Abstract An 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

中文翻译：

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基于光强相关性的双色双曝光粒子追踪测速中的颜色污染校正

摘要 针对双色双曝光粒子跟踪测速(PTV)，提出了一种颜色污染校正算法。本研究中使用的双色 PTV 系统由蓝色和绿色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，用于实现 50 ns 的光脉冲，以应用于气流。在 PTV 中，相机捕捉由一系列绿色和蓝色光脉冲以特定时间间隔照射的示踪粒子图像。由于拜耳滤光片的光谱特性，蓝色通道中的相机传感器会对粒子散射的绿光做出响应。这种颜色污染会导致蓝色通道中出现伪粒子。伪粒子占据的像素在绿色和蓝色通道之间具有非常高的光强度相关性。在所提出的方法中，基于高相关性检测并去除由颜色污染引起的伪粒子。目前的颜色污染校正几乎不会影响由蓝色激光二极管照射的真实粒子。由直流风扇引起的气流测量证实，建议的带有颜色污染校正的系统适用于 PTV。图形摘要