一种用于厚度在线检测的光学装置

An Optical Device for On-Line Measurement of Thickness

设计并制作了一套基于迈克耳孙结构的光学装置,可用于利用干涉的方法对单层的透明或半透明薄膜或光学平片的厚度做在线检测,测量范围可从微米到毫米量级。该装置采用光胶工艺将不同长度和不同热特性的玻璃材料组合在一起,使装置能够对环境温度变化做自动补偿;同时,输入和输出光信号的光纤准直器与装置为一个整体,因此在检测过程中不像普通干涉系统一样易受外界干扰。使用Agilent波长测试仪对装置产生的干涉信号做检测,在振动的环境中,测量自由光谱范围(FSR)变化的95%置信区间为±0.0005 nm,体现了很好的抗干扰能力。为了演示该装置用作自动实时在线检测的可行性,检测了厚度为(177.4±0.7)mm的标准盖玻片,其结果与现有商用系统可比较。

An optical device based on Michelson interferometer configuration is introduced, which can be used for on-line film thickness measurement. Optical cement is used to splice the glass modules with different lengths and thermal properties, so that the device can make compensation to the environmental temperature variation. Additionally, the double-fiber collimator which is used to input and output the optical signal and the device containing the glass modules are a whole. So the device will not be disturbed by the environment compared to the other interferometers during testing. The stability of the device is tested by an Agilent wavelength measurement system, and the output interference signal shows the excellent performance that the 95% confidential interval of the variation of the free spectral range （FSR） is ± 0.0005 nm in the disturbed environment （while the acquisition resolution of the Agilent system is 0.001 nm）. So we believe this device can be used for on-line interference measurement. To demonstrate the feasibility of the automatic measurement of this device in real-time, the thickness of the cover slice is measured, the result is （177.4± 0.7）μm, which is comparable with the commercial thickness measurement equipment.