技术领域technical field
本发明具体涉及一种实时单次快照多频解调空间频域成像方法。The invention specifically relates to a real-time single snapshot multi-frequency demodulation space frequency domain imaging method.
背景技术Background technique
传统的SFDI系统通常使用传统三相移法进行解调，但是传统三相移法需要三个不同的相位(0,2π/3,and 4π/3)的空间调制图像才能完整解析单个频率的调制深度(MTF)，存在解调速度慢，有运动鬼影等问题。Traditional SFDI systems usually use the traditional three-phase shift method for demodulation, but the traditional three-phase shift method requires three different phases (0, 2π/3, and 4π/3) of the spatial modulation image to fully resolve the modulation of a single frequency Depth (MTF), there are problems such as slow demodulation speed and motion ghosting.
发明内容Contents of the invention
为了解决以上技术问题，本发明提出一种实时单次快照多频解调空间频域成像方法。In order to solve the above technical problems, the present invention proposes a real-time single snapshot multi-frequency demodulation spatial frequency domain imaging method.
本发明提供一种实时单次快照多频解调空间频域成像方法，其包括以下步骤：The present invention provides a real-time single snapshot multi-frequency demodulation space frequency domain imaging method, which comprises the following steps:
一、实时投影一个空间调制图案在待测物体上，该空间调制图案包括多个调制频率的成分；1. Real-time projection of a spatial modulation pattern on the object to be tested, the spatial modulation pattern includes components of multiple modulation frequencies;
二、采集待测物体漫反射后的反射光强，获取空间调制图像I(x,y)；2. Collect the reflected light intensity after the diffuse reflection of the object to be measured, and obtain the spatially modulated image I(x,y);
三、通过单次快照多频解调法3. Multi-frequency demodulation method through a single snapshot
获取反射光强的直流值IDC和针对每一调制频率相应的分流值IAC,i，其中I(x,y)为测得的二维图像，fx,i，fy,i是第i个调制成分的x、y轴的空间频率，T1、T2是所有1/fx,i，1/fy,i的最小公倍数；Obtain the DC value IDC of the reflected light intensity and the corresponding shunt value IAC,i for each modulation frequency, where I(x,y) is the measured two-dimensional image, fx,i , fy,i are the first The spatial frequencies of the x and y axes of i modulation components, T1 and T2 are the least common multiples of all 1/fx,i and 1/fy,i ;
四、获取反射光强的直流值IDC和分流值IAC,i之后，得到调制深度其中是入射的第i调制频率成分强度，是入射直流成分强度；4. After obtaining the DC value IDC and shunt value IAC,i of the reflected light intensity, the modulation depth is obtained in is the intensity of the incident i-th modulation frequency component, is the intensity of the incident DC component;
五、根据获得的调制深度，通过与光在介质中传播的模型比较获取介质的光学参数。Fifth, according to the obtained modulation depth, the optical parameters of the medium are obtained by comparing with the model of light propagating in the medium.
步骤一中，将一个空间调制图案通过分光镜作用在待测物体上。In step 1, a spatial modulation pattern is applied to the object to be measured through a beam splitter.
步骤三中，单次快照多频解调法可对由多个空间调制频率组成的图案中单幅解析出多个空间调制频率的各自的反射光强的直流值IDC和分流值IAC,i，获取不同深度的光学信息。In step 3, the single snapshot multi-frequency demodulation method can analyze the direct current value IDC and the shunt value IAC of the respective reflected light intensities of multiple spatial modulation frequencies for a single image in a pattern composed of multiple spatial modulation frequencies, i , to obtain optical information at different depths.
一种基于上述的实时单次快照多频解调空间频域成像方法在深度分辨的成像上的应用。An application of the above-mentioned real-time single snapshot multi-frequency demodulation spatial frequency domain imaging method in depth-resolved imaging.
一种基于上述的实时单次快照多频解调空间频域成像方法在3D重构上建模的应用。An application of the real-time single-snapshot multi-frequency demodulation space-frequency domain imaging method to modeling on 3D reconstruction.
一种基于上述的实时单次快照多频解调空间频域成像方法在皮肤大面积成像的应用。An application of the above-mentioned real-time single snapshot multi-frequency demodulation spatial frequency domain imaging method in large-area skin imaging.
一种基于上述的实时单次快照多频解调空间频域成像方法在内窥镜表面粘膜层大面积成像的应用。An application of the real-time single-snapshot multi-frequency demodulation spatial frequency domain imaging method based on the above-mentioned large-area imaging of the mucosal layer on the surface of the endoscope.
本发明的有益效果：解决了传统解调技术速度慢，有运动鬼影的问题，并且此解调技术有很高的信噪比，以此技术搭建的SSMD-SFDI系统能够实时解调出MTF，因此可实时获取光学信息和生理信息。Beneficial effects of the present invention: it solves the problems of slow speed and motion ghost in traditional demodulation technology, and this demodulation technology has a high signal-to-noise ratio, and the SSMD-SFDI system built with this technology can demodulate MTF in real time , so optical information and physiological information can be obtained in real time.
附图说明Description of drawings
图1为SSMD与标准三相移技术的对比示意图。Figure 1 is a schematic diagram of the comparison between SSMD and standard three-phase shift technology.
图2为SSMD-SFDI装置示意图。Figure 2 is a schematic diagram of the SSMD-SFDI device.
图3为典型被测者在前臂反应性充血实验中氧合血红蛋白浓度(a)、脱氧血红蛋白浓度(b)、总血红蛋白浓度(c)和血氧饱和度变化过程(d)的示意图。Fig. 3 is a schematic diagram of the change process of oxygenated hemoglobin concentration (a), deoxygenated hemoglobin concentration (b), total hemoglobin concentration (c) and blood oxygen saturation (d) in the forearm reactive hyperemia test of a typical subject.
图4为在前臂反应性充血实验中黑色素含量和表皮层厚度的示意图。Fig. 4 is a schematic diagram of melanin content and epidermal layer thickness in forearm reactive hyperemia test.
图5为表皮层(a-c)和真皮层(d-f)各波长下的吸收系数和皮肤的散射系数(g)和散射能力(h)的示意图。Fig. 5 is a schematic diagram of the absorption coefficient of the epidermis (a-c) and the dermis (d-f) at various wavelengths, and the scattering coefficient (g) and scattering power (h) of the skin.
图6为SSMD-SFDI系统下被测区域，虚线矩形区域为感兴趣区域。Figure 6 shows the measured area under the SSMD-SFDI system, and the dotted rectangular area is the area of interest.
图7为正常组织和黑痣光学参数(各波长各层吸收系数(a-f)，散射系数(g)和散射能力(h))的分布图。Fig. 7 is a distribution diagram of optical parameters (absorption coefficient (a-f), scattering coefficient (g) and scattering power (h) of each wavelength and each layer) of normal tissue and mole.
图8为正常组织和黑痣生理参数(，含氧血红蛋白(a)，缺氧血红蛋白(b)，总含氧血红蛋白(c)，血氧饱和度(d)，黑色素(e)和表皮层厚度(f))的分布图。Figure 8 shows the physiological parameters of normal tissue and nevus (, oxygenated hemoglobin (a), hypoxic hemoglobin (b), total oxygenated hemoglobin (c), blood oxygen saturation (d), melanin (e) and epidermal thickness (f)) distribution map.
具体实施方式Detailed ways
下面结合附图对本发明实施例作进一步说明：Embodiments of the present invention will be further described below in conjunction with accompanying drawings:
本发明提供一种实时单次快照多频解调空间频域成像方法，The present invention provides a real-time single snapshot multi-frequency demodulation space frequency domain imaging method,
其包括以下步骤：It includes the following steps:
一、实时投影一个空间调制图案，通过分光镜作用在待测物体上，该空间调制图案包括多个调制频率的成分；1. A spatial modulation pattern is projected in real time, and acts on the object to be measured through a spectroscope. The spatial modulation pattern includes components of multiple modulation frequencies;
二、采集待测物体漫反射后的反射光强，获取空间调制图像I(x,y)；2. Collect the reflected light intensity after the diffuse reflection of the object to be measured, and obtain the spatially modulated image I(x,y);
三、通过单次快照多频解调法3. Multi-frequency demodulation method through a single snapshot
获取反射光强的直流值IDC和针对每一调制频率相应的分流值IAC,i，其中I(x,y)为测得的二维图像，fx,i，fy,i是第i个调制成分的x、y轴的空间频率，T1、T2是所有1/fx,i，1/fy,i的最小公倍数；Obtain the DC value IDC of the reflected light intensity and the corresponding shunt value IAC,i for each modulation frequency, where I(x,y) is the measured two-dimensional image, fx,i , fy,i are the first The spatial frequencies of the x and y axes of i modulation components, T1 and T2 are the least common multiples of all 1/fx,i and 1/fy,i ;
单次快照多频解调法可对由多个空间调制频率组成的图案中单幅解析出多个空间调制频率的各自的反射光强的直流值IDC和分流值IAC,i，获取不同深度的光学信息；The single-snapshot multi-frequency demodulation method can analyze the direct current value IDC and shunt value IAC,i of the reflected light intensity of multiple spatial modulation frequencies in a single pattern composed of multiple spatial modulation frequencies, and obtain different Depth optical information;
单次快照多频解调法可对单幅空间调制频率图案解调出反射光强的直流值IDC和针对每一调制频率相应的分流值IAC,iThe single snapshot multi-frequency demodulation method can demodulate a single spatial modulation frequency pattern to obtain the direct current value IDC of the reflected light intensity and the corresponding shunt value IAC,i for each modulation frequency
四、获取反射光强的直流值IDC和分流值IAC,i之后，利用入射光强I0，得到调制深度其中是各调制频率下反射光强IAC,i的入射光强，是IDC的入射光强；4. After obtaining the DC value IDC and shunt value IAC,i of the reflected light intensity, use the incident light intensity I0 to obtain the modulation depth in is the incident light intensity of reflected light intensity IAC,i at each modulation frequency, is the incident light intensity of IDC ;
五、根据获得的调制深度，通过与光在介质中传播的模型比较获取介质的光学参数。Fifth, according to the obtained modulation depth, the optical parameters of the medium are obtained by comparing with the model of light propagating in the medium.
本发明可以在3D重构上建模的应用。The invention can be applied to modeling in 3D reconstruction.
本发明可以在皮肤大面积成像的应用。The present invention can be applied in large-area imaging of skin.
本发明可以在内窥镜表面粘膜层大面积成像的应用。The present invention can be applied to large-area imaging of the mucous membrane layer on the surface of the endoscope.
本发明可以通过DMD投影一个相位的空间调制图案，同时也可以采用其他设备，而后则可以利用CCD获取采集待测物体漫反射后的反射光强，这里也可以使用CCD，光谱仪，光纤探头等技术。The present invention can project a spatial modulation pattern of a phase through the DMD, and other equipment can also be used at the same time, and then the CCD can be used to acquire and collect the reflected light intensity after the diffuse reflection of the object to be measured. CCD, spectrometer, fiber optic probe and other technologies can also be used here .
本发明可以通过单个相位的空间调制图案，快速的解析出MTF，解决了传统三相移存在的问题，同时，SSMD技术可以提高图像的信噪比。The invention can quickly analyze the MTF through the spatial modulation pattern of a single phase, which solves the problems existing in the traditional three-phase shift, and at the same time, the SSMD technology can improve the signal-to-noise ratio of the image.
步骤三中采用的单次快照多频解调法与传统标准三相移法相比，可在单幅空间调制频率图案中解调出反射光强的直流值IDC和针对每一调制频率相应的分流值IAC,i，并且保持较高的信噪比。克服了传统标准三相移法需3幅不同相位的空间调制频率图案才能正常工作，而引起的运动鬼影和无法实时解析的问题。由于不同的空间调制频率探测深度各不相同(空间频率越大探测深度越浅)。因此，多个空间调制频率组合，可以得到不同深度的光学信息，可以用于3D重构。Compared with the traditional standard three-phase shift method, the single snapshot multi-frequency demodulation method adopted in step 3 can demodulate the direct current value IDC of the reflected light intensity and the corresponding I DC for each modulation frequency in a single space modulation frequency pattern. shunt value IAC,i , and maintain a high signal-to-noise ratio. It overcomes the problems that the traditional standard three-phase shift method requires three spatial modulation frequency patterns with different phases to work normally, which causes motion ghosts and cannot be analyzed in real time. The detection depth varies with different spatial modulation frequencies (the larger the spatial frequency, the shallower the detection depth). Therefore, the combination of multiple spatial modulation frequencies can obtain optical information at different depths, which can be used for 3D reconstruction.
应用实例1：前臂反应性充血实验Application example 1: Forearm reactive hyperemia experiment
实验方案:Experimental program:
使用我们设计的实时SSMD-SFDI设备对志愿者(n＝6)手臂背面进行实时检测，DMD设备投射波长为623nm，540nm和460nm，空间频率f＝0.2的调制图案，探测器(Point GreyGrasshop3GS3-U3-51S5C)以每秒3帧的速度进行采集。志愿者按照如下实验方案：正常状3分钟，压脉带给手臂产生压强(200mmg)维持4分钟，释放压脉带休息3分钟，共采集10分钟。使用SSMD技术快速的解调出反射图案的直流和交流信息。Use the real-time SSMD-SFDI device we designed to detect the back of volunteers' (n=6) arms in real time. The DMD device projects modulation patterns with wavelengths of 623nm, 540nm and 460nm and spatial frequency f=0.2. The detector (Point GrayGrasshop3GS3-U3 -51S5C) was acquired at 3 frames per second. Volunteers followed the following experimental plan: 3 minutes in normal condition, the pressure cuff (200mmg) was maintained on the arm for 4 minutes, the cuff was released and rested for 3 minutes, and the collection was 10 minutes in total. Use SSMD technology to quickly demodulate the DC and AC information of the reflected pattern.
整个实验现象分析：Analysis of the whole experimental phenomenon:
图3显示了一个典型的被测者在前臂反应性充血实验中氧合血红蛋白浓度、脱氧血红蛋白浓度、总血红蛋白浓度和血氧饱和度变化过程。当袖带阻塞静脉和动脉的血流量时，由于远端静脉阻塞，血液淤积在皮下血管，使血管充血扩张，导致总血红蛋白(HbO2和Hb之和，(图3(c))轻微上升。血管阻塞导致组织中的氧快速消耗，使组织氧合血红蛋白(HbO2浓度，图3(a))快速下降，组织脱氧血红蛋白浓度(Hb，图3(b))增加。在袖口释放时，表现出典型的充血反应，大量新鲜血液流入在阻塞期间已耗尽血氧的组织中。如图3(a)袖带释放段。组织氧饱和度(StO2)最初为0.82，在袖带阻塞后降至0.56，最后在袖带释放后迅速回升到0.85。结合SSMD-SFDI系统和层状结构映射模型很好的剥离表皮层黑色素(图4)的影响，得到真皮层血氧变化(图3)，表皮层厚度和各层的光学信息(图5)(散射系数和各层的吸收系数)。Figure 3 shows the change process of oxygenated hemoglobin concentration, deoxygenated hemoglobin concentration, total hemoglobin concentration and blood oxygen saturation in a typical test subject in the forearm reactive hyperemia test. When the cuff blocks blood flow in veins and arteries, due to distal venous occlusion, blood stagnates in the subcutaneous vessels, congesting and dilating the vessels, resulting in a slight increase in total hemoglobin (the sum of HbO and Hb, (Fig.3 (c)). Vascular occlusion leads to rapid consumption of oxygen in tissues, resulting in a rapid decrease in tissue oxyhemoglobin (HbO2 concentration, Fig. 3(a)) and an increase in tissue deoxygenated hemoglobin concentration (Hb, Fig. 3(b)). Upon cuff release, the expression A typical hyperemia reaction, a large amount of fresh blood flows into the tissue that has depleted blood oxygen during the occlusion period. As shown in Figure 3(a) the cuff release section. The tissue oxygen saturation (StO2 ) was initially 0.82, and after the cuff occlusion It dropped to 0.56, and finally rose quickly to 0.85 after the cuff was released. Combined with the SSMD-SFDI system and the layered structure mapping model, the effect of peeling off the epidermal melanin (Figure 4) was very good, and the blood oxygen changes in the dermis were obtained (Figure 3) , the thickness of the epidermis and the optical information of each layer (Fig. 5) (scattering coefficient and absorption coefficient of each layer).
应用实例2：黑痣生理信息和光学信息检测Application example 2: Mole physiological information and optical information detection
使用SSMD-SFDI系统与层状结构映射模型相结合对皮肤的黑痣进行检测。Using SSMD-SFDI system combined with layered structure mapping model to detect skin moles.
通过SSMD-SFDI系统，可以区分黑痣区域与旁边正常区域丰富的光学信息和生理信息，如图6所示。Through the SSMD-SFDI system, the rich optical information and physiological information of the nevus area and the adjacent normal area can be distinguished, as shown in Figure 6.
图7分别得到各波长下(λ＝460nm,540nm,623nm)表皮层(a-c)，真皮层的吸收系数(d-f)，散射系数(λ＝540nm,g)和散射能力(h)。图8分别得到了含氧血红蛋白(a)，缺氧血红蛋白(b)，总血红蛋白(c)，血氧饱和度(d)，黑色素(e)和表皮层厚度(f)。Fig. 7 respectively obtains (λ=460nm, 540nm, 623nm) epidermis (a-c), dermis absorption coefficient (d-f), scattering coefficient (λ=540nm, g) and scattering ability (h) under each wavelength. Figure 8 obtained oxygenated hemoglobin (a), hypoxic hemoglobin (b), total hemoglobin (c), blood oxygen saturation (d), melanin (e) and epidermal layer thickness (f).
通过2个实验的应用，充分证明了SSMD-SFDI系统和层状结构映射模型的可行性，以此我们可以得到区域组织实时的，连续的，2维的多个生理参数时间变化图。Through the application of two experiments, the feasibility of the SSMD-SFDI system and the layered structure mapping model has been fully proved, so that we can obtain real-time, continuous, 2-dimensional time-varying maps of multiple physiological parameters of regional tissues.
实施例不应视为对本发明的限制，任何基于本发明的精神所作的改进，都应在本发明的保护范围之内。The embodiment should not be regarded as limiting the present invention, and any improvement based on the spirit of the present invention should be within the protection scope of the present invention.
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| CN201711041861.4ACN107802269A (en) | 2017-10-30 | 2017-10-30 | Real-time single snap shot multifrequency demodulation spatial frequency domain imaging method |
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