Type of waveplate
According to the structure, the waveplate can be divided into three types: multi-order waveplate, composite waveplate and true zero-order waveplate.
The true zero-order waveplate has low wavelength sensitivity of retardation, high temperature stability, large effective acceptance angle, and its performance is much better than the other two waveplates. However, true zero-order waveplates are often very thin. Taking quartz as an example, its birefringence coefficient in the visible part is about ~0.0092. A true zero-order quarter-quartz waveplate with a center wavelength of 550nm has a thickness of only 15um. Such a thin waveplate will encounter many difficulties in manufacture and use.
The thickness of the multi-stage waveplate is equal to the thickness of multiple full waves plus a thickness of required retardation. Multi-order waveplates are relatively easy to manufacture, but their disadvantages are that they are sensitive to wavelength, temperature, and incident angle.
A composite waveplate is two multi-level waveplates glued together. The full-wave optical path difference is eliminated by aligning the fast axis of one waveplate with the slow axis of the other waveplate, leaving only the desired optical path difference. The glued waveplate can improve the influence of temperature on the waveplate to a certain extent, but another result is that it increases the sensitivity of the retardation of the waveplate to the incident angle and wavelength.
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