基于图像功率谱的激光散斑评价方法

Laser speckle evaluation methods based on power spectrum of images

激光散斑在相干光成像、全息术、多模光纤通信、计量等领域具有重要的应用。为了对激光散斑进行评价,提出一种在频域采用散斑图像功率谱谱宽作为激光散斑评价的方法,设计了一种基于光纤振动的功率谱散斑评价实验装置。采用0.5W,532nm激光作为光源,通过电压驱动音圈电机振动光纤对激光散斑进行控制,利用CCD图像采集卡采集图像后,分别采用散斑图像的对比度方法和功率谱方法对不同驱动电压下的散斑图像进行了分析评价。结果表明,功率谱方法具有较高的灵敏度及较宽的评价范围。

Laser speckle has important applications in many areas, such as optical coherence tomography,holography,multimode optical fiber communication and metrology. In order to evaluate the laser speckle,the power spectrum width of speckle image in frequency domain was proposed as the evaluation method of laser speckle. The experiment device of power spectrum speckle evaluation was designed based on optical fiber vibration. A 0. 5W,532 nm laser was used as light source and a voltage-driven voice coil motor was used to vibrate the fiber and control laser speckle.A CCD image acquisition card was used to collect images. Speckle contrast method and power spectrum method were respectively used to evaluate the speckle images under different driving voltages. The results show that the method of power spectrum has higher sensitivity and wider range of evaluation.