Color contamination correction based on light intensity correlation in two-color, double-exposure particle tracking velocimetry
Color contamination correction based on light intensity correlation in two-color, double-exposure particle tracking velocimetry
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DOI：
10.1007/s00348-020-02964-0
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发表时间：
2020-06
影响因子：
2.4
通讯作者：
Kentaka Aruga;Tomoaki Watanabe;K. Nagata
中科院分区：
文献类型：
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作者：
Kentaka Aruga;Tomoaki Watanabe;K. Nagata
摘要针对双色双曝光粒子跟踪测速仪(PTV)，提出了一种颜色污染校正算法。本研究中使用的双色PTV系统由蓝绿激光二极管和消费类数码相机组成，其中开发了带有雪崩晶体管的激光脉冲发生器，以获得50 ns的光脉冲，用于气流中。在PTV中，相机捕捉到示踪剂颗粒被一定时间间隔的一系列绿光和蓝光脉冲照射的图像。由于拜耳滤光片的光谱特性，蓝色通道中的摄像头传感器对粒子散射的绿光做出反应。这种颜色污染会导致蓝色通道中出现伪粒子。被伪粒子占据的像素在绿色和蓝色通道之间具有很高的光强度相关性。在该方法中，基于较高的相关性，检测并去除了由颜色污染引起的伪颗粒。目前的颜色污染校正对蓝色激光二极管照射的真实粒子几乎没有影响。对直流风扇诱导的气流的测量证实，所提出的系统具有颜色污染校正功能，适用于PTV。
AbstractAn algorithm for correcting color contamination is proposed for two-color, double-exposure particle tracking velocimetry (PTV). A two-color PTV system used in this study consists of blue and green laser diodes and a consumer digital camera, where a laser pulser with an avalanche transistor is developed for achieving optical pulses of 50 ns for application in airflows. In the PTV, the camera captures images of tracer particles illuminated by a sequence of green and blue light pulses with a certain time interval. Because of spectral characteristics of a Bayer filter, camera sensors in a blue channel respond to green light scattered by the particles. This color contamination results in pseudo-particles in the blue channel. Pixels occupied by the pseudo-particles have very high correlation of light intensity between green and blue channels. In the proposed method, the pseudo-particles caused by the color contamination are detected and removed based on the high correlation. The present color contamination correction hardly affects real particles illuminated by the blue laser diodes. Measurements of an airflow induced by DC fans confirm that the proposed system with the color contamination correction works well for PTV.Graphic abstract