Twyman effect in thin curved optics
Friday, March 26, 2021
Grinding of thin curved optics introduces surface-localized stresses that causes bending deformations. These deformations depend on the local thickness of the optic as well as curvature. We use numerical techniques and analytical solutions to assess the effect of these variables on shallow and deeply curved axisymmetric optics. A flat optic of similar thickness serves as a useful metric of comparison for shallow optics. For deeply curved optics, deformations are smaller and concentrated in a boundary layer close to the optic free-edge. In assessing the effect of local thickness on the Twyman effect, we use only numerical results due to the absence of analytical solutions. Our results show that positive optics (thickness at the center greater than the tip) are well approximated by constant thickness optics. However, in the case of negative optics, deformations near the apex are more pronounced thus extending significant deformation throughout the optic.