摘要
为了克服在数字全息术中激光源高相干度造成的散斑噪声降低成像质量问题,论文提出将石英退偏器与电控液晶散射片相结合用于数字全息术中。通过在物光路中加入一个石英退偏器,利用退偏器的退偏性能使物光光路中的线偏光变成随机偏振光,降低与参考光的相干程度,实现对散斑噪声的抑制;通过给液晶散射片外加电场可以引起液晶分子的运动和光轴取向改变,调整液晶驱动电压大小来改变入射光的不同散射效果,有效地降低了光源的相干性;分别将单独采用石英退偏器和电控液晶散射片的重建图像与组合装置的重建图像进行对比分析,通过实验验证了所提方法的有效性。实验结果表明:两种实验对象在组合装置下的重建像峰值信噪比分别达到16.91和18.30,结构相似度为0.47和0.43,等效视数较原始重建像提高了42%和30%,散斑指数为1.52和1.29。论文提出的方法可较好地去除散斑噪声,保留更多的图像细节部分。
In digital holography, the speckle noise caused by the high coherence of laser source will reduce the imaging quality. In order to overcome this problem, the combination of a quartz depolarizer and an electronically controlled liquid crystal diffuser for digital holography was proposed. By adding a quartz depolarizer to the object light path, the depolarization performance of the depolarizer was used to make the linearly polarized light in the object light path into randomly polarized light, which reduced the degree of coherence with the reference light and realized the suppression of speckle noise. By applying an electric field to the liquid crystal diffuser, the movement of the liquid crystal molecules and the orientation change of the optical axis could be caused. The liquid crystal driving voltage could be adjusted to change the different scattering effects on the incident light, thereby effectively reducing the coherence of the light source. The reconstructed images using the quartz depolarizer and the electronically controlled liquid crystal diffuser were compared and analyzed respectively with the reconstructed images of the combined device. The effectiveness of the proposed method was verified by experiments. The experimental results show that the peak signal to noise ratio of the reconstructed images of two experimental objects under the combined device reaches 16.91and 18.30, the structural similarity is 0.47 and 0.43, the equivalent number of looks is 42% and 30% higher than the original reconstructed image, and the speckle index is 1.52 and 1.29, respectively. The proposed method can better remove the speckle noises and retain more details of the image.
作者
王春阳
孔勇
李欢
吴虎
张贺
王梦
WANG Chunyang;KONG Yong;LI Huan;WU Hu;ZHANG He;WANG Meng(School of Electrical and Electronic Engineering,Shanghai University of Engineering Science,Shanghai 201620,China)
出处
《应用光学》
CAS
北大核心
2023年第2期275-285,共11页
Journal of Applied Optics
基金
上海市自然科学基金(19ZR1421700)。
关键词
数字全息
噪声抑制
液晶
退偏器
偏振态
digital holography
noise suppression
liquid crystal
depolarizer
polarization state
