激光与光电子学进展, 2017, 54 (6): 060901, 网络出版: 2017-06-08
高通滤波器尺寸对粒子离轴滤波全息像的影响
Effect of the Size of High-Pass Filter on the Off-Axis Particle Holographic Image
摘要
粒子场离轴滤波全息技术是减少背景噪声影响、改善粒子场再现像质量的有效方法。滤波器尺寸与再现粒子像密切相关,合适的滤波器尺寸有利于粒子的识别和测量。解析分析了高通滤波器尺寸、4F系统前焦距及粒径对圆形粒子离轴滤波全息再现像强度分布的影响规律,数值模拟了不同尺寸的高通滤波器对相同粒径粒子全息再现像强度分布的影响,并开展了离轴滤波全息实验。研究结果表明,高通滤波器可以有效提高粒子图像的对比度;粒子尺寸不变时,滤波器尺寸越小或4F系统前焦距越大,再现粒子像强度分布越均匀,同时边界梯度越大;滤波器尺寸和4F系统前焦距恒定时,粒子越大,再现粒子像内部逐渐呈现明暗相间变化的圆环,同时粒子边界越来越清晰。
Abstract
The holography of particle field by off-axis filter is an effective method for reducing the background noises and improving the reconstructed image quality. The filter size and the reconstructed particle image are closely related, a suitable filter size is important for the particle recognition and measurement. The relationship between the high-pass filter size, front focal length of 4F system, particle size and the intensity distribution of holographic reconstructed images of circle particle by off-axis filter are analyzed respectively, and the influences of different high-pass filter sizes on the same size particle images are simulated numerically. In addition,the off-axis filtering holography experiment is carried out. The results show that, the particle image contrasts are increased effectively by the high-pass filter. The uniformity of the reconstructed image intensity distribution becomes better, and the boundary gradient increases with the smaller the filter size or the larger the front focal length of 4F system, while with the increasing of particle size, some black and white circles appear gradually in the reconstructed particle image interior, and the particle boundary becomes increasingly clear.
张连永, 徐青, 曹娜, 曹亮, 李斌康, 刘运牙, 雷岚. 高通滤波器尺寸对粒子离轴滤波全息像的影响[J]. 激光与光电子学进展, 2017, 54(6): 060901. Zhang Lianyong, Xu Qing, Cao Na, Cao Liang, Li Binkang, Liu Yunya, Lei Lan. Effect of the Size of High-Pass Filter on the Off-Axis Particle Holographic Image[J]. Laser & Optoelectronics Progress, 2017, 54(6): 060901.