Imaging laser diffractometer for traceable grating pitch calibration
Imaging laser diffractometer for traceable grating pitch calibration
复制标题
用于可追踪光栅间距校准的成像激光衍射仪
DOI：
10.1088/0957-0233/18/2/s08
复制
发表时间：
2007
影响因子：
2.4
通讯作者：
J. Decker
中科院分区：
文献类型：
--
作者：
J. Pekelsky;B. Eves;P. R. Nistico;J. Decker
加拿大国家研究委员会（NRC）正在研发一种用于校准光栅间距的激光衍射仪。它基于瑞士联邦计量研究院（METAS）的设计，具有一个精密转台，样品光栅采用利特罗（Littrow）配置安装，一个准直的空间滤波激光源，以及由分束器通过聚焦透镜将回射衍射级发送到零位光电探测器。可以依次测量各种衍射级的角度，并结合激光波长的知识来计算光栅的间距。NRC系统使用电荷耦合器件（CCD）摄像机来捕捉衍射图案的图像，而非通常的四象限光电探测器。图像处理能够精确测量衍射级质心坐标，不会因背景噪声或相邻图案伪影而产生系统误差。图像坐标系还用于调整仪器和光栅的对准，并研究这些系统误差的来源。本文给出了间距在700纳米到10微米之间的一维样品光栅的初步结果。
A laser diffractometer for calibrating grating pitch is being developed at the National Research Council (NRC). Based on the METAS design, it features a precision rotary table, the sample grating mounted in Littrow configuration, a collimated spatially filtered laser source and the retroreflected diffraction order sent by a beamsplitter through a focusing lens to the null-position photodetector. The angle of various diffraction orders can be measured in sequence and used with knowledge of the laser wavelength to calculate the pitch of the grating. Instead of the usual quad-photodetector, the NRC system uses a charge-coupled device (CCD) video camera to capture an image of the diffraction pattern. Image processing accurately measures diffraction order centroid coordinates without a systematic error due to background noise or neighbouring pattern artefacts. The image coordinate system is also used to adjust the instrument and grating alignment and to investigate these sources of systematic error. Preliminary results with 1D sample gratings ranging in pitch from 700 nm to 10 µm are presented.