Abstract: A high-precision microsphere radius measurement model was proposed based on the principle of rotary axis method and two-point method， and the microsphere roundness evaluation was realized based on the amount of radius changes. A model was established that might separate the spindle runout errors and calculate the corresponding radius of each measurement points. Using the microsphere roundness measurement system developed by the authors group based on a high-precision air-bearing rotary table and two Michelson interferometers， the equatorial circular cross section of a ruby sphere with a nominal diameter of 300 μm and a roundness of 250 nm was scanned and measured. The roundness of the measured microsphere was evaluated by the minimum zone circle method， based on the measured radius by the proposed model and the calculated radius by the diameter. The results show that the roundness of the microspheres obtained by the proposed model and the conventional diameter evaluation method are as 280 nm and 403 nm with standard deviations of 2 nm and 23 nm， respectively， the proposed radius measurement model is accurate and reliable， and the roundness of the microspheres evaluated by the proposed model and the minimum zone circle method is more accurate and reliable. The proposed method may be used to obtain the radius of the measured microspheres easily and accurately， and may be applied to the accurate evaluation of the roundness of microspheres.

Key words: two-point method, roundness measurement, microsphere, error separation

摘要： 提出了一种基于回转轴法和两点法原理的高精度微球半径测量模型，实现了基于半径变化量的微球圆度评定。建立了可以分离主轴跳动误差和计算各测量点对应半径的模型。利用团队开发的基于高精度气浮转台和两个迈克尔逊干涉仪的微球圆度测量系统，对标称直径为300 μm、圆度为250 nm的红宝石球的赤道圆截面进行了扫描测量。将采用所建模型测得的微球半径与采用直径算得的半径进行对比，并通过最小区域法对所测微球圆度进行评定，结果表明：所建模型与传统直径评定方法得到的微球圆度分别为280 nm和403 nm，标准差分别为2 nm和23 nm，所建微球半径测量模型准确可靠，利用所建模型和最小区域法评定出的微球圆度更加准确可靠。所建模型可以方便准确地获得被测微球的半径，可应用于微球圆度准确评定。

关键词: 两点法, 圆度测量, 微球, 误差分离