为1024x1024的CCD按2><2像素拼接模式来提高探测单元尺度,从而扩展CCD 的动态范围。 As A. Dubois, etc. in the paper "Three-dimensional cellular-level imaging using flill-field optical coherence tomography" (Physics in medicine and biology, 49, 1227-1234, 2004) where the number of CCD pixels 1024x1024 Press 2> <2 mosaic pixel patterns to improve detection unit scale, to extend the dynamic range of CCD. 其缺点是CCD有效像素数变少,有效分辨单元尺寸变大。 The disadvantage is that the effective number of CCD pixels is reduced, the effective resolution element size becomes large. 谱域OCT (Spectral-domain OCT)的层析信号来自样品表面直到内部深层各处的后向散射光。 Spectral domain OCT (Spectral-domain OCT) chromatography until the signal from the rear surface of the sample throughout the deep internal scattered light. 鉴于样品表层和深层处的散射光强度差异往往巨大,谱域探测面接收到的低频信号和高频信号的调制度因而相差悬殊,利用单一CCD获取如此大动态范围的干涉光谱信号存在一定难度。 Given the difference in intensity of scattered light at the sample surface and deep often huge, spectral domain detection surface modulation to the received low frequency signal and high frequency signal differences between Accordingly, using a single CCD obtain such a large dynamic range of the interference signal spectrum there is a certain degree of difficulty. 采用两次或多次曝光的方法, 可以获得宽动态范围图像的同时,保证较高的信噪比。 The method of using two or multiple exposures, wide dynamic range image can be obtained while ensuring a high signal to noise ratio. 但前后多次曝光必然要增加测量时间,而高成像速度一直是OCT追求的目标。 But many times before and after exposure is bound to increase the measurement time, and the high speed imaging has been the OCT goal. 所以,这种方法在OCT 中并不可取。 Therefore, this method is not desirable in OCT. 发明内容为了克服背景技术的不足,本发明的目的是提供一种扩展光学相干层析成像动态范围的方法。 SUMMARY To overcome the shortcomings of the background art, the object of the present invention is to provide a method of optical coherence tomography extended dynamic range. 在采用线照明方式面阵CCD探测的并行谱域OCT系统的探测臂处,使用一块具有较高分光比的分光板对干涉光谱信号进行分光,分别由面阵CCD探测器来采集光谱图像并作傅立叶变换后,得到两幅不同曝光量的OCT图像。 In the detection of the parallel arm spectral domain OCT system uses line illumination area CCD detection using a beam splitter having a high splitting ratio of spectral interference spectrum signal, respectively, by the area CCD detector to acquire a spectral image and for after the Fourier transform, to obtain two different exposure amounts OCT image. 然后用基于人眼灰度识别特性的数字图像合成方法,把这两幅图像合成为一幅动态范围扩展了的OCT图像。 Followed by human eyes gradation digital image synthesis method based on identifying characteristics, these two images into an extended dynamic range of the OCT image. 本发明解决其技术问题所采用的技术方案是-一、 一种扩展光学相干层析成像动态范围的方法,其具体步骤如下-1) 经成像透镜来的干涉光谱信号被具有高分光比的分光板分成透射和反射部分,分别由面阵CCD探测器探测,再经多路图像采集与模数转换卡输入给计算机;2) 分别对两幅CCD采集信号进行沿光谱展开方向的一维傅立叶变换,得到两幅曝光量不同的OCT图像;3) 把两幅OCT图像显示为8位灰度图像,并把灰度级32和192分别确定为图像合成时灰度判别的下阈值和上阈值;4) 对两幅图像相同像素点的灰度值&和&,分别乘于权重因子",和^后相加,得到合成后图像该像素点的灰度值^ ="《1+"2&;权重因子",和"2按如下原则确定:①当(&+&)/2<32时,ai=(g1+g2)/128 , a2=l-fll ; ②当32《(g,+g2)/2《192时,a,a,0.5; ③当(g, + g2)/2 〉 192时,01=卜"2, "2=[256-(g1+g2)/2]/128;5) 图像的所有 The present invention solves the technical problem using the technical solution - a, a method of optical coherence tomography dynamic range expansion, the specific steps are as follows -1) through the imaging lens to the interference spectrum signal light having high spectral ratio plate into transmission and reflection portions are respectively detected by the CCD area array detector, and then the multi-channel analog to digital conversion and image acquisition card input to the computer; 2), respectively two in the CCD signal acquired spectrum unwinding direction one-dimensional Fourier transform to give two different exposure amounts OCT image; 3) the OCT image is displayed as two 8-bit grayscale image, and the gray level 32 and 192, respectively upper and lower threshold determination threshold value when the gradation image synthesis discrimination; 4) & gradation value and pixel & same two images are multiplied by weighting factors ", and after the addition ^, the combined image obtained after the gradation pixel value ^ =" "1 +" & 2; weighting factor ", and" 2 determined according to the following principles: ① when the time (& + &) / 2 <32, ai = (g1 + g2) / 128, a2 = l-fll; ② when the 32 "(g, + g2 ) / 2 "192, a, a, 0.5; ③ when (g, + g2) / 2> 192, 01 = Bu" 2, "2 = [256- (g1 + g2) / 2] / 128; All 5) image 像素点按步骤4)进行处理,得到一幅动态范围扩展了的OCT 图像;6) 计算机经数模转换卡驱动扫描振镜进行横向扫描,使光束照射在样品的不同横向位置处,重复以上步骤,可得到三维OCT图像。二、 一种扩展光学相干层析成像动态范围的系统,包括宽带光源、准直透镜、柱透镜、宽带分光棱镜、扫描振镜、 一对相同的物镜、参考镜、精密平移台、第一透镜、狭缝、第二透镜、衍射光栅、成像透镜、分光板、 一对相同的面阵CCD探测器、多路图像采集与模数转换卡、计算机和数模转换卡;宽带光源发出的光依次经准直透镜、柱透镜和带分光棱镜后被分成两路: 一路经扫描振镜和第一物镜到样品;另一路经第二物镜到参考镜,参考镜固定在精密平移台上;从样品反射或后向散射的光,和从参考镜反射的光,按原路返回到宽带分光棱镜后,依次经第一透镜 Tap pixel step 4) to give a dynamic range expansion of the OCT image; 6) transversely scanning the computer card DAC driving a scanning galvanometer, a light beam at a different lateral position of the sample, and repeating the above steps obtained three-dimensional OCT image. Second, an extension of the dynamic range of the optical coherence tomography system, including a broadband light source, a collimator lens, cylindrical lens, broadband dichroic prism, a scanning galvanometer, the same objective lens pair of the reference mirror, precision translation stage, a first lens, a slit, a second lens, a diffraction grating, an imaging lens, beam splitter, a pair of identical array CCD detectors, image acquisition and multi-channel analog to digital conversion card, computer digital to analog conversion card ; broadband light source are sequentially emitted by the collimator lens, cylindrical lens, and after the band splitting prism into two: the way through the first objective lens and the scanning mirror to the sample; another path of the second reference mirror to the objective lens, the reference mirror is fixed precision translation stage; backward light, and the light reflected from the reference mirror scattered, reflected from the sample returns to the original way after the broadband dichroic prism or sequentially through the first lens 、狭缝、第二透镜、衍射光栅、成像透镜和分光板后被分成透射光和反射光,分别被第一、第二面阵CCD探测器探测;第一、 第二面阵CCD探测器经多路图像采集与模数转换卡接计算机,计算机经数模转换卡接扫描振镜。所述的宽带光源位于准直透镜的前焦面上,扫描振镜位于柱透镜的后焦面、 第一物镜与第一透镜的前焦面上,狭缝位于第一透镜的后焦面和第二透镜的前焦面上,衍射光栅位于第二透镜的后焦面和成像透镜的前焦面上。所述的分光板是透反射率比大于0.9,或者透反射率比小于Ol的高分光比宽带分光板,它以薄玻璃平板为基片,在玻璃平板的上表面镀上述透反射率比的介质分光膜,下表面镀增透膜制作而成。 Slits, a second lens, a diffraction grating, beam splitter and after the imaging lens into transmitted light and reflected light, respectively detecting a first, a second array CCD detectors; a first, second area CCD detector via multiple image acquisition and analog-digital conversion card access, a computer connected by the digital to analog converter card scanning galvanometer. the broadband light source located in the front focal plane of the collimator lens, the scanning galvanometer is located in the focal plane of the cylindrical lens, the first the front focal plane of the front focal plane, a diffraction grating before and after the focal plane of the objective lens and a first lens, a slit at the first focal plane of the lens and the second lens in the second lens and the focal plane of the imaging lens the transparent plate is a spectral reflectance ratio greater than 0.9, or less than Ol reflectance through the high ratio of broadband light beam splitter, it is a thin plate glass substrate, said transparent coating reflectivity than the surface of the glass plate medium splitter film, the lower surface of the AR coating produced. 与背景技术相比,本发明具有如下优点:1、 不增加OCT装置对样品进行扫描及采集的时间:采用分光的方式,由两个CCD来同步采集干涉光谱信号,没有额外增加对样品的扫描及采集时间。 Compared to the background art, the present invention has the following advantages: 1, the OCT apparatus without increasing the time of sample collection and scanning: optical splitter, the two CCD signal to interference spectrum synchronous acquisition without additional scanning of the sample and acquisition time. 对两幅曝光量不同的OCT图像进行加权合成的运算,只是简单的比较判断、乘法及加法运算,不会过多增加计算机的处理时间。 Two different exposure amounts OCT image weighting calculation, comparison and judgment simply, multiplication and addition operations, without much increase in the processing time of the computer. 所以,OCT完成一次样品成像的总时间没有太大增加,这对追求快速检测的OCT来说意义重大;2、 因采用本方法而额外增加的器件很少,成本没有太大增加:只增加了一块分光板和一个CCD探测器;3、 扩展动态范围效果显著,扩展后基本能满足OCT成像要求:理论计算表明,当分光板的透反射率比为0.94或者0.06时,可以把OCT图像的动态范围扩展近24dB,此时采用科学级CCD来探测干涉光谱,基本能满足要求;4、 本发明的OCT动态范围扩展方法具有很强的可移植性:不同的OCT系统结构及探测方式均可应用本方法来扩展动态范围。 So, OCT imaging to complete a sample of the total increase is not much time, which is significant for the pursuit of rapid tests for OCT; 2, due to the use of this method and a device little extra, there is not much cost increase: an increase of only a beam splitter and a CCD detector; 3, extended dynamic range effect is remarkable, substantially after expansion to meet the OCT imaging requirements: theoretical calculations show that, when the transflective of the beam splitter ratio of 0.94 or 0.06, can be the dynamic range of OCT images extended nearly 24dB, scientific grade CCD at this time to detect the interference spectrum, can satisfy the requirements;. 4, OCT dynamic range expansion process of the invention very portable: different probe and an OCT system configuration of the present embodiment can be applied A method to extend the dynamic range. 系统结构可以是:光纤型、 自由空间型、光纤与自由空间的混合型;探测方式可以是:点扫描探测、线扫描探测和面探测。 The system structure may be: the hybrid type optical fiber, free-space type optical fiber and free space; detection mode may be: a scanning point detection, face detection and scan detection lines. 附图说明图1是本发明用以扩展光学相干层析成像动态范围的系统结构在水平面内的示意图;图2是本发明用以扩展光学相干层析成像动态范围的系统结构在垂直面内的示意图;图3是本发明用以扩展光学相干层析成像动态范围的控制系统框图。 BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a system configuration of optical coherence tomography for expanding the dynamic range of the present invention is a schematic diagram in the horizontal plane; FIG. 2 is a system configuration of the present invention in a vertical plane of optical coherence tomography for expanding the dynamic range schematic; FIG. 3 is a block diagram of a control system used to extend the dynamic range of the optical coherence tomography according to the present invention. 图中:l.宽带光源,2.准直透镜,3.柱透镜,4.宽带分光棱镜,5.扫描振镜,6、 7.—对相同的物镜,8.样品,9.参考镜,IO.精密平移台,ll.透镜,12.狭缝,13.透镜,14.衍射光栅,15.成像透镜,16.分光板,17、 18.面阵CCD探测器,19.多路图像采集与模数转换卡,20.计算机,21.数模转换卡。 FIG.:.... L broadband light source, a collimator lens 2, cylindrical lens 3, broadband dichroic prism 4, scanning mirror 5, the same objective lens 6, 7 .- pair of samples 8, the reference mirror 9,... the IO. precision translation stage, LL lens, 12 slit, 13 lens, 14 a diffraction grating 15. The imaging lens 16. beamsplitter, 17, 18. The area CCD detector 19. The multi-channel image acquisition analog to digital conversion card, 20 computer, 21 digital to analogue converter card. 具体实施方式下面结合附图对本发明作进一步的说明:样品的浅层区域为高照度区域,尤其是表层会发生强烈的界面反射现象; 而深层区域,尤其在接近穿透深度极限的区域,为低照度区域。 DETAILED DESCRIPTION OF THE DRAWINGS The present invention will be further described: superficial area of ​​the sample as a high illuminance region, particularly a strong interfacial surface reflection phenomenon occurs; the deep region, particularly in the area near the depth of penetration limit, as low-light areas. 探测浅层区域对应的干涉光谱时探测器容易饱和,而深层区域则会因曝光不足而淹没在噪音中。 When detecting the shallow region corresponding to the interference spectroscopy probe easily saturated, and will result in deep areas underexposure submerged in the noise. 如果探测时把干涉光谱信号光分成强度相差很大的两束来分别探测,那么对强光束的探测仍可保留深层区域的信息,而对弱光束的探测则用于浅层区域信息的获取。 If the interference spectrum of the probe light into a signal intensity difference between the two beams are large detection, the detection of the beam intensity can retain information of the deep region, while the probe beam is weak shallow for acquiring region information. 按照某种原则,把这两幅曝光量不同的图像合成起来,就有可能在CCD动态范围内获得从浅层到深层的全部细节信息,进而实现OCT图像动态范围的扩展。 According to some principle, these two different exposure amount of images are synthesized, it is possible to obtain all the details from shallow to deep within the dynamic range of the CCD, so as to realize an OCT image of extended dynamic range. OCT图像一般显示为8位灰度图像,即灰度值范围为0~255。 OCT images generally shown as 8-bit grayscale image, i.e. the gray value range of 0 to 255. 由人眼对灰度的分辨能力统计规律可知:在图像灰度值很高或很低的情况下,人眼对灰度分辨能力差;而在图像灰度适中的情况下,人眼的分别能力强,其中人眼比较敏感的区域是32〜192之间的区域。 Seen from the statistical regularity of the gradation resolution of the human eye: In the case where the image gradation value is high or low, The human eye resolution of the gradation; in the case of moderate gray image, respectively, the human eye ability, which the human eye is more sensitive area is the area between 32~192. 根据人眼的这一视觉特性,可对图像进行相应的处理:在低灰度和高灰度区域,可将灰度级间隔拉伸,使人眼便于分辨; 在中等灰度区域,适当地压縮灰度级间隔,而将剩余的灰度级数分配给低灰度和高灰度区域。 The visual characteristics of the human eye, the image can be processed: in the low gradation region and high gradation, the gradation level interval may be stretched, for easy identification by the human eye; the middle tone region, suitably gradation compression interval, and the remaining gray levels assigned to the low gradation region and high gradation. 基于以上的分析,申请人发明了一种扩展光学相干层析成像动态范围的方法,本发明以提出的动态范围扩展方法在谱域OCT中的应用为实施例,建立一套采用线聚焦照明方式面阵CCD探测器探测的谱域OCT系统,使用柱透镜来实现线聚焦照明。 Based on the above analysis, the applicant has invented a method of optical coherence tomography extended dynamic range, the dynamic range expansion applied method of the present invention is to set forth in the spectral domain OCT in an embodiment, to establish a line-focus illumination using area CCD detector detects the spectral domain OCT systems, is achieved using a cylindrical lens focusing the illumination line. 由于柱透镜的使用使得光束在水平面和垂直面内具有不同的光束形状,为了显示直观和叙述方便,分别画出了系统结构在水平面和垂直面内的示意图如图1和图2所示。 The use of a cylindrical lens such that the light beams having different beam shapes in the horizontal and vertical planes, for convenient and intuitive display and described, respectively shown the system configuration of the horizontal and vertical planes in the schematic shown in Figures 1 and 2. 宽带光源1发出的光经准直透镜2准直后,平行入射到柱透镜3上,柱透镜3的轴线沿水平面内放置。 Broadband light source 1 emits a light through the collimator lens after the collimator, the parallel incident on the cylindrical lens 3, the axis of the cylindrical lens 3 is placed along a horizontal plane. 如图1所示,在柱透镜3的轴线方向,光束不聚焦,平行入射到宽带分光棱镜4上,被分成透射光和反射光:透射光被扫描振镜5反射后到达物镜6,被聚焦在样品8上,扫描振镜5在水平面内旋转进行横向扫描;反射光达到物镜7后被聚焦在参考镜9上,参考镜9固定在精密平移台10上。 1, in the axial direction of the cylindrical lens 3, the beam is not focused, incident on the parallel broadband dichroic prism 4, is divided into transmitted light and reflected light: the transmitted light reaching the objective lens 6 is scanned after vibrating mirror 5 is focused 8 on the sample, scanning mirror 5 rotating in a horizontal plane transversely scanned; after the reflected light reaches the objective lens 7 is focused on the reference mirror 9, the reference mirror 9 is fixed on a precision translation stage 10. 从样品8反射或后向散射的光,和从参考镜9反射的光沿原路返回到宽带分光棱镜4后,依次经透镜11和13后平行入射到衍射光栅14上。 Light reflected from the sample 8, and from the reference mirror 9 to backtrack along the light reflected or scattered back to the broadband dichroic prism 4, followed by a lens 11 and is incident parallel to the diffraction grating 13 to 14. 透镜11 和透镜13构成扩束器,使光线扩束来充分利用大尺度衍射光栅14的分光潜能, 以便提高系统的分辨率。 Lens 11 and the lens 13 constituting the beam expander, so that the light beam expanding to take advantage of the potential large scale grating spectroscope 14 so as to increase the resolution of the system. 透镜11的后焦面和透镜13的前焦面重合,狭缝12就放置在这一重合的焦面处(狭缝的长边沿垂直方向),用以滤除杂散光。 The back focal plane of the lens 11 and the lens 13 coincides with the front focal plane, the slit 12 is placed on the focal plane coincides (direction perpendicular to the long sides of the slit), for filtering out stray light. 衍射光栅14位于透镜13的后焦面和成像透镜15的前焦面上,被衍射光栅14衍射后的光线经成像透镜15和分光板16后被分成透射光和反射光,分别被成像透镜15聚焦在面阵CCD探测器17和18上。 After the diffraction grating 14 is located in the focal plane of the lens 13 and the imaging lens 15 of the front focal plane, after the diffraction grating is diffracted ray 14 through the imaging lens 15 and the beam splitter 16 is divided into transmitted light and reflected light, an imaging lens 15 are focused on the area CCD 17 and the detector 18. 为了使动态范围扩展的效果显著,要求分光板16的分光比尽可能高,所以把它设计成透反射率比大于0.9,或者透反射率比小于Ol的宽带分光板,它以薄玻璃平片为基片,在玻璃平片的上表面镀上述透反射率比的介质分光膜,下表面镀增透膜制作而成。 In order that the dynamic range expansion effect is remarkable, required beam splitter as high splitting ratio 16, so it is designed to penetrate the reflectance is greater than 0.9, or permeability reflectance less than Ol broadband beam splitter, it is a thin flat glass sheets used as a substrate, plating the medium through the splitter film reflectivity than the flat surface of the glass sheet, the lower surface of the AR coating produced. 如图2所示,在垂直面内柱透镜3相当于一个凸透镜。 As shown, the cylindrical lens 3 in the vertical plane 2 corresponds to a lens. 被宽带分光棱镜4 透射的光被柱透镜3聚焦在扫描振镜5上,扫描振镜5在垂直面内没有旋转扫描运动,被扫描振镜5反射的光经物镜6后平行入射在样品8上。 The broadband light transmitted dichroic prism 4 is incident on the sample cylindrical lens 3 is focused on the scanning galvanometer 5, 5 no rotational scanning galvanometer scanning movement in the vertical plane, parallel to the post 6 5 galvanometer scanning light reflected by the objective lens 8 on. 被宽带分光棱镜5反射的光经物镜7后平行入射在参考镜9上。 7 is incident in parallel to the dichroic prism broadband light via the objective lens 5 is reflected on the reference mirror 9. 从样品8和参考镜9返回的光经透镜11后平行入射到透镜13上,然后被聚焦在衍射光栅14上。 Returning from the sample 8 and the reference mirror 9 is incident parallel light by a lens 13 onto the rear lens 11, and then focused on the diffraction grating 14. 被衍射光栅14衍射后的光线经成像透镜15后,平行入射在面阵CCD探测器17和18 上。 Rays diffracted by the diffraction grating 14 after the imaging lens 15, parallel incident on the area array CCD detectors 17 and 18. 综合以上水平和垂直面内的情况,可以知道:l)照射到样品8和参考镜9 上的是一条线聚焦光束,该线聚焦光束由扫描振镜5的旋转可作横向扫描运动, 而参考线聚焦光束固定不动;2)入射到衍射光栅14上的也是一条线,线上每一点的光谱被衍射光栅14沿与线垂直的方向衍射而分开。 Based on the above where the horizontal and vertical planes, can know: l) irradiated to the sample 8 and the reference mirror 9 is a line focused beam, the line beam focused by the rotating scanning mirror 5 may be laterally scanning motion, and reference line focus beam stationary; 2) is incident on a diffraction grating 14 on the line, every point of the spectral line direction of the diffraction grating 14 is along a line perpendicular to the diffraction separated. 入射到面阵CCD探测器17和18上时,就是一幅在水平面内为一维并行的探测点,在垂直面内为这些探测点光谱的展开图像。 When entering the area array CCD detectors 17 and 18 is a one-dimensionally in a horizontal plane parallel to the detection point, in the vertical plane to expand these detection points spectral image. 本发明的控制系统如图3示。 The control system 3 according to the present invention shown in FIG. 面阵CCD探测器17和18的输出信号经多路图像采集与模数转换卡19输入给计算机20,并由计算机20来控制面阵CCD探测器17和18进行图像采集。 The output signal of the detector 17 and the area CCD 18 of the image acquisition by the multiplexer and analog to digital converter card 19 to the computer input 20, 20 is controlled by a computer array CCD detectors 17 and 18 for image acquisition. 计算机20的输出信号经数模转换卡21控制扫描振镜5转动,实现样品的横向扫描成像。 Output signal from the computer 20 via a digital to analog converter card 21 controls the scanning galvanometer 5 rotates, achieve horizontal scan imaging sample. 多路图像采集与模数转换卡19和数模转换卡21均为现成产品,可从市场购买,前者如北京大恒图像公司的DH-CG410,后者如北京中泰研创科技公司的USB7322。 Multiple image acquisition card 19 and the analog to digital conversion and digital to analog converter card 21 are ready-made products can be purchased from the market, the former company's image as Beijing Daheng DH-CG410, which, as Beijing Sino-Thai Research and Innovation Technologies USB7322 . 本发明提出的扩展光学相干层析成像动态范围的方法,其具体步骤如下:1) 经成像透镜来的干涉光谱信号被具有高分光比的分光板分成透射和反射部分,分别由面阵CCD探测器探测,再经多路图像采集与模数转换卡输入给计算机;2) 分别对两幅CCD采集信号进行沿光谱展开方向的一维傅立叶变换,得到两幅曝光量不同的OCT图像;3) 把两幅OCT图像显示为8位灰度图像,并把灰度级32和192分别确定为图像合成时灰度判别的下阈值和上阈值;4) 对两幅图像相同像素点的灰度值g,和A,分别乘于权重因子^和《2后相加,得到合成后图像该像素点的灰度值g^,g,+A&;权重因子^和"2按如下原则确定:①当(g,+g2)/2<32时,ai=(g,+g2)/128 , "2=1-②当32S(g,+g2)/2^192时,a2=a,=0.5; ③当(g,+g2)/2 > 192时,a, =1 —a2, "2 =[256-(g,+g2)/2]/128;5) 图像的所有像素点按步骤4)进行处理,得到一幅动态范围 The optical coherence tomography method extends the dynamic range by the present invention, the specific steps are as follows: 1) through the imaging lens to the interference spectrum signal having a high light transmittance ratio and the reflective plate into the spectroscopic portion, respectively, by detecting area CCD detection is then input to the computer via the multiplexed image acquisition card analog to digital converter; 2) were collected on two CCD signal spectrum expand in the direction of a one-dimensional Fourier transform, to obtain two different exposure amounts OCT image; 3) the OCT image is displayed as two 8-bit grayscale image, and the gray level 32 and 192, respectively, is determined gradation image synthesis is determined lower threshold and upper threshold; 4) of the same gray value pixels of the two images g, and a, respectively, multiplied by the weighting factor ^ and "rear second addition, after obtaining synthesized image gray level of the pixel value g ^, g, + a &; weighting factor ^ and" 2 follows the principle of determination: ① when (g, + g2) when / 2 <32, ai = (g, + g2) / 128, "2 = 1-② when 32S (g, + g2) / 2 ^ 192, a2 ​​= a, = 0.5; ③ when (g, + g2) / 2> 192, a, = 1 -a2, "2 = [256- (g, + g2) / 2] / 128; 5 all pixels) of the image according to step 4) processed to obtain a dynamic range 展了的OCT 图像;6) 计算机经数模转换卡驱动扫描振镜进行横向扫描,使光束照射在样品的不同横向位置处,重复以上步骤,可得到三维OCT图像。 Development of the OCT image; 6) transversely scanning the computer card DAC driving a scanning galvanometer, a light beam at a different lateral position of the sample, repeat the above steps to obtain a three-dimensional OCT image.

Claims (1)

  1. 1. 一种扩展光学相干层析成像动态范围的方法,其特征在于包括以下步骤: 1)经成像透镜来的干涉光谱信号被具有透反射率比大于0.9或者小于0.1的高分光比的分光板分成透射和反射部分,分别由面阵CCD探测器探测,再经多路图像采集与模数转换卡输入给计算机; 2)分别对两幅CCD采集信号进行沿光谱展开方向的一维傅立叶变换,得到两幅曝光量不同的OCT图像; 3)把两幅OCT图像显示为8位灰度图像,并把灰度级32和192分别确定为图像合成时灰度判别的下阈值和上阈值; 4)对两幅图像相同像素点的灰度值g1和g2,分别乘于权重因子a1和a2后相加,得到合成后图像该像素点的灰度值g=a1g1+a2g2;权重因子a1和a2按如下原则确定:①当(g1+g2)/2<32时,a1=(g1+g2)/128,a2=1-a1;②当32≤(g1+g2)/2≤192时,a2=a1=0.5;③当(g1+g2)/2>192时,a1=1-a2,a2=[256-(g1+g2)/2]/128; 5)图像的 A method of optical coherence tomography extended dynamic range, comprising the steps of: 1) through the imaging lens to the interference signal having a spectral reflectance through the beam splitter high ratio of greater than 0.9 or less than 0.1 of the ratio of light into transmission and reflection portions respectively detected by the CCD area array detector, and then the multi-channel analog to digital conversion and image acquisition card input to the computer; 2) were collected on two CCD signal spectrum expand along the direction of a one-dimensional Fourier transform, to give two different exposure amounts OCT image; 3) the OCT image is displayed as two 8-bit grayscale image, and the gray level 32 and 192, respectively, is determined gradation image synthesis is determined lower threshold and upper threshold; 4 ) grayscale image of the same two pixel values ​​g1 and G2, are multiplied by the weighting factor to the sum a1 and a2, the gradation value g = a1g1 + a2g2 image of the pixel obtained after synthesis; weight factors a1 and a2 principle determined as follows: ① when the time (g1 + g2) / 2 <32, a1 = (g1 + g2) / 128, a2 = 1-a1; ② when 32≤ (g1 + g2) / 2≤192 time, a2 = a1 = 0.5; ③ when (g1 + g2) / 2> 192, a1 = 1-a2, a2 ​​= [256- (g1 + g2) / 2] / 128; 5) of the image 所有像素点按步骤4)进行处理,得到一幅动态范围扩展了的OCT图像; 6)计算机经数模转换卡驱动扫描振镜沿与线聚焦入射光束垂直方向进行横向扫描,使线聚焦入射光束照射在样品的不同横向位置处,重复以上步骤,可得到三维OCT图像。 All pixels by step 4) is processed to obtain an expanded dynamic range of the OCT image; 6) via a computer driven analog conversion card scanning mirror focusing the incident beam along a line perpendicular to the horizontal scanning direction of the line focus of the incident beam irradiating at different lateral position of the sample, repeat the above steps to obtain a three-dimensional OCT image.
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