Kang Chu-Shik, Kim Jong-Ahn, Eom Tae Bong, Jang Roma, Park Hae Yong, Kim Jae-Wan
Length & Time Metrology Center, Physical Metrology Division, Korea Research Institute of Standards and Science, Yuseong-Gu, Daejeon, Republic of Korea.
Opt Express. 2009 Feb 2;17(3):1442-6. doi: 10.1364/oe.17.001442.
We present a high speed phase shifting interferometer which utilizes the self injection locking of a frequency tunable laser diode. By using a confocal Fabry-Perot cavity made of ultra low expansion glass, and linearly modulating the laser diode current, the laser frequency could be injection locked to the resonant modes of the Fabry-Perot cavity consecutively. It provided equal phase steps to the interferograms which are ideal to be analyzed by the Carré algorithm. The phase step error was evaluated to be about 3 MHz which corresponds to 0.2 nm in length measurement. With this technique, profile measurements are insensitive to external vibration since four 640x480 pixels images can be acquired within 4 ms. Difference of two profile measurements, each made with and without vibration isolation, respectively, was evaluated to be 0.5 nm (rms).
我们展示了一种高速相移干涉仪，它利用了频率可调谐激光二极管的自注入锁定。通过使用由超低膨胀玻璃制成的共焦法布里-珀罗腔，并对激光二极管电流进行线性调制，激光频率可以连续地注入锁定到法布里-珀罗腔的谐振模式。它为干涉图提供了相等的相位步长，这对于用卡雷算法进行分析是理想的。相位步长误差经评估约为3兆赫兹，这在长度测量中对应于0.2纳米。采用这种技术，轮廓测量对外部振动不敏感，因为可以在4毫秒内采集到四张640×480像素的图像。分别在有和没有隔振的情况下进行的两次轮廓测量的差异经评估为0.5纳米（均方根）。
