平面近场测试高斯波束束腰半径的方法

高斯波束理论广泛应用于准光学、毫米波领域，束腰半径作为高斯波束最重要的参数，在工程应用中具有重要价值，有必要对其进行精确测量。提出了一种基于平面近场测试高斯波束束腰半径的方法，对准光学、毫米波装置的出射波束进行平面近场测试，根据采集的近场数据，反演远场方向图计算出束腰半径大小。进一步对近场电场数据进行高斯函数拟合及后处理，并利用高斯波束传输理论计算出束腰半径位置。本方法完全借用平面近场测试条件，通用性好，特别是解决了大口径装置束腰半径难以测试的难题。

Method for Measuring Gaussian Beam Waist Radius of Using Near Field Measurement

Gaussian beam theory is widely used in quasi-optic and millimeter wave field. The beam waist radius is the key parameter for Gaussian beam and has important value in engineering application, so it is necessary to confirm its exact value accurately. This paper proposes a method to measure Gaussian beam waist radius using near field measurement. The outgoing beam of quasi-optic or millimeter wave device is measured, and the value of beam waist radius is computed by far field pattern which is transformed by near field data. The position of beam waist is computed by Gaussian beam transmission theory through Gaussian function fitting and post-processing of near field data. This method works completely under the plane near field measurement condition, so it has good versatility. Especially, it solves the difficulty to measure the beam waist radius of large diameter device.