物理学报2016，Vol.65Issue(8)：084201-1-084201-7,7.DOI:10.7498/aps.65.084201
浑浊介质中图像对比度与成像方式的关系∗
Image contrast for different imaging metho ds in turbid media
摘要
Abstract
The physics-based methods that can effectively improve the image contrast in turbid media while truly preserving all the detailed information, have received great attention in recent years. The range-gated imaging (RGI), polarization difference method (PD) and polarization-based range-gated technology (PRG) are three effective methods of enhancing the contrast. However, the relationship between the extent of contrast enhancement and the imaging distance for each method has not been revealed. In this paper, a compact disc (CD) plate is set to be in the intralipid with different concentrations contained in a glass cell and imaged by RGI, PD, PRG and raw intensity imaging (RI). The Indian ink is used as the absorber which eliminates the multiple scattered photons and achieves the range-gated technology. In order to investigate the number of the scattered photons filtered out by the 4 methods, the image intensity curves are acquired while the imaging distance, the distance between the target surface and the front surface of the cell, is set to be 26 mm. The results indicate that PRG filters out the largest number of the scattered photons, followed by PD and RGI because the long imaging distance results in more multiple scattering photons. Then the influence of the imaging distance on the image intensity is investigated by the 4 methods. The image intensity is recorded while the imaging distance varies from 22 mm to 30 mm with even increments. Then four sets of intensity curves are plotted against the imaging distance corresponding to RI, RGI, PD and PRG respectively. Based on the RI, three sets of image intensity difference curves of RGI, PD and PRG are also calculated. The tendencies of the curves show that these imaging methods have their own imaging distance thresholds. It implies that the numbers of the photons filtered out by these methods are all constant when their imaging distances exceed their thresholds of 22 mm, 30 mm and 30 mm, respectively. Finally, the effect of the imaging distance on the contrast variation is studied in turbid media with two different scattering coefficient 0.714 cm−1 and 1.19 cm−1. The results show that PRG is superior to other methods in contrast enhancement. In addition, the imaging distances of the 4 methods under the same image contrast are obtained, showing that under the same contrast increment, the PRG presents the largest imaging distance enhancement, followed by PD, RGI and RI. The increase of scattering coefficient could also cause the decrease of the imaging distance. These results can be very useful to understand the mechanism of imaging in turbid media and are of great significance for improving the ability to recognize the target.关键词
偏振差分/距离选通/偏振距离选通/对比度Key words
polarization difference imaging/range-gated imaging/polarization-based range-gated tech-nology/contrast引用本文复制引用
田恒,朱京平,张云尧,管今哥,侯洵..浑浊介质中图像对比度与成像方式的关系∗[J].物理学报,2016,65(8):084201-1-084201-7,7.基金项目
中央高校基本科研业务费(批准号：xkjc2013008)和北京石油化工学院光机电装备技术北京市重点实验室开放课题基金(批准号:KF2014-01)资助的课题.* Project supported by the Fundamental Research Funds for the Central Universities, China (Grant No. xkjc2013008) and the Beijing Area Key Lab of Opto-Mechatronic Equipment Technology, China (Grant No. KF2014-01) （批准号：xkjc2013008）
