Abstract: An optical notching filter is disclosed in which an optical spatial filter therein is formed by a spatial light modulator which is written into by light. The optical notching filter system of the present invention provides a linear phase and amplitude response with applications for high speed adaptive filtering to filter out noise and signals of no interest. In one particular disclosed embodiment, the write with light optical notching filter system of the present invention is designed to adaptively excise interference from Radio Frequency (RF) signals, such as are utilized in communications or radar systems. The technical approach of the present invention provides a more compact system design than similar electronically addressed optical notching filtering systems, and also significantly reduces the complexity and attendant power requirements of the system. Different embodiments of a write with light optical notching filter system can operate with either nonochromatic or polychromatic light sources.

Abstract: An optical notching filter in which a band of radio frequencies such as the RF input of a radio receiver is an input signal. The input signal modulates a laser beam and the modulated beam is optically Fourier transformed. A programmable optical notching filter spatially filters the electromagnetic interference noise from the transformed beam and the thus filtered beam is optically inverse Fourier transformed. A photo-combining of the filtered beam with a focused laser local oscillator beam down-converts the filtered beam to the original input signal minus electromagnetic interference.

Abstract: A method and apparatus for delivering constant water flow rates to the fire hose of a pumper truck at each of a plurality of selectable flow rate settings including the steps of transmitting a digital signal corresponding to a particular fire hose and pumper truck, receiving and decoding the digital signal, activating a multi-position valve in response to the decoded signal to set a particular valve position, and maintaining a constant flow rate to the fire hose by automatically varying the valve position in response to changes in the output pressure of the pump and pressure drop in the fire hose.