Single-grid moire interferometer

A moire interferometer is described which uses only one grid rather than th e more normal two. The instrument is useful in line imaging applications wh ere the object must be well separated from the optics, such as in productio n environments. Depth resolution can be changed simply by replacing the moi re grid, which does not require system re-alignment. The design equations f or the system are derived and the design process is described. An example i nstrument has been assembled and performance results are presented.