利用激光回馈测量波片相位延迟精度高的优越性，以激光回馈技术为基础，实现光学波片的在盘测量，即在加工过程中，波片光胶于光胶盘的状态下测量波片位相延迟，以提高波片生产效率和成品率。采用凹面镜作为回馈镜以提高回馈信号调制深度,对激光回馈内、外腔长进行稳定,提高了系统可靠性; 研究了波片与光胶盘光胶对波片测量的影响，提出并验证了在光胶盘上开孔，在打孔的光胶盘上光胶、加工、测量波片的新工艺，最终实现了波片在盘测量，测量长期重复性优于1°，经过激光频率分裂系统校正后，系统精度优于0.5°。

A technique to measure the phase difference of wave plate in the process of wave-plate production is introduced. It is based on the laser feedback method and achieves the ‘on contact block’ measurement, which means to measure the wave plate when it is bonded on the contact block. On the basis of achieving on contact block measurement, we studied the stabilization of laser cavity length, the influence of the radius of feedback mirror and the optical contact bonding layer. The system reaches the measurement uncertainty of 1° and the measurement precision of 0.5°.