| 摘要 |
In a system for producing a three-dimensional image (45) of a corneal surface (30), a laser beam (27) passes through a beamsplitter (26) and objective lens (38) to impinge on the cornea (30), and is reflected back through the objective lens. The return beam (37) is reflected by the beamsplitter (26) through an imaging lens (40) and dual phase plate (42) onto an imaging screen (43), and onto a photosensitive array (44). The dual phase plate includes periodic features along two orthogonal directions, and is incremented at 45 degrees relative to these two directions, simultaneously producing phase shear along both directions. The resulting intensities at each pixel of a CCD camera (44) are digitized for computation of an "OPD phase map" of the deviation of the corneal surface from the impinging spherical wavefront. Various d-spacings of the dual phase plate, in conjunction with corresponding capture intervals during incrementing, allow scaling of the system for "close-up" viewing of the cornea. |
