2D Walter mirror
A 2D Walter mirror consists of an ellipsoidal face and a hyperboloidal face on a single substrate. The Advanced KB mirror (1D Walter mirror) is a focusing system requiring four reflections in vertical and horizontal directions and both elliptical and hyperbolic shapes. A 2D Walter mirror realizes the same optical system with only two reflections.
The 2D Walter mirror has a shape with steep curvature in the sagittal direction in addition to being an ellipsoidal mirror. Therefore, shape measurement with high accuracy is difficult. Additionally, the high accuracy in the relative positional relationship between the ellipsoidal and hyperboloidal surfaces is very important.
JTEC Corporation has developed 3D shape measuring equipment that can realize a high-precision 2D Walter mirror.