US Patent 7317527 Spatial light modulator fourier transform

A filter to selectively block light from passing through the filter and to selectively permit light to pass through the filter. The filter includes an array with a plurality of individually addressable filter elements. Each filter element is selectively settable to have a variable transmittance to the light of between substantially zero percent and substantially one hundred percent. In this manner, the filter according to the present invention provides areas that pass only a portion of the light, and thus can block the light using patterns other than just an abrupt on/off filtering. By so doing, the filter is able to dramatically reduce, and in some embodiments eliminate, the light ringing that typically accompanies such on/off filters.