纸质遮挡物对太赫兹二次曝光数字全息的影响  

Influence of Paper Shelters on Terahertz Double Exposure Digital Holography

作　　者：成珂阳 李琦[1] Cheng Keyang;Li Qi(State Key Laboratory of Science and Technology on Tunable Laser,Harbin Institute of Technology,Harbin,Heilongjiang 150080,China)

机构地区：[1]哈尔滨工业大学可调谐激光技术国家级重点实验室,黑龙江哈尔滨150080

出　　处：《中国激光》2021年第20期195-205,共11页Chinese Journal of Lasers

基　　金：国家自然科学基金(61377110)。

摘　　要：太赫兹数字全息成像过程中,遮挡物的透过率、噪声等因素均会影响成像效果;而太赫兹成像技术在安全检测、医学成像等方面具有广泛的实际应用,因此遮挡物成为需要研究的重要问题。针对2.52 THz波进行了纸质遮挡的二次曝光数字全息成像的研究。通过实验估测B5纸和热敏纸的噪声分布和透过率以及探测器引起的误差,确立了仿真模型的参数,并仿真了两种纸张遮挡的影响。通过实验获得了热敏纸遮挡的横向分辨率为0.2 mm的目标及B5纸遮挡的横向分辨率为0.3 mm的目标等的重建振幅像。热敏纸遮挡的0.3 mm分辨率目标与外围区域的对比度为0.46,偏差为0.07,这最接近遮挡物仿真结果。Objective In terahertz digital holographic imaging,factors such as the transmittance and noise of shelters will affect the imaging effect,and when combined with practical applications of terahertz imaging technology such as security detection and medical imaging,shelters have become an important issue that needs to be studied.Double-exposure digital holography can achieve better imaging quality than single-exposure for relatively stationary targets.According to our investigation,there are no reports on the influence of shelters in terahertz double-exposure digital holography.Paper is a common material that does not transmit visible light but has high terahertz wave transmittance,and it is easy to change the noise and transmittance conditions in the experiment by changing the material;thus,studying the influence of paper shelters in the terahertz imaging process has a good reference value for the use of other materials.Methods In this study,the imaging results and objective evaluation indexes of material targets with lateral resolutions of 0.2 mm and 0.3 mm under different shelters are obtained through simulation and experiments by the D-APRA(double-exposure amplitude constrained phase retrieval algorithm)using a terahertz double-exposure digital holographic imaging system with a wavelength of 118.83μm,a detector pixel size of 0.1mm,and a pixel number of124×124.Through comparative analysis,we study the effect of B5paper and thermal paper on the reconstruction of amplitude images.Results and Discussions First,the transmittance and noise distribution of a single sheet of B5paper and thermal paper are measured to determine the shelter’s simulation parameters (Fig.4).The transmittances are 0.4 and 0.7,respectively,with 0.002and 0.006Gaussian noise variances.Second,the detector’s noise parameters are deduced from the experimental data.The mean value of the detector’s Gaussian noise is about 0.15,and the variance is about 0.0009(Fig.5).The imaging results of two targets with resolutions of 0.2mm and 0.3mm under

关 键 词：成像系统 太赫兹数字全息 二次曝光 遮挡物 

分 类 号：TN29[电子电信—物理电子学]