Technologies

The Fourier moiré sensor represents a huge advance over other moiré deflectometry techniques, which typically require computer Fourier-transform and phase-shifting algorithms. A vast array of computer routines has been written to “automatically” process data, all of which require the ability to resolve and determine where the fringes are – not a trivial task when fringes close into loops or branch. Because in the present invention optical Fourier processing is automatically performed within the optical device, information is available literally at the speed of light, the deflectogram does not have to be digitized, and the fringes do not have to be resolved by detection equipment. Hence resolution is determined by pixel size, not fringe spacing or algorithm matrix size.
There are also other advantages over currently used techniques. For example, the Schlieren technique gives the magnitude of wavefront distortion, but not the sense of curvature. The device known as the Shack-Hartmann sensor is vastly popular for wavefront correction, but suffers from trade-offs between diffractive effects and sensitivity. A Shack-Hartmann system can also cost upwards of $30,000. The Fourier moiré wavefront sensor overcomes the technical difficulties of previous techniques, at minimal cost – it can be constructed of items typically found in any teaching laboratory. The device could actually be housed much like camera-lenses are. This way, important parameters, such as relative grating angle and grating separation, can easily be adjusted and measured in order to vary sensitivity and dynamic range.