Acta Photonica Sinica, Volume. 47, Issue 2, 205001(2018)
Locking of the Fringe Position and Period in Largesize Holographic Grating Exposure
The position and period of grating fringes will vary against the substrate during double beam interference exposure due to temperature variation, air flow, vibration and other factors in the fabrication of largesize holographic gratings. It will result in the decrease of grating contrast. The dynamic change of fringes was analyzed during largesize grating exposure. The RootMeanSquare (RMS) errors of fringe translation and period in 3 hours are 1.87 and 1.20 period respectively. The corresponding simulative grating contrasts are 12.83% and 67.37% respectively. A fringe locking system composed of three monitoring subsystems, a computation and control subsystem and two piezo nanopositioners was set up. The translation and period of fringes can be locked at the same time. The groove shape and contrast of gratings are improved significantly after locking. The precision of this fringe locking system: the 3σ value of fringe translation and corresponding contrast are 0.009 period and 99.99% respectively; the RMS error of period change and corresponding contrast are 0.017 period and 99.77% respectively. This locking system satisfies the requirements of fringe stability for the exposure of largesize gratings.
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ZHANG Dong, ZHAO Chengqiang, XU Wendong, ZHANG Yibin, YAN Yuqi. Locking of the Fringe Position and Period in Largesize Holographic Grating Exposure[J]. Acta Photonica Sinica, 2018, 47(2): 205001
Received: Aug. 14, 2017
Accepted: --
Published Online: Jan. 30, 2018
The Author Email: Dong ZHANG (zhangdongsdu@163.com)