Absolute measurement approach for crystal growth height based on a polarization-synchronized phase-shifting interferometer.

The quality of the solid deuterium-deuterium (D-D) layer in the inertial confinement fusion (ICF) target plays a vital role in the success of fusion experiments. A good understanding of how the quality is affected by the unstable growth of D-D crystal is required. This article provides an approach of measuring D-D layer absolute height in real time by combining monitoring algorithms and a synchronous phase-shifting interferometer. In the approach taken, a real-time monitoring technology, in which an antivibration algorithm is added, is used to get an absolute height of monitoring zone, overcoming the inability to accurately detect the saltus step in the interferometric measurement. Meanwhile, the polarization-synchronized phase-shifting technology is propitious to retrieve the D-D height distribution in a whole interferogram. Consequently, the categorical altitude of the D-D layer in entire crystalline regions can be obtained. Simulation analysis together with experiments have proved that a non-contact, rapid, and high-precision measurement of the D-D crystal absolute height can be realized by using the interferometer and method proposed.